Charles Della Santina, M.D., Ph.D.

• Director, Johns Hopkins Listening Center (Cochlear Implant Program)
• Professor of Otolaryngology - Head and Neck Surgery

https://www.hopkinsmedicine.org/profiles/results/directory/profile/0009415/charles-della-santina

From a military perspective women's health lowell ma order 25mg clomid fast delivery, environmental health and environmental health related problems accounted for almost eighty percent of personnel losses during past conflicts in which the United States was involved pregnancy effacement buy clomid 100 mg free shipping. For the purposes of this chapter women's health center baytown discount clomid 50mg mastercard, environmental health encompasses the disciplines of preventive medicine menstrual pads buy genuine clomid line, sanitation and occupational health pregnancy test meme order clomid with visa. These "walk through" should be done in an informal manner but items requiring correction will be brought to the attention of the department head responsible for the berthing area pregnancy symptoms before missed period buy clomid 100 mg amex. Food consumption, with the exception of coffee and condiments, will be limited to messing areas and lounges. Coffee messes provide a potential food source for insects and rodents if they are not properly located and kept scrupulously clean. For these reasons, permission to establish a coffee mess must be obtained from the Commanding Officer by the department desiring to establish a mess prior to its establishment. Food contact areas (surrounding counter or table tops) must be non porous and kept free of spillage and food debris. Chlorine/Bromine residual testing will be performed before receiving any water onboard, and also about 30 minutes after an initial halogenation has been accomplished. A water log shall be kept and the results of the daily halogen testing recorded in it. Four test sites should be selected: forward, aft, amidships and as far above the 0-1 deck as possible. Lack of a residual or a residual reading that is significantly lower than results at the other locations indicate possible contamination. Systematic testing from areas with low residuals "backward" to areas with "average" residuals will help locate the source or general area of contamination. At least weekly, potable water samples for bacteriological analysis will be collected from two of the four test sites selected for halogen residual testing, as well as a sample collected directly from the potable water tanks. At least weekly, samples of ice must also be collected from any machines making ice used for human consumption and tested for bacteriological growth. The results of bacteriological testing will be entered into the Potable Water Quality Log. The need for sanitary and hygienic living and working spaces is essential for good health and morale of the crew. The fitness and exercise facility will be inspected for cleanliness and compliance with general sanitation standards on a schedule determined by the command. Dockside inspection of all food stores brought on board is a must if insects are to be excluded. Produce with "loose" husks or skin such as onions provide common harborage for roaches as does the corrugation of cardboard boxes. Careful inspection with a good light and adjuncts such as an aerosolized flushing agent can identify harborages from which cans and stores can be removed prior to their being brought aboard. Roach traps containing pheromones work well in areas with small or isolated infestations. Such personnel have been properly trained in pesticide selection, application, safety and handling precautions. Pesticide application may be available through Coast Guard Integrated Support Commands with attached Preventive Medicine Technicians. Any insect surveillance activity, general report of findings, or pesticide application, will be reported in the Health Services Log. Pest control services may also be contracted for from civilian pest control firms. The contractor must provide a report of pest control operations which includes, trade and chemical name of product used, strength and formulation applied, type of application (crack and crevice, etc. In general, such action consists of identifying infested or suspect lots, removing them from storage with other food stuffs with the potential to become infested, and application of pesticide to control flying insects. Underway, control is limited to identification of infested or suspect lots and their removal. Proper installation of rat guards is required on all mooring and service lines when the vessel is in port. The deraterization certificate must be renewed every 6 months, and must be included as a pre-deployment checklist item. It is not necessary to complete an "Accident Report" for any and all injuries unless command policy dictates otherwise. Each unit will have appointed a Hazardous Materials Control Officer with overall responsibility for carrying out the program. Safety glasses or goggles will be provided for all crewmembers involved in eye-hazardous tasks. Tools with strong potential for eye hazard will be identified with an adhesive warning label. Fixed machinery with eye hazard potential will have posted nearby an easily visible warning placard, and eye protection will be easily accessible and clearly visible. Eyewash stations will be located in any space or work area with strong potential for splashes to , or foreign body injury of the eye. Eyewash stations shall be flushed weekly for 15 seconds and flushed and drained according to the recommendations of the biostat ingredient manufacturer used in the station. Eyewash stations will be "tagged" with a maintenance record tag and inspection or maintenance activities will be recorded when performed. The person designated in writing as responsible for the pharmacy is accountable to the Chief, Health Services Division, or the executive officer for properly storing and dispensing drugs, record keeping, and maintaining a pharmacy policy and procedures manual. Through medical administration persons responsible for daily pharmacy operations shall request adequate funding to provide the level of pharmaceutical care required in Section 10. These minimum standards of qualifications must be documented in the training file of all pharmacy watchstanders. Pharmacy officer collateral duty oversight shall be provided for all clinics and sickbays that do not have pharmacy officers assigned. This formulary shall be standardized to provide a list of medications stocked in the therapeutic category format. These should be marked for a specific patient only and removed when the patient no longer requires them. Prescriptions by uniformed service physicians and dentists, other than Coast Guard, shall be honored when ever possible. Prescriptions by these providers shall be written on the prescription forms authorized by their service. Clinic formularies shall be established based on the Coast Guard Core Formulary and the prescribing habits of the providers assigned to that clinic. Items will not be maintained on the formulary primarily to meet civilian prescription demand. Military practitioners or contract providers shall not countersign civilian prescriptions nor shall civilian prescriptions be rewritten during cursory outpatient visits with the intent of authorizing the prescription for dispensing at the facility. Authorized prescribers shall not prescribe controlled medications for themselves and/or their family members. Prescriptions written by health services technicians shall be filled only at the facility were written. The prescriber must write and sign the prescription as soon afterwards as possible. Health Services Technicians shall not contact civilian prescribers to resolve prescription problems but return the problem prescription to the patient and explain why he or she cannot dispense it. Professional supervisors (pharmacy officers or senior medical officers) may authorize, via the Pharmacy Policy and Procedures Manual, pharmacy technicians to make telephone contact with civilian prescribers to resolve problems. All authorized telephone transactions will be clearly defined; those transactions not listed shall be unauthorized. If more than one member of a family is prescribed the same drug, a separate prescription blank must be used for each member. Items prescribed must treat conditions within the normal scope of professional practice and the ethics of the prescriber. Prescriptions for medications to treat cosmetic conditions (baldness, wrinkles, etc. Clinics shall ensure in-house prescriptions meet the requirements to use these items cost-effectively. The medical record thus becomes a more comprehensive repository for all patient health information and also ensures the pharmacy staff has access to the necessary clinical information (age, weight, allergies, lab values, vital signs, etc. In clinics that maintain dental records separately, the dental staff may use prescription forms. Under the "Plan" section list the drug name, strength, directions, quantity, and refills. A maintenance medication is defined as any medication used to treat a chronic condition. The term maintenance implies that a prescriber and patient have gone through a dosage titration process and have determined that the patient should be maintained on an effective dose of a medication that is well tolerated. Ultimately, the individuals in a position to make such a determination are the patient and the prescriber. If it is necessary to deviate from this amount, prescribe quantities in 30-day increments (30, 60, 90, etc. If pharmacy staff in consultation with the prescriber deem it advantageous to the patient due to travel, deployment, operational commitments, packaging, etc. The pharmacy need not maintain a health care record if the patient receives only basic pharmaceutical care from the facility. No prescription or order shall be filled unless it bears the signature of an individual authorized to write prescriptions. Pharmacy personnel shall maintain signature examples for in-house and contract prescribers. Professional judgment shall be used to verify authenticity of prescriptions from other sources. The pharmacy shall serve as the source of supply from which clinics or satellite activities normally obtain required pharmaceuticals and related supplies. In addition, the pharmacy dispenses required, authorized preparations directly to patients. If pharmacy staff receive an illegible prescription or question its authenticity, dosage, compatibility, or directions to the patient, staff shall obtain clarification from the prescriber before dispensing the medication(s). When dispensing medication, the dispenser shall identify the patient and ensure his or her eligibility. Use child-resistant containers to dispense all prescription legend medications except nitroglycerin, which is dispensed in the original container. The practitioner or patient may specifically request a conventional closure; a practitioner must so indicate on the prescription order. If the patient requests such a closure, enter a statement so saying on the back of the prescription; have the patient sign it. When refilling prescriptions, the pharmacy must ensure the safety closure still functions and the label is legible before dispensing in the original container. No prescription shall be refilled after more than one year from the date it was written. Coast Guard clinics are encouraged to establish non-prescription medication programs under the following guidelines: (1) Commanding Officer of Coast Guard units assigned health care personnel may elect to operate a nonprescription drug program. Condoms shall be made available to beneficiaries under 18 years of age unless specifically forbidden by law. Pharmacy and Therapeutics Committees (if available) and collateral duty pharmacy officers shall provide guidance and monitor any such extensions. Individuals suspected of this shall be referred to a medical officer and may have their access to this privilege denied. Local Pharmacy and Therapeutics Committees may develop supplemental information on sheets to provide additional dosage or drug information to the patient. Local flight surgeons, via the Pharmacy and Therapeutics Committee, shall determine which products may be acquired by personnel on flight status. This figure shall be separated from regular pharmacy workload statistics and not be counted as a prescription number. Only those items which have been dispensed by a written prescription shall be counted in the facility prescription number totals. I understand that the medication is for minor illness or conditions and that if symptoms worsen or persist longer than 48 hours, the person for whom this medication is intended should be seen by a health care provider. If on flight status, I understand that I am only authorized to receive over-the counter items approved by the flight surgeon. When the pharmacy is closed, a medical or dental officer, or a person so authorized, may dispense medication from a locked cabinet or locker containing pre-packaged or limited supplies of after-hours medications. These drugs are dispensed under the same procedures required when the pharmacy is open, including appropriate labeling and complete as an entry in the health record. Do not fill prescriptions from civilian prescribers from the after-hours locker except for emergency pain medications and/or antibiotics to treat acute infection. Bulk items for use in the clinic may be issued on authorized prescription forms or locally approved requisition forms. A sign shall be posted outside of the pharmacy in a highly visible location stating Please inform our pharmacy staff if you are breast feeding or may be pregnant.

Consistent with this finding is a report from a study of lung function among snuff industry workers in Nigeria women's health issues in australia effective clomid 25mg, which showed that chronic exposure to snuff dust was associated with impaired lung function which was worse depending on the length of 37 exposure in the industry menstrual 2 weeks early discount clomid online. Heavy snuff use among South African women has been associated with significantly increased blood 10 pressure to levels that increase the risk for cardiovascular diseases at a population level women's health center at baptist generic clomid 50 mg otc. A small study from 1992 in Nigeria also demonstrated that snuff use was associated with increased systolic and diastolic pressure womens health specialist yuma az discount clomid 25 mg online, although this effect was less pronounced when natron was not an ingredient in the 38 snuff mixture breast cancer apparel buy cheap clomid. A previous South African qualitative study found that as many as 36% of women snuff users who reported having made an attempt to quit had no success women's medical health issues discount clomid 25mg line, but about 67% of surveyed 20 users wished to quit, thus suggesting that snuff use is as difficult to quit as cigarette smoking. Another study among an elderly Nigerian population also reported that as many as 50% of those surveyed were 41 diagnosed with snuff tobacco dependence. Traditional or custom-made brands are more commonly used in rural areas, whereas 42 commercially manufactured brands are more common in urban areas. A private company, Bentchikou Tabacs Algerie, which accounts for the remaining market share, has gained ground since it entered the country in 2006 with its brands Naffa Africaine, Makla Ifriquia, and Makla Bouhlel (Figure 12-1). However, Bentchikou Tabacs Algerie, which imports its products 13 from its headquarters in Belgium, is steadily gaining market share in Algeria. The two leading premade manufactured brands in South Africa, Taxi and Ntsu, were largely under the control of two small local manufacturers until 1999, when Swedish Match bought out the company 43 that manufactures Taxi. Products used in Nigeria, similar to products used in the rest of Africa, are largely locally made by cottage industries, but limited numbers of premade manufactured brands are also available. The most commonly found imported brand is Medicated Snuff 99, manufactured by Joseph & H. Distribution In Algeria, news agents/tobacconists or kiosks remain the leading distribution channel, representing 67% of the sales volume in 2009. Tobacconists and kiosks are widely distributed across the country, 13 and they offer the largest stock range. They distribute both legal and illegal products, although illicit tobacco products may also be available from other street or local vendors. Smokeless tobacco products in South Africa are sold mostly by street vendors, local convenience stores, or at kiosks, where they are displayed together with cigarettes, candy, and confections. More recently, South African snuff brands manufactured by Philip Morris International have become available on an Internet snuff sales website based in the United Kingdom. Custom-made or traditional snuff products are sold from plastic buckets in open markets in South Africa and Nigeria and are dispensed in spoon-sized portions that are transferred to plastic bags, as requested by the customer. In Nigeria, it is also possible to request a mixture of local products and imported products. Smokeless Tobacco Use in the African Region Smokeless Tobacco Products Marketing Being primarily a cottage industry or custom-made product in this region, smokeless tobacco is not widely advertised. Larger industries such as British American Tobacco and Swedish Match attempted to introduce snus equivalents, particularly in South Africa, between 2001 and 2008, but have had limited 26,27 success. In this region, snus has also been promoted with health claims and for use in situations where smoking is not permitted (Figure 12-2), which may encourage dual use. Previously confidential industry documents suggest that additives or flavorings may be added to mask the poor quality of some products or to target certain population groups, as indicated by the following quotes related to snuff manufacture in Nigeria and South Africa, respectively: Many snuff formulations are flavoured with added levels or top dressing flavours. I suggest a menthol and peppermint flavoured version might be appropriate for the Nigerian market as a significant proportion of your cigarettes are mentholated. The added flavour may also help to cover some of the product deficiencies (sic) that a connoisseur of classic European snuff might find in a simple domestic product. Duncan, Nigerian Tobacco Company, July 3, 1985)45 One major point is that with our wet snuff there must be a noticeable ammonia nose to the product, all products have this distinct characteristic and [it] is sought after by the Black consumer in this country. Louw, British American Tobacco Company, October 12, 1987)46 368 Smokeless Tobacco and Public Health: A Global Perspective Figure 12-2. Snus information leaflets promoting situational use Note: these leaflets are available at points of sale in South Africa. However, as a result of limited Internet penetration, the introduction of payment cards, and inadequate delivery 13 systems, Internet sales do not exist in Algeria for any category of tobacco products. Summary and Conclusions 52 the Demographic and Health Survey conducted in many African countries provides an opportunity to study the prevalence and, in some instances, the health effects of these products. Smokeless tobacco products in the African Region are consumed in a variety of ways (sniffed, chewed, sucked, or applied to teeth and gums) and for a variety of reasons, including the perception that snuff has medicinal properties. With a few exceptions, most products available in the region are produced by small cottage industries and sold by local vendors. There are a few exceptions, but for the most part, premade manufactured products tend to have lower levels of tobacco-specific nitrosamines than custom-made products. Nasal snuff use is associated with increased risks of nasopharyngeal cancer and respiratory disease. Public education could include teaching local vendors and small-scale producers how to limit nitrosamine content through best practices in agronomics (such as by using N. Smokeless Tobacco Use in the African Region Smokeless Tobacco Products References 1. Geneva: World Health Organization, Framework Convention on Tobacco Control; [updated 2013 June 25] [cited 2013 Sep 25]. A systematic literature review of tobacco use among adults 15 years and older in sub-Saharan Africa. Trends in adult tobacco use from two South African Demographic and Health Surveys conducted in 1998 and 2003. Mineral profile of Ghanaian dried tobacco leaves and local snuff: a comparative study. Prevalence and determinants of snuff use among adult women in Mabopane, North-West Province [M. Smokeless tobacco products on the South African market do not inhibit oral bacterial flora: a pilot study. Smokeless tobacco use among adults in the Northern Province of South Africa: qualitative data from focus groups. Cannabis, tobacco and domestic fumes intake are associated with nasopharyngeal carcinoma in North Africa. The influence of maternal cigarette smoking, snuff use and passive smoking on pregnancy outcomes: the Birth to Ten Study. Tobacco use and secondhand smoke exposure during pregnancy in two African countries: Zambia and the Democratic Republic of the Congo. Association of snuff use with chronic bronchitis among South African women: implications for tobacco harm reduction. Effect of occupational exposure to local powdered tobacco (snuff) on pulmonary function in south eastern Nigerians. The effect of Nicotiana tabacum (snuff) on blood pressure and pulse rate of Nigerians. The pattern of psychiatric disorders among the aged in a selected community in Nigeria. Swedish Match acquires snuff and pipe tobacco company in South Africa [press release]. Swedish Match finalizes the sale of its South African operation to Philip Morris International and repurchases own shares [press release]. Regulations relating to the labelling, advertising, and sale of tobacco products (June 22, 1993). Prevalence of current cigarette smoking and tobacco use among women and men in developing countries. Smokeless Tobacco Use in the South-East Asia Region Smokeless Tobacco Products Tables, Figures, and Maps Table 13-1 Population and land area of countries of the South-East Asia Region. Six of them are geographically located in South Asia: India, Bangladesh, Nepal, Bhutan, Sri Lanka, and the Maldives. Four are located in South-East Asia: Thailand, Myanmar, Indonesia, and Timor-Leste. Five countries account for nearly 96% of the total population of the South-East Asia Region: India, Indonesia, Bangladesh, Thailand, and Myanmar (Table 13-1). Products may be as simple and inexpensive as unmanufactured, loose flakes of tobacco leaves that are sold by weight and may be chewed with only slaked lime (calcium hydroxide) paste, or as complex as a paste made from boiled tobacco and spice flavorings. A common way of consuming chewing tobacco in the region is as an ingredient in betel quid. Tobacco was added as an ingredient in the quid beginning around 1600, and it is now used in betel quid in many parts of South-East Asia. Betel quid is composed of pieces of areca nuts (from the Areca catechu palm), betel leaf from the Piper betle L. They are combined by vendors and users and made into fresh betel quids for immediate consumption. Historically, betel quid has been 10,11 incorrectly believed to have beneficial medicinal properties. The user who incorporates tobacco into 12 it may not consider tobacco a harmful addition. Smokeless tobacco products of different kinds with different names are often incorporated into betel quid, although some are also used separately. The most common type of tobacco incorporated into betel quid is plain tobacco flakes (also called sada pata); sometimes flavored tobacco flakes such as zarda or khaini may be added. Snuff-type products, which tend to be applied to gums or teeth rather than chewed, are not used with betel quid. Although areca nut itself is mildly addictive, a betel quid user may not 8 understand the much higher addictive potential of tobacco in the quid. The manufactured products were designed to be easily carried and consumed anywhere at any time, unlike betel quid, which is highly perishable and inconvenient to carry because of its high moisture content. In addition to being dried and packaged in single-use doses, these manufactured products contain preservatives to lengthen their shelf life. They may also contain other ingredients, such as small pieces of areca nut, calcium hydroxide, catechu, sweeteners, perfumes, tobacco flakes and/or powder, and flavorings such as menthol, cardamom, and clove. Gutka and pan masala products frequently carry the same brand names, allowing manufacturers to circumvent laws banning tobacco advertisements since they are able to advertise a product that appears identical to 6 tobacco-containing gutka. Smokeless Tobacco Use in the South-East Asia Region Smokeless Tobacco Products Map 13-1. Smokeless tobacco users aged 15 years and older in three countries in the South-East Asia Region (India, Bangladesh, and Myanmar) number close to 259 million. These findings demonstrate that the centuries-old practice of chewing betel quid with tobacco has become less prevalent than use of gutka, which is essentially a dry, commercially 8 manufactured version of betel quid developed in the late 1960s. Using betel quid with tobacco in India is still the most common practice in the Northeastern States and Odisha (formerly known as Orissa); elsewhere gutka has overtaken betel quid. The study found that prevalence of chewing betel quid with tobacco was comparatively high in central Nepal (men, 43. Data from the Myanmar Sentinel Prevalence Studies of Tobacco Use show that prevalence among men increased from 23. Definitive data on trends in most countries are unavailable, because successive surveys with the same methodology have not yet been conducted. Smokeless Tobacco Use in the South-East Asia Region Smokeless Tobacco Products Figure 13-1. Prevalence of current smokeless tobacco use among adults (15 years) in Myanmar, 2001, 2004, and 2007 Source: Ministry of Health (Myanmar) 2009 (31). Smokeless tobacco use among women is generally more common 33 than smoking, except in Nepal. In a cross-sectional study of women in a town in Nepal, 35 tobacco smokers were twice as likely as non-smokers to chew tobacco (p<0. In addition, the use of areca nut with tobacco introduces other harmful 8 constituents. Table 13-4 includes the nicotine and nitrosamine levels of several regional products, including gul powder, zarda, gutka (both commercially manufactured and cottage industry products), and khaini. Cancer Incidence of oral and pharyngeal cancers is high in the countries of this region compared to most of the 37 world. Estimated incidence rates for oral cancers (lip and oral cavity) for the countries of the region are shown in Table 13-5.

However women health center purchase 50mg clomid, analyses treating all non risks were noted as additional contributing factors women's health clinic minneapolis purchase clomid 50 mg with amex. This primarily single-sex studies involving exposure in adulthood menstrual quotes tumblr clomid 25 mg with amex, was done both to yield more stable risk estimates and be thus providing little information on the modifying effects of cause updated leukemia incidence data (which would allow these factors menopause 50 years old buy clomid mastercard. Several studies have confirmed the persistence distinctions by subtype) were not available breast cancer volleyball socks order 100 mg clomid fast delivery. Although there are a few esti due to the higher-quality diagnostic information compared mates from medical studies that seem incompatible with with that based on death certificates breast cancer 8mm in size cheap clomid online. The longer follow-up period and larger number of cancer deaths As discussed in Chapter 8, the most promising studies for and cases allowed more precise evaluation of risk and also direct assessment of risk at low doses and low dose rates are more reliable assessment of the long-term effects of radia those of nuclear workers who have been monitored for ra tion exposure. Esti and thyroid, several medically exposed groups offer quanti mates from these studies are summarized in Table 8-7. Two of the most important sources of uncer variables that might be typical of workers are shown. It tainty are (1) the possible reduction in risk for exposure at would be expected that the average age of exposure for work low doses and low dose rates. This made it possible to give much mates based on the assumption that the excess risk is inde Copyright National Academy of Sciences. Consideration of els were developed for mortality from leukemia, breast can additional sources of uncertainty would increase the width cer, respiratory cancer, digestive cancer, and all other can of these intervals. The model for breast cancer mortality was the committee also presents estimates for each of several based on both A-bomb survivor data and Canadian fluoros specific cancer sites and for other exposure scenarios, al copy patients. For many cancer sites, un thyroid cancer incidence, although no lifetime risk estimates certainty is very large, with subjective 95% confidence in based on these models were presented. The thyroid cancer incidence model was for various ages at exposure, for time since exposure, and for based on children in the Israel Tinea Capitis Study (Ron and the two sexes. Based on this approach, about 500 cancer linear extrapolation by a factor between 2 and 10 for doses deaths would be predicted from exposure of 0. Although a major objective in develop used was the excess lifetime risk, which excludes radiation ing these weighting factors was to estimate the detrimental induced deaths in persons who would have died from the effects of radiation exposures that deliver nonuniform doses same cause at a later time in the absence of radiation expo to various organs of the body, they can also be used to obtain sure. This is done by mul tality from leukemia and all cancers except leukemia ex tiplying these factors by the lifetime risk estimates for all pected to result from a single exposure to 0. Esti mated lifetime risks for several types of cancer using age mates of the number of excess deaths (with confidence inter specific risk coefficients from Japanese A-bomb survivors vals), the total years of life lost, and the average years of life (taken from Shimizu and others 1990). For the single exposure wanted its factors to be useful for a world population, sepa scenario, separate estimates were presented for leukemia, rate calculations were made for five reference countries (Ja breast cancer, respiratory cancer, digestive cancer, and other pan, United States, United Kingdom, Puerto Rico, and cancers, with each presented for both sexes and nine age-at China) and were based on three sets of assumptions for pro exposure groups. Final recommendations were based on results obtained tical uncertainties in its lifetime risk estimates for leukemia by averaging results over countries and over two of the mod Copyright National Academy of Sciences. Nuclear tion, excess risks for the first 5 years after exposure were Regulatory Commission (Gilbert 1991). Risk esti oped from data on Massachusetts fluoroscopy patients mates based on the following two models were presented: (Hrubec and others 1989) and New York postpartum mastitis patients (Shore and others 1986). Even though there was little evidence of heterogeneity Copyright National Academy of Sciences. Estimates based on both relative and absolute trans onset of such disease developed cancer as a result of these portation models were presented. Although these efforts were not directly ad assumed to be proportional to the baseline risk. No recom dressed at estimating lifetime risks, developing estimates of mendations were made as to which approach is preferred. Table 12A-1 summarizes lifetime risk Baseline risk + risk due to radiation exposure estimates from the reports discussed above. Estimates are based on linear models with no modification for low doses and low dose rates, although in some cases reduction by a factor of 2 or so was recommended. The first estimate is based on relative risk transportation; the second on absolute risk transportation. Exceptions were thyroid can better fit to the data than a model that allowed risks to vary cer, where models were based on a pooled analysis of data over the full range of exposure and attained ages [i. Nonmelanoma skin cancer risks were estimated tistically stable estimates at the extremes of the exposure from a special A-bomb survivor data set used by Ron and ages and attained ages. Models for leukemia were based on data the parameters, and were estimated from an analy from Preston and coworkers (1994). With this approach, the common val cific cancers that have not been clearly linked with radiation ues noted above were used unless there was evidence that exposure. The rationale for this was that the range of uncer the site-specific values differed significantly from these com tainty is of interest regardless of whether or not a statistically mon values. All leukemia mod estimated parameters, some of which were site-specific and els were based on a linear-quadratic function of dose, with some of which were common to several sites, was complex equal contributions of the linear and quadratic terms. The following uncertainty sources were in Copyright National Academy of Sciences. With the exception of dence intervals (95%) were usually calculated as the esti sampling variability, the uncertainty distributions for the in mate plus and minus 1. For dividual sources were based on informed but nevertheless estimates of linear coefficients of dose, these were calcu subjective judgments. Occasionally (as noted) confi dence intervals were calculated using the likelihood profile. The risk hort of atomic bomb survivors that were conducted to of radiation-induced cancer was modeled as described in the develop these models. Preston and colleagues (2004) note that it has not cline with increasing age at exposure. The material that follows describes analyses that dose, d, to the colon was used for the combined category of were conducted to evaluate several possible models for solid all solid cancers or all solid cancers excluding thyroid and cancer risks, including models that allow for dependence on nonmelanoma skin cancer. Analyses of mortality from individual organ sites (based on doses to these organs), and all solid cancers and from leukemia were based on deaths thus should not be subject to this bias. If the chosen model is not correct, then risks of solid cancers in the last decade have included a term estimated exposure age effects may be influenced by secular that allowed for such a decline. Further discussion and others 1994; Pierce and others 1996) emphasized models of secular trends and their influence on estimating the effects of the form of age at exposure can be found in Preston and colleagues (2003). Most medically exposed cohorts involve lim age-time patterns in A-bomb survivor cancer incidence data ited ranges of exposure age, and there is no medically ex and discusses difficulties in interpreting them. He also dis posed cohort that covers the full range of exposure ages from cusses a possible biological rationale for a model in which early childhood to old age. Table 12B-1B shows incidence data will allow for dependencies on both exposure the distribution of site-specific cancers by sex, with the num age and attained age. In particular, the parameter that quantifies the and Number of Deaths from Solid Cancer by Sex and dependence on attained age describes the strong increase in Colon Dose excess risk with this variable. Cancer Site Males Females Total Males Females Total Analyses of Incidence Data on All Solid Cancers Excluding Stomach 1,899 1,703 3,602 1,555 1,312 2,867 Thyroid and Nonmelanoma Skin Cancer and of Mortality Colon 547 618 1,165 206 272 478 Data on All Solid Cancers Liver 676 470 1,146 722 514 1,236 Lung 770 574 1,344 716 548 1,264 the analyses of cancer incidence data described in this Breast 7 847 854 3 272 275 section were based on the category of all solid cancers ex Prostate 281 0 281 104 0 104 cluding thyroid cancer and nonmelanoma skin cancer. These Ovary 0 190 190 0 136 136 exclusions were made primarily because both thyroid cancer Uterus 0 875 875 0 518 518 Bladder 227 125 352 83 67 150 and nonmelanoma skin cancer exhibit exceptionally strong Other solid 1,416 1,553 2,969 1,036 1,175 2,211 age dependencies that do not seem to be typical of cancers of Total 5,823 6,955 12,778 4,425 4,814 9,239 other sites (Thompson and others 1994). The function h includes parameters to thyroid cancer and nonmelanoma skin cancer and on mortal be estimated. The committee conducted a series of analyses of all solid cancers excluding thyroid cancer and h(e, a) = f(e) + g(a). Others (Kellerer and exposure, and attained age as described by Pierce and col Barclay 1992) have developed models with g(a) = a. In general, the greater the deviance difference, the better is the fit of the model. Thus, the simpler notation e* exposure age (or a function of exposure age) or only attained = e u30 is introduced. Of these choices, model 4 larly for the mortality data), whereas comparison with model resulted in the best fit (greatest deviance difference) for both 7 indicates that log (a) is a slightly better choice than log incidence and mortality data, although differences between (a) u50. However, the fits of models 1, 4, and 7 do not differ models 1 and 4 were not great. The model, which is as follows, spectively, models 8, 9, and 10) or that also included e30 (models 11, 12, and 13). That is, the fol positive, indicating an increase in risks for those exposed at lowing model was fitted: older ages. With mortality data, there was little indication that adding where j indexes the five age-at-exposure categories. The difference be Models 1B and 4B were comparable to models 1 and 4 tween the coefficients j for the two oldest age-at-exposure except that they were based on parametric modeling of the groups was statistically significant for the incidence data (p baseline risks. Again, model 4C (with e*) provides a somewhat better fit than does model 1C (with e). Model 1C is subsequently re degree-of-freedom test resulted in p-values that exceeded. Table 12-3) indicate that only about 3% of incident cancers the committee also evaluated mortality data on all solid are of these types. Furthermore, risks for stomach and liver cancers to compare the use of 5 and 10-year minimal latent cancers may be affected by infectious agents such as periods. Although the reason for the relatively high estimate for the later follow-up period (p =. Results are shown for a model in which all four of the cancer incidence and mortality, models for site-specific can parameters M, F, and were estimated and are also cers were based mainly on cancer incidence data. This was shown for a model in which the parameters quantifying the done primarily because site-specific cancer incidence data modifying effects of age of exposure and attained age and are based on diagnostic information that is more detailed and were set equal to the values obtained from analysis of the accurate than death certificate data and because, for several category all solid cancers excluding thyroid and non sites, the number of incident cases is considerably larger than melanoma skin cancers; these values are referred to subse the number of deaths. In ing p-value based on a two-degree-of-freedom test compar addition, mortality data may be more subject than incidence ing the fits of the two models. This test does not take account data to changes over time brought about because of improved of uncertainty in the estimates of the common values of survival. In addition, the committee fitted models in which just ever evaluated for consistency with mortality data. Since one of the parameters and was fixed, with the other esti there is little evidence that radiation-induced cancers are mated allowing a one-degree-of-freedom test for each of the more rapidly fatal than cancer that occurs for other reasons, parameters. For other solid cancers, a test for the parameter solid cancers excluding thyroid and nonmelanoma skin can alone resulted in a p-value of. This Column 8 is based on analyses in which all four of the pa model (labeled alternative 2) provided a significantly better rameters M, F, and were set equal to the values esti fit (p <. However, it was fitting four-parameter models for cancers of the prostate and of interest to compare these results with those obtained from uterus, these sites are not shown in Table 12B-4B. Only for models based on the same approach as most other cancer colon cancer and for all other solid cancers was there a sug sites. The last column of based on the incidence data, the committee chose to use the Table 12B-5D shows the deviance differences for models common values for this site. For all other solid cancers, the based on the mortality data and the alternative models shown alternative model developed from the incidence data was in Table 12B-5C.

In this situa tion menstruation cramps relief order clomid cheap, they may use case-finding to reach out to the population to identify additional individuals who are experiencing the health problem or illness menstruation 11 years old generic clomid 50 mg without a prescription. Level of evidence A number of studies identified in key points from evidence have a high evidence level (experimental and quasi-experimental studies) pregnancy pillows purchase clomid paypal. Outreach by community health workers Evidence supports the effectiveness of outreach conducted by community health workers breast cancer 7 cm tumor safe 25mg clomid. The role of the community health worker has emerged in response to eco nomic pressures and health care reform measures (Kauer women's health center hershey pa order clomid from india, 2016) menstrual hemorrhaging symptoms order clomid 25mg without a prescription. Barriers related to mammography use for breast cancer screening among minority women. Physical activity in the park: A randomized controlled trail using community engagement. Effect of a mailed brochure on appointment-keeping for screening colonoscopy: A randomized trial. Identifying new strategies to assess and promote online health communication and social media outreach: An application in bullying prevention. A comparison of African American and Latina social networks as indicators for culturally tailoring a breast and cervical cancer education intervention. Medicaid savings resulted when community health workers matches those with needs to home and community care. The novella approach to inform women living on low income about early breast cancer detection. Breast cancer screening among Vietnamese Americans: A randomized controlled trial of lay health worker outreach. Screening aims to: 1) detect health risks and disease to reduce adverse consequences, transmission of disease, and suffering, and 2) improve prevention and treatment out comes (World Health Organization, 2013). Three types of screening exist: Mass: Screening the general population for a single risk or multiple health risks at community events or locations, such as health fairs at work sites or health appraisal surveys at county fairs (community level). Examples include breast and cervical cancer screening among age-appropriate women, well child screening, and the follow along associated with early childhood development programs (individual/family level). Problem: Children exposed to environmental lead exhibit neurotoxic effects, including learning and behavior problems, lower intelligence, slowed growth and development, hearing and speech problems, and anemia. Because the water treatment did not include a chemical corrosion-inhibiting compound, lead leached into the water supply from plumbing. Higher rates of elevated blood levels occurred in socially disadvantaged neighborhoods with older homes (Hanna-Attisha, LaChance, Sadler, & Schnepp, 2016; Hanna-Attisha, 2017; Maqsood, Stanbury, & Miller, 2017). Michigan State University and the Hurley Medical Center in Flint launched the Pediatric Public Health Initiative to mitigate the effects of the Flint water crisis. Community level the Michigan Department of Health and Human Services offers a Lead Safe Home Program that provides lead testing and hazard control services to qualifying families through grants. The Michigan Department of Community Health created a Finding a Healthy Home checklist, which assists families in screening a potential new home for safety. Public health nurses offer these resources when they screen families with young children for lead toxicity. Relationship with other interventions Social marketing and outreach interventions frequently occur prior to the screening intervention, especially with regard to the mass screening intervention. Referral and follow-up interventions often occur for those requiring further assessment of risk or symptoms. Basic steps the following steps are adapted from the World Health Organization (2013): 1. Assess the situation Before initiating screening, determine the health risk or disease threat to population health and whether interventions exist to follow up on screening results. Determine previous screening activities and results in the population, including cost-effectiveness and outcomes. Identify relevant groups for partnership (organizations providing health services, supportive community leaders, and providers and health workers who conduct the screening and follow-up treatment services). Referral of individuals with positive results to treatment, monitoring, and support 3. Prioritize risk groups Screening population groups with the highest risk effectively identifies individuals most likely to benefit: a. Prioritize risk groups in each setting: Assess potential benefits and harms, acceptability of screening approach, number needed to screen, and cost-effectiveness. Screening algorithms identify the steps in the process and communicates the process (for an example of developmental screening, see Figure 1). Algorithm selection depends on the risk group, health risk or disease prevalence, resource availability, and plan feasibility. Evidence to consider when selecting a screening tool (Adam & Hilfinger, 2016): Reliability: What is the consistency of the screening tool in obtaining accu rate results When selecting a screening approach, identify strategies to ensure: Consent Mitigation of potential stigma or negative social consequences Communication of relevance Incentives 5. Plan, budget, and implement Ensure adequate resources, including funding and personnel for implementation. Criteria for evaluating screening strategies (Dans, Asuncion, & Silvestre, 2011, p. Identification of available resources for implementation, including funding, hu man resources, and feasible interventions and treatment d. Hiring and training staff for identified roles Outreach and/or contact investigations Data entry, management, monitoring, and analysis Program management, coordination, and problem solving. Monitor and evaluate Evaluate the effectiveness of the screening approach and determine changes needed for future screening activities. Conduct an outcomes analysis; use mathematical modelling to estimate the im pact on the incidence and prevalence of the health risk or disease in the targeted community. Assess the situation In April 2014, the city of Flint, Michigan changes its water supply to the Flint River while waiting for a new pipeline from Lake Huron. After the switch, city residents report concerns about water color, taste, and odor, and negative effects on health, such as skin rashes. Due to lack of a corrosion inhibitor and the high percentage of lead pipes and plumbing in the water distribution system, the chemical makeup of the Flint River water contribute to lead leaching into the drinking water. Although researchers from Virginia Tech University report increases in water lead levels, the impact on blood lead levels remains unknown. Develop the program Staff analyze differences in pediatric elevated blood lead level incidence before and after Flint. Prioritize risk groups the highest risk group included children under 5 years of age living within the city of Flint receiving water from the city. Children living outside the city with an unchanged water source provided a comparison group. The laboratory tests for blood lead level uses a venous or capillary blood sample. Capillary blood tests may produce false positive results; confirmation of elevated capillary blood tests occurs with a venous blood test. Plan, budget, and implement Screeners communicate the lead testing status of children to Medicaid managed care plans, who use the data to contact providers not compliant with Medicaid lead screening requirements. Local health departments conduct follow-up with Medicaid fee-for-service providers not in compliance with the Medicaid screening require ments. Local health departments receive a weekly update of blood tests, indicating venous or capillary. Monitor and evaluate Key recommendations to improve the lead poisoning screening strategy: Improve the completeness, accuracy, and timeliness of the surveillance system by implementing a modernized data management system and automating the process of receiving and compiling reports from laboratories. Principles and guidelines for effective health screening In 1968, the World Health Organization published of principles/guidelines for effec tive health screening: the condition should be an important health problem that carries with it notable morbidity and mortality. Successful screening programs A successful screening program is: Valid (accurate) Reliable (precise) Capable of large-group administration Minimally invasive Worth the effort and expense Ethical and effective (meets public health goal, benefits outweigh possible harms) Simple, rapid, inexpensive, safe, and acceptable Level 5 sources: Adams & Hilfinger, 2016 Friss & Sellers, 2014 3. Asking the right questions Questions to ask when planning a screening program: Is the health problem important to the individual and community Considering ethical issues Ethical issues to consider when conducting screening: Preventing harm: Does the risk of screening offset the benefits Using standardized screening instruments A systematic review on developmental screening in children under 5 years old admin istered primarily by nurses, found that training nurses to use standardized instru ments contributed to an acceptable level of reliability and improved screening effi ciency. When limited screening is appropriate Experts determined that adopting a population-based screening program for asthma is not recommended, given a lack of evidence of improvement in health outcomes. Limited screening may be appropriate in areas with a high prevalence of undiagnosed asthma and where identified clients have access to high quality asthma care. The au thors recommended applying World Health Organization criteria for assessing screening programs to decision-making about asthma screening. When screening is harmful Based on a systematic review the United States Preventive Services Task Force con cluded that the harms of screening adolescents for idiopathic scoliosis exceed poten tial benefits. Most cases detected during screening are not clinically significant, those who need aggressive treatment are likely to be detected without screening, and po tential harms include unnecessary brace wear and referral for specialty care. Screening for abuse Using domestic abuse screening tools increases violence disclosure rates and safety planning. Screening tool strengths include the presence of an opening statement about the prevalence and impact of abuse (provides justification for the screening), screening for all types of abuse, and non-judgmental and sensitive questions. Safe guards included: a) accurate and reliable equipment, b) staff training, c) follow-up resources, d) parent notification of results, and e) providing referrals. Implications for school nursing practice include: be familiar with safeguards; communicate importance of safeguards to school administrators; participate in train ing on the safeguards; and collaborate with other school staff, other schools, and community partnerships to share safeguard equipment and costs. Level 3 sources: Sliwa, Brener, Lundeen, & Lee, 2018 Stalter, Chaudry, & Polivka, 2010 10. Review current evidence and determine cost effectiveness and harm versus benefit. In the past, school nurses offered scoliosis screening; current evidence does not support scoliosis screening because of the high rate of false positives and follow-up expense (United States Preventive Services Task Force, 2014). Preventing harm: Cultural/racial factors Consider ethical concerns when conducting screening: preventing harm, self-deter mination, confidentiality, and equity. Knowledge about cultural differences and experi ence promotes ethical screening actions. For example, a medical provider unfamiliar with Mongolian spots (variations in skin pigment in babies of African, Asian, Indian, or Mediterranean descent) may interpret them as bruises related to possible child abuse. Be fore initiating screening activities, ensure that referral and follow-up options exist. Referral and follow-up options also contribute to the ability to evaluate the effective ness of the prevention/treatment in decreasing the health risk or severity of disease. Trade-off between benefit and harm is crucial in health screening recommendations. Elevated blood lead levels in children associated with the Flint drinking water crisis: A spatial analysis of risk and public health response. Mental health screening at school: Instrumentation, implementation, and critical issues. Archived Final Recommendation Statement: Idiopathic Scoliosis in Adolescents: Screening. Maternal child home visiting program improves nursing practice for screening of woman abuse. Case-finding is a one-to-one intervention operating only at the individual/family level. Case-finding serves as the individual/family level of intervention for surveillance, dis ease and health event investigation, outreach, and screening. In an editorial in the American Journal of Nursing, Kennedy (2016) stated: [Case-finding] falls within the purview of all nurses. All of us, wherever we work and live, must be alert for patterns of illness and be proactive in bringing them to light (p. A follow-up investigation revealed an anencephalic birth rate four times the national average. The fol low-up investigation led to identifying a new illness related to pig brain proteins released into the air during meat processing. Recommending testing for Zika infection contributes to identifying and reporting possible outbreaks, which can lead to implementing control measures. Case-finding from outreach A rural street nurse provided outreach in British Columbia to a marginalized popu lation. Settings included schools, a drop-in center, a mall, a youth center, and the street. Case-finding, as the individual/family practice level of surveil lance, disease and health event investigation, outreach, and screening, often leads to referral and follow-up. Identify individuals and families at risk through information from surveillance, disease and health event investigation, and/or outreach Effective case-finding occurs when targeting at-risk populations. Risk severity increases with factors that make individuals and families unaware, una ble, or unwilling to respond: a. Unaware of risk: Lacking information or understanding of the risk Isolated from media b. Unable to respond: Unable to receive or understand the message, due to illiteracy, hearing and vision impairments, or cognitive impairment Non-English-speaking or other language barriers Contrasting cultural beliefs Lacking resources, such as financial resources, transportation, child care, or social skills c. Unwilling to respond, fearing that negative consequences exceed benefits: Fear of deportation Unable to afford out-of-pocket costs 2. Connect with formal and informal networks to find those identified as at-risk this strategy helps identify the at-risk target population. If the level of risk suggests endangerment to the individual, family, or community, provide direct access to necessary services the risk of potential harm requires intervention to prevent that harm, which supports the ethical principles of prevention, not causing harm, and promoting good.

The prioritization of water quality interventions should focus on those aspects that are estimated to contribute more than breast cancer 49er hats cheap clomid 100 mg fast delivery. In many parts of the world menstrual gingivitis order cheap clomid on line, the implementation of a water quality intervention that results in an estimated health gain of more than 5% would 134 7 breast cancer 85 clomid 100 mg free shipping. Where a specied quantied disease reduction is identied as a health outcome target women's health issues in the 19th century order discount clomid online, it may be advisable to undertake ongoing proactive public health surveillance among representative communities rather than through passive surveillance women's health issues in politics buy 25mg clomid amex. This requires an understanding of the quality of source water and the efficacy of control measures menstruation 21 days cycle cheap 25 mg clomid with mastercard. Validation is important both in ensuring that treatment will achieve the desired goals (performance targets) and in assessing areas in which efficacy may be improved. In surface waters, potential pathogen sources include point sources, such as munic ipal sewerage and urban stormwater overows, as well as non-point sources, such as contaminated runoff from agricultural areas and areas with sanitation through on site septic systems and latrines. Other sources are wildlife and direct access of live stock to surface water bodies. Many pathogens in surface water bodies will reduce in concentration due to dilution, settling and die-off due to environmental effects (thermal, sunlight, predation, etc. Groundwater is often less vulnerable to the immediate inuence of contamination sources due to the barrier effects provided by the overlying soil and its unsaturated zone. Groundwater contamination is more frequent where these protective barriers are breached, allowing direct contamination. This may occur through contaminated or abandoned wells or underground pollution sources, such as latrines and sewer lines. However, a number of studies have demonstrated pathogens and indicator organisms in groundwater, even at depth in the absence of such hazardous circum stances, especially where surface contamination is intense, as with land application of manures or other faecal impacts from intensive animal husbandry. Impacts of these contamination sources can be greatly reduced by, for example, aquifer protection measures and proper well design and construction. For more detailed discussion on both pathogen sources and key factors determin ing their fate, refer to the supporting documents Protecting Surface Waters for Health and Protecting Groundwaters for Health (section 1. High values have been presented because they repre sent higher-risk situations and, therefore, greater degrees of vulnerability. The table includes two categories of data for rivers and streams: one for impacted sources and one for less impacted sources. More detailed information about these data is published in a variety of references, including several papers cited in Dangendorf et al. However, there are a number of limitations and sources of uncertainty in these data, including: 136 7. While the table provides an indication of concentrations that might be present in water sources, by far the most accurate way of determining pathogen loads and con centrations in specic catchments and other water sources is by analysing water quality over a period of time, taking care to include consideration of seasonal varia tion and peak events such as storms. More typically, water treatment is required to remove or destroy pathogenic microorganisms. This is because it is generally the case that treatment efficacy for microbial reduction differs among these microbial groups due to the inherently different properties of the microbes. Such differences do occur, however, and the table pres ents conservative estimates of microbial reductions based on the more resistant or persistent pathogenic members of that microbial group. Where differences in removal by treatment between specic members of a microbial group are great, the results for the individual microbes are presented separately in the table. Non-piped water supplies such as roof catchments (rainwater harvesting) and water collected from wells or springs may often be contaminated with pathogens. Many of the processes used for water treatment in households are the same as those used for community-managed and other piped water supplies (Table 7. The performance of these treatment processes at the household level is likely to be similar to that for baseline removal of microbes, as shown in Table 7. However, there are additional water treatment technologies recommended for use in non-piped water supplies at the household level that typically are not used for piped supplies. Further information about these water treatment processes, their operations and their performance for pathogen reduction is provided in more detail in supporting documents (for piped water supplies: Water Treatment and Pathogen Control;for non-piped [primarily household] water supplies: Managing Water in the Home;see section 1. Certain pathogenic bac teria are also able to multiply in food or beverages, thereby perpetuating or even increasing the chances of infection. Faecal indicator bacteria should full certain criteria to give meaningful results. They should be universally present in high numbers in the faeces of humans and other warm-blooded animals, should be readily detectable by simple methods and should not grow in natural water. In the majority of cases, monitoring for indicator bacteria provides a high degree of safety because of their large numbers in polluted waters. Pathogens more resistant to conventional environmental conditions or treatment technologies may be present in treated drinking-water in the absence of E. Ret rospective studies of waterborne disease outbreaks and advances in the understand ing of the behaviour of pathogens in water have shown that continued reliance on assumptions surrounding the absence or presence of E. Protozoa and some enteroviruses are more resistant to many disinfectants, includ ing chlorine, and may remain viable (and pathogenic) in drinking-water following disinfection. Other organisms may be more appropriate indicators of persistent microbial hazards, and their selection as additional indicators should be evaluated in relation to local circumstances and scientic understanding. Therefore, verication may require analysis of a range of organisms, such as intestinal enterococci, (spores of) Clostridium perfringens and bacteriophages. Total coliform bacteria are not acceptable indicators of the sanitary quality of water supplies,particularly in tropical areas,where many bacteria of no sanitary signicance occur in almost all untreated supplies. Especially under these conditions,medium-term targets for the progressive improvement of water supplies should be set. A consequence of variable susceptibility to pathogens is that exposure to drinking water of a particular quality may lead to different health effects in different popula tions. For guideline derivation, it is necessary to dene reference populations or, in some cases, to focus on specic sensitive subgroups. National or local authorities may wish to apply specic characteristics of their populations in deriving national standards. Because the growth medium and the conditions of incubation, as well as the nature and age of the water sample, can inuence the species isolated and the count, microbiological examinations may have variable accuracy. This means that the standardization of methods and of laboratory procedures is of great importance if criteria for the microbial quality of water are to be uniform in different laboratories and internationally. International standard methods should be evaluated under local circumstances before being adopted. It is desirable that established standard methods be used for routine examinations. Typically, changes in water quality occur progressively, except for those substances that are discharged or leach intermittently to owing surface waters or groundwater supplies from, for example, contaminated landll sites. In some cases, control of chloro form levels and, where appropriate, trichloroacetic acid levels will also provide an adequate measure of control over other chlorination by-products. Several of the inorganic elements for which guideline values have been recom mended are recognized to be essential elements in human nutrition. No attempt has been made here at this time to dene a minimum desirable concentration of such substances in drinking-water. For those contaminants for which a guideline value has been established, the fact sheets include a brief toxicological overview of the chemical, the basis for guideline derivation, treatment achievability and analytical limit of detection. However, this is only a very small proportion of the chemicals that may reach drinking-water from various sources. The substances considered here have been assessed for possible health effects, and guideline values have been proposed only on the basis of health concerns. Some substances other chemicals not addressed will be of health concern have effects on the absent. For such substances, health-based guideline values are needed, for instance, for use in interpreting data collected in response to consumer complaints. This may lead to national standards that differ apprecia bly from these Guidelines. The probability that any particular chemical may occur in signicant concentra tions in any particular setting must be assessed on a case-by-case basis. The presence of certain chemicals may already be known within a particular country, but others may be more difficult to assess. In most countries, whether developing or industrialized, water sector profession als are likely to be aware of a number of chemicals that are present in signicant con centrations in drinking-water supplies. A body of local knowledge that has been built up by practical experience over a period of time is invaluable. Hence, the presence of a limited number of chemical contaminants in drinking-water is usually already known in many countries and in many local systems. Signicant problems, even crises, can occur, however, when chemicals posing high health risk are widespread but their presence is unknown because their long-term health effect is caused by chronic expo sure as opposed to acute exposure. Such has been the case of arsenic in groundwater in Bangladesh and West Bengal, for example. For some contaminants, there will be exposure from sources other than drinking water, and this may need to be taken into account when setting standards and con sidering the need for standards. In some cases, drinking-water will be a minor source of exposure, and controlling levels in water will have little impact on overall exposure. In other cases, controlling a contaminant in water may be the most cost-effective way of reducing exposure. Drinking-water monitoring strategies, therefore, should not be considered in isolation from other potential routes of exposure to chemicals in the environment. This information is important in helping to modify guideline values to suit national requirements or in assessing the signicance for health of concentrations of a con taminant that are greater than the guideline value. This aids in the development of approaches that are designed to prevent or minimize con tamination, rather than those that rely primarily on the measurement of contaminant levels in nal waters. In general, approaches to the management of chemical hazards in drinking-water vary between those where the source water is a signicant contributor (with control effected, for example, through source water selection, pollution control, treatment or blending) and those from materials and chemicals used in the production and distri bution of drinking-water (controlled by process optimization or product specica tion). In these Guidelines, chemicals are therefore divided into six major source groups, as shown in Table 8. The group of naturally occurring contami nants,for example,includes many inorganic chemicals that are found in drinking-water as a consequence of release from rocks and soils by rainfall, some of which may become problematical where there is environmental disturbance, such as in mining areas. A guideline value normally represents the concentration of a constituent that does not result in any signicant risk to health over a lifetime of consumption. A number of provisional guideline values have been established at concentrations that are reason ably achievable through practical treatment approaches or in analytical laboratories; in these cases, the guideline value is above the concentration that would normally represent the calculated health-based value. Guideline values are also designated as provisional when there is a high degree of uncertainty in the toxicology and health data (see also section 8. There are two principal sources of information on health effects resulting from exposure to chemicals that can be used in deriving guideline values. However, the value of such studies for many substances is limited, owing to lack of quantitative information on the concen tration to which people have been exposed or on simultaneous exposure to other agents. However, for some substances, such studies are the primary basis on which guideline values are developed. The second and most frequently used source of infor mation is toxicity studies using laboratory animals. The limitations of toxicology studies include the relatively small number of animals used and the relatively high doses administered, which create uncertainty as to the relevance of particular nd ings to human health. This is because there is a need to extrapolate the results from animals to humans and to the low doses to which human populations are usually exposed. In most cases, the study used to derive the guideline value is supported by a range of other studies, including human data, and these are also considered in carry ing out a health risk assessment. In order to derive a guideline value to protect human health, it is necessary to select the most suitable study or studies. Expert judgement was exercised in the selection of the most appropriate study from the range of infor mation available. On the other hand, there are carcinogens that are capable of producing tumours in animals or humans without exerting a geno toxic activity, but acting through an indirect mechanism. It is generally believed that a demonstrable threshold dose exists for non-genotoxic carcinogens. In deriving guideline values for carcinogens, consideration was given to the potential mechanism(s) by which the substance may cause cancer, in order to decide whether a threshold or non-threshold approach should be used (see sections 8. The evaluation of the potential carcinogenicity of chemical substances is usually based on long-term animal studies. Sometimes data are available on carcinogenicity in humans, mostly from occupational exposure. For chemical contaminants, which usually have no intended function in drinking-water, the term tolerable daily intake is more appropriate than acceptable daily intake, as it signies permissibility rather than acceptability. The derivation of these factors requires expert judgement and careful consideration of the available scientic evidence. This comprises two 10-fold factors, one for interspecies differences and one for interindividual variabil ity in humans (see Table 8. Extra uncertainty factors may be incorporated to allow for database deciencies and for the severity and irreversibility of effects. Factors lower than 10 were used, for example, for interspecies variation when humans are known to be less sensitive than the animal species studied. For substances for which the uncertainty factors were greater than 1000, guideline values are designated as provisional in order to emphasize the higher level of uncer tainty inherent in these values. A high uncertainty factor indicates that the guideline value may be considerably lower than the concentration at which health effects would actually occur in a real human population.

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