Noninfectious And Noncommunicable Diseases And Conditions Associated With The Water Environment

Background

The terms noncommunicable and noninfectious are used interchangeably. The noncommunicable diseases are the major causes of death in developed areas of the world, whereas the communicable diseases are the major causes of death in the developing areas of the world. The major noncommunicable disease deaths in the United States in 1988 were due to diseases of the heart, malignant neoplasms, cerebrovascular diseases, accidents, atheriosclerosis, diabetes mellitus, and chronic liver disease and cirrhosis (accounting for 73 percent of all deaths). An analysis of mortality due to noncommunicable diseases in five subregions of the Americas in 1980 showed 75 percent of the total mortality attributed to noncommunicable diseases in North America (United States and Canada); 60 percent in Temperate South American countries (Argentina, Chile, and Uruguay); 57 percent in the Caribbean area (including Cuba, the Dominican Republic, and Haiti); 45 percent in Tropical South America (including the Andean countries, Brazil, French Guiana, Guyana, Paraguay, and Suriname); and 28 percent in Continental Middle America (Central America, Mexico, and Panama).117 The mortality can be expected to shift more to noncommunicable causes in the developing countries as social and economic conditions improve and communicable diseases are brought under control. Major diseases of developing countries are gastrointestinal, schistosomiasis, malaria, trachoma, and malnutrition.

Treatment of the environment supplements treatment of the individual but requires more effort and knowledge. The total environment is the most important determinant of health. A review of more than 10 years of research conducted in Buffalo, New York, showed that the overall death rate for people living in heavily polluted areas was twice as high, and the death rates for tuberculosis and stomach cancer three times as high, as the rates in less polluted areas.118 Rene Dubos points out that "many of man's medical problems have their origin in the biological and mental adaptive responses that allowed him earlier in life to cope with environmental threats. All too often, the wisdom of the body is a shortsighted wisdom."119

Whereas microbiological causes of most communicable diseases are known and are under control or being brought under control in many parts of the world (with some possible exceptions such as malaria and schistosomiasis), the physiologic and toxicologic effects on human health of the presence or absence of certain chemicals in air, water, and food in trace amounts have not yet been clearly demonstrated. The cumulative body burden of all deleterious substances, especially organic and inorganic chemicals, gaining access to the body must be examined both individually and in combination. The synergistic, additive, and neutralizing effects must be learned in order that the most effective preventive measures may be applied. As noted earlier, chemicals contributed to 12 percent of drinking water outbreaks during the period 1971 to 2002, which is greater than the fraction attributed to viruses.18 Some elements, such as fluorine for the control of tooth decay, iodine to control goiter, and iron to control iron deficiency anemia, have been recognized as being beneficial in proper amounts. But the action of trace amounts ingested individually and in combination of the pollutants shown in Figure 1.3 and other inorganic and organic chemicals is often insidious. Their probable carcinogenic, mutagenic, and teratogenic effects are extended in time, perhaps for 10, 20, or 30 years, to the point where direct causal relationships with

Pollutant

Aldehydes Aldrin/Dieldrin

Arsenic Asbestos Benzene Benzidine Benzo-a-pyrene Beryllium Cadmium Calcium Chromate Carbon monoxide DDT Lead

Nickel carbonyl Oxidants

Oxides of nitrogen Particulates Silica Sulfates Sulfur oxides Vinyl chloride

FIGURE 1.3 Known or suspected links between selected pollutants and disease. (Source: First Annual Report by the Task Force on Environmental Cancer and Heart and Lung Disease, Printing Management Office, U.S. Environmental Protection Agency, Washington, DC, August 7, 1978.)

morbidity and mortality are difficult, if not impossible, to conclusively prove in view of the many possible intervening and confusing factors.

There are an estimated 2 million recognized chemical compounds and more than 60,000 chemical substances in past or present commercial uses. Approximately 600 to 700 new chemicals are introduced each year, but only about 15,000 have been animal tested with published reports. Limited trained personnel and laboratory facilities for carcinogenesis testing in the United States by government and industry will permit testing of no more than 500 chemicals per year. Each animal experiment requires 3 to 6 years and a cost of more than $300,000.120 Another estimate is $500,000 just to establish the carcinogenicity of one compound with the National Cancer Institute test protocol, requiring at least two species of rodents and 3 years' time.121 A full toxicologic test, including those for carcinogenicity, can take five years and cost in excess of $1.25 million for

FIGURE 1.3 Known or suspected links between selected pollutants and disease. (Source: First Annual Report by the Task Force on Environmental Cancer and Heart and Lung Disease, Printing Management Office, U.S. Environmental Protection Agency, Washington, DC, August 7, 1978.)

each compound. The chemicals are viewed by Harmison122 as falling into four groups: (1) halogenated hydrocarbons and other organics, (2) heavy metals, (3) nonmetallic inorganics, and (4) biological contaminants, animal and human drugs, and food additives.

In group 1 may be polychlorinated biphenyls (PCBs); chlorinated organic pesticides such as DDT, Kepone, Mirex, and endrin; polybrominated biphenyls (PBBs); fluorocarbons; chloroform; and vinyl chloride. These chemicals are persistent, often bioaccumulate in food organisms, and may in small quantities cause cancer, nervous disorders, kidney and brain damage, and toxic reactions. A recently recognized undesirable role for pharmaceuticals, herbicides, and pesticides in natural waterways is as endocrine disruptors.123 The extraordinary production and use of these compounds, coupled with their persistence through wastewater treatment processes, has resulted in long residence times of such materials in the environment. Aquatic life have been impacted through the ability of endocrine disruptor-active compounds to mimic hormonal control of reproductive systems, organ development, and sensory functions. There is concern that contaminants falling into the category of endocrine disruptors may exist in finished drinking waters. The route by which herbicides and pesticides may gain entry to natural waters is through agricultural runoff. PCBs are no longer manufactured, but their residues are still present in aquatic sediments and the tissues of aquatic vertebrates and invertebrates. Other chlorinated compounds may appear in soils and waters from leaking storage drums, uncontained industrial lagoons, and accidental landfill leachates.

Another group of nine chlorinated compounds that may appear in drinking water as a consequence of the use of chlorine as a post water treatment disinfectant is the haloacetic acids or disinfection byproducts (DBP). Trihalomethanes are a subset of the haloacetic acids that are regarded as the major carcinogens among DBP in relation to colon and rectal cancers124 and reproductive disorders including spontaneous abortions, fetal deaths, miscarriages, and birth defects.119 Precursors to the formation of DBP are naturally occurring organic molecules present in raw water supplies. Unlike the plethora of organic substances referred to in the AP report, DBP are regulated in the drinking water standards. However, only five of the nine DPB compounds are monitored.

Group 2 includes heavy metals such as lead, mercury, cadmium, barium, nickel, vanadium, selenium, beryllium. These metals do not degrade; they are very toxic and may build up in exposed vegetation, animals, fish, and shellfish. Some of them (e.g., lead, mercury, cadmium, and beryllium) have no role in human metabolism and are inhibitors of enzymes at very low concentrations. As poisons, they can affect the functions of various organs (e.g., kidney, liver, brain) and damage the central nervous system, cardiovascular system, and gastrointestinal tract. Children and pregnant women are especially vulnerable. The levels of heavy metals in drinking water are highly regulated. Heavy metals variably appear in many manufactured products, including metal goods and electronic devices, as well as naturally occurring minerals and coal deposits. Hence, there is ample opportunity for contamination of natural waters through runoff from insecure toxic waste containment sites, improper disposal and storage, and anthropogenic discharges such as power plant emissions.

Group 3 represents nonmetallic inorganics such as arsenic (metalloid) and asbestos, which are carcinogens.

Group 4 includes biological contaminants such as aflatoxins and pathogenic microorganisms; animal and human drugs such as diethylstilbestrol (DES) and other synthetic hormones; and food additives such as red dye No. 2. An Associated Press report released March 9, 2008 (available at http://www. metrowestdailynews.com/homepage/x1574803402), outlined the appearance of antibiotics, hormonal preparations, personal care chemicals, antidepressants, cholesterol control and cardiovascular medications, and pain relievers in ultra-small concentrations (ppb and ppt) in drinking-water samples from 24 of 28 metropolitan areas of the United States. All of these chemical substances are undetectable by the human senses.

Evaluation of the toxicity of existing and new chemicals on workers, users, and the environment and their release for use represent a monumental task, as already noted. Monitoring the total effect of a chemical pollutant on humans requires environmental monitoring and medical surveillance to determine exposure and the amount absorbed by the body. The sophisticated analytical equipment available can detect chemical contaminants in the parts-per-billion or parts-per-trillion range. Mere detection does not mean that the chemical substance is automatically toxic or hazardous. But detection does alert the observer to trends and the possible need for preventive measures. Short-term testing of chemicals, such as the microbial Ames test, is valuable to screen inexpensively for carcinogens and mutagens. The Ames test determines the mutagenic potential of a chemical based on the mutation rate of bacteria that are exposed to the chemical. However, positive results suggest the need for further testing, and negative results do not establish the safety of the agent. Other tests use mammalian cell cultures and cell transformation to determine mutagenicity.

Prevention and Control

Prevention of the major causes of death, such as diseases of the heart, malignant neoplasms, cerebrovascular disease, accidents, and other noninfectious chronic and degenerative diseases, should now receive high priority. Prevention calls for control of the source, mode of transmission, and/or susceptibles as appropriate and as noted in Figure 1.1.

The prevention and control of environmental pollutants generally involves the following three procedures:

1. Eliminate or control of the pollutant at the source. Minimize or prevent production and sale; substitute nontoxic or less toxic chemical; materials and process control and changes; recover and reuse; waste treatment, separation, concentration, incineration, detoxification, and neutralization.

2. Intercept the travel or transmission of the pollutant. Control air and water pollution and prevent leachate travel.

3. Protect humans by eliminating or minimizing the effects of the pollutant. This affects water treatment, air conditioning, land-use planning, and occupational protection.

At the same time, the air, sources of drinking water, food, aquatic plants, fish and other wildlife, surface runoff, leachates, precipitation, surface waters, and humans should be monitored. This should be done for potentially toxic and deleterious chemicals, as indicated by specific situations. Table 1.4 also lists characteristics of noninfectious diseases due to the ingestion of poisonous plants and animals and chemical poisons in contaminated water or food.

INVESTIGATION OF A WATER DISEASE OUTBREAK General

The successful outcome in the investigation of any disease outbreak, no matter the source, depends on expedient execution of a preplanned process. Extensive investigations are economically burdensome to all parties involved, and the target of the study (e.g., a municipal water supply) in the end is faced with a public-relations problem in winning back the confidence of the community concerning the safety of the drinking water.

Hunter125 delineated a nine-step "cradle to grave" program for the conduct of a waterborne outbreak study (Figure 1.4).

Each of the steps in the chronology of an investigation is elaborated on in the following sections. Although investigation of a waterborne incident is described here, the steps put forth would be applicable to a foodborne outbreak, also. Details on foodborne outbreaks are presented in Chapter 3.

Preparation Requisite to the investigation of an elevated incidence of disease, there must be in place a team of individuals having the collective expertise to handle all phases of the study. Ideally, this would include an epidemiologist, field engineer, preferably trained in matters of public health, and assistants. Each of the individuals must have an assigned role to play in the team effort to characterize an outbreak and provide suggestions to solve the problem. Responsible leadership, typically under direction of an epidemiologist, must be established in order to monitor and coordinate team activities and seek approval of the plan from pertinent pubic officials.

Detection The first stage of a potential outbreak event is the unusual level of sick individuals in the population requiring medical attention within a short time frame. Similarity in patient symptoms and results of laboratory examinations of specimens may provide preliminary evidence of the possibility of an outbreak. However, it is imperative that prompt reporting of laboratory data to public health authorities take place in order that there be an evaluation and dispensing of information to appropriate individuals to confirm the existence of an outbreak.

Flow Diagram The Lotus Outbreak 1997
FIGURE 1.4 Flow diagram depicting the incremental steps in the investigation of a waterborne outbreak. Source: P. R. Hunter, Waterborne Disease-Epidemiology and Ecology, John Wiley & Sons, New York, 1997.

Hunter125 cautions that many variables contribute to the inefficiency of identifying the existence of a waterborne disease, including difficulty in assembling patient data, proper diagnosis and laboratory testing for etiologic agents of prospective diseases, and underestimates of the number of afflicted people. For these and other reasons, much time and effort can be lost between the onset of illness in the population and the resolution of an outbreak.

Confirmation A redoubling of the effort on the part of authorities to substantiate from all information received that, indeed, an outbreak has occurred. This will involve a review of physician and laboratory records and ensuring that proper reporting of data to public health bureaus has taken place.

Description Upon confirmation that an outbreak has occurred, the investigating team should be activated and initial steps undertaken. It is not a simple matter to quickly determine the cause of illness due to water, food, or other vehicle, but a preliminary study of the symptoms, incubation periods, food and water consumed, housing, bathing area, and sanitary conditions may provide early clues and form a basis for formulating a quick response control action.

What is to be considered an outbreak case? The answer will require a preliminary set of parameters with which to define the case (e.g., limits of time regarding onset of the illness, symptoms of the illness, geographical boundaries of the affected area, and microbiological description of the disease etiology). The more rigid the definitions of parameters, the more likely it is that fewer cases will qualify for inclusion in the outbreak. However, parameter definitions should be flexible in relation to the availability of new information over time.

Following agreement on definition of a case, quantitative accounting of the number of cases involved is in order. Reliability of physician diagnoses and the collection of completed questionnaires of the type presented in Figure 1.5 are important. The information gathered from questionnaires contributes to the medical survey. If it appears that the number of completed questionnaires is insufficient, similar kinds of information can be collected and tabulated in the field when assistance is available. The tabulation horizontal headings would include the following seven categories:

1. Names of persons served food and/or water;

4. Day and time ill;

5. Incubation period in hours (time between consumption of ingestibles and first signs of illness);

6. Foods and water served at suspected meals—previous 12 to 72 hours (foods eaten are checked)

7. Symptoms—nausea, vomiting, diarrhea, blood in stool, fever, thirst, constipation, stomach ache, sweating, sore throat, headache, dizziness, cough, chills, pain in chest, weakness, cramps, other

Other analyses may include a summary of persons showing a particular symptom such as vomiting, diarrhea, and nausea, as shown in Figure 1.5, or those using a specific facility for calculation of incidence rates. For complete investigation details, consult references as appropriate.126129

A common method of determining the probable offending water is a tabulation as shown in Figure 1.6, which is made from the illness questionnaire provided in Figure 1.5 or similar version. Comparison of the attack rates for each water will usually implicate or absolve a particular water. The water implicated is that showing the highest percentage difference between those who ate the specified water and became ill and those who did not eat the specified water and

Please answer the questions below to the best of your ability. This information is desired by the health department to determine the cause of the recent sickness and to prevent its recurrence. Leave this sheet, after you have completed it, at the desk on your way out. (If mailed, enclose self-addressed and stamped envelope and request return of completed questionnarie as soon as possible.)

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