Document Yj2Bk1kJzzKdJQa5g6vXj5zMN

Occupational Exposure to Pesticides by M olly Joel Coye, M D , M P H ^ -- 1 1) The symptoms are almost always non-specific, meaning 14W hy hasn't my physician told me more about the pesticide that they could be caused by many different chemicals, by an hazards 1 am facing?" influenza or cold, by physical exhaustion or even psycholog * "Why is s/he reluctant to diagnose my illness as pesticide-related ical stress. Mild organophosphate exposure may only produce when it seems at least an obvious possibility?" headache, fatigue, weakness, nausea and sweating, all those These are questions frequently asked by workers when being classic signs of a beginning bout of flu. Dermatitis they first learn about the possible hazards they face from ex caused by a pesticide could easily be diagnosed as a reaction posure to pesticides on their job. One answer is that their to a soap or plant at home rather than a pesticide in the work physician may not have been trained to investigate occupa place. Medical students learn to "look for the zebras" (i.e. tional exposure as a cause of illness. y think of exotic explanations for common findings) while they In a 1979 survey of U.S. medical schools, 70% o f the are in school, but everyday practice in the real world teaches responding schools indicated they required no formal instruc must physicians that "if it looks like a horse, it probably is not tion in occupational or environmental medicine. Among the a zebra." In other words, if there is a logical, common expla- L30% that did require such instruction, the median time re nation, for a set of symptoms, why try to dig up another ex- quired was four hours during the four years of medical educa planatiun? __ _ - tion. In a repeat survey conducted in 1964, 54% of the 2) In most cases if will not be easy for the physician to "prove" schools included such instruction, but the median time re the diagnosis. Making a diagnosis means both a) quired was still four hours (Levy 1985). demonstrating the probability that a certain agent (e g. a Acute, Severe Poisoning pesticide) caused the illness, and b) ruling out other causes What most physicians know about pesticide toxicity is ' (e g. demonstrating that the patient doesn't have the flu or a limited to the specific signs of acute, severe poisonings. Some cold). Since many illnesses like a cold or flu can't be con chemicals produce characteristic physiologic changes which clusively ruled out in most situations, diagnosis depends upon make diagnosis easier, but almost ail of these signs and symp toms occur only after a substantial exposure. In cases of direct making a strong case for the probability that pesticides caused the illness. exposure to large amounts of a pesticide (e.g. following a Biological testing for pesticides in the blood or urine is spill, accidental ingestion, or direct spray by a helicopter), relatively difficult and very expensive (the usual method is some effects will be so specific that they suggest the diagnosis gas chromatography and it may cost several hundred dollars of pesticide poisoning. per test), and not very helpful in low-level exposures. Ex Not very many categories of pesticides have specific posure to organophosphate or carbamate compounds is "signs," however, and even these signals may be misinter measured by the activity of the enzyme cholinesterase in preted if the link to pesticide exposure is not made. For exam blood. The interpretation of this test is difficult in mild or pie, a sign of moderately severe organophosphate or car moderate exposures, however, because there is a wide range bamate poisoning is miosis, or pin-point pupils. If pesticide exposure is not mentioned by the patient or by the person who brings the patient to the emergency room or clinic, of variation in enzyme activity between individuals. A mild effect in one person is almost impossible to detect without a baseline measurement for that person prior to the exposure most physicians would initially suspect narcotics abuse because it is the most common reason for this finding in a pa tient. When pesticide exposure is mentioned, and the symp toms are severe, many nurses and physicians will recognize the presenting symptoms as signs of pesticide poisoning or will make use of a poison control center and other resources to investigate the pqgsibili^.2 Lgeshcide poisoning. for comparison. As a result, a physician who says "1 think this patient has a headache and nausea because she worked on a railcar that was shipping pesticides" has no way of demon strating why that patient didn't just have a mild case of flu. 3) In some cases the exposure occurred a long time before the onset o f symptoms, or the symptoms have existed for a while before the patient realizes that a past exposure might have caused them. Chronic, Low-level Poisoning Again, unless there is some symptom or finding which clearly Acute severe poisonings are relatively rare, however, in demonstrates the link with the pesticide exposure in the past comparison with low-level pesticide exposures at work or in (for example, a peripheral neuropathy developing several home and garden use. The effects of low-level exposure are . weeks after exposure to certain organophosphates), this is dif- much more difficult to diagnose, for a number of reasons: f ficult to diagnose. Even the most sympathetic physician, one very interested in pursuing occupational etiologies (causes), M olly Coye has served the last five years as M edical Investigative has a tough time defending a diagnosis in cases like this. Officer for the National Institute o f Occupational Safety and 4) Vi nj little research has been done on the clinical toxicology of Health (N IO SH ) in San Francisco. This month she-has begun a pesticides, and even less is published in medical journals and texts. new job as Public Health Advisor to New Jersey's Governor When a physician is puzzled by a clinical situation, she or he Kean. l turns first to textbooks in the office. If a case is very unusual NCAP NEWS / SPRING 195 5