Assessment of certain hematological responses of factory workers exposed to pesticides

Plasma 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) levels and immune response

For determination of whether plasma 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) pesticide levels (< or =1-32 ppb) are associated with immune suppression or DNA damage in lymphocytes, 302 individuals residing in Moore County, North Carolina, in 1994-1996 provided a blood specimen, underwent a skin test, and answered a questionnaire concerning factors affecting plasma organochlorine pesticide levels and the immune system. The blood specimens were analyzed for levels of plasma DDE (a metabolite of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane), numbers and types of blood cells, immunoglobulin levels, mitogen-induced lymphoproliferative activity, and lymphocyte micronuclei. When DDE levels were categorized as 1 or less, more than 1 to 2, more than 2 to 4.3, more than 4.3 to 7.6, and more than 7.6 ppb, individuals with higher plasma DDE levels had lowered mitogen-induced lymphoproliferative activity (concanavalin A, range: 74,218 dropping to 55,880 counts per minute, p = 0.03) and modestly increased total lymphocytes (range: 2.0-2.3 x 10(3)/microl, p = 0.05) and immunoglobulin A levels (range: 210-252 mg/dl, p = 0.04). There were no consistent differences in response to the skin tests by plasma DDE levels. Plasma DDE levels were not associated with a higher frequency of micronuclei. The authors conclude that relatively low levels of plasma DDE are associated with statistically significant changes in immune markers, although the magnitude of the effects are of uncertain clinical importance.

Effects on the immune system associated with living near a pesticide dump site

In this paper, we report results of the second phase of a larger study designed to evaluate the effects on the immune system of living near a Superfund site containing organochlorine pesticides, volatile organic compounds, and metals. Phase II was conducted to determine whether living near the site, consisting of six locations in Aberdeen, North Carolina, is associated with higher plasma organochlorine levels, immune suppression, or DNA damage. Each of 302 residents of Aberdeen and neighboring communities provided a blood specimen, underwent a skin test, and answered a questionnaire. Blood specimens were analyzed for organochlorine pesticides, immune markers, and micronuclei. Of 20 organochlorines tested, only DDE was detected in the blood of participants (except for one individual). Age-adjusted mean plasma DDE levels were 4.05 ppb for Aberdeen residents and 2.95 ppb (p = 0.01) for residents of neighboring communities. Residents of 40-59 years of age who lived within a mile of any site, but particularly the Farm Chemicals site, had higher plasma DDE levels than residents who lived farther away. Residents who lived near the Farm Chemicals site before versus after 1985 also had higher plasma DDE levels. Overall, there were few differences in immune markers between residents of Aberdeen and the neighboring communities. However, residents who lived closer to the dump sites had statistically significantly lower mitogen-induced lymphoproliferative activity than residents who lived farther away (p < 0.05). Residential location was not consistently associated with frequency of micronuclei or skin test responses. Although some statistically significant differences in immune markers were noted in association with residential location, the magnitude of effects are of uncertain clinical importance.

Self reported symptoms and inhibition of acetylcholinesterase activity among Kenyan agricultural workers

OBJECTIVES

This study was part of the East African pesticides project. The general objective was to assess health hazards posed by handling, storage, and use of pesticides, on agricultural estates and small farms with a view to developing strategies for prevention and control of pesticide poisoning. The aim of this paper is to describe the prevalence of symptoms in this population, to relate levels of inhibition to reported symptoms and evaluate at which levels of inhibition symptoms become increased.

METHODS

Complete data were available for 256 exposed subjects and 152 controls from four regions in Kenya. A structured questionnaire on symptoms experienced at the time of interview was given to all subjects and controls. Information was also obtained on sex, age, main occupation, and level of education. Symptoms reported during the high exposure period, were initially clustered in broader symptom categories from reference literature on health effects of pesticides that inhibit cholinesterase (organophosphate and carbamate). Prevalence ratios were estimated for symptoms with changes in cholinesterase activity in serum.

RESULTS

Symptom prevalence in exposed subjects was higher during the high exposure period than the low exposure period, although these differences were not significant. Interestingly, a clear and significant change in symptoms prevalence was found in the controls with a higher prevalence in the low exposure period. Analysis of the relation between cholinesterase inhibition and symptoms showed that prevalence ratios were significantly > 1 for respiratory, eye, and central nervous system symptoms for workers with > 30% inhibition. Similar results were found for analyses with the actual level of acetylcholinesterase activity.

CONCLUSION

The results suggest the presence of a relation between exposure and acetylcholinesterase inhibition, acetylcholinesterase activity, and respiratory, eye, and central nervous system symptoms. Increased symptom prevalence was found at acetylcholinesterase activities generally considered to be non-adverse.