Neurologic symptoms in licensed pesticide applicators in the Agricultural Health Study

Abstract

Exposure to high levels of many pesticides has both acute and long-term neurologic consequences, but little is known about the neurotoxicity of chronic exposure to moderate pesticide levels. We analysed cross-sectional data from 18 782 Caucasian, male, licensed pesticide applicators, enrolled in the Agricultural Health Study from 1993 to 1997. Applicators provided information on lifetime pesticide use, and 23 neurologic symptoms typically associated with pesticide intoxication. Increased risk of experiencing ≥10 symptoms during the year before enrollment was associated with cumulative pesticide use, personally mixing or applying pesticides, pesticide-related medical care, diagnosed pesticide poisoning, and events involving high personal pesticide exposure. Greatest risk was associated with use of organophosphate and organochlorine insecticides. Results were similar after stratification by pesticide use during the year before enrollment, or exclusion of applicators with a history of pesticide poisoning, or high-exposure events. Use of pesticide application methods likely to involve high personal exposure was associated with greater risk. Groups of symptoms reflecting several neurologic domains, including affect, cognition, autonomic and motor function, and vision, were also associated with pesticide exposure. These results suggest that neurologic symptoms are associated with cumulative exposure to moderate levels of organophosphate and organochlorine insecticides, regardless of recent exposure or history of poisoning.

Keywords

insecticides neurologic symptoms organochlorine insecticides organophosphate insecticides pesticides pesticide applicators

References

US EPA Office of Pesticide Programs . FY 2002 annual report, 2002. Retrieved 14 June 2005, from http://www.epa.gov/oppfead1/annual/2002/2002annualreport.pdf

Ecobichon DJ . Toxic effects of pesticides. In Klaassen DC , Amdur MO , Doull J eds. Casarett and Doull's toxicology: the basic science of poisons. McGraw-Hill, 1996: 643-689.

Keifer M , Mahurin R . Chronic neurologic effects of pesticide overexposure. Occup Med 1997; 12: 291-304.

Kamel F , Hoppin JA . Association of pesticide exposure with neurologic dysfunction and disease. Environ Health Perspect 2004; 112: 950-958.

Savage E et al. Chronic neurological sequelae of acute organophosphate pesticide poisoning. Arch Environ Health 1988; 43: 38-45.

Wesseling C , Keifer M , Al A , McConnell R , Moon JD , Rosenstock L , Hogsted C . Long-term neurobehavioral effects of mild poisonings with organophosphate and n-methyl carbamate pesticides among banana workers. Int J Occup Environ Health 2002; 8: 27-34.

Moser VC . Animal models of chronic pesticide neurotoxicity. Hum Exp Toxicol, in review.

Alavanja MCR , Sandler DP , McMaster SB , Zahm SH , Mc Donnell CJ , Lynch CF , Pennybacker M , Rothman N , Dosemeci M , Bond AE , Blair A . The Agricultural Health Study. Environ Health Perspect 1996; 104: 362-369.

Alavanja MC et al. Characteristics of pesticide use in a pesticide applicator cohort: the Agricultural Health Study. Environ Res 1999; 80: 172-179.

10.

Kamel F et al. Neurologic symptoms in licensed private pesticide applicators in the Agricultural Health Study. Environ Health Perspect 2005; 113: 877-882.

11.

Tarone RE et al. The Agricultural Health Study: factors affecting completion and return of self-administered questionnaires in a large prospective cohort study of pesticide applicators. Am J Ind Med 1997; 31: 233-242.

12.

Lundberg I , Hogberg M , Michelsen H , Nise G , Hogstedt C . Evaluation of the Q16 questionnaire on neurotoxic symptoms and a review of its use. Occup Environ Med 1997; 54: 343-350.

13.

London L , Nell V , Thompson M , Myers J . Effects of long-term organophosphate exposures on neurological symptoms, vibration sense and tremor among South African farm workers. Scand J Work Environ Health 1998; 24: 18-29.

14.

Gomes J , Lloyd O , Revitt MD , Basha M . Morbidity among farm workers in a desert country in relation to long-term exposure to pesticides. Scand J Work Environ Health 1998; 24: 213-219.

15.

Bazylewicz-Walczak B , Majczakowa W , Szymczak M . Behavioral effects of occupational exposure to organophosphorous pesticides in female greenhouse planting workers. Neurotoxicology 1999; 20: 819-826.

16.

Steenland K et al. Neurologic function among termiticide applicators exposed to chlorpyrifos. Environ Health Perspect 2000; 108: 293-300.

17.

Ohayo-Mitoko GJ et al. Self reported symptoms and inhibition of acetylcholinesterase activity among Kenyan agricultural workers. Occup Environ Med 2000; 57: 195-200.

18.

Pilkington A et al. An epidemiological study of the relations between exposure to organophosphate pesticides and indices of chronic peripheral neuropathy and neuropsychological abnormalities in sheep farmers and dippers. Occup Environ Med 2001; 58: 702-710.

19.

Smit L . Neurologic symptoms among Sri Lankan farmers occupationally exposed to acetylcholinesterase-inhibiting insecticides. 2003; 44: 254-264.

20.

Strong LL , Thompson B , Coronado GD , Griffith WC , Vigoren EM , Islas I . Health symptoms and exposure to organophosphate pesticides in farmworkers. Am J Ind Med 2004; 46: 599-606.

21.

Leng G , Lewalter J . Role of individual susceptibility in risk assessment of pesticides. Occup Environ Med 1999; 56: 449-453.

22.

Ciesielski S , Loomis DP , Mims SR , Auer A . Pesticide exposures, cholinesterase depression, and symptoms among North Carolina Migrant Farmworkers. Am J Publ Health 1994; 84: 446-451.

23.

Lee BW , London L , Paulauskis J , Myers J , Christiani DC . Association between human paraoxonase gene polymorphism and chronic symptoms in pesticide exposed workers. J Occup Environ Med 2003; 45: 118-122.

24.

van Wendel de Joode B et al. Chronic nervous-system effects of long-term occupational exposure to DDT. Lancet 2001; 357: 1014-1016.

25.

Anger W et al. Neurobehavioral evaluation of soil and structural fumigators using methyl bromide and sulfuryl fluoride. Neurotoxicology 1986; 7: 137-156.

26.

Ames R et al. Chronic neurologic sequelae to cholinesterase inhibition among agricultural pesticide applicators. Arch Environ Health 1995; 50: 440-444.

27.

Fiedler N , Kipen H , Kelly-McNeil K , Fenske R . Long-term use of organophosphates and neuropsychological performance. Am J Ind Med 1997; 32: 487-496.

28.

van der Hoek JA , Verberk MM , Hageman G . Criteria for solvent-induced chronic toxic encephalopathy: a systematic review. Int Arch Occup Environ Health 2000; 73: 362-368.

29.

Blair A et al. Reliability of reporting on life-style and agricultural factors by a sample of participants in the Agricultural Health Study from Iowa. Epidemiology 2002; 13: 94-99.

30.

Hoppin JA , Yucel F , Dosemeci M , Sandler DP . Accuracy of self-reported pesticide use duration information from licensed pesticide applicators in the Agricultural Health Study. J Expo Anal Environ Epidemiol 2002; 12: 313-318.