Neuropsychiatric symptoms in past users of sheep dip and other pesticides

Christine Solomon ¹, Jason Poole ¹, Keith T. Palmer ², Robert Peveler ³ and David Coggon ^1*

¹ MRC Epidemiology Resource Centre, United Kingdom
² MRC Epidemiology Resource Centre, United Kingdom
³ Community Clinical Sciences, United Kingdom

^* To whom correspondence should be addressed. E-mail: dnc{at}mrc.soton.ac.uk.

Accepted 5 October 2006

Abstract

Objectives: To explore the prevalence and pattern of neuropsychiatric symptoms in past users of sheep dip and other pesticides. Methods: From a postal survey of men born between 1933 and 1977 and resident in three rural areas of England and Wales (response rate 31%), we obtained data on lifetime history of work with pesticides; neurological symptoms in the past month; current mental health; and tendency to be troubled by non-neurological somatic symptoms (summarised as a somatising tendency score). Risk factors for current neuropsychiatric symptoms were assessed by modified Cox regression. Results: Data were available for 9,844 men, including 1,913 who had worked with sheep dip, 832 with other insecticides but not sheep dip, and 990 with other pesticides but never with sheep dip or insecticides. Neurological symptoms were consistently more common in past users of sheep dip than in men who had never worked with pesticides (crude prevalence ratios (PRs) 1.2 to 1.6), but their prevalence was also elevated in men who had worked only with pesticides other than sheep dip or insecticides. They clustered strongly within individuals, but this clustering was not specific to men who had worked with sheep dip. Report of 3+ neurological symptoms was associated with somatising tendency (PR 15.0, 95%CI 11.4-19.5 for the highest v the lowest category of somatisation), and was more common in users of sheep dip (PR 1.3, 95%CI 1.0-1.6), other insecticides (PR 1.4, 95%CI 1.0-1.8) and other pesticides (PR 1.3, 95%CI 1.0-1.7) than in non-users. Among users of sheep dip, prevalence was higher in men who had dipped most often, but not in those who had worked with concentrate. Past use of pesticides was not associated with current anxiety or depression. Conclusion: Neurological symptoms are more common in men who have worked with sheep dip, but the association is not specific to sheep dip or insecticides. A toxic cause for the excess cannot be ruled out, but several features of our observations suggest that psychological mechanisms have a role.

Keywords: chronic toxicity, neuropsychiatric, organophosphates, pesticides, sheep dip

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• Solomon, C., Poole, J., Palmer, K. T., Peveler, R., Coggon, D. (2007). Acute symptoms following work with pesticides. Occup Med (Lond) 0: kqm066v1- [Abstract] [Full Text]