Neuropsychological and psychiatric functioning in sheep farmers exposed to low levels of organophosphate pesticides.
The study aim was to determine whether low level exposure to organophosphate pesticides (OPs) causes neuropsychological or psychiatric impairment. Methodological weaknesses of earlier studies were addressed by: recruiting participants who had retired on ill health grounds; excluding participants with a history of acute poisoning, medical or psychiatric conditions that might account for ill health; and exploring factors which may render some individuals more vulnerable to the effects of OPs than others. Performance on tests of cognition and mood of 127 exposed sheep farmers (67 working, 60 retired) was compared with 78 unexposed controls (38 working, 40 retired) and published test norms derived from a cross section of several thousand adults in the general population. Over 40% of the exposed cohort reported clinically significant levels of anxiety and depression compared to less than 23% of controls. Exposed subjects performed significantly worse than controls and standardisation samples on tests of memory, response speed, fine motor control, mental flexibility and strategy making, even after controlling for the effects of mood. The pattern was similar for both working and retired groups. The cognitive deficits identified cannot be attributed to mood disorder, malingering, a history of acute exposure or genetic vulnerability in terms of PON1(192) polymorphisms. Results suggest a relationship may exist between low level exposure to organophosphates and impaired neurobehavioural functioning and these findings have implications for working practice and for other occupational groups exposed to OPs such as aviation workers and Gulf War veterans.
Research Department of Clinical, Educational and Health Psychology, University College London, Gower Street, London WC1E 6BT, United Kingdom. s.mackenzie-ross@ucl.ac.uk
Sarah Jane
SJ
Mackenzie Ross
Chris Ray
CR
Brewin
Helen Valerie
HV
Curran
Clement Eugene
CE
Furlong
Kelly Michelle
KM
Abraham-Smith
Virginia
V
Harrison
D000382:Agricultural Workers' Diseases / Q000139:chemically induced* / Q000235:genetics / Q000523:psychology*; D001007:Anxiety / Q000139:chemically induced*; D043303:Aryldialkylphosphatase / Q000235:genetics; D003071:Cognition / Q000187:drug effects; D003863:Depression / Q000139:chemically induced*; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects*; D010755:Organophosphates / Q000633:toxicity*; D010575:Pesticides / Q000009:adverse effects*; D011110:Polymorphism, Genetic; D011597:Psychomotor Performance / Q000187:drug effects
D010755:Organophosphates; D010575:Pesticides; D043303:Aryldialkylphosphatase; C468406:PON1 protein, human