An Investigation into Neurologic and Neurobehavioral Effects of Long-Term Agrichemical Use among Deciduous Fruit Farm Workers in the Western Cape, South Africa 1,2 L. London,* J. E. Myers,* V. Nell,† T. Taylor,‡ and M. L. Thompson§ *Occupational Health Research Unit, Department of Community Health, and §Department of Statistical Sciences, University of Cape Town, Cape Town, South Africa; †Health Psychology Unit, University of South Africa, Pretoria, South Africa; and ‡Human Sciences Research Council, Johannesburg, South Africa Received March 5, 1996 Long-term exposure to organophosphates (OPs) in the absence of acute poisoning is increasingly suspected of causing chronic neurologic and neuro- behavioral effects. A cross-sectional survey of 163 spray operators on deciduous fruit farms in the Western Cape, South Africa, and 84 nonspraying labororers was conducted in 1993 to investigate the relationship between long-term OP exposures and neurological and neurobehavioral outcomes. The study also sought to evaluate the performance of a set of neurobehavioral test batteries based on the information-processing theory of cognitive psychol- ogy, relative to the more established World Health Organization’s Neurobehavioral Core Test Battery (WHO NCTB). These information-processing tests were designed for use in studies of subjects with little education, which are frequently conducted in developing countries in agriculture. They draw on experience from a previous South African study in which problems were encountered with a lack of cross-cultural validity of conventional test batter- ies. No evidence was found of a relationship be- tween long-term OP exposure and loss of vibration sense. Small associations were found with the NCTB Pursuit-Aiming and Santa Ana (nondominant hand) subtests. The overall evidence of neurologic and neurobehavioral effects of long-term OP expo- sure was small; exposure misclassification may have contributed to this finding. Important con- founders such as brain injury, alcohol consumption, and nutritional status were identified. © 1997 Academic Press INTRODUCTION Increasingly, agrichemical exposure has been rec- ognized as a possible cause of adverse, chronic, hu- man health effects, particularly related to central nervous system function (Savage et al., 1988; U.S. Office of Technology Assessment, 1990; Davies, 1990a; Rosenstock et al., 1991). For example, it has been shown that a number of organophosphates (OPs) can cause a delayed peripheral neuropathy in survivors of acute poisoning (Hierons and Johnson, 1978; Senanyake and Johnson, 1982; Vasilescu et al., 1984; Lotti, 1992). Adverse, chronic, central ner- vous system effects also might be detected in sub- jects years after acute OP poisoning (Savage et al., 1988; Rosenstock et al., 1991). However, much of this evidence stems from stud- ies about the effects of acute intoxication (that is, short-term, high-dose exposures). Few data exist on the chronic effects of long-term, low-dose agrichemi- cal exposures in the absence of acute poisoning. Such data would have substantial public health im- 1 This study was supported by research grants from the Inter- national Development Research Centre (IDRC-Canada), the South African Medical Research Council, the Ernst and Ethel Erikson Trust, and the Guy Elliot Research Fellowship in the Department of Medicine at the University of Cape Town. 2 This study was conducted in accordance with the Declaration of Helsinki of the 25th World Medical Assembly and the guide- lines established by the South African Medical Research Council. Ethical approval for the protocol was obtained from the Ethics and Research Committee of the University of Cape Town. All workers who participated in the study did so on the basis of in- formed consent, given in writing after full explanation of the pur- pose and methods of the investigation. Consent was transacted in Afrikaans, the first language of the subjects. Full confidentiality was observed for the subjects. Only when appropriate (for ex- ample, if blood chemistry was found to be low) were the usual medical attendants of the workers informed of the need for re- testing or for withdrawal from any additional pesticide exposure. Follow-up of affected workers was provided through tertiary hos- pital facilities. ENVIRONMENTAL RESEARCH 73, 132–145 (1997) ARTICLE NO. ER973715 132 0013-9351/97 $25.00 Copyright © 1997 by Academic Press All rights of reproduction in any form reserved.