Chronic Fatigue and Organophosphate Pesticides in Sheep Farming: A Retrospective Study Amongst People Reporting to a UK Pharmacovigilance Scheme

Abstract

The Department of Health has recently published a report from the CFS/ME Working Group which concluded that chronic fatigue syndrome (CFS) should be recognized as a chronic illness. Symptoms consistent with CFS are often reported by people who consider their health has been affected by exposure to pesticides, but the Working Group concluded that this type of exposure is not a common trigger for the syndrome. The Veterinary Medicines Directorate (VMD) collects self-assessed reports of ill health in humans associated with veterinary medicines under their Suspected Adverse Reaction Surveillance Scheme. The reporters have mainly been sheep farmers. These reports were used to investigate the possible relationship between chronic fatigue (CF) and exposure to organophosphate pesticides in sheep farming. The overall aim of the study was to investigate a possible association between exposure to organophosphates and the development of CF amongst people who consider their health has been affected by pesticides in sheep farming. The hypothesis investigated was that repeated exposure to organophosphate pesticides in sheep dip may increase the probability of developing CF. A group of mostly sheep farmers who had reported to the VMD surveillance scheme were identified. We planned to use a retrospective case-control study design but the initial symptoms reports were not sufficiently reliable to enable this. The study population was asked to complete two questionnaires. The first questionnaire was designed to identify the history of exposure of subjects to organophosphate pesticides, and their exposure was then reconstructed using a metric specifically developed for this purpose. The second questionnaire collected detailed information to identify whether the subjects had CF when they originally reported to the VMD and at the time of the survey. The questionnaire was sent to a total of 206 subjects, of whom 28 had moved home. A total of 37% of the remaining 178 subjects participated. There was a high prevalence of CF amongst those who completed the questionnaire and this has generally persisted since the subjects reported to the VMD. Higher CF scores were associated with higher exposure to organophosphate pesticides. CF is very common amongst those who consider their health was affected by pesticides and we have shown there is limited evidence of an association between exposure to organophosphates and CF. Further research is needed to investigate the cause of this syndrome amongst farmers exposed to pesticides.

Metabolic features of Gulf War illness

“…Just as there are veterans with GWI who have symptoms compatible with CFS, so there may be civilians with ME/CFS who have had similar chemical or biological exposures encountered outside of military service, but express a chemical phenotype similar to GWI. Chronic fatiguing illness has been reported after non-military exposure to organophosphate pesticides [86]. Organophosphate pesticides are inhibitors of acetylcholinesterase.…”

Auditory event-related potential changes in chronic occupational exposure to organophosphate pesticides

“…The latter is of particular importance as OP compounds have been the principal means of agricultural pest control throughout the world since 1980s (Stephens et al, 1995). Neurocognitive effects of long-term exposure to OPs have been studied in many occupational groups including farmers (Fiedler et al, 1997; Stallones and Beseler, 2002), farm-workers (Daniell et al, 1992; Farahat et al, 2003; Catano et al, 2007), sheep-dippers (Stephens et al, 1995; Jamal et al, 2002; Tahmaz et al, 2003) and termiticide applicators (Steenland et al, 2000).…”

Vitamin C attenuates chronic chlorpyrifos-induced alteration of neurobehavioral parameters in Wistar rats

“…The reduced motor strength may be related to the development of chronic fatigue syndrome that has been associated with OP poisoning. [48]…”