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Gene-environmental interactions and organophosphate toxicity
1Centre for Occupational and Environmental Health, School of Community-Based Medicine, Faculty of Medical and Human Sciences, University of Manchester, Ellen Wilkinson Building, Devas Street, Manchester M139PT, United Kingdom. apovey@manchester.ac.uk
Toxicology
|February 17, 2010
Summary
Sheep farmers exposed to organophosphates (OPs) may face chronic health issues, particularly those with specific genetic variations in the PON1 enzyme. Further research is needed to confirm OP exposure and identify susceptible populations.
Area of Science:
- Environmental Health
- Toxicology
- Genetics
Background:
- Organophosphates (OPs) are widely used insecticides in UK agriculture, particularly for sheep ectoparasite treatment.
- While acute OP toxicity is understood, chronic health effects from prolonged exposure remain controversial.
- Sheep farmers report chronic ill-health attributed to repeated OP exposure, suggesting a need to investigate underlying mechanisms.
Purpose of the Study:
- To investigate the hypothesis that specific genetic defects in OP metabolism increase the risk of chronic ill-health following OP exposure.
- To characterize OP exposure and the metabolic pathways involved in the formation and detoxification of active OP metabolites.
- To explore the role of serum paraoxonase (PON1) polymorphisms in mediating susceptibility to OP-induced chronic ill-health in sheep farmers.
Main Methods:
- Analysis of OP metabolites in farmers' urine post-treatment to assess exposure levels.
- Investigation of cytochrome P450 (CYP) metabolism in the activation of organothiophosphates like diazinon to toxic oxons.
- Genotyping of PON1 polymorphisms (Q192R and L55M) and assessment of their association with self-reported chronic ill-health in UK sheep farmers.
Main Results:
- Detectable levels of OP metabolites were found in farmers' urine shortly after treatment, with minimal reduction in plasma cholinesterase activity.
- The Q192R polymorphism in PON1 was investigated, noting that the R allele metabolizes diazoxon less efficiently.
- A significant association was observed between the PON1 R allele and increased self-reported chronic ill-health among UK sheep farmers.
Conclusions:
- The findings support the hypothesis that certain PON1 genotypes may confer increased susceptibility to chronic ill-health from OP exposure.
- Characterizing OP exposure and identifying susceptible populations, particularly those with specific PON1 polymorphisms, is crucial for understanding OP-related health risks.
- Further research is required to refine exposure assessment and confirm the role of genetic factors in chronic OP toxicity.
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