Organophosphate Pesticides

What are Organophosphate Pesticides?

  • Organophosphate-based pesticides (“OP pesticides”) are the most commonly used form of agricultural insecticide in the U.S., including on fruits and vegetables. Recent reporting indicates that the use of OP pesticides in the U.S. is now in decline.
  • OP pesticides have been banned for home use in the U.S. and have attracted significant attention for their known harmful effects on the nervous system. OP pesticides were developed after World War II, based on wartime nerve gases.
  • It is thought that OP pesticides break down quickly when exposed to light and air, and so are favored over organochlorine pesticides (OC pesticides) like DDT. However, it is not known whether OP pesticides ever degrade fully and they have been detected in soil and drinking water long after application.
  • Furthermore, exposure to large amounts of OP pesticides is more harmful to human health than the same large amount of OC pesticides.

Findings from CERCH Research on Organophosphate Pesticides:

From the CHAMACOS Health Outcomes Study –

Mothers’ exposure to organophosphate (OP) pesticides during pregnancy is associated with:

  • Shorter duration of pregnancy. (Go to publication)
  • Poorer neonatal reflexes. (Go to publication)
  • Lower IQ and poorer cognitive functioning in children. (Go to publication 1, 2)
  • Increased risk of attention problems in children. (Go to publication)

From the CHAMACOS Functional Genomics PON1 Study –

The PON1 gene, and the PON1 enzyme that it codes for, impact the body’s ability to detoxify organophosphate pesticides and eliminate them from the body.

  • Children, particularly newborns, have much lower levels of PON1 enzyme levels and activities than adults and may therefore be more susceptible to pesticide exposures. (Go to Publication 1, 2, 3)
  • PON1 enzyme activities were elevated in mothers during pregnancy and at the time of delivery compared to when they were not pregnant. (Go to Publication)

Genetic Control of PON1 Enzyme Levels and Activity:

  • PON1 polymorphisms may affect susceptibility to pesticide exposures:
    • The Genetic polymorphism PON1-108 was associated with PON1 levels.
    • The Genetic polymorphism PON1-192 was associated with PON1 activity. (Go to Publication)
  • Genetic control of PON1 enzymatic activity is different in children compared to adults. (Go to Publication 1, 2)
  • The relative influence of genetic polymorphisms on PON1 phenotypes (enzyme quantity and activity) varied in mothers and their children. (Go to Publication 1, 2)

Associations of PON1 with Health Outcomes:

  • Certain PON1 genetic polymorphisms were also associated with:
    • Shorter gestational duration (Go to Publication)
    • Smaller head circumference (Go to Publication)
    • Lower mental and psychomotor development (MDI & PDI) scores. (Go to Publication)
    • Increased risk of pervasive development disorder (PDD), a category of developmental disorders that include several autism spectrum disorders. (Go to Publication)

From the CERCH Environmental Exposures Studies –


  • Eating organically-grown fruits and vegetables reduces exposure compared with eating conventionally-grown produce.*
  • Wearing protective gloves and clothing during agricultural work greatly reduces exposure.

Maternal Organophosphate Pesticide Metabolites in Urine

  • The CHAMACOS cohort of pregnant women have levels of organophosphate (OP) pesticide metabolite levels in urine 30-40% higher than U.S. national reference levels reported for women of child-bearing age (18-40 yrs old) by NHANES.  (Go to publication)
  • Based on cumulative OP pesticide dose estimates, 14.8% of pregnant women in the CHAMACOS cohort may exceed health-based exposure benchmarks.(Go to publication)
  • We also measured 34 metabolites of current-use pesticides and other precursor compounds in urine samples collected from women twice during pregnancy.(Go to publication)
  • Detected metabolites may be related to home or agricultural pesticide use in the Salinas Valley, household products, and other sources of chlorinated phenols. (Go to publication)
  • More than 78% of CHAMACOS women had detectable levels of at least one OP pesticide-specific metabolite, and > 30% had two or more. (Go to publication)
  • The 95th percentile values of six of the most commonly detected compounds were significantly higher among the CHAMACOS women compared to U.S. national reference levels for pregnant women after controlling for age, race, socioeconomic status, and smoking. (Go to publication)
  • Findings suggest that the CHAMACOS cohort has an additional burden of pesticide exposure compared with the national sample, possibly from living and/or working in an agricultural area(Go to publication)

Organophosphate Pesticide Exposure Modeling

  • Biomarker comparisons and model results showed that women in the CHAMACOS cohort have a slightly but significantly higher intake of OP pesticides compared to women in the US general population as reported in NHANES. (Go to publication)
  • Results from this comparison suggest that diet is the common and dominant exposure pathway in both populations. (Go to publication)

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