A new study on organophosphate chemical exposure in humans, published in the Environmental Health Perspectives Journal, provides more evidence to show that eating organic produce is a good way to avoid eating pesticides.

The study provides a better understanding of the health risks of pesticides exposure and is the largest conducted among the general population of U.S. adults. It is also the first to combine pesticide exposure measurement with information on organic food consumption.

“The health benefits of eating fruits and vegetables—whether organic or conventional—are well established. Our research strengthens claims that selecting organic produce reduces exposure to organophosphates” says study leader Cynthia Curl, an assistant professor at Boise State University’s (Idaho) School of Health Sciences.

The study Estimating Pesticide Exposure from Dietary Intake and Organic Food Choices appears in EHP, (Vol 123, No 5, May 2015). The Multi-Ethnic Study of Atherosclerosis (MESA) looked at organophosphate pesticides (OPs), the most commonly used insecticides in the United States for more than three decades.

The U.S. Environmental Protection Agency (EPA) conducted chemical-specific risk reassessments of all OPs after the passage of the Food Quality Protection Act of 1996. This Act required food tolerance decisions to consider cumulative and aggregate risk (Food Quality Protection Act 1996).

Data from the National Health and Nutrition Examination Survey from 2003 to 2004 reveals metabolites of OPs were detected in the urine of more than 75% of the U.S. population (Barr et al. 2011).

In the study, researchers assessed long-term dietary OP exposure in a cohort of 4,466 participants by combining self-reported information on the typical dietary intake with average residue levels in those items from a national database.

“We further assessed the relationship between these estimates and DAP urinary concentrations in a subset of participants with conventional diets (n= 480). This analysis was intended as a check on the face validity of our estimates. In a second subset of participants (n = 240), we investigated the association between self-reported organic produce consumption habits and urinary DAP levels,” the authors said.

To evaluate the impact of organic consumption habits, the researchers were also interested in understanding the influence of self-reported organic produce consumption habits on urinary DAP levels (Dialkylphosphate metabolites, which are common by-products of the metabolism of most OPs).

Selected were 80 sets of three participants. Each set contained one participant from each category of self-reported organic produce consumption: “rarely or never,” “sometimes,” or “often or always.” These sets were matched on estimated exposure, such that the standard deviation of the exposure estimates was less than 0.5 nmol OP/day within a given set.

By matching on estimated exposure (by definition, a weighted metric of produce intake) it was ensured that any differences in DAP concentrations were based exclusively on differences in organic consumption habits rather than on differences in produce intake. Urinary DAP levels were compared across the resulting three groups; the selected sets were constructed separately from the subsets of 240 participants described above.

Looking at the participants in the study this was a diverse group; 41%  were Caucasian, 12% Chinese American, 26% African-American, and 22% Hispanic. The gender ratio was fairly equal, with slightly more women (53%) than men (47%).

Over a third of this group were 55–64 years of age, another third 65–74 years, and the remainder ≥ 75 years of age.

Among the cohort as a whole, participants who reported more frequent consumption of organic produce also reported eating more produce overall. Median produce consumption among individuals, who reported that they “often or always” ate organic produce was 3.7 servings/day, compared with 3.0 servings/day among those who “sometimes” ate organic produce and 2.2 servings/day among those who “rarely or never” did so (probability less than 0.0001).

The authors said that the study provides estimates of long-term dietary OP exposure in a population for which information on organic food consumption is also available. The estimates were consistent with the results of urinary DAP biomonitoring, increasing their confidence in this methodology.

In addition to estimating dietary OP exposure, observed was a significant relationship between increasing consumption of organic produce and lower DAP levels among individuals who were matched on FCCR-based exposure (essentially, a weighted metric of produce intake).

This finding is consistent with previous studies showing that consumption of organic food measurably reduces OP exposure (Lu et al. 2006, 2008).

This study is the first of its kind to include information on organic food consumption habits, but it is not the first to use a “food consumption–chemical residue” approach to estimating dietary exposure.

In an earlier Danish study, Jensen et al. (2003) evaluated the potential cumulative effects of exposure to OP and carbamate pesticides by combining dietary intake data from a nationwide food consumption survey with residue data from a Danish pesticide residue monitoring program.