Participants (based in the United States) followed their normal diet of non-organic foods for the first five days of the study, then ate only organic foods for the next six days. Participants could either have organic meals prepared for them by a caterer or have their choice of organic food ingredients delivered to their home.
The figure below shows the reduction in certain pesticide metabolite levels during the organic dietary phase.
Image: Figure 1, Hyland et al. Percent decrease in urinary metabolite concentration from conventional to organic diet phase from mixed effects models (n = 16 participants; n=158 urine samples). 2,4-D = 2,4-Dichlorophenoxyacetic acid, 3PBA = 3-Phenoxybenzoic acid, cDCCA = cis-2,2-(Dichloro)-2-dimethylvinylcyclopropane carboxylic acid, Cloth = Clothianidin, FPBA = 4-fluoro-3-phenoxybenzoic acid, MDA = Malathion dicarboxylic acid, TCPy = 3,5,6-trichloro-2-pyridinol , tDCCA = trans-2,2-(Dichloro)-2-dimethylvinylcyclopropane carboxylic acid.
Some media commentary has drawn attention to the fact that the study only considered those pesticides that are permitted in conventional agriculture, and not any pesticides that are permitted in organic agriculture (such as methyl eugenol or copper sulphate). See for example A new study claims eating organic reduces pesticide intake. It’s totally misleading.
Previous diet intervention studies indicate that an organic diet can reduce urinary pesticide metabolite excretion; however, they have largely focused on organophosphate (OP) pesticides. Knowledge gaps exist regarding the impact of an organic diet on exposure to other pesticides, including pyrethroids and neonicotinoids, which are increasing in use in the United States and globally.
To investigate the impact of an organic diet intervention on levels of insecticides, herbicides, and fungicides or their metabolites in urine collected from adults and children.
We collected urine samples from four racially and geographically diverse families in the United States before and after an organic diet intervention (n = 16 participants and a total of 158 urine samples).
We observed significant reductions in urinary levels of thirteen pesticide metabolites and parent compounds representing OP, neonicotinoid, and pyrethroid insecticides and the herbicide 2,4-D following the introduction of an organic diet. The greatest reductions were observed for clothianidin (− 82.7%; 95% confidence interval [95% CI]: − 86.6%, − 77.6%; p < 0.01), malathion dicarboxylic acid (MDA), a metabolite of malathion (− 95.0%; 95% CI: − 97.0%, − 91.8%; p < 0.01), and 3,5,6-trichlor-2-pyridinol (TCPy), a metabolite of chlorpyrifos (− 60.7%; 95% CI: − 69.6%, − 49.2%; p < 0.01). Metabolites or parent compounds of the fungicides boscalid, iprodione, and thiabendazole and the neonicotinoid insecticide imidacloprid were not detected among participants in our study.
An organic diet was associated with significant reductions in urinary excretion of several pesticide metabolites and parent compounds. This study adds to a growing body of literature indicating that an organic diet may reduce exposure to a range of pesticides in children and adults. Additional research is needed to evaluate dietary exposure to neonicotinoids, which are now the most widely used class of insecticides in the world.
Hyland, C., Bradman, A., Gerona, R., Patton, S., Zakharevich, I., Gunier, R. B. and Klein, K., 2019. Organic diet intervention significantly reduces urinary pesticide levels in U.S. children and adults, Environmental Research, In Press, Corrected Proof.
Read the full paper here. See also the Foodsource resource How are food systems and health connected and influenced?