Organic diet can drastically eliminate pesticide residues in urine, UC Berkeley study finds

Facts about organic diet intervention on fruits and vegetables
Ashley Zhang/Staff

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UC Berkeley researchers recently found that an organic diet can dramatically decrease the presence of pesticide residues in urine.

The study — co-authored by campus doctoral student Carly Hyland, campus environmental health science professor Asa Bradman and assistant researcher Robert Gunier in collaboration with researchers from UCSF — was made available online Feb. 12 on ScienceDirect.

Hyland said in an email that she hopes the study will better inform consumers about pesticides and the foods they eat. She added that while the study results predict better health outcomes for those who eat organic foods, there are other ways people can avoid increased pesticide intake.

“This study indicates that switching to an organic diet is associated with significant reductions in pesticide exposures,” said Justin Remais, head of environmental health sciences at the UC Berkeley School of Public Health, who was not involved in the study. “These researchers have added to our understanding of the plasticity of dietary exposures to pesticides and highlights the importance of ensuring greater access to healthy organic food.”

The study involved monitoring the pesticide exposure of four families from different parts of the United States, including Oakland, Minneapolis, Baltimore and Atlanta.

For the first six days of the study, the families followed their typical nonorganic diets. During the six days after, the families ate a 100 percent organic diet in which all of the food was provided to them, according to Hyland.

For each day of the 12-day study, the participants provided a urine sample. These samples were sent to UCSF and the National Public Health Institute of Quebec where they were tested for markers of different pesticides.

The urine samples taken while the participants were consuming an organic diet showed significantly fewer biomarkers of exposure to more than 40 of the most commonly used agricultural pesticides.

More specifically, exposure to malathion and chlorpyrifos, both organophosphates, decreased by 95 percent and 61 percent, respectively. Concentrations of the insecticide clothianidin experienced a similar decline of 83 percent.

Hyland said that though people who consume nonorganic diets are more exposed to higher levels of pesticides, those who cannot afford organic food should not be discouraged.

“I think it is important that the results of this study are not interpreted to discourage fruit and vegetable consumption, whether conventional or organic,” Hyland said in an email. “For the majority of Americans who can’t afford to eat a fully organic diet, including myself, there are still steps we can take to reduce our exposure to pesticides.”

She suggested that people who do not buy organic produce wash their fruits and vegetables to “remove as much pesticide residue as possible.” Hyland also recommended that people look at the Environmental Working Group’s “Dirty Dozen” list, which identifies produce items with the highest amount of pesticide residues.

According to Hyland, the study’s intent was not to look at adverse health effects but rather, to assess the impact of an organic diet on urinary pesticide levels.

“I think consumers are often inundated with headlines about harmful chemicals and often don’t have access to information about ways to mitigate risk from common exposures,” Hyland said in the email. “Diet is the primary source of pesticide exposure in the general public, and our study contributes to the growing body of literature indicating that an organic diet can significantly reduce exposure to potentially harmful pesticides.”

Contact Mallika Seshadri at [email protected] and follow her on Twitter at @SeshadriMallika.