Organophosphates (OPs) are the most common and toxic pesticides used today, namely on conventionally grown produce. The U.S. Environmental Protection Agency classified OPs as highly or moderately toxic; low levels are suspected to be enough to affect the human nervous system. While prior research deduced these conclusions by relying solely on urinary biomarkers, a new study predicts exposure to OPs based on people’s diets.

“The magnitude of pesticide exposure from diet depends partly upon personal decisions such as which foods to eat and whether to choose organic food,” researchers wrote. So they culled data from 4,466 participants already taking part in the Multi-Ethnic Study of Atherosclerosis — a medical research study involving men and women from six communities in the U.S. This data included the types and amounts of produce each participant ate in a year, as well as how often each participant ate organic foods.

Participant-level exposure was estimated by combining the information on typical intake of specific foods with average OPs residue levels on those items. And among conventional participants (they reported rarely or never eating organic produce), researchers assessed the levels of pesticides excreted in urine. They found among “conventional consumers,” increased OPs exposure from produce was associated with higher OPs in their urine.

As for participants who bought organic produce, levels were significantly lower — and that’s if they occasionally bought and ate organic produce. For those who often or always bought organic fruits and vegetables, they experienced around 65 percent lower levels of pesticides in their urine. Live Science reported this study is among the first to consider pesticide residue levels through a person’s diet.

OPs, Live Science added, degrade quickly, so solely using urine tests only detects a person’s exposures in the past day or two. Combining these tests with a participant’s typical diet, researchers said they can better estimate a person’s long-term exposure. Though there is one caveat: The present study only considers OPs; it does not consider other pesticides that may be used on produce.

However, on its own, the present study fuels the existing argument organic produce is better for consumers than conventional produce. The longer-term, lower dose effects of OPs have been associated with behavioral problems, like ADHD, certain cancers, neurological disorders. and lower levels of testosterone and other sex hormones.

A lot of the concern that stems from being told to buy organic is that it's more expensive than conventional produce. Though the fact levels were lower when only occasionally buying organic takes some of the pressure off, it may still be too much to expense. In which case, The Environmental Working Group curated the Dirty Dozen List. Consult the list for the produce the EWG recommended consumers always buy organic, plus the produce they can get away with buying conventional.

Source: Curl C.L, et al. Estimating Pesticide Exposure from Dietary Intake and Organic Food Choices: The Multi-Ethnic Study of Atherosclerosis (MESA). Environmental Health Perspectives. 2015.