Diethylphosphate Test · Urine

You can eat what looks like a clean diet and still carry measurable traces of pesticides in your body. DEP (diethylphosphate) is one of the clearest urine markers of how much your body has recently broken down from a class of farm and household pesticides called organophosphates.

This is not a disease test. It is an exposure test. It tells you whether the foods you eat, the places you live, and the products in your home are loading your body with chemicals that human research has linked to changes in liver labs, blood sugar, mood, and pregnancy outcomes.

What This Test Actually Measures

Organophosphate pesticides are sprayed on crops and used in some household and industrial products. When your body processes them, it produces a small family of breakdown products called dialkylphosphates. DEP is one of those breakdown products. A large share of an organophosphate dose is converted to these breakdown products and flushed out in urine within roughly 6 to 24 hours.

Because DEP is excreted quickly, a urine sample reflects exposure from roughly the last day or two, not your lifetime burden. The breakdown products themselves are not believed to be toxic and do not block the nerve enzyme (acetylcholinesterase) that high-dose organophosphate poisoning targets. They are useful as a quiet record of recent exposure, not as a measure of poisoning.

Where the Exposure Comes From

For most people who do not work with pesticides, food is the main source. Studies of midlife American women, urban adults in China, and children in agricultural areas have repeatedly traced higher DEP and related breakdown products back to specific dietary patterns.

• Produce: fruits and vegetables grown with organophosphate sprays
• Animal products: pork and poultry, particularly in urban Chinese adults where these were the leading dietary drivers
• Processed and packaged foods: higher intake associated with higher exposure
• Occupational and near-field exposure: agricultural workers and people living near sprayed fields
• Household factors: alcohol intake, time spent indoors, and parental work in pesticide-using occupations

How Common Is Detectable DEP

DEP shows up in urine in most people who get tested. In a U.S. national survey of people aged 6 to 59, DEP was detected in roughly 71% of samples, with a typical level near 1 microgram per liter (a unit for very small concentrations in urine). In a study of urban Chinese adults, DEP was detected in over 99% of urine samples. Among midlife American women, the typical level of diethyl breakdown products was about 26.8 nanomoles per liter, with higher levels in Black women than in White women.

What this means for you: detectable DEP is the norm, not a red flag. The question is not whether you have any exposure, but how high your level sits relative to other people and to the patterns of exposure that human studies have tied to health changes.

Liver Health

Higher urinary DEP, measured along with other organophosphate breakdown products, has been linearly associated with worse readings on two common liver indicators: the AST/ALT ratio (a comparison of two liver enzymes) and the FIB-4 score (a calculation that estimates liver scarring using age, platelets, and liver enzymes). When researchers analyzed the breakdown products as a mixture, the overall pattern pointed toward more liver stress at higher exposure.

What this means for you: if your liver enzymes have been creeping up and you cannot pin it on alcohol, weight, or a virus, your pesticide exposure is one of the things worth quantifying rather than guessing at.

Blood Sugar and Diabetes

In a cross-sectional analysis of U.S. adults, higher urinary DEP showed a positive trend with diabetes prevalence. When investigators modeled all the organophosphate breakdown products together, DEP was the largest single contributor to the overall association. This is observational data, so it does not prove that DEP causes diabetes, but it does say that people with higher DEP are more likely to have diabetes than people with lower DEP, even after accounting for the usual suspects.

Mood and Depression

Among several thousand U.S. adults in a NHANES analysis, people in the highest quarter of urinary DEP had a higher risk of depression than people in the lowest quarter. The association was strongest in men and in young and middle-aged adults. When the breakdown products were analyzed as a mixture, the overall pattern pointed in the same direction.

Pregnancy and Early Development

Most readers will not be ordering this test during pregnancy, but the pregnancy data are some of the strongest evidence that organophosphate exposure matters biologically.

• Birth timing: in agricultural workers' infants, higher diethyl breakdown products including DEP were linked to shorter pregnancies and lower Apgar scores (a quick newborn health check done at birth)
• Cellular aging: in a Palestinian cohort, higher diethyl breakdown products were associated with shorter telomeres in mothers (the protective caps on the ends of chromosomes that shorten with age)
• Placenta biology: prenatal DEP was tied to changes in placental gene activity related to oxygen handling and tissue development
• Child neurodevelopment: prenatal exposure has been associated with poorer executive function and social development scores in some child cohorts
• Child cardiovascular markers: in one cohort, gestational diethyl breakdown products were linked to lower carotid artery wall thickness and higher HDL cholesterol in children, with effects modified by the PON1 gene (a liver-made enzyme that helps detoxify organophosphates)

A Counterintuitive Finding on Body Weight

In a NHANES analysis of about 9,500 American adults, higher urinary DEP and other organophosphate breakdown products were associated with lower BMI, smaller waist circumference, and lower obesity prevalence. This points in the opposite direction of the diabetes and depression findings, which can be confusing.

Here is the framework that makes both true. DEP is not a good number versus bad number marker. It is an exposure marker, and exposure to organophosphates can affect different body systems in different ways. Lower body weight in people with higher DEP could reflect appetite or metabolic effects of chronic chemical exposure, dietary patterns that bring in both pesticides and lower calories, or unmeasured confounders. The takeaway is that lower body weight in someone with higher DEP is not protection against the liver, glucose, and mood signals seen in other studies. Treat DEP as a load measurement, not a verdict on whether your weight is healthy.

Reference Ranges

DEP does not have universal clinical cutoffs. The numbers below come from population biomonitoring and risk-based reference work, and they vary by lab, country, and whether results are adjusted for urine creatinine. They are illustrative orientation, not a target. Your lab will likely report different units and ranges.

Compare your results within the same lab over time for the most meaningful trend. A single number from one lab and a single number from another lab cannot be lined up as if they are equivalent.

Why One Reading Is Not Enough

DEP is excreted within roughly 6 to 24 hours, which means a single urine sample is essentially a snapshot of your last day or two. If you happened to eat conventional strawberries the night before your test, your DEP will look different than if you ate a plate of organic vegetables. This is the most important thing to understand about a single reading.

Trending matters more than any one number. A reasonable approach is to get a baseline, retest in 3 to 6 months if you are changing your diet or environment, and then at least annually after that. If you want to know whether switching to organic produce or a different protein source is actually changing your body burden, two or three repeats of the same test will tell you something a single measurement cannot.

When Results Can Be Misleading

• Recent meals: because DEP clears within a day, what you ate in the last 24 to 48 hours can dominate your result. A single result is more about your recent exposure than your usual exposure.
• Hydration: very dilute urine can lower the apparent concentration; very concentrated urine can raise it. Many labs adjust for urine creatinine to account for this.
• Specimen choice: urine reflects recent exposure. Hair samples capture longer-term cumulative exposure but are not what most clinical labs measure.
• Non-specificity: DEP can come from several different organophosphate pesticides, and small amounts of preformed breakdown products can be present in food and environmental samples, which can overestimate the true active exposure.

What to Do With an Elevated Result

An elevated DEP is a signal to investigate, not to panic. Practical next steps include reviewing the foods you ate in the days before your test, checking whether you live or work near agricultural fields or had pesticide use in your home, and pairing this result with other markers of related strain. Companion tests worth considering include a liver panel (ALT, AST, GGT) to look for the liver-stress pattern seen in human studies, fasting glucose and HbA1c given the diabetes association, and a comprehensive metabolic panel to rule out kidney issues that could affect how you clear these compounds. If your levels stay elevated across repeated tests despite environmental changes, that is the point at which an environmental medicine or occupational health clinician can help interpret the pattern in context.