Diethylthiophosphate (DETP)

If you eat mostly conventionally grown produce, live near farmland, or use pesticides around your home, some of that exposure passes through your body and leaves a trace in your urine. This test measures one of those traces.

It will not tell you that you are sick. What it can tell you is whether a common class of farm and household pesticides reached your body in roughly the last day or two, which is useful information if you are trying to conceive or simply want to lower your everyday chemical load.

What This Test Actually Measures

The molecule being measured is DETP (diethylthiophosphate), one of six small breakdown products that scientists group together as dialkyl phosphates. Your body makes DETP when it processes a family of bug-killing chemicals called organophosphate pesticides, specifically the diethyl types such as chlorpyrifos, diazinon, and parathion. About three-quarters of the organophosphate pesticides registered in the United States break down into one or more of these six markers, which is why they are used to gauge exposure to the whole class.

This marker is nonspecific, and that matters for how you read it. A detectable result tells you that a diethyl organophosphate pesticide reached your body, but it cannot name the exact chemical. DETP can also come from breakdown products already present in food or the environment, not only from a pesticide your body actively processed, so the number reflects contact with this class rather than proof of one particular product.

This is a research-grade exposure marker, not an established clinical test. There are no standardized cutoffs that separate safe from dangerous, and different labs use different detection limits. That does not make it useless. It makes a single number less meaningful on its own than a trend you can watch over time as you change what reaches your body.

Fertility and Time to Pregnancy

The clearest human signal tied to this specific marker is in female fertility. In a study of women planning pregnancy, those with the highest urinary DETP had about twice the odds of infertility compared with those in the lowest group (odds ratio 2.17), and they took longer to conceive, with roughly a third lower odds of conceiving in any given cycle. The link held even among women having their first child.

That finding does not carry across every fertility study cleanly. Among women going through in vitro fertilization, the strongest signal for lower implantation and pregnancy came from a related metabolite (DEP, diethylphosphate) and from the combined total of these markers, rather than from DETP measured by itself. So the fertility association is real and worth taking seriously, but DETP is one piece of a broader exposure picture, not a stand-alone verdict.

What this means for you: if you are trying to conceive and your level is on the higher side, the practical response is to look at where the exposure is coming from, not to treat the number as a diagnosis. Repeat testing and a review of diet and home pesticide use tell you more than one reading ever could.

Liver Protein Signals

In large U.S. survey data, higher urinary DETP was linked to slightly lower blood levels of two proteins the liver makes: albumin and total protein. These same analyses did not find a clear link between DETP and the standard liver enzymes (ALT and AST, the markers most people know from a routine panel) or with fatty liver scores.

The signal is suggestive, not settled. It comes from snapshot studies that measure exposure and blood proteins at a single point, which cannot prove that pesticide exposure caused the change. The takeaway is modest: this marker may pick up an early stress on liver-related proteins that routine liver enzymes miss, which is a reason to track it alongside standard labs rather than in place of them.

Metabolic and Hormone Signals

Higher DETP has been associated with higher blood triglycerides (a blood fat linked to heart and metabolic risk) in U.S. survey data of adults, where it was among the metabolites contributing most to an unfavorable lipid pattern. It was not linked to type 2 diabetes markers in the same body of data; that association appeared for a different metabolite. In male adolescents, detectable DETP was tied to only marginal shifts in testosterone, thyroid hormone, FSH (follicle-stimulating hormone, which helps regulate reproduction), and AMH (anti-Mullerian hormone, a hormone that reflects reproductive gland activity, best established as a measure of ovarian reserve in women).

One survey reported something that looks backward at first: higher DETP was linked to a lower chance of obesity. This is not evidence that pesticide exposure protects your weight. The most likely explanation is diet. People who eat more fresh fruit and vegetables tend to have both higher pesticide-metabolite readings and lower obesity, so the produce, not the pesticide, is doing the heavy lifting. Read this marker as a signal of exposure, not as a good number or a bad number by itself.

In children, one case-control study found that those with the highest urinary DETP had roughly 80% higher odds of dyslexia (odds ratio 1.82) than those with the lowest, though the authors cautioned that a single urine sample and the study design limit what can be concluded. In male farmers, higher DETP tracked with markers of oxidative stress, a form of cellular wear and tear. These are early, hypothesis-generating findings rather than proof of harm.

A Snapshot, Not a Stockpile

The pesticides that produce DETP do not linger in the body. They are processed quickly, with the resulting urine markers cleared with a half-life of roughly 6 to 30 hours (the higher end reflecting slower absorption through the skin), and most of an absorbed dose is gone within one to three days. A spot urine sample mostly captures what reached you in the previous day or two, not a lifetime of accumulation.

This is the single most important fact for interpreting your result. A high reading means recent contact, often traceable to a specific meal, a home application, or a work shift. A low or undetectable reading means less recent contact, but it does not rule out regular exposure that happened to be quiet on the day you tested. For a picture of longer-term, cumulative exposure, hair testing captures a wider window than urine, though the two do not track each other closely.

Why One Reading Can Fool You

This marker swings a lot within the same person from day to day. In repeated-sampling studies, the variation within one individual over time was larger than the variation between different people, and reproducibility across visits was poor (a statistical measure of consistency between repeat samples sat around 0.19 to 0.28, where 1.0 would be perfect agreement). One value, taken on one day, is a weak guide to your usual exposure.

• Timing of your last exposure: because the marker clears within a day or two, a recent meal of conventionally grown produce or a home pesticide application can drive a high reading that would not appear a few days later.
• Age and sex: children tend to run higher than adolescents, adult levels tend to rise with age, and men tend to run lower than women, so results are not directly comparable across groups.
• It cannot name the source: DETP reflects the diethyl organophosphate class as a group, so a single result cannot identify which pesticide, or confirm poisoning, on its own.

Why Tracking Beats a Single Test

Given how much this marker fluctuates, a trend is far more informative than any one reading. Research in pregnancy found that collecting several samples, on the order of six, gave a much more accurate picture of true exposure than one or two. You do not need six draws for personal use, but you do need more than one, ideally on different days and under your normal routine.

A sensible cadence: get a baseline, then retest after a few weeks if you change your diet or reduce home pesticide use, then check periodically to confirm the change held. One caveat on tracking whether an intervention is working: the strongest evidence that organic eating lowers exposure comes from studies measuring the whole dialkyl phosphate family, with DETP specifically tending to follow, rather than from trials that isolated DETP alone. Read a drop as encouraging, not as a precise DETP-specific proof.

What to Do With an Unexpected Result

A single high number is a prompt to investigate, not to panic. Start by repeating the test on a different day, ideally away from a recent meal of conventional produce or a home pesticide application, to see whether the level is a spike or a pattern. Then look at the obvious sources: what you eat most, whether pesticides are used in or around your home, and whether your work or neighborhood involves agriculture.

For interpretation in context, this marker pairs well with related tests. Other dialkyl phosphate metabolites and their summed total show whether the exposure is broad or narrow. Blood cholinesterase activity reflects a functional effect of organophosphates, though no reliable threshold links this urine marker to cholinesterase suppression, so the two answer different questions. An oxidative-stress marker can add biological context.

If you are pregnant, planning pregnancy, working with pesticides, or have symptoms you think may be exposure-related, bring the result to a licensed clinician or an occupational and environmental medicine specialist. They can weigh timing, repeat samples, symptoms, and exposure history in a way a single urine value cannot.