Bisphenol S Test · Urine

BPA-free does not mean chemical-free. When manufacturers stopped using bisphenol A in plastics and paper receipts, many switched to bisphenol S, a close cousin with a nearly identical effect on hormone signaling. About 89% of Americans now have detectable BPS in their urine, which means most people reading this are carrying it right now.

This test measures how much BPS is in your urine, giving you a direct snapshot of recent exposure from food packaging, receipts, and consumer products. It is one of the few practical ways to check whether your efforts to avoid plastic-related chemicals are translating into a lower body burden.

What This Test Measures

BPS (bisphenol S) is not produced by your body. It is a manufactured chemical that enters through food, skin contact with treated paper, and dust in indoor air. Your liver clears it within hours, so urinary BPS reflects exposure over roughly the past day or two, not lifetime accumulation.

Results are reported in micrograms per gram of creatinine, a unit that adjusts for how concentrated or dilute your urine is at the moment of collection. This adjustment matters because urine concentration alone can shift a raw number by several-fold even when actual exposure is identical.

Why It Matters: Type 2 Diabetes Risk

The strongest long-term human evidence ties BPS exposure to diabetes. In a French study of 755 adults followed for nine years, those with detectable BPS in their urine were about 2.8 times as likely to develop type 2 diabetes as those without (hazard ratio 2.81, 95% CI 1.74 to 4.53). The link held after adjustment for standard risk factors.

Cross-sectional U.S. data add supporting signals. Higher urinary BPS has been linked to non-alcoholic fatty liver disease in 960 American adults, to higher uric acid and gout prevalence, and to changes in body composition including more fat mass. None of these are proof of cause, but the pattern points consistently toward metabolic disruption.

Why It Matters: Heart Disease Risk

Among 1,267 American adults in NHANES 2013 to 2016, those in the highest third of urinary BPS had nearly twice the odds of cardiovascular disease compared with the lowest third (odds ratio 1.99, 95% CI 1.16 to 3.40). For coronary heart disease specifically, the highest third had about 2.2 times the odds (odds ratio 2.22, 95% CI 1.04 to 4.74). The signal was clearest in adults aged 50 to 80.

Why It Matters: Pregnancy and Fetal Development

BPS crosses the placenta and reaches the developing fetus. In a Chinese study of 1,841 pregnant women, higher first-trimester BPS was associated with higher fasting blood sugar at the standard mid-pregnancy diabetes screen, with stronger effects when carrying a female fetus. A separate Chinese case-control study of 500 women found that women in the middle exposure group were about 1.8 times as likely to develop gestational diabetes as the lowest exposure group (odds ratio 1.77, 95% CI 1.01 to 3.13).

BPS exposure has also been linked to preterm birth. In 480 American pregnancies, detectable BPS in late pregnancy roughly doubled the odds of preterm delivery (adjusted odds ratio 2.05, 95% CI 1.09 to 3.89). A Wuhan birth cohort of 845 women found that higher BPS during certain trimesters tracked with lower birth weight and length.

Resolving a Mixed Signal in Pregnancy Data

Not every pregnancy study points the same way. A Dutch cohort of 1,379 women found that any first-trimester BPS detection was associated with about 44% lower odds of being born small for gestational age (odds ratio 0.56, 95% CI 0.38 to 0.74), the opposite direction of the Wuhan findings. This kind of inconsistency is common with environmental exposures, where background levels, co-exposure to other bisphenols, dietary patterns, and the specific window of pregnancy measured all shape what shows up. Treat BPS in pregnancy as a flag worth lowering, not as a confirmed cause of any single outcome.

Why It Matters: Male Fertility

Among 158 men attending a U.S. fertility clinic, those with detectable urinary BPS had measurably weaker semen across every parameter checked. Volume averaged 2.66 versus 2.91 mL (about 9% lower), sperm concentration averaged 30.7 versus 38.3 million per mL (about 20% lower), total sperm count averaged 76.8 versus 90.0 million (about 15% lower), and motility averaged 43.7% versus 47.0%. A separate study of 462 reproductive-aged Chinese men found that higher BPS was associated with lower estrogen levels and lower sex hormone binding globulin (SHBG, the protein that carries sex hormones in the blood).

Reference Ranges

There are no clinical reference ranges for BPS. The values below come from US NHANES 2013 to 2016, a national survey of 1,267 adults aged 20 to 80, and are illustrative orientation, not health-based targets. Your lab will likely report different units and numbers.

Source: Wang et al., NHANES 2013 to 2016. Lab-to-lab assay differences are real, so compare your results within the same lab over time rather than treating any single number as a fixed threshold.

Why One Reading Is Not Enough

BPS is one of the most variable biomarkers you can measure. In 10 healthy adults sampled across five days, the intraclass correlation coefficient (a statistic where 1.0 means a measurement is perfectly stable within a person and 0 means it is essentially random) ranged from under 0.01 to 0.128 for BPS. Day-to-day variation accounted for as much as 100% of the total variance. A single spot urine can miss your typical exposure by an order of magnitude in either direction.

The practical implication: treat any single BPS reading as a snapshot, not a verdict. A useful tracking pattern is to get a baseline, retest in 3 to 6 months after making changes to your exposure sources, and continue at least annually. Collecting first morning urine at consistent times improves comparability across tests.

When Results Can Be Misleading

• Time of day: BPS levels tend to peak in the morning, dip around noon, and rise again in the afternoon and evening, mirroring meal-related exposure. A morning sample can read meaningfully higher than an afternoon sample from the same person on the same day.
• Recent contact with thermal paper: Handling cash register receipts shortly before the test can elevate the result. The chemical transfers to skin within seconds.
• Hydration and urine concentration: A very dilute or very concentrated sample can distort the raw value. Reports adjusted for creatinine are more reliable, but extreme hydration states can still shift results.
• Recent meal patterns: A meal eaten from canned food, plastic-wrapped takeout, or packaged products in the day before the test can spike levels temporarily without reflecting your usual exposure.

What to Do With an Elevated Result

If your BPS comes back in the higher range, the most useful next step is an exposure audit rather than another medical test. Common high-yield changes are switching food storage from plastic to glass or stainless steel, avoiding canned foods or choosing brands with verified BPS-free linings, declining paper receipts when possible, and reducing handling of fabric softener, paints, and solvents that have been linked to higher levels in observational data.

Pair BPS with a bisphenol A (BPA) test to see your full bisphenol exposure picture. If BPS is high alongside elevated fasting glucose, HbA1c (the three-month average blood sugar marker), or fasting insulin, the combination is worth investigating with a primary care physician or endocrinologist focused on metabolic health, particularly given the diabetes signal in long-term cohort data. If you are pregnant or trying to conceive, raise an elevated result with your obstetrician or fertility specialist as part of an environmental exposure review. Retest in 3 to 6 months after changes to confirm your trend is moving down.