Association between two common environmental toxicants (phthalates and melamine) and urinary markers of renal injury in the third trimester of pregnant women: The Taiwan Maternal and Infant Cohort Study (TMICS)

Exposure to either melamine or phthalate, two common toxicants, during pregnancy may cause adverse health effects, including kidney damage. We investigated the independent and interactive effect of exposure to melamine and phthalates, particularly di-(2-ethylhexyl) phthalate (DEHP), on markers of early renal injury in women their third trimester of pregnancy in one nationwide birth cohort, the Taiwan Maternal and Infant Cohort Study (TMICS). Between October, 2012 and May, 2015, participants were administered questionnaires, physical examinations, and blood and urine tests during their third trimester. One-spot overnight urine specimens were used to simultaneously measure melamine, 11 phthalate metabolites, and two markers of renal injury, microalbumin and N-acetyl-beta-D-glucosaminidas (NAG). Estimated daily DEHP intake was calculated based on measurement of three urinary DEHP metabolites. Microalbuminuria was defined as having a urinary albumin/creatinine ratio (ACR) higher than 3.5 mg/mmol. Total 1433 pregnant women were analyzed. The median value for urinary melamine was 0.63 μg/mmol Cr and estimated DEHP intake was 1.84 μg/kg/day. We found subjects in the highest quartile of estimated DEHP intake to have significantly higher urinary ACR (β = 0.095, p = 0.043) and the prevalence of microalbuminuria (adjusted OR = 1.752, 95% confidence interval = 1.118–2.746), compared to those in the lowest quartile. In addition, there was a significant interactive effect between urinary melamine and estimated DEHP intake on urinary ACR and NAG. Our results suggest these two ubiquitous chemicals together may be associated with markers of early kidney injury in pregnant women. •The exposure of two toxicants (melamine and phthalates) daily during pregnancy is common.•We investigate the interactive effect of exposure to melamine and phthalates, particularly di-(2-ethylhexyl) phthalate (DEHP), on markers of renal injury in the third trimester of pregnant women.•A higher estimated DEHP intake may lead to the increased excretion of urinary albumin/creatinine ratio (ACR).•A significant interactive effect of melamine in urine and estimated DEHP intake with urinary ACR and N-acetyl-beta-D-glucosaminidas (NAG) was found.•These two ubiquitous chemicals together may be associated with markers of early kidney injury in pregnant women.