Background
Di-n-hexyl phthalate (DnHxP) is one of the most potent phthalates with adverse effects on the male reproductive system. Despite a European ban on DnHxP since 2020, high urinary excretion of mono-n-hexyl phthalate (MnHxP), the major metabolite of DnHxP, has been observed in recent European human biomonitoring (HBM) studies. Sunscreen products containing the UV-filter diethylamino hydroxybenzyl hexyl benzoate (DHHB), which can be contaminated with DnHxP, were pointed out as a relevant source of exposure to DnHxP.
Objective
To study possible seasonal variation in urinary excretion of MnHxP in different Danish study populations.
Method
MnHxP was measured by LC-MS/MS in 1591 urine samples collected in 2016–2022 from pregnant women, 7-year-old children, and infants and their parents participating in three different cohort studies.
Results
Urinary MnHxP was above the limit of detection (0.04 μg/L) in 84 % and above 1 μg/L in 33 % of samples. The 7-year-old children was the study population with the highest excretion rate (97 %). The highest urinary MnHxP concentration (72.5 μg/L) exceeded the health-based guidance value (HBM-I value) of 60 μg/L.
A significantly higher urinary excretion of MnHxP was observed in the summer compared to the winter season in all study populations. 80 % of the urine samples with MnHxP concentrations > 1 μg/L were from the summer season. 40 % of Danish sunscreen products contain DHHB.
Conclusion
The marked seasonal variation with higher MnHxP excretions in the summer season supports the hypothesis that the recently unveiled DnHxP contamination of the UV-filter DHHB in sunscreen products could be driving these exposures.
