Evaluation of exposure to phthalate esters and DINCH in urine and nails from a Norwegian study population

Phthalate esters (PEs) and 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH) used as additives innumerous consumer products are continuously released into the environment, leading to subsequenthuman exposure which might cause adverse health effects. The human biomonitoring approach allows thedetection of PEs and DINCH in specific populations, by taking into account all possible routes of exposure(e.g. inhalation, transdermal and oral) and all relevant sources (e.g. air, dust, personal care products, diet).

We have investigated the presence of nine PE and two DINCH metabolites and their exposure determi-nants in 61 adult residents of the Oslo area (Norway). Three urine spots andfingernails were collectedfrom each participant according to established sampling protocols. Metabolite analysis was performed byLC-MS/MS. Metabolite levels in urine were used to back-calculate the total exposure to their correspondingparent compound. The primary monoesters, such as monomethyl phthalate (MMP, geometric mean89.7 ng/g), monoethyl phthalate (MEP, 104.8 ng/g) and mono-n-butyl phthalate (MnBP, 89.3 ng/g) wereobserved in higher levels in nails, whereas the secondary bis(2-ethylhexyl) phthalate (DEHP) and DINCHoxidative metabolites were more abundant in urine (detection frequency 84–100%). The estimated daily intakes of PEs and DINCH for this Norwegian population did not exceed the established tolerable dailyintake and reference doses, and the cumulative risk assessment for combined exposure to plasticizers withsimilar toxic endpoints indicated no health concerns for the selected population.

We found a moderatepositive correlation between MEP levels in 3 urine spots and nails (range: 0.56–0.68). Higher frequency ofpersonal care products use was associated with greater MEP concentrations in both urine and nail samples.Increased age, smoking, wearing plastic gloves during house cleaning, consuming food with plasticpackaging and eating with hands were associated with higher levels in urine and nails for some of themetabolites. In contrast, frequent hair and hand washing was associated with lower urinary levels ofmonoisobutyl phthalate (MiBP) and mono(2-ethyl-5-hydroxyhexyl) phthalate (5-OH-MEHP), respectively.

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