No abstract

The German Environmental Specimen Bank (ESB) continuously collects 24-h urine samples since the early 1980s in Germany. In this study we analyzed 300 urine samples from the years 2007 to 2015 for 21 phthalate metabolites (representing exposure to 11 parent phthalates) and combined the data with two previous retrospective measurement campaigns (1988 to 2003 and 2002 to 2008). The combined dataset comprised 1162 24-h urine samples spanning the years 1988 to 2015. With this detailed set of human biomonitoring data we describe the time course of phthalate exposure in Germany over a time frame of 27 years. For the metabolites of the endocrine disrupting phthalates di(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DnBP) and butylbenzyl phthalate (BBzP) we observed a roughly ten-fold decline in median metabolite levels from their peak levels in the late 1980s/early 1990s compared to most recent levels from 2015. Probably, bans (first enacted in 1999) and classifications/labelings (enacted in 2001 and 2004) in the European Union lead to this drop. A decline in di-isobutyl phthalate (DiBP) metabolite levels set in only quite recently, possibly due to its later classification as a reproductive toxicant in the EU in 2009. In a considerable number of samples collected before 2002 health based guidance values (BE, HBM I) have been exceeded for DnBP (27.2%) and DEHP (2.3%) but also in recent samples some individual exceedances can still be observed (DEHP 1.0%). A decrease in concentration for all low molecular weight phthalates, labelled or not, was seen in the most recent years of sampling. For the high molecular weight phthalates, DEHP seems to have been substituted in part by di-isononyl phthalate (DiNP), but DiNP metabolite levels have also been declining in the last years. Probably, non-phthalate alternatives increasingly take over for the phthalates in Germany. A comparison with NHANES (National Health and Nutrition Examination Survey) data from the United States covering the years 1999 to 2012 revealed both similarities and differences in phthalate exposure between Germany and the US. Exposure to critical phthalates has decreased in both countries with metabolite levels more and more aligning with each other, but high molecular weight phthalates substituting DEHP (such as DiNP) seem to become more important in the US than in Germany.

Hexamoll(®) DINCH(®) (diisononyl-cyclohexane-1,2-dicarboxylate) is a new high-molecular-weight plasticizer and a phthalate substitute. In this study, the metabolism of DINCH(®) was investigated by oral dosage of three male volunteers with approximately 50 mg Hexamoll(®) DINCH(®) (resulting in individual doses between 0.552 and 0.606 mg/kg body weight). Their urine samples were consecutively collected over 48 h. In analogy to di-iso-nonylphthalate (DINP) metabolism, we quantified the simple monoester mono-isononyl-cyclohexane-1,2-dicarboxylate (MINCH) and its secondary oxidized metabolites with HPLC-MS/MS via isotope dilution analysis. Additionally, we quantified the unspecific full breakdown product, cyclohexane-1,2-dicarboxylic acid (CHDA), via standard addition. All postulated metabolites were present in all samples analyzed. The unspecific CHDA was identified as the major urinary metabolite representing 23.7 % of the dose as the mean of the three volunteers (range 20.0-26.5 %). 14.8 % (11.3-16.7 %) of the dose was excreted as monoesters with oxidative modifications, in particular OH-MINCH 10.7 % (7.7-12.9 %), oxo-MINCH 2.0 % (1.5-2.6 %) and carboxy-MINCH 2.0 % (1.8-2.3 %). Less than 1 % was excreted as the simple monoester MINCH. In sum, 39.2 % (35.9-42.4 %) of the DINCH(®) dose was excreted as these metabolites in urine within 48 h. Over 90 % of the metabolites investigated were excreted within 24 h after application. The secondary oxidized metabolites, with elimination half-times between 10 and 18 h, proved to be apt and specific biomarkers to determine DINCH(®) exposure. With this study, we provide reliable urinary excretion factors to calculate DINCH(®) intakes based on these metabolites in environmental and occupational studies.

In this preliminary study, we have investigated whether dermal uptake of nicotine directly from air or indirectly from clothing can be a meaningful exposure pathway. Two participants wearing only shorts and a third participant wearing clean cotton clothes were exposed to environmental tobacco smoke (ETS), generated by mechanically “smoking” cigarettes, for three hours in a chamber while breathing clean air from head-enveloping hoods. The average nicotine concentration (420 μg/m3) was comparable to the highest levels reported for smoking sections of pubs. Urine samples were collected immediately before exposure and 60 hour post-exposure for bare-skinned participants. For the clothed participant, post-exposure urine samples were collected for 24 hour. This participant then entered the chamber for another three-hour exposure wearing a hood and clothes, including a shirt that had been exposed for five days to elevated nicotine levels. The urine samples were analyzed for nicotine and two metabolites—cotinine and 3OH-cotinine. Peak urinary cotinine and 3OH-cotinine concentrations for the bare-skinned participants were comparable to levels measured among non-smokers in hospitality environments before smoking bans. The amount of dermally absorbed nicotine for each bare-skinned participant was conservatively estimated at 570 μg, but may have been larger. For the participant wearing clean clothes, uptake was ~20 μg, and while wearing a shirt previously exposed to nicotine, uptake was ~80 μg. This study demonstrates meaningful dermal uptake of nicotine directly from air or from nicotine-exposed clothes. The findings are especially relevant for children in homes with smoking or vaping

This study aims to elucidate in greater detail the dermal uptake of nicotine from air or from nicotine-exposed clothes, which was demonstrated recently in a preliminary study. Six non-smoking participants were exposed to gaseous nicotine (between 236 and 304 μg/m ) over 5 hours while breathing clean air through a hood. Four of the participants wore only shorts and 2 wore a set of clean clothes. One week later, 2 of the bare-skinned participants were again exposed in the chamber, but they showered immediately after exposure instead of the following morning. The 2 participants who wore clean clothes on week 1 were now exposed wearing a set of clothes that had been exposed to nicotine. All urine was collected for 84 hours after exposure and analyzed for nicotine and its metabolites, cotinine and 3OH-cotinine. All participants except those wearing fresh clothes excreted substantial amounts of biomarkers, comparable to levels expected from inhalation intake. Uptake for 1 participant wearing exposed clothes exceeded estimated intake via inhalation by >50%. Biomarker excretion continued during the entire urine collection period, indicating that nicotine accumulates in the skin and is released over several days. Absorbed nicotine was significantly lower after showering in 1 subject but not the other. Differences in the normalized uptakes and in the excretion patterns were observed among the participants. The observed cotinine half-lives suggest that non-smokers exposed to airborne nicotine may receive a substantial fraction through the dermal pathway. Washing skin and clothes exposed to nicotine may meaningfully decrease exposure.