Entering markets and bodies: increasing levels of the novel plasticizer Hexamoll® DINCH® in 24 h urine samples from the German Environmental Specimen Bank.

DINCH (diisononylcyclohexane-1,2-dicarboxylate) was introduced into the world market in 2002 as a non-aromatic plasticizer and phthalate substitute. We analyzed 300 urine samples (24 h voids) of the German Environmental Specimen Bank (ESB for Human tissues, ESB Hum) for specific DINCH metabolites by on-line HPLC-MS/MS with isotope dilution quantification. Urine samples of the ESB Hum were from the years 1999, 2003, 2006, 2009 and 2012, chosen to investigate the appearance and a possible trend of DINCH exposure since its market introduction. No DINCH metabolites were detected in the 1999 and 2003 samples. From 2006 on, the percentage of samples with DINCH metabolites above the LOQ increased significantly over the years (7% in 2006, 43% in 2009 and 98% in 2012). The cyclohexane-1,2-dicarboxylic acid-mono(hydroxy-isononyl) ester (OH-MINCH) was the predominant metabolite. Median (and 95th percentile) concentrations (in μg/l) increased from <LOQ (0.09) in 2006, to <LOQ (1.02) in 2009 to 0.39 (2.09) in 2012. All oxidized DINCH metabolites (OH-MINCH, cx-MINCH, oxo-MINCH) correlated strongly among each other (ρ>0.75, p<0.001). The median (95th percentile) DINCH intake in 2012 was calculated to be 0.14 (1.07)μg/kg body weight/day which is considerably below daily intakes currently deemed tolerable. DINCH is regarded to have a preferred toxicological profile over certain anti-androgenic phthalates. The continuation of DINCH measurements in the ESB Hum and other human biomonitoring studies like the German Environmental Survey (GerES) allows tracking the development of DINCH body burdens, the distribution of exposure levels and daily intakes, providing basic data for future toxicological assessment and further epidemiological studies.

Schütze A ，Kolossa-Gehring M ，Apel P ，Brüning T ，Koch HM ... -  《-》

Time trend of exposure to the phthalate plasticizer substitute DINCH in Germany from 1999 to 2017: Biomonitoring data on young adults from the Environmental Specimen Bank (ESB).

DINCH (cyclohexane-1,2-dicarboxylic acid-diisononyl ester) is a phthalate plasticizer substitute introduced into the market in 2002. It is increasingly used especially in the production of toys, food contact materials and medical devices. In this measurement campaign on 24-h urine samples of young adults (20-29 years) from the German Environmental Specimen Bank (ESB) collected in 2010, 2011, 2013, 2015 and 2017 (in total 300 samples, 60 samples/year) we analyzed three specific, oxidized DINCH metabolites (OH-MINCH: cyclohexane-1,2-dicarboxylic acid-mono(hydroxy-isononyl) ester; cx-MINCH: cyclohexane-1,2-dicarboxylic acid-mono(carboxy-isooctyl) ester, oxo-MINCH: cyclohexane-1,2-dicarboxylic acid-mono(oxo-isononyl) ester). We merged these data with earlier data of the ESB from the years 1999-2012 and are now able to report levels and time trends of internal DINCH exposure from 1999 to 2017. After first detections of the major oxidized DINCH metabolite OH-MINCH in 2006 (6.7%) detection rates rapidly increased to 43.3% in 2009, 80% in 2010 and 98.3% in 2011 and 2012. From the year 2013 on we could detect OH-MINCH in every urine sample analyzed. The median concentrations of OH-MINCH rapidly increased from 0.15 μg/L in 2010 to twice the concentration in 2011 (0.31 μg/L) with further increases in 2013 (0.37 μg/L), 2015 (0.59 μg/L) and 2017 (0.70 μg/L). Similar increases, albeit at lower detection rates and concentration levels, could be observed for cx-MINCH and oxo-MINCH. All metabolites strongly correlate with each other. For the ESB study population, DINCH exposures are still far below health based guidance values such as the German Human Biomonitoring Value (HBM-I; 4,500 μg/L for the sum of OH-MINCH and cx-MINCH) or the tolerable daily intake (TDI) of EFSA (1 mg/kg bw/d). The median daily DINCH intake (DI) calculated for 2017 was 0.23 μg/kg bw/d, thus 4,310-times lower than the TDI. The maximum DI calculated for one individual in 2012 (42.60 μg/kg bw/d) was a factor of more than 20 below the TDI. The ongoing increase in DINCH exposure needs to be closely monitored in the future, including populations with potentially higher exposures such as children. This close monitoring will enable timely exposure and risk reduction measures if exposures reached critical levels, or if new toxicological data lead to lower health based guidance values. DINCH belongs to the European Human Biomonitoring Initiative (HBM4EU) priority substances for which policy relevant questions still have to be answered.

Kasper-Sonnenberg M ，Koch HM ，Apel P ，Rüther M ，Pälmke C ，Brüning T ，Kolossa-Gehring M ... -  《-》

Non-phthalate plasticizers in German daycare centers and human biomonitoring of DINCH metabolites in children attending the centers (LUPE 3).

Plasticizers have been widely used for decades as additives in diverse applications, including consumer and building products, toys, cables, and floorings. Due to toxicological concerns and restrictions of different dialkyl ortho-phthalates, other plasticizers have been increasingly used in recent years. Therefore, di-isononyl cyclohexane-1,2-dicarboxylate (DINCH), di(2-ethylhexyl) terephthalate (DEHT), di(2-ethylhexyl) adipate (DEHA), acetyl tri-n-butyl citrate (ATBC), and trioctyl trimellitate (TOTM) plasticizer levels in indoor air and dust samples from 63 daycare centers in Germany were measured. Moreover, the urine samples of 208 children who attend 27 of these facilities were analyzed for the presence of four DINCH metabolites. DINCH, DEHT, and DEHA were present in indoor air with median values of 108 ng/m(3), 20 ng/m(3), and 34 ng/m(3), respectively. Median values of 302 mg/kg for DINCH, 49 mg/kg for DEHA, 40 mg/kg for DEHT, and 24 mg/kg ATBC were found in dust. In the urine samples, the three secondary metabolites of DINCH were observed with median values (95th percentiles) of 1.7 μg/l (10.0 μg/l) for OH-MINCH, 1.5 μg/l (8.0 μg/l) for oxo-MINCH, and 1.1 μg/l (6.1 μg/l) for cx-MINCH. Overall, these metabolite levels are orders of magnitude lower than the current HBM I values set by the German Human Biomonitoring Commission. Using general exposure assumptions, the intake resulting from dust ingestion and inhalation is low for children. The total daily DINCH intake calculated from biomonitoring data was 0.5 μg/kg b.w. using median values and 9.8 μg/kg b.w. as the maximum value. At present, non-phthalate plasticizers, especially DINCH, can be found in considerable amounts in dust samples from daycare centers and as DINCH metabolites in the urine of children. In relation to previous studies, the concentrations of DINCH in dust and urine have an increasing time trend. Compared with tolerable daily intake values, the total daily intake of DINCH reached only 1% of its maximum value to date; however, due to its increased use, higher exposure of DINCH is expected in the future.

Fromme H ，Schütze A ，Lahrz T ，Kraft M ，Fembacher L ，Siewering S ，Burkardt R ，Dietrich S ，Koch HM ，Völkel W ... -  《-》

Quantification of biomarkers of environmental exposure to di(isononyl)cyclohexane-1,2-dicarboxylate (DINCH) in urine via HPLC-MS/MS.

Di(isononyl)cyclohexane-1,2-dicarboxylate (DINCH) is a major substitute for some high molecular weight phthalates that adversely affect reproductive function. Like for the phthalates a broad exposure of the population has to be expected. We postulated the DINCH monoester (MINCH) and secondary oxidized metabolites (OH-MINCH, cx-MINCH and oxo-MINCH) as human metabolites and possible biomarkers of DINCH exposure. We developed an on-line HPLC-MS/MS method for their determination in human urine. Identification was performed with authentic standard substances and quantification via isotope dilution. The analytical method is highly selective and sensitive with limits of quantification (LOQ) between 0.05 μg/l and 0.1 μg/l. In a pilot study with 22 volunteers from the general German population oxidized DINCH metabolites were found in above 80% of the samples. OH-MINCH was most abundant (mean 0.71 μg/l; maximum 3.69 μg/l) followed by cx-MINCH (0.61 μg/l; 2.82 μg/l) and oxo-MINCH (0.33 μg/l; 1.05 μg/l). All three oxidized metabolites correlated strongly among each other (ρ ≥ 0.76). MINCH was detected in one sample only and has to be regarded a weak marker of exposure. With this analytical method we are able to perform human metabolism studies to provide metabolic conversion factors and to investigate the extent of DINCH exposure in the general population.

Schütze A ，Pälmke C ，Angerer J ，Weiss T ，Brüning T ，Koch HM ... -  《-》

Hexamoll® DINCH and DPHP metabolites in urine of children and adolescents in Germany. Human biomonitoring results of the German Environmental Survey GerES V, 2014-2017.

The production and use of the plasticisers Hexamoll® DINCH (di-(iso-nonyl)-cyclohexane-1,2-dicarboxylate) and DPHP (di-(2-propylheptyl) phthalate) have increased after both chemicals were introduced into the market in the early 2000s as substitutes for restricted high molecular weight phthalates. During the population representative German Environmental Survey (GerES) of Children and Adolescents (GerES V, 2014-2017), we collected urine samples and measured the concentrations of DINCH and DPHP metabolites in 2228 and in a subsample of 516 participants, respectively. We detected DINCH and DPHP metabolites in 100% and 62% of the 3-17 years old children and adolescents, respectively. Geometric means of DINCH metabolites were 2.27 μg/L for OH-MINCH, 0.93 μg/L for oxo-MINCH, 1.14 μg/L for cx-MINCH and 3.47 μg/L for DINCH (Σ of OH-MINCH + cx-MINCH). Geometric means of DPHP metabolites were 0.30 μg/L for OH-MPHP, 0.32 µg/L for oxo-MPHP and 0.64 μg/L for DPHP (Σ of OH-MPHP + oxo-MPHP). The 3-5 years old children had almost 3-fold higher DINCH biomarkers levels than adolescents (14-17 years). Higher concentrations of DPHP biomarkers among young children only became apparent after creatinine adjustment. Urinary levels of DINCH but not of DPHP biomarkers were associated with the levels of the respective plasticisers in house dust. When compared to HBM health-based guidance values, we observed no exceedance of the HBM-I value of 1 mg/L for DPHP (Σ of OH-MPHP + oxo-MPHP). However, 0.04% of the children exceeded the health based guidance value HBM-I of 3 mg/L for DINCH (Σ of OH-MINCH + cx-MINCH). This finding shows that even a less toxic replacement of restricted chemicals can reach exposures in some individuals, at which, according to current knowledge, health impacts cannot be excluded with sufficient certainty. In conclusion, we provide representative data on DINCH and DPHP exposure of children and adolescents in Germany. Further surveillance is warranted to assess the substitution process of plasticisers, and to advise exposure reduction measures, especially for highly exposed children and adolescents. Providing the results to the European HBM Initiative HBM4EU will support risk assessment and risk management not only in Germany but also in Europe.

Schwedler G ，Conrad A ，Rucic E ，Koch HM ，Leng G ，Schulz C ，Schmied-Tobies MIH ，Kolossa-Gehring M ... -  《-》