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.