Environmental occurrence, human exposure, and endocrine disruption of di-iso-nonyl phthalate and di-iso-decyl phthalate: A systematic review

Di-iso-nonyl phthalate (DINP) and di-iso-decyl phthalate (DIDP) have been employed increasingly as plasticizers to replace di-(2-ethylhexyl) phthalate (DEHP), a hormonal disruptor. Through this systematic review, we reviewed their (1) contamination levels in the environmental media, foods, and consumer products, (2) human exposure levels in national biomonitoring studies, and (3) associations with human sex and thyroid hormone disruption. PubMed, Scopus, and Web of Science were searched and eligible studies were identified. DINP and DIDP were found at higher concentrations in indoor environments, especially with high human activity and PVC use. In foods, contamination levels vary by production methods and tend to be higher in fatty foods. In children’s products, both plasticizers were more highly detected in samples measured before 2010. National biomonitoring data from several countries demonstrated that urinary levels of DINP and DIDP metabolites were relatively lower than those of DEHP. However, exposure to DINP has been associated with anti-androgenic potential in male offspring and adults and decreased thyroid hormones in mother–child pairs. In conclusion, existing literatures demonstrated widespread occurrence of DINP and DIDP in the indoor environment, diet, and children’s products, and in the human populations worldwide. At the current levels of exposure, DINP exhibited endocrine disruption potentials similar to those of DEHP, especially among males and pregnant women. Knowledge gaps in DIDP exposure among the human population were identified and should be considered for future studies.