Cumulative risk assessment of phthalate exposure of Danish children and adolescents using the hazard index approach

Human risk assessment of chemicals is traditionally presented as the ratio between the actual level of exposure and an acceptable level of exposure, with the acceptable level of exposure most often being estimated by appropriate authorities. This approach is generally sound when assessing the risk of individual chemicals. However, several chemicals may concurrently target the same receptor, work through the same mechanism or in other ways induce the same effect(s) in the body. In these cases, cumulative risk assessment should be applied. The present study uses biomonitoring data from 129 Danish children and adolescents and resulting estimated daily intakes of four different phthalates. These daily intake estimates are used for a cumulative risk assessment with anti-androgenic effects as the endpoint using Tolerable Daily Intake (TDI) values determined by the European Food Safety Authorities (EFSA) or Reference Doses for Anti-Androgenicity (RfD AA) determined by Kortenkamp and Faust [Int J Androl 33 (2010) 463] as acceptable levels of exposure. United States Environmental Protection Agency Reference Doses (US EPA RfD) could not be used as none of them identifies anti-androgenic effects as the most sensitive endpoint for the phthalates included in this article. Using the EFSA TDI values, 12 children exceeded the hazard quotient for the sum of di-n-butyl phthalate and di-iso-butyl phthalate (?DBP(i+n)) and one child exceeded the hazard quotient for di-(2-ethylhexyl)phthalate (DEHP). Nineteen children exceeded the cumulated hazard index for three phthalates. Using the RfD AA values, one child exceeded the hazard quotient for DEHP and the same child exceeded the cumulated hazard index for four phthalates. The EFSA TDI approach thus is more restrictive and identifies ?DBP(i+n) as the compound(s) associated with the greatest risk, while DEHP is the compound associated with the greatest risk when using the RfD AA approach.