Exposure Assessment Of Phthalate Pollution In Indoor Environment And Skin Surface

Phthalate acid esters(PAEs)are widely used as plasticizers in the manufacturing process of daily products.The occurrence of PAEs is commonly reported in indoor environment.Exposure to PAEs has been linked to the dysfunction of reproductive system,endocrine system and respiratory system.Therefore,detailed information on indoor concentration and exposure pathway is important for predicting,estimating and controlling health risks.External exposure estimates usually predict phthalate concentrations using equlibirum model.Dermal exposure includes complex pathways.However,the comprehensive effects of environmental concentrations and human behaviors on dermal exposure are not clear yet.And there is limited method for conveniently and accurately estimating total dermal exposures.On the other hand,most investigations have not given the information about the health risk categories.The age sensitivity has been seldom used in the selection of benchmarks for risk estimates.Therefore,relevant studies have been carried out and presented in this dissertation.The primary conclusions are as follows:Firstly,the phthalate gas-and dust-phase levels were studied in Chongqing residences for the first time.It showed that phthalate pollution was still pervasive in Southwestern China.Predominant compounds were DiBP,DnBP and DEHP.The steady state between multi-phases can be hardly reached in real environment by analyzing the partitioning between gas-and dust-phase levels.The particle-phase concentrations were predicted based on equilibrium and dynamic models.The results indicated that the airborne concentrations could be overestimated by 1.6-2.4 times when using an equilibrium model.These findings provide guidance for better estimating indoor phthalate concentrations for external exposure assessment.Secondly,the relationships between hand washing,environmental concentrations and handwipes were studied.A dermal exposure modifying factor was carried out for describing the relationship between total dermal absorption and gas-phase absorption.Except for DiBP,handwipe concentrations in the “less than 2h” hand washing group were roughly 25-52% less than those in the “more than 2h” group.Using linear regression,DEHP levels in the palms were found to be more influenced by hand washing behaviors and dust-phase concentrations than by gas-phase concentrations.The dermal exposure modifying factor for DiBP,DnBP and DEHP was 1.4,2.7 and 2.2,respectively.These results provide basis for accurately and conveniently estimating total exposure via dermal pathway.Finally,based on “Safe Harbor Level” and age sensitivity factor,a method for assessing the reproductive and carcinogenic risks for phthalate exposures was carried out using environmental concentrations and dermal exposure modifying factor.For DEHP,non-dietary ingestion was the most predominant pathway,and the contributions for inhalation and dermal absorption were comparable.For DEP,Di BP and DnBP,dermal exposure was the most important.For DMP,inhalation and dermal absorption were equally important.It indicated that children's exposure to DnBP had considerable reproductive risk,whereas exposure to DEHP might lead to carcinogenic risk.The reproductive risk from DnBP was high for adults.These results provide basis for controlling exposure to PAEs and corresponding health risks for Chinese population.