A Study Of Dermal Exposure Of Phthalates Among Adults And Children In Southern China

Phthalates are widely used in industrial production and daily life as universal plasticizers and solvents.Phthalates are released into the environment during production,consumption and waste disposal.High concentrations of phthalates have been found in air,indoor dust,soil and sediment,which makes them become organic pollutants of concern.Individual exposure to phthalates occurs via ingestion,inhalation and dermal absorption,and their metabolites were also frequently detected in human urine,blood and breast milk.However,there were very limited evidences for the introduction of phthalates through dermal exposure pathways,particularly lack of studies that systematically assess their contribution to individual dermal exposure.In this study,paired handwipes and urine samples were collected from adults（n=130）and children（n=82）in a typical urban community from southern China,to examine the relationships between external and internal exposure,as well as the contribution of dermal adsorption to the internal exposure of phthalates.The results showed that the concentrations and composition profiles of phthalates were similar in handwipes for both adults and children,containing mainly di-2-ethylhexyl phthalate（DEHP）,di-n-butyl phthalate（Dn BP）,and di-iso-butyl phthalate（Di BP）,were 100%detected in handwipe samples of adults and children.The median concentrations were 6.39×10~5 ng/m~2 and 3.91×10~5 ng/m~2 for DEHP,3.72×10~4 ng/m~2and 4.47×10~4 ng/m~2 for Dn BP and 1.87×10~4 ng/m~2 and 1.29×10~4 ng/m~2,for Di BP,respectively.The major metabolites of these phthalates,i.e.,mono-n-butyl phthalate（mn BP）from Dn BP,mono-iso-butyl phthalate（mi BP）from Di BP,and three metabolites of DEHP（m EHP,m EHHP and m EOHP）were also widely detected in all paired urine samples.The composition profiles of the metabolites of phthalates were also similar for adults and children.However,the urinary levels of three metabolites of DEHP in children were significantly higher than that of adults（58.4 ng/m L for children and 36.4 ng/m L for adults,p<0.01）,while relatively higher urinary levels of mn BP and mi BP were found for adults,which may be due to the different in exposure and metabolic pathways between children and adults.Positive correlations were found between contamination levels of Di BP and Dn BP in handwipes and their corresponding urinary metabolites mi BP and mn BP.The correlation coefficients between Dn BP and mn BP（r=0.227,p<0.01 for adults and r=0.212,p<0.05 for children）were slightly higher than those for Di BP and mi BP（r=0.202,p<0.05 for adults and r=0.187,p<0.05 for children）,While no significant correlation was observed for DEHP.This indicated that dermal adsorption might be an important exposure pathway particularly for these low molecular weight phthalates.As compared with adults,the proportion of dermal uptake to the internal exposure of phthalates was clearly higher for children.Our study clearly shown that dermal adsorption was a non-negligible exposure pathway for phthalates,with children are particularly sensitive,should be include in future exposure and risk assessments.