Pollution Characteristics Of Phthalates In Northern Indoor Environments And Their Exposure Routes For Infants

Phthalates are a group of synthetic compounds with high productions and wide applications.Phthalates are widely used as plasticizers in many applications,such as polyvinyl chloride products,building materials,furnitures,personal care products,medical equipments,and children's toys.Phthalates have endocrine disrupting toxicity and reproductive and developmental toxicities,phthalates in products can release into the surroundings,and enter the human body via inhalation,ingestion,and dermal absorption,which might pose a potential health risk.As is known,while infants are developing,they are easily affected by phthalates.Infants generally spend more than 95% of time in the indoor environment,and there are much more potential phthalate sources in their homes than those in general homes,such as increased plastic products and foam floor mats,these might elevate the phthalate concentrations in infant living environment.To date,studies on human exposure to phthalates have focused on dietary and living habits of general population,and the exposure routes are limited,these studies cannot meet the infant case,due to their limited food and activity.In order to comprehensively and systematically study the pollution of phthalates in infant living environment,and the impact on the infants by the potential phthalate sources,twenty-five 3-to 6-month-old infants in Harbin were selected as participants.The environmental samples in their homes were collected to analyze the pollution characteristics and the partitioning behavior of the six common phthalates,including dust/gas-phase air partitioning and window film/gas-phase air partitioning.Additionally,combined with the infant potential phthalate source samples(breast milk,infant formulas,drinking water,medicines,infant cotton clothing,and baby powder)and infant excretion samples(urine and feces),exposure analysis of phthalates entering the infant body via different matrices and exposure routes were performed.According to our determination of phthalates in infant homes,phthalates were widely detected in infant homes,indicating that they are ubiquitous in infant homes.The median concentrations of the total phthalates in house air(gas phase+particle phase),dust,and window film were 1090 ng/m3,440 ?g/g,and 168 ?g/m2,respectively.Di-iso-butyl phthalate(Di BP),di-n-butyl phthalate(DBP),and bis(2-ethylhexyl)phthalate(DEHP)had the greatest contributions in infant homes.The result of the partitioning behavior between dust and gas-phase air and between window film and gas-phase air of phthalates suggests that the theory of steady state was more fitted with the dust/gas-phase air and window film/gas-phase air partitioning behavior of phthalates,than the theory of equilibrium,and it has been applied to the study on the partitioning behavior of semi-volatile organic compounds(SVOCs),including polycyclic aromatic hydrocarbons(PAHs),polybrominated diphenyl ethers(PBDEs),and organophosphate esters(OPEs).When the logarithm of octanol/air partition coefficient(logKOA)was greater than 11.5,SVOCs reached the maximum dust/gas-phase air partition domain,and the logarithm of dust/gas-phase air partition coefficient(logKD)was equal to-2.62;when logKOA>11.8,SVOCs reached the maximum window film/gas-phase air partition domain,and the logarithm of window film/gas-phase air partition coefficient(logKF)was equal to-1.55.Additionally,it indicated linear correlation among the concentrations of SVOCs,whose logKOA were less than 10.4 or greater than 11.8,in indoor air,dust,and window film.According to our determination of phthalates and their metabolites in infant potential phthalate sources(breast milk,infant formulas,drinking water,medicines,infant cotton clothing,and baby powder)and infant excretions(urine and feces),phthalates or their metabolites were found in these samples with different detection rates.According to our estimated exposure levels of phthalates for infants from different matrices and exposure routes,breast milk was found to be the greatest phthalate contributor via external exposure,followed by the indoor environment;among the 3 exposure routes,ingestion contributed the most,followed by dermal absorption.In different internal exposure routes,the route of urine was the main excretion pathway for phthalates.In comparison of external and internal exposure,the estimated daily intakes(EDIs)of phthalates for infants were greater than the estimated daily excretions(EDEs)of phthalates,suggesting that the residues of phthalates or their metabolites existed in infants' bodies.Based on the median values of the ratio of the EDIs of phthalates via external exposure routes to those via urine,which were corrected with the fue values,diethyl phthalate(DEP),DBP,and DEHP reached the mass balance,indicating that our study comprehensively considered all the exposure sources of DEP,DBP,and DEHP entering the infant body.In this study,combined with the previous studies worldwide,we extended and applied the steady state model of the particle/gas partitioning of PBDEs in the atmosphere to the partitioning between dust and gas-phase air and between window film and gas-phase air of phthalates in the indoor environment,and more SVOCs in the indoor environment.Additionally,based on our determination of phthalates and their metabolites in infant potential phthalate sources and infant excretions,we comprehensively and systematically analyzed the exposure routes of phthalates entering and exiting in the infants' bodies.Our results will provide the idea for studying the endocrine disruptors with lower volatilities,and lipophicities,and high metabolism entering the human body.