Novel Analytical Method And Human Exposure Risk Assessment Of Microplastics In Complex Environmental Matrices

Microplastics(MPs)is an important emerging pollutant,which exists widely in the environment.Release of various additives from MPs,adsorption of environmental organic pollutants by MPs,and transportation to human body are able to cause several adverse effects and pose serious threats to human health,including oxidative stress,cytotoxicity,inflammation and reproductive toxicity.At present,most researches mainly focused on the quantitative concentration of MPs using density separation method as a pretreatment procedure for MPs analysis in various environmental matrices.However,the mass concentration is also one of the important indicated parameters to evaluate the pollution status of MPs,which has not been greatly concerned.The measurement of mass concentration can reflect the occurrence level of MPs in environmental matrices and provide basic data for the overall assessment and monitoring of environmental pollution of MPs.Therefore,it is particularly important to establish mass concentration measurement technology of MPs for the human exposure risk assessment.To accurately measure the mass concentration of MPs in samples,a selective-purification procedure based on solubility parameter(δ)calculation was developed in this study.The technical roadmap of accelerated solvent extraction(ASE)-selective precipitation of MPs-Fourier Transform infrared spectroscopy(FTIR)analysis was established.Six types of MPs [polypropylene(PP),polyethylene(PE),polystyrene(PS),polycarbonate(PC),polyvinyl chloride(PVC)and polyethylene terephthalate(PET)] were spiked into sediments for method development.The obtained extract was treated in three different ways:(a)direct filtration;(b)concentration;(c)adjust solubility parameters of the solvent system after concentration.The effect of three kinds of purification treatments was evaluated.The results indicated that the recoveries of MPs increased obviously with the increase of│Δδ│ value between the solubility parameters of the solvent system and the MPs.Besides,the interference of FTIR analysis could be removed obviously by increasing the │Δδ│ value.The established method was successfully applied to the analysis of 30 sediment samples.Four kinds of MPs were detected,and their occurrence characteristics were consistent with the previous reports.In order to evaluate the exposure risk of MPs to human body,the solubility parameter method was further applied to indoor dust samples collected from laboratories and dormitories in this study.The results indicated that the detection rate of MPs was 80.65%.The average concentrations of MPs in laboratories and dormitories were 12.26 mg/g and 14.05 mg/g,respectively.The types of microplastics detected by FTIR were PET,PP+PE copolymer,PP and PC.Compared with existing literature reported,the concentration of MPs in indoor dust of this study was at a moderate level.Two exposure models were used to calculate the estimated daily intake(EDI)value of microplastics in indoor dust.The comprehensive comparison with the existing reported human exposure data showed that EDI value of adults in this study was at a moderate level,which indicated that human exposure risk of MPs in indoor environment could not been ignored.This work provided technical support to meet the need of accurate measurement of MPs in complex environment solid matrices.