| Organophosphate esters（OPEs）and phthalic acid esters（PAEs）are two types of semi-volatile organic pollutants that are commonly used as new flame retardants,plasticizers and additives in construction materials,plastic products,electronic devices and furniture making materials.Since OPEs and PAEs are not chemically bonded with materials,they tend to escape from materials during use and thus enter environmental media.So far,OPEs and PAEs have been widely detected in various environmental media and have become typical organic pollutants in the environment,thus their environmental pollution and ecotoxicological effects have attracted more and more attention worldwide.Since December 2019,the coronavirus pandemic（COVID-19）has posed a significant threat to human health.Wearing face masks is known as an effective measure for controlling the wide spread of COVID-19 and its variants.But on the other hand,face masks may be a potential source of contamination for human exposure to OPEs and PAEs.PAEs and OPEs could be released from masks during prolonged wear and ingested into the body with human respiration,thus posing a potential health risk to humans.However,knowledge associated with the occurrence,release behavior,as well as inhalation risks of OPEs and PAEs in masks is limited.In this study,the following three parts are discussed:（1）∑11OPEs and∑6PAEs were detected in 9 masks ranging from 36.7 to 855 ng/g and from 251 to 3827 ng/g,respectively.The average concentrations of OPEs were in the following:N95 masks（855 ng/g）>disposable medical masks（189 ng/g）>medical surgical masks（184 ng/g）>KN95 masks（117 ng/g）>masks for children（36.7 ng/g）.The average concentrations of PAEs were as follows:medical surgical masks（2185 ng/g）>KN95 masks（1534 ng/g）>disposable medical masks（1204 ng/g）>N95 masks（595ng/g）>masks for children（537 ng/g）.The concentrations of OPEs and PAEs in the masks for children were lower than those in all types of masks for adults,that is also consistent with our strict regulations on the addition of chemicals to children’s direct contact products.Among all samples,tri-n-butyl phosphate（TNBP）,tripropyl phosphate（TPr P）,tri（1,3-dichloro-2-propyl）phosphate（TDCIPP）and triphenyl phosphate（TPh P）were the four monomers with the highest frequency of detection（DFs）of OPEs,with DFs of 100%,88.9%,88.9%and 88.9%,respectively.In terms of composition,the average percentages of TNBP,TPr P,TDCIPP and TPh P were 10.7%,1.45%,22.9%and 20.3%,respectively.Dimethyl phthalate（DMP）,diethyl phthalate（DEP）and di-n-butyl phthalate（Dn BP）were the three monomers with the highest DFs among PAEs,all with 100%DFs.The average composition of DMP,DEP and Dn BP accounted for 8.71%,1.08%and 28.3%.It can be seen that the monomer composition of OPEs and PAEs varies from one mask sample to another,but in general,TNBP,TEP,TPh P and TDCIPP were the most dominant OPEs monomers in the masks,and Di BP and Dn BP were the most abundant PAEs substances in the masks.（2）The release behaviour of OPEs and PAEs in masks and the risk of human intake were investigated by constructing a mask release and human inhalation model.The release results showed that there were significant differences in the release behaviour of disposable medical masks and N95 masks,with the release of OPEs from disposable medical masks concentrated in the first 4 hours,and the release of OPEs from N95 masks was slow over 12 hours,while the release of PAEs from both masks was concentrated after 4 hours.The trendency in the content of TCP and DEHP in disposable medical masks over time was in good agreement with the exponential decay curve,with R2 values of0.985 and 0.941 respectively.A porous and easily adsorbable polyurethane foam（PUF）was used to simulate the human inhalation process,and a significant negative correlation（P<0.05）was found between the decrease in OPEs in the mask and the increase in OPEs in the corresponding PUF during the simulation.It indicates that the OPEs released from the masks can be well captured by PUF,and the trends of capturing and absorbing TCP（R2=0.999）and DEHP（R2=0.986）in disposable medical masks correspond to exponential growth curves.In this study,the inhalation exposure risk of OPEs and PAEs was estimated based on the increment of contaminants in PUFs,and the daily intake（EDI）,hazard index（HI）and carcinogenic risk（CR）were calculated,and the results showed that the total EDIinhalation of OPEs and PAEs ranging from 0.04 to 4.69 ng/kg bw/day and 0.04to 15.8 ng/kg bw/day and increasing over time,with HI values ranging from 1.91×10-6to 2.57×10-4 and 3.72×10-7 to 7.89×10-4,respectively,and cumulative CR values ranging from 7.48×10-9 to 3.51×10-7 and from 7.57×10-9 to 4.36×10-7,respectively.The values obtained were all within the safety threshold levels,indicating that the risk of inhalation exposure to OPEs and PAEs from breathing through the mask alone does not pose a safety risk when the mask is worn continuously for no more than 12 h.However,overall it appears that reducing the duration of wear can reduce the inhalation risk of OPEs and PAEs from the mask.（3）Photodegradation studies based on mask substrates show that OPEs selectively absorb different wavelengths of light,and they can absorb more photons in the UVC band of light.The application of UV light significantly increased the rate of degradation of OPEs,and the longer the light exposure time,the more energy was absorbed by OPEs and the more they were degraded.The photodegradation of OPEs in the mask matrix under unhumidified conditions was in accordance with the primary kinetic reaction,and the OPEs were degraded faster and with shorter half-lives in the disposable medical mask matrix compared to the N95 mask matrix.The degradation rates in the disposable medical masks of TCP,2-ethylhexyl diphenyl phosphate（EDHPP）,TNBP,tributyl ethyl phosphate（TBEP）and TDCIPP increased by 7.02%,8.32%,39.1%,83.6%and 257%,respectively,compared to those in the N95 masks.The degradation pathways of TBEP included hydroxylation,oxidation and hydrolysis reactions,while the degradation pathways of TCEP,TCIPP and TDCIPP were all hydrolysis reactions.Finally,the ecotoxicity of all degradation products was predicted using the Ecological Structure-Activity Relationship（ECOSAR）software model,and the results showed that the degradation products of these four monomers were less ecotoxic than the parent compounds.The results of this study provide comprehensive basic data for understanding the environmental behavior and the risk of human ingestion of PAEs and OPEs in masks. |
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