Indoor Pollution Charateristics And Health Risk Assessment Of SCCPs In North China

Short chain chlorinated paraffins?SCCPs?are high production volume chemicals used as plasticizer and flame retardant,which meet the Stockholm Convention criterial for persistence,bioaccumulation and long-range transport.SCCPs are widely used in many kinds of household products and can enter human body,consequently causing adverse effects to human health.Since human beings are generally exposed to contanminants in indoor environment,it is very important to identify the concentration levels and compositon features,sources and fate of SCCPs in indoor environment for better understanding of human health risk assessment.Indoor dustfall and indoor air samples were collected in Harbin city to analyze the concentration levels and compositon features of SCCPs in different types of indoor environments.It showed that SCCPs levels in indoor dustfall in Harbin city ranged from 10.1 to 173 ?g/g.The most abundant compounds in indoor dustfall samples were homologues of C₁₃ group?35.8%?,Cl₇ group?32.4%?and N₂₀?21.0%??N is the total number of C and Cl?group.In the five microenvironments,commercial stores were more frequently exposed to shorter carbon chained(C_10,11),higher chlorinated(Cl_8-10) and lower molecular weight (N_15-18)homologues in indoor dustfall.The SCCPs levels in indoor air in Harbin city ranged from 94.3 to 693 ng/m³.The most abundant compounds in indoor air samples were homologues of C₁₀ group?41.7%?,Cl₆ group?42.9%?and N₁₇ group?26.1%?.On the basis of monitoring data,the potential sources of SCCPs indoor environments were idendified using multiple linear regression of factor score model and correspondence analysis.Three potential sources for SCCPs were identified in indoor dustfall in Harbin city,including an unknown source,technical mixtures of CP–52b?52% chlorine,w/w?and CP–42?42% chlorine,w/w?,with contributions of 38.7%,32% and 29%,respectively.Two potential sources for SCCPs were identified in indoor air in Harbin city,including technical mixtures of CP–42?64.1%?and CP–52b?31.3%?.It showed that CP–42 was the major source of shorter carbon chained and lower chlorinated homologues,while CP–52b was the major source of longer carbon chained and higher chlorinated homologues in indoor environment.The analysis of dustfall-gas phase distribution charateristics showed that shorter carbon chained,lower chlorinated and lower molecular weight SCCPs homologues were enriched in indoor air.Inversely,longer carbon chained,higher chlorinated and higher molecular weight SCCPs homologues were enriched in indoor dustfall.The distribution and exchange patterns of SCCPs in indoor environment were futher explored by introducing dustfall-gas phase partition coefficient?KD?and fugacity ratio?ff?.It showed that the environmental behaviors of SCCPs in indoor environment were depend on their KOA values.Higher KOA value induced higher K'D value,lower K'D/KD value and lower ff,leading to a transference of SCCPs from gas phase to dustfall.In this case,gas phase and dustfall play roles of source and sink,respectively.On the other hand,lower KOA value induced lower K'D value,higher K'D/KD value and higher ff,leading to a transference of SCCPs from dustfall to gas phase,herein gas phase and dustfall play roles of sink and source,respectively.Before health risk assessment,developmental toxicities of SCCPs were observed and compared using zebrafish embryos and larvae as a sensitive model.Observations on malformation,survival rates,hatching rates and thyroid hormone levels indicated that the C₁₀-groups were more toxic than the C₁₂-groups and Cereclor 63 L.C₁₀H₁₈Cl₄ significantly decreased the m RNA expression of tyr,ttr,dio2 and dio3 at a dosedependent manner suggesting that the specific mode of actions differ with different congeners.C₁₀H₁₈Cl₄ might inhibit T3 production through the inhibition effect on dio2.These results indicated that the developmental toxicity of SCCPs increased with decreasing carbon chains.On the basis of monitoring data and results of SCCPs developmental toxicity,human exposure and health risk of SCCPs were calculated and evaluated by using SCCPs exposure models.It demonstrated that the daily exposure doses and hazard quotients?HQ?from indoor dustfall and indoor air for different age groups were all below the reference doses and threshold values,respectively,which implied SCCPs in indoor environment do no cause health risk yet.In addition,the total daily exposure dose of SCCPs via indoor environment and dietary exposure for infant,toddler,children,teenager and adult were calculated to be 12.3?0.815?0.543?0.385 and 0.295 ?g/kg-bw·day,respectively.Infant group exceeded the reference doses?Rf Ds?for neoplastic effects recommended by International Program on Chemical Safety?IPCS?,indicating SCCPs cause potential health risk for infants.Futhermore,SCCPs-NC homologue exposure charateristics and developmental health risk for infants and toddlers were evaluated depend on results of developmental toxicity of SCCPs.The daily exposure dose of C_10,11 homologues was calculated to be 9.781 ?g/kg-bw·day for infants,which might be potential to cause developmental health risk for infants.Taking together,total daily exposue of SCCPs,especially C_10,11 homologues exposure should be concerned in SCCPs health risk control policy for infant.Overall,the comprehensive analysis on the pollution charateristics in indoor environment and developmental toxicity of SCCPs in zebrafish embryo model supplied with important basic data for daily exposure dose and health risk assessment of SCCPs for different age groups,especially for developmental health risk assessment of C_10,11 homologues for infant group.Our results on the pollution charateristics and human exposures of SCCPs will be useful to provide a better understanding of SCCPs behaviors in indoor environment,and to support environmental risk evaluation and regulation of SCCPs in China.