Occurrence,release Characteristics And Environmental Exposure Effects Of HBCD In Building Exterior Insulation Materials

BackgroundIn recent years,the number and scale of buildings in China have been growing.With the continuous improvement of energy-saving standards,the demand and supply of building external insulation materials（BEIM）have increased sharply.Since the 1960 s,hexabromocyclododecane（HBCD）,as an alicyclic brominated flame retardant with high bromine content,has been continuously used in organic BEIM.HBCD is added to polystyrene matrix in the form of physical mixing,which is easy to be released to the environment in various forms.HBCD has biological amplification effect,bioaccumulation,long-distance migration and a variety of toxic effects.It is very important to clarify the release characteristics of HBCD in BEIM,the largest source of HBCD storage and use in China,and its environmental health impact.ObjectivesThrough experimental measurement,enterprise and relevant literature investigation and emission list construction,this paper reveals the occurrence and release characteristics of HBCD in BEIM in China,discusses the possible environmental exposure health risks of HBCD release,in order to clarify the current situation and potential impact of HBCD disposal in China,and provide possible technical support and decision-making suggestions for the subsequent study of the migration law of HBCD in BEIM to different environmental media and the harmless disposal of HBCD in BEIM waste.Methods1.Select typical construction enterprises and garbage dumps in Luoyang,Henan Province with relatively concentrated capacity of thermal insulation materials to carry out sampling,and collect organic BEIM samples of expanded polystyrene（EPS）and extruded polystyrene（XPS）respectively according to different chemical compositions;The content of HBCD in the sample was analyzed qualitatively and quantitatively by triple four-stage rod gas chromatography-mass spectrometry（GC-MS）.2.Build the emission factor database of HBCD release in different stages of the whole life cycle of BEIM and the activity level database of BEIM in China,and calculate the emission characteristics of HBCD in organic BEIM by emission factor method.3.Through literature research,determine the concentration level of HBCD in ambient air in different regions,build a model system,calculate the daily average exposure dose of HBCD in different populations,and evaluate the possible non carcinogenic risk of atmospheric HBCD exposure in different populations.Results1.In BEIM,the diastereomer of brominated flame retardant HBCD is α-HBCD andγ-HBCD.The actual concentration of HBCD in XPS is significantly higher than that in EPS.The order of concentration of diastereomer of HBCD in XPS is as follows:α-HBCD> β-HBCD > γ-HBCD.The concentration order of HBCD diastereomers in HBCD and EPS is γ-HBCD > α-HBCD > β-HBCD.2.HBCD emission characteristics in different life cycle stages of EPS: thermal cutting0.82 t,natural release 3.90 t and 16008.72 g/L in landfill leachate;Emission characteristics from 2000 to 2020: thermal cutting 10.84 t,natural release 52.12 t and 211670.92 g/L in landfill leachate;Emission characteristics at the end of 2021: thermal cutting 8.29 t,natural release 39.86 t and 161866.00 g/L in landfill leachate;Emission characteristics from 2010 to 2017: thermal cutting 2.51-3.33 t,successively 2.51 t、2.68 t、3.06 t、3.33 t、3.30 t、2.77 t、2.83 t and 3.00 t;natural release 12.04-16.02 t,successively 12.04 t、12.88 t、14.71t、16.02 t、15.86 t、13.33 t、13.59 t and 14.44 t;landfill leachate 48914.02-65048.91 g/L,successively 48914.02 g/L、52294.86 g/L、59743.12 g/L、65048.91 g/L、64412.21 g/L、54118.99 g/L、55180.15 g/L and 58628.91 g/L.3.Emission characteristics of HBCD in different life cycle stages of XPS: thermal cutting 0.32 t,natural release 0.01 t and 10284.67 g/L in landfill leachate;Emission characteristics from 2000 to 2020: thermal cutting 4.21 t,natural release 0.19 t and135986.25 g/L in landfill leachate;Emission characteristics at the end of 2021: thermal cutting 3.22 t,natural release 0.14 t and 103989.49 g/L in landfill leachate;Emission characteristics from 2010 to 2017: thermal cutting 0.35-0.46 t,successively 0.35 t、0.37 t、0.42 t、0.46 t、0.46 t、0.38 t、0.39 t and 0.42 t;0.02 t for natural release;landfill leachate11183.24-14872.17 g/L,successively 11183.24 g/L、11956.20 g/L、13659.10 g/L、14872.17g/L、14726.60 g/L、12373.25 g/L、12615.87 g/L 和 13404.36 g/L.4.In the 10 cities or regions at home and abroad involved in the study,the order of non carcinogenic risk values of children and adults is Prague > Laizhou Bay > Beijing >South Korea > Brno > Dalian > Shanghai > Guangdong > the Great Lakes basin> Chicago.The non carcinogenic risk of children is higher than that of adults.ConclusionsBased on the measured concentration level and diastereomer distribution characteristics of HBCD in organic BEIM,this study constructed the emission factor database of HBCD release at different stages in the whole life cycle of BEIM and the activity level database of BEIM in China,calculated the emission characteristics of HBCD in organic BEIM,and evaluated the possible non carcinogenic risk of atmospheric HBCD exposure in different populations.It is found that the actual concentration of HBCD in XPS is obviously higher than that in EPS,and there is no obvious difference between the HBCD and XPS isomers in XPS and EPS foam plates.Diastereomers of HBCD α-HBCD and γ-HBCD Mainly.HBCD emission characteristics in different life cycle stages of EPS: thermal cutting 0.82 t,natural release 3.90 t and 16008.72 g/L in landfill leachate.Emission characteristics of HBCD in different life cycle stages of XPS: thermal cutting 0.32 t,natural release 0.01 t and 10284.67g/L in landfill leachate.The calculated value of noncarcinogenic risk shows that the health impact of atmospheric HBCD on children is higher than that of adults.