Distribution,Accumulation,Transformation And Risk Assessment Of Bisphenol Compounds

Bisphenol compounds?BPs?,one of the environmental endocrine disrupters,are widely used in industrial and consumer products such as coatings,membrane materials,electronic products,packaging materials,and other consumer goods.Even at low concentrations,BPs have the potential to disrupt the endocrine system of humans and animals,and affect their reproductive and developmental process.Research on environmental toxicology,environmental behavior and safety assessment of BPs are among the hot topics in environmental science.To date,a lot of studies have been conducted on environmental exposure and risk assessment of bisphenol A?BPA?,however,information on environmental behavior and risk assessment on its alternatives,i.e.,other bisphenol compounds,are limited with most of the reports focusing on the determination of BPs in food,heat-sensitive paper,dust and surface water.Distribution of BPs in school supplies and learning materials and the health risk assessment is scarce.In this study,the analysis method of BPs in school supplies and learning materials at micro or trace level was developed.The distribution of 16 BPs in school supplies and learning materials was analyzed and the health risk assessment was explored.In addition,the uptake,distribution,bioconcentration and biotransformation of bisphenol S?BPS?,one of the most commonly used BPA substitutes,were studied in SD rats by intragastric infusion method.Main results in this thesis are as follows:1.An analysis method for BPs in school supplies and learning materials at trace level was successfully established through the optimization of sample pretreatment?i.e.,SPE column,extractant,extraction times and reconstruction volume,etc.?.The methods were as follows:?1?For the paper samples:The sample was extracted twice with 8 ml acetonitrile by sonication for 15 min each time,followed by centrifugation at 4000 rpm for 15min.The combined supernatant was purified using PEP column.The recovery of 16 BPs ranged from 79.59%to 131.22%.?2?For the cloth sample:The sample was extracted three times with 8 ml MTBE by sonication for 15 min each time,followed by centrifugation at 4000 rpm for 15min.The recovery of 16 BPs ranged from 64.37%to 129.11%.?3?For rubber samples:The sample was extracted twice with 8 ml methanol by sonication for 15 min each time,followed by centrifugation at 4000 rpm for 15min.The recovery of 16 BPs ranged from 63.23%to 137.47%.?4?For plastic materials:The sample was extracted twice with 8 ml methanol by sonication for 15 min each time,followed by centrifugation at 4000 rpm for 15min.The recovery of 16 BPs ranged from 57.01%to 120.94%.2.The concentrations and distribution characteristics of 16 BPs in 15 kinds of student supplies?n=121?were studied.The risk assessment of 16 BPs was evaluated by the total daily intake of 16 BPs in general and occupational exposure group,respectively.The results showed that BPA,BPF and BPS had higher concentrations?median concentration:160.99 ng/g,23.64 ng/g and 14.11 ng/g?and higher detection frequencies?93.15%,85.62%and 82.53%?in school supplies.The detection level and frequency of BPPH,BPE,4-CP and BPB were relatively high as well.TBBPA was detected in 14.04%of the samples,especially in document bags,schoolbags,automatic pencils and neutral pens,with concentrations of<LOQ-1.2445 mg/g.The median BW-EDI values of?₁₆BPs were 0.4120 ng/?kg·d?and 2.4111 ng/?kg·d?for general exposure group and occupational exposure group,respectively.3.The uptake,distribution,bioconcentration and biotransformation of BPS were studied in SD rats by intragastric infusion method.BPS was immediately accumulated in the stomach with a concentration of up to 2765260±708865 ng/g dw within 1 h,and decreased rapidly to 3983±1302 ng/g dw thereafter.The concentrations of BPS in intestinal tract and feces increased rapidly in 6 h after exposure,and reached 252653±27481 ng/g dw,while up to 344043±35079 ng/g dw BPS was detected in feces at 12h.The concentration began to decrease at 12 h after exposure,and kept almost unchanged.At 168 h,the concentration of BPS was 1086±120 ng/g dw,985±549ng/g dw and 4653±956 ng/g dw,respectively,in intestinal contents,intestinal wall and feces.Additionally,the content of BPS increased rapidly within 1 h after exposure in other organs?brain,heart,kidneys,spleen,lung,liver and testis?,then decreased slowly.A total of 4 metabolites in rats,i.e.,TP 408,TP 328,TP 300 and TP 196 were identified by UPLC-MS/MS after 168 h exposure.The hydroxylation,the conjunction with oxalic acid,the cleavage of S-C band and the following alkylation and recombination contributed to the transformation of BPS in rats.