Plastics are widely used in modern life, and their unbound chemicals Bisphenol A and Phthalates, which are important chemical-building blocks, can leach out into the surrounding environment. They are also ubiquitous contaminants in the human body, wildlife, and the environment. BPA and PAEs have recently attracted the special attention of the scientific community, regulatory agencies, and the general public because of their high-production volume, widespread use of plastics, and endocrine-disrupting effects.
TopBisphenol A
BPA is (4,4-isopropylidenediphenol 2,2-bis(4- hydroxyphenyl)-propane). an organic synthetic compound with the chemical formula (CH3)2C(C6H4OH)2 belonging to the group of diphenylmethane derivatives and bisphenols, with two hydroxyphenyl groups. It contains two functional phenol groups that allow the chemical to interact with estrogen and androgen receptors as both an agonist and antagonist. (Michalowicz J. 2014) BPA is classified as a xenoestrogen (environmental estrogen). Its ability to stimulate the estrogen receptor further classifies it as an endocrine disrupting chemical (EDC). (Vandenberg LN, et al.2007. Vandenberg LN, et al. 2009) (The estrogenic activity of BPA has been estimated to be 1/1,000 to 1/10,000 of that of 17β- estradiol. (Guo H, et al.2010)
BPA is contained in polycarbonate plastics and epoxy resins and is used in the production of polyvinyl chloride. (Rosenfeld CS. 2015) Items containing BPA include children's toys, dental sealants, lining of water pipes, food and beverage containers such as plastic water bottles, food packaging and the inner coating of cans and bottles. (Konieczna A, Rutkowska A, Rachon D. 2015) It estimated that each year greater than 15 billion pounds of BPA are produced and over 100 tons are released into the atmosphere. The primary route of exposure of BPA is oral, mainly from eating or drinking from products containing BPA. Other potential exposures include inhalation from dust particles and atmospheric exposure. Once the compound is introduced via the oral route it is absorbed in the gastrointestinal tract and undergoes hepatic metabolism including oxidation and hydrolysis, which leads to the production of several metabolites including BPA monosulfate, BPA glucuronide, and BPA disulfate. (Matthews JB, Twomey K, Zacharewski TR, 2001) These metabolites then undergo conjugation and can be excreted in the urine and feces. The presence of BPA and its metabolites can be measured in bodily fluids, including urine and serum, by using the combined techniques of solid-phase extraction coupled with isotope dilution high-performance liquid chromatography and mass spectrometry.(Vandenberg LN, et al. 2010) Small studies have estimated the half-life of excretion of urinary BPA to approximate 4-5 hours.(Stahlhut RW, Welshons WV, Swan SH. 2009)Subsequent pharmacokinetic analyses suggest that the rate of excretion of BPA is not greatly affected by fasting, implying that either BPA is excreted slowly from the body or there exists other significant areas of exposure beyond dietary routes.
TopPhthalates
Phthalates are synthetic diesters of phthalic acid- dialkyl- or alkyl/aryl esters of 1,2-benzenedicarboxylic acid. (North ML, et al. 2014). The chemical structures of each individual phthalate vary, mostly according to their side chains and molecular weight. They can be grouped into two broad categories: low molecular weight and high molecular weight. Low molecular weight phthalates include dimethyl phthalate (DMP), diethyl phthalate (DEP), and dibutyl phthalate (DBP). High molecular weight phthalates include diethyl hexyl phthalate (DEHP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP) and benzyl butyl phthalate (BBzP).