Hoá Chất Biosphenol A an toàn hay không?

Introduction For the last 50 years, bisphenol A (BPA – CAS Nọ 80-05-7) is a chemical used primarily to make polycarbonate plastic and epoxy resins. Polycarbonate plastic possesses a unique balance of toughness, optical clarity, high heat resistance, and excellent electrical resistance and has many industrial uses including media products (eg., CDs, DVDs), electronic equipments, sport equipments, bicycle helmets, food containers, drink containers, baby bottles, medical devices and many other products. Epoxy resins are commonly used to coat metal cans to protect the safety and integrity of canned foods and beverages and also are used as dental sealants. Exposure...
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Hoá Chất Biosphenol A an toàn hay không? Hoá Chất Biosphenol A an toàn hay không? Introduction For the last 50 years, bisphenol A (BPA – CAS Nọ 80-05-7) is achemical used primarily to make polycarbonate plastic and epoxy resins.Polycarbonate plastic possesses a unique balance of toughness, opticalclarity, high heat resistance, and excellent electrical resistance and has manyindustrial uses including media products (eg., CDs, DVDs), electronicequipments, sport equipments, bicycle helmets, food containers, drinkcontainers, baby bottles, medical devices and many other products. Epoxyresins are commonly used to coat metal cans to protect the safety andintegrity of canned foods and beverages and also are used as dental sealants. Exposure to BPA Human exposure to BPA is via the use of plastic containers, bottles,food and beverage cans and dental sealants. BPA has been found to leachfrom bottle and can liners and migrates into foods and beverages.Researchers from government agencies, academia, and industry worldwidehave studied the migration potential of BPA from polycarbonate productsinto foods and beverages. These studies consistently show that the level ofBPA migrating into food is extremely low, generally less than 5 parts perbillion under conditions typical for uses of polycarbonate products.Although BPA may be found in canned beverages and foods, it occurs onlyat extremely low levels (generally less than 37 parts per billion). Why BPA is of concern? In recent years, a “low dose hypothesis” has been advanced claimingthat exposure to extremely low doses of certain substances could causeadverse health effects in humans, including disruption of normal hormonalfunctions. According to this low dose hypothesis, reproductive anddevelopmental effects may result from exposure to low doses of BPA sinceBPA was considered as having estrogenic activity in ovariectomized rats(Dodds and Lawson, 1936). In 1970, Bitman and Cecil assayed DDT and 52structurally related compounds (including BPA) in immature rats and theauthors reported an increase in uterine glycogen content. According to somescientists, BPA thus mimics estrogen, a hormone that controls thedevelopment of the brain, the reproductive system and many other systemsin the developing fetus and therefore BPA is an endocrineđisruptingchemical and may harm the fetuses, infants, children or subsequently, adults. What is an endocrine disrupting chemical? Many chemicals are capable of disrupting the endocrine system ofanimals including fish, wildlife, and human and are referred to asendocrineđisrupting chemicals (EDCs). Indeed, our hormonal systems canbe disrupted by numerous different anthropogenic chemicals including anti-androgens, androgens, estrogens, AhR agonists, steroid-hormoneantagonists, retinoid agonists, anti-thyroid substances, etc. Many of theassociations between EDCs and human health effects remain controversial,but others, like the effects of diethylstilbestrol (DES), the androgenic drugsdanazol and methyltestosterone, and aminoglutethimide are widelyrecognized. Recently, the increased availability of androgen products forcutaneous application has increased the risk of virilization in childrenthrough skin contact. Estrogen containing shampoos and skin oils wereshown to be causative factors for pseudo-precocious puberty in girls andgynecomastia in boys. EDCs are not limited to pharmaceutical agents butextend to industrial chemicals. In fact, the effects of PCBs (polychlorinatedbiphenyls) on human neurological and immune development are wellknown. Children exposed to PCBs in utero or in the early developmentalstages have lower birth weight, reduced IQ and cognitive abilities, reducedsperm motility, and reduced in fertilizing capacitỵ Several phthalate esters,used as plasticizers, are antiandrogens, which gives cause for concern.Nowadays, US scientists also express concern about the potential role ofECBs in increasing trends in obesity and type II diabetes noted in the generalpopulation. Is bisphenol-A an endocrineđisrupting chemical? From previous investigations, BPA exhibits extremely weak hormonalactivity in in vitro assays and in laboratory animals at high doses. In morerecent years, extensive studies were conducted to determine if BPA couldcause reproductive or developmental adverse effects. In no study has BPAbeen shown to be a reproductive or developmental toxicant. The “lowđosehypothesis” for BPA has been thoroughly tested by numerous investigatorsand agencies and the consistent lack of lowđose effects found in thesestudies raise doubt about the validity of the “lowđose hypothesis”. Data fromthe University of Arizona (Pritchett et al., 2002) indicated that, in humans,BPA is rapidly metabolized to a hormonally-inactive form and excretedrapidly from the bodỵ Collectively, the weight of evidence provided by thesestudies demonstrates that BPA is not an endocrineđisrupting chemical andthere is no basis for human health concerns from exposure to low doses ofBPA. Is bisphenol-A a carcinogen? BPA is not a carcinogen. Based on lifetime exposure cancer bioassaysin laboratory animals, the US National Toxicology Program concluded thatBPA is not a carcinogen (NTP, 1982). The International Agency forResearch on Cancer (IARC) and the US EPA also conclude that BPA is nota carcinogenic risk to humans (Haighton et al., 2002). Bisphenol-A : Fear and perception Depending on whom you talk to, BPA can be either a health risk or aperfectly safe chemical. A number of concerned parents and adults believethat exposure to BPA during pregnancy raises the risk of cancer andchildhood behavioral problems such as hyperactivity, AĐ, and autism. Tothese ...