Hoá Chất Biosphenol A an toàn hay không?

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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? 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 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 leach
from bottle and can liners and migrates into foods and beverages. Researchers from government agencies, academia, and industry worldwide have studied the migration potential of BPA from polycarbonate products into foods and beverages. These studies consistently show that the level of BPA migrating into food is extremely low, generally less than 5 parts per billion under conditions typical for uses of polycarbonate products. Although BPA may be found in canned beverages and foods, it occurs only at 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 claiming that exposure to extremely low doses of certain substances could cause adverse health effects in humans, including disruption of normal hormonal functions. According to this "low dose hypothesis", reproductive and developmental effects may result from exposure to low doses of BPA since BPA was considered as having estrogenic activity in ovariectomized rats (Dodds and Lawson, 1936). In 1970, Bitman and Cecil assayed DDT and 52 structurally related compounds (including BPA) in immature rats and the authors reported an increase in uterine glycogen content. According to some scientists, BPA thus mimics estrogen, a hormone that controls the
development of the brain, the reproductive system and many other systems in the developing fetus and therefore BPA is an endocrineđisrupting chemical 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 of animals including fish, wildlife, and human and are referred to as endocrineđisrupting chemicals (EDCs). Indeed, our hormonal systems can be disrupted by numerous different anthropogenic chemicals including anti- androgens, androgens, estrogens, AhR agonists, steroid-hormone antagonists, retinoid agonists, anti-thyroid substances, etc. Many of the associations between EDCs and human health effects remain controversial, but others, like the effects of diethylstilbestrol (DES), the androgenic drugs danazol and methyltestosterone, and aminoglutethimide are widely recognized. Recently, the increased availability of androgen products for cutaneous application has increased the risk of virilization in children through skin contact. Estrogen containing shampoos and skin oils were shown to be causative factors for pseudo-precocious puberty in girls and gynecomastia in boys. EDCs are not limited to pharmaceutical agents but extend to industrial chemicals. In fact, the effects of PCBs (polychlorinated
biphenyls) on human neurological and immune development are well known. Children exposed to PCBs in utero or in the early developmental stages have lower birth weight, reduced IQ and cognitive abilities, reduced sperm 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 of ECBs in increasing trends in obesity and type II diabetes noted in the general population. Is bisphenol-A an endocrineđisrupting chemical? From previous investigations, BPA exhibits extremely weak hormonal activity in in vitro assays and in laboratory animals at high doses. In more recent years, extensive studies were conducted to determine if BPA could cause reproductive or developmental adverse effects. In no study has BPA been shown to be a reproductive or developmental toxicant. The “lowđose hypothesis” for BPA has been thoroughly tested by numerous investigators and agencies and the consistent lack of lowđose effects found in these studies raise doubt about the validity of the “lowđose hypothesis”. Data from the University of Arizona (Pritchett et al., 2002) indicated that, in humans, BPA is rapidly metabolized to a hormonally-inactive form and excreted
rapidly from the bodỵ Collectively, the weight of evidence provided by these studies demonstrates that BPA is not an endocrineđisrupting chemical and there is no basis for human health concerns from exposure to low doses of BPA. Is bisphenol-A a carcinogen? BPA is not a carcinogen. Based on lifetime exposure cancer bioassays in laboratory animals, the US National Toxicology Program concluded that BPA is not a carcinogen (NTP, 1982). The International Agency for Research on Cancer (IARC) and the US EPA also conclude that BPA is not a 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 a perfectly safe chemical. A number of concerned parents and adults believe that exposure to BPA during pregnancy raises the risk of cancer and childhood behavioral problems such as hyperactivity, AĐ, and autism. To these individuals, BPA must be banned from the lining of milk bottles, can foods and can beverages. On the other hand, the US FDA, the US EPA, the United Kingdom Standards Agency, the European Scientific Committee on
Foods and other government bodies worldwide continue to recognize BPA as safe at low doses. I, personally, don’t think that BPA at doses found in can and beverage linings is a risk to human health. However, to err on the safe side, to limit your exposure to BPA, do not microwave in polycarbonate plastic food containers. Until the next time, stay health Ts Bùi quốc Quang