Abstract
BackgroundChemicals that have estrogenic activity (EA) can potentially cause adverse health effects in mammals including humans, sometimes at low doses in fetal through juvenile stages with effects detected in adults. Polycarbonate (PC) thermoplastic resins made from bisphenol A (BPA), a chemical that has EA, are now often avoided in products used by babies. Other BPA-free thermoplastic resins, some hypothesized or advertised to be EA-free, are replacing PC resins used to make reusable hard and clear thermoplastic products such as baby bottles.MethodsWe used two very sensitive and accurate in vitro assays (MCF-7 and BG1Luc human cell lines) to quantify the EA of chemicals leached into ethanol or water/saline extracts of fourteen unstressed or stressed (autoclaving, microwaving, UV radiation) thermoplastic resins. Estrogen receptor (ER)-dependent agonist responses were confirmed by their inhibition with the ER antagonist ICI 182,780.ResultsOur data showed that some (4/14) unstressed and stressed BPA-free thermoplastic resins leached chemicals having significant levels of EA, including one polystyrene (PS), and three Tritan™ resins, the latter reportedly EA-free. Exposure to UV radiation in natural sunlight resulted in an increased release of EA from Tritan™ resins. Triphenyl-phosphate (TPP), an additive used to manufacture some thermoplastic resins such as Tritan™, exhibited EA in both MCF-7 and BG1Luc assays. Ten unstressed or stressed glycol-modified polyethylene terephthalate (PETG), cyclic olefin polymer (COP) or copolymer (COC) thermoplastic resins did not release chemicals with detectable EA under any test condition.ConclusionsThis hazard survey study assessed the release of chemicals exhibiting EA as detected by two sensitive, widely used and accepted, human cell line in vitro assays. Four PC replacement resins (Tritan™ and PS) released chemicals having EA. However, ten other PC-replacement resins did not leach chemicals having EA (EA-free-resins). These results indicate that PC-replacement plastic products could be made from EA-free resins (if appropriate EA-free additives are chosen) that maintain advantages of re-usable plastic items (price, weight, shatter resistance) without releasing chemicals having EA that potentially produce adverse health effects on current or future generations.
Highlights
Chemicals that have estrogenic activity (EA) can potentially cause adverse health effects in mammals including humans, sometimes at low doses in fetal through juvenile stages with effects detected in adults
All chemicals used to manufacture a plastic resin are almost never fully disclosed by the manufacturer who typically does not know what additional chemicals might be generated by polymer synthesis at high temperatures (e.g., >230°C) and pressures
MCF-7 assays of saline extracts of PS resins that were autoclaved (n = 2/2) or exposed to 180-280 nm short wavelength UV (UVC) (n = 2/2) consistently showed significant levels of EA (Figure 2), as did four BG1Luc assays of TritanTM TX 2001 plaques extracted by EtOH and exposed to UVC or 315–400 nm long wavelength UV (UVA) (Figure 3)
Summary
Chemicals that have estrogenic activity (EA) can potentially cause adverse health effects in mammals including humans, sometimes at low doses in fetal through juvenile stages with effects detected in adults. Newborn, and juvenile mammals are reported to be sensitive to chemicals having EA, and effects have been observed at very low doses. Such adverse health effects are often first detected in the adult mammal [4,8,9,10,11]. -other thermoplastic resins such as cyclic olefin copolymer (COC), polystyrene (PS) and polycarbonate (PC) resins are used to manufacture hard, clear and very durable (re-usable) products such as baby bottles and food storage containers
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