Drink from plastic bottles can raise the body’s levels of a controversial "gender-bending" chemical by more than two thirds, acc

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问题     Drink from plastic bottles can raise the body’s levels of a controversial "gender-bending" chemical by more than two thirds, according to tests.
    Experts have been concerned about the possible health effects of bisphenol A(BPA)—an everyday chemical used in many plastic food and drink containers and tins as well as clear baby bottles—which is officially classified as toxic in some countries.
    A study found that participants who drank for a week from polycarbonate(聚碳酸酯)bottles showed a 69 percent increase in their urine(尿液)of BPA.
    Researchers did not say how much liquid was drunk per day. Researchers from Harvard School of Public Health studied 77 students, who had first undergone a seven-day "washout" phase in which they drank all cold beverages(饮料)from stainless steel bottles in order to minimise BPA exposure.
    They were then given two polycarbonate bottles and asked to drink all cold beverages from them during the next week. Previous studies have suggested that high levels of BPA consumption are linked to birth defects, growth problems and an increased risk of heart disease. In particular there are fears that heating the bottles, as parents would do when warming their baby’s milk, causes the chemical to leak in potentially dangerous quantities into the liquid contained within.
    "If you heat those bottles, as is the case with baby bottles, we would expect the levels to be considerably higher. This would be of concern since infants may be particularly susceptible to BPA’s hormone gland-disrupting(扰乱腺体激素分泌)potential. " said the senior author of the latest study, Karin B. Michels.
    Most adults carry BPA in their bodies but expert opinion on the risks is divided. The European Food Safety Authority believes that people naturally convert the chemical into less harmful substances in the body.
    Previous studies had found that BPA could leach(渗出)from polycarbonate bottles into their contents, but this study is the first to show the size of the corresponding increase in urinary BPA concentrations in humans.
    Harvard researcher Jenny Carwile said, " While previous studies have demonstrated that BPA is linked to adverse health effects, this study fills in a missing piece of the puzzle—whether or not polycarbonate plastic bottles are an important contributor to the amount of BPA in the body. "
What is the significance of the study talked about in this passage?

选项 A、It proved the assumption on BPA that studies previously.
B、It clarified the high risks that BPA may pose to people’s health.
C、It confirmed the principal source of the substance BPA.
D、It showed what’s responsible for the rising level of BPA in humans.

答案D

解析 事实细节题。由定位句可知,这项新研究填补了以前的推断的空白,即PC塑料瓶是否是人体内BPA含量增高的罪魁祸首,D)与之相符,故为答案。由前文previous studies have demonstrated that BPA islinked to adverse health effects可知,以前的研究已经得到确定的结果,不只是猜测,故排除A);原文引用以前的研究结果论述了BPA是否会对人体健康造成影响,但不是为了阐明BPA的高风险性,故排除B);原文谈到很多塑料制品都含有BPA这种成分,但只是为了介绍这种物质,并不是此项研究的意义,故排除C)。
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