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  3. "Is the environment making us fat?" That is the intriguing question posed by

"Is the environment making us fat?" That is the intriguing question posed by

游客2023-12-22  57
问题     "Is the environment making us fat?" That is the intriguing question posed by Bruce Blumberg of the University of California, Irvine. His research into endocrine disrupters—chemical compounds that interfere with the body’s normal processing of hormones such as oestrogen—has led him to conclude that some of them may well encourage obesity.
    The notion of such "obesogens", as Dr. Blumberg calls them, is controversial. Some insist that diet and exercise (or, rather, the lack thereof) are the simpler explanations for obesity, with perhaps a dash of genetic predisposition thrown in. However, a panel of experts convened at the American Association for the Advancement of Science meeting argued that those factors are insufficient to explain the dramatic increase in obesity seen across the world since 1980. Caloric intake and exercise levels have not altered enough to explain the difference, the scientists maintained, and human genes cannot have changed in such a short time.
    Some environmental-health experts suspect that fetal exposure to nasties found in everyday plastics might be the underlying explanation of the recent obesity trend. John Peterson Meyers of Environmental Health Sciences, an advocacy group, observes that a number of synthetic chemicals widely found in the environment have been shown to alter the activity of genes, even when they are present at extremely low concentrations. This disruptive effect has not been fully appreciated, he argues, because safety trials on these substances have concentrated on the risks posed by high concentrations rather than low ones.
    Research on animals seems to bolster this hypothesis. Retha Newbold of the National Institute of Environmental Health Sciences, a government agency in America, points to diethylstilbestrol (DES) as an example. This drug, the first orally absorbable synthetic oestrogen, was given to pregnant women in the 1950s to help them avoid miscarriage. The drug fell out of favour when it transpired that children exposed to it ended up with damaged reproductive organs. Ms. Newbold has now discovered that early DES exposure also leads to obesity in adult mice. As her experiments controlled for both diet and exercise, she thinks fetal exposure to the drug must play a role in the fattening that was evident later in life. How this happens is unclear, but she speculates that the compound may interfere with the body’s ability to deal with glucose in the blood.
    Other synthetic hormones and endocrine disrupters common in the modern world seem to have a similar impact, and not just in the womb. A study of Japanese women has suggested a link between obesity and adult exposure to bisphenol-A, a component of plastic bottles. Frederick vom Saal of the University of Missouri has investigated the impact of early exposure to this compound. His work on laboratory animals showed that fetal exposure to bisphenol-A led to obesity and cancer. Dr. vom Saal says that new research should be done to clarify the role of "perinatal programming of obesity".
    Plastics are not the only potential culprits. Dr. Blumberg has identified tributyl tin, which is found not only in PVC plastics but also in fungicides. Tributyl tin is part of a larger group of chemicals known as organo-tins, which combine tin and hydrocarbons; the link with obesity was discovered only relatively recently. Dr. Blumberg believes the compound interferes with the body’s normal fat-formation process, and puts its fat-storage mechanism on overdrive, plumping up the person.
    Dr. Meyers claims this amounts to "a revolution unfolding in environmental-health sciences". Perhaps. It is possible that the long-marginalised scientists of the environmental-health field are right, and that these endocrine disrupters do play a part in explaining the ongoing trends in obesity. However, as the more cautious of them admit, that cannot be verified until the animal experiments are scaled up to proper, long-term human studies which can verify their hypothesis. Until then, it is probably best to go easy on the pizza—and work out at the gym. [br] The example of Retha Newbold’s experiment shows______.
选项 A、fetal exposure to improper substance has a negative effect on babies and may cause obesity
B、DES can avoid miscarriage but will damage newborn babies’ organs
C、DES causes obesity
D、DES may interfere with the body’s ability to deal with glucose in the blood
答案 A
解析
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