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zoom RSS プラスチック哺乳瓶の安全性に残る疑問/米国

<<   作成日時 : 2008/09/05 00:12   >>

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画像 政府の毒物学者は、FDA食品医薬品局が安全であると宣言したほんの数週後に哺乳びんと食品容器の中で使われている化学薬品についての安全懸念を繰り返している。水曜日のレポートで、幼児と子供の脳とホルモンシステムにビスフェノールAが発達上の問題を起こす可能性のある「いくらかの懸念」があると伝えた。しかし、その懸念は動物実験からの研究結果に基づいている。
 プラスチック製品メーカーの代理であるアメリカ化学協議会は、動物からの研究が「限定的で、決定的でない証拠」を提供していると強調した。
 毒物学グループが、化学薬品が女子の思春期を促進する可能性のある「いくらかの懸念」があると4月に伝えていたのに対して、最終報告は、現在、それらのリスクについて「最小の懸念」だけがあると述べている。全国的な毒物学プログラムは「無視してよい懸念」から「重大な懸念」までの5段階スケールの化学リスクについてその結論をランク付けしている。
 ウォルマートやトイザらスなど主要な小売店は、来年は化学薬品によって作られた哺乳びんを売るのをやめるであろうという。EvefloとBornFreeのようなより小さい会社はガラス哺乳びんの生産を立ち上げた。
 カナダは、哺乳びんへの化学薬品の使用を禁止するつもりであると言い、州と連邦の議員は、米国の子供用製品にビスフェノールを禁止するために立法を導入した。
 60億ポンドを超えるビスフェノールが米国で毎年Dow Chemical、バイエル、および他のメーカーによって生産されている。
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FDA プラスチック製品のビスフェノールAは安全との報告/米国
http://kurie.at.webry.info/200808/article_35.html
プラスチック製品のビスフェノールAを有毒の表示に/カナダ
http://kurie.at.webry.info/200804/article_29.html
プラスチック製の水筒や哺乳瓶の安全性に疑問
http://kurie.at.webry.info/200804/article_24.html
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Questions About Safety of Plastic in Baby Bottles Remain
http://www.nytimes.com/aponline/us/AP-Bisphenol-Safety.html
By THE ASSOCIATED PRESS
Published: September 3, 2008
Filed at 4:27 p.m. ET

WASHINGTON (AP) -- Government toxicologists have reiterated safety concerns about a chemical used in baby bottles and food containers, just weeks after the Food and Drug Administration declared the substance safe.

A report issued Wednesday said there is "some concern" that bisphenol A can cause developmental problems in the brain and hormonal systems of infants and children.

The conclusion from the National Toxicology Program repeats initial findings issued in April. The group -- which includes scientists from the National Institutes of Health and other agencies -- said bisphenol's risks to humans cannot be ruled out, but acknowledged its concerns are based on the findings of studies on animals.

The American Chemistry Council, which represents plastics manufacturers, stressed that studies from animals provide "limited and inconclusive evidence." The group has spent the last year defending the safety of bisphenol from new concerns about the risks of plastics to children.

Bisphenol is a plastic-hardening chemical used to seal canned food and make baby bottles. After more than a year of complaints from consumer and parent groups, the FDA has agreed to revisit the chemical's safety. The agency last month said the trace amounts that leach out of food containers are not a threat to children or adults.

But the toxicology group said that may not be true.

"More research is clearly needed to understand exactly how these findings relate to human health and development," said Michael Shelby, who directed the group's report. "But at this point we can't dismiss the possibility that the effects we're seeing in animals may occur in humans."

The FDA said it would consider the new report as it continues reviewing bisphenol. The agency has scheduled a meeting later this month where its outside advisers will weigh in on the chemical's safety. A final report is expected later in the year.

The toxicology group did back away from one issue raised in its draft report. While the group said in April there was "some concern" the chemical could speed up puberty in girls, the final report states there is now only "minimal concern" about those risks.

The National Toxicology Program ranks its conclusions about chemical risks on a five-tiered scale ranging from "negligible concern" to "serious concern."

Shelby said it is too early to recommend changes in what consumers buy and eat, but he added that parents who are concerned can avoid buying food containers made from bisphenol.

Several major retailers -- including Wal-Mart Stores Inc. and Toys "R" Us Inc. -- have said they would stop selling baby bottles made with the chemical next year. And smaller companies like Eveflo and BornFree have ramped up production of glass baby bottles as a bisphenol-free alternative.

Canada has said it intends to ban the use of the chemical in baby bottles, and state and federal lawmakers have introduced legislation to ban bisphenol in U.S. children's products.

More than 6 billion pounds of bisphenol are produced in the U.S. each year by Dow Chemical, Bayer AG and other manufacturers.
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Chemical in Plastic Causes Health Problems in Monkeys
Plastic has been connected with health problems in primates, for the first time, after researchers at the Yale School of Medicine find link to a chemical found in everyday plastics to problems with brain function in monkeys.Chemical in Plastic Causes Health Problems in Monkeys
Plastic has been connected with health problems in primates, for the first time, after researchers at the Yale School of Medicine find link to a chemical found in everyday plastics to problems with brain function in monkeys.
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More Evidence That BPA Found in Clear Plastics Impairs Brain Function
http://opa.yale.edu/news/article.aspx?id=5978
Published: September 3, 2008

New Haven, Conn. ― Yale School of Medicine researchers reported today that the chemical bisphenol-A (BPA), a building block for polycarbonate plastics found in common household items, causes the loss of connections between brain cells. This synaptic loss may cause memory/learning impairments and depression, according to study results published in the Proceedings of the National Academy of Sciences (PNAS).

Unlike previous studies that looked at the effect of BPA on rodents, the team examined the effects in a primate model. They also used lower levels of the chemical than in past studies. “Our goal was to more closely mimic the slow and continuous conditions under which humans would normally be exposed to BPA,” said study author Csaba Leranth, M.D., professor in the Department of Obstetrics, Gynecology & Reproductive Sciences and in Neurobiology at Yale. “As a result, this study is more indicative than past research of how BPA may actually affect humans.”

Over a 28-day period, Leranth and his team gave each primate 50 micrograms/kg of BPA per day, adjusted for body weight, the amount considered safe for human consumption by the Environmental Protection Agency (EPA). The team also administered estradiol, the major form of hormonal estrogen that modulates nerve cell connections in the brain. Best known as one of the principal hormone products of the ovary, estrogen has also been shown in past studies to be synthesized in the brain, where it aids the development and function of the hippocampus and prefrontal cortex.

The team then used an electron microscope to count nerve cell connections in the brain. They found that BPA inhibits creation of the synaptic connections in the hippocampus and prefrontal cortex, areas of the brain involved with regulation of mood and formation of memory.

“Our primate model indicates that BPA could negatively affect brain function in humans,” said study co-author Tibor Hajszan, M.D., associate research scientist in Yale Ob/Gyn. “Based on these new findings, we think the EPA may wish to consider lowering its ‘safe daily limit’ for human BPA consumption.”

Hajszan said that although daily exposure of an average person to BPA usually does not reach the level that was applied in this study, human exposure to BPA is not limited to a single month, but rather is continuous over a lifetime. “The negative effect of BPA may also be amplified when estradiol levels are naturally lower than in healthy adults. That is why exposure to BPA may particularly be risky in the case of babies and the elderly.”

Other authors on the study included Klara Szigeti-Buck, Jeremy Bober and Neil J. MacLusky.

The study was supported by the National Institutes of Health and by a National Alliance for Research on Schizophrenia and Depression Young Investigator Award.

Citation: PNAS Online Early Edition, 10.1073/pnas.0806139105 (September 2, 2008)

PRESS CONTACT: Karen N. Peart 203-432-1326
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Bisphenol A prevents the synaptogenic response to estradiol in hippocampus and prefrontal cortex of ovariectomized nonhuman primates
1. Csaba Leranth*,†,‡,
2. Tibor Hajszan*,
3. Klara Szigeti-Buck*,§,
4. Jeremy Bober*, and
5. Neil J. MacLusky¶
+Author Affiliations
1. Departments of *Obstetrics, Gynecology, and Reproductive Sciences;
2.†Neurobiology, and
3.§Pharmacology, Yale University School of Medicine, New Haven, CT 06520; and
4.-¶Department of Biomedical Sciences, Ontario Veterinary College, Guelph, ON, Canada N1G 2W1

1.
Edited by Bruce S. McEwen, The Rockefeller University, New York, NY, and approved July 14, 2008 (received for review June 25, 2008)

Abstract
Exposure measurements from several countries indicate that humans are routinely exposed to low levels of bisphenol A (BPA), a synthetic xenoestrogen widely used in the production of polycarbonate plastics. There is considerable debate about whether this exposure represents an environmental risk, based on reports that BPA interferes with the development of many organs and that it may alter cognitive functions and mood. Consistent with these reports, we have previously demonstrated that BPA antagonizes spine synapse formation induced by estrogens and testosterone in limbic brain areas of gonadectomized female and male rats. An important limitation of these studies, however, is that they were based on rodent animal models, which may not be representative of the effects of human BPA exposure. To address this issue, we examined the influence of continuous BPA administration, at a daily dose equal to the current U.S. Environmental Protection Agency's reference safe daily limit, on estradiol-induced spine synapse formation in the hippocampus and prefrontal cortex of a nonhuman primate model. Our data indicate that even at this relatively low exposure level, BPA completely abolishes the synaptogenic response to estradiol. Because remodeling of spine synapses may play a critical role in cognition and mood, the ability of BPA to interfere with spine synapse formation has profound implications. This study is the first to demonstrate an adverse effect of BPA on the brain in a nonhuman primate model and further amplifies concerns about the widespread use of BPA in medical equipment, and in food preparation and storage.

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