Bisphenol A
Post
07/04/07, Martin Mittelstaedt, 'Inherently toxic' chemical faces its future, (Source).
06/04/07, Margaret Wente, 'Zero is the new black', (Source).
11/04/07, Martin Mittelstaedt, The mystery of the missing boys, (Source).
07/04/07, Martin Mittelstaedt, 'Inherently toxic' chemical faces its future, (Back).
Bisphenol A is ingested by practically everyone in Canada who eats canned foods or drinks from a can or hard plastic water bottles.
Now a controversy is raging over the safety of widespread public exposure to the chemical, which is known to act like a synthetic female sex hormone.
At the heart of the intense debate over bisphenol A is that it challenges the main tenet of modern toxicology, the idea that the dose makes the poison, a principle credited to the 15th-century Swiss alchemist Theophrastus Paracelsus.
Under this principle, a two-pack-a-day smoker is more at risk of cancer than a one-pack-a-day user, and the belief that rising doses make a substance more dangerous is the basis of all government regulations that seek to set safe exposures for harmful chemicals.
It seems obvious that a high dose of a poison would be more dangerous than a lower one, but bisphenol A is creating a stir because it doesn't follow this seemingly common-sense rule. Researchers say this oddity results from the fact that bisphenol A isn't a conventional harmful agent, such as cigarette smoke, but behaves in the unconventional way typical of hormones, where even vanishingly small exposures can be harmful.
This is why some environmentalists and scientists contend that bisphenol A, which leaches in trace amounts from food and beverage packaging, is among the scariest manufactured substances in use, an eerie modern version of the vaunted lead water pipes by which ancient Romans were unknowingly poisoned.
Extrapolating from the results of animal experiments, they suspect bisphenol A has its fingerprints all over the unexplained human health trends emerging in recent decades hinting at something going haywire with sex hormones, including the early onset of puberty, declining sperm counts, and the huge increase in breast and prostate cancer, among other ailments.
But manufacturers — which include some of the world's biggest chemical companies — insist bisphenol A is harmless and say those claiming otherwise have it wrong.
Welcome to the heated controversy over bisphenol A.
Derived from petroleum, bisphenol A is the chief ingredient in polycarbonate, the rigid, translucent hard plastic used in water bottles and many baby bottles. It's also used to make the resins that line most tin cans, dental sealants, car parts, microwaveable plastics, sports helmets and CDs.
Environment Canada and Health Canada last year selected it as one of 200 substances that a preliminary review deemed possibly dangerous and in need of thorough safety assessments. The 200 were culled as the most worrisome chemicals from among about 23,000 substances in use in the 1980s and grandfathered from detailed safety studies when Canada adopted its first modern pollution laws.
Government scientists classified bisphenol A as "inherently toxic," and companies making it will be challenged by the assessment to prove that continued use is safe.
The assessment is expected to begin next month and provide a glimpse into one of the biggest public-health and scientific controversies in the world.
Some researchers with close-up views of bisphenol A are so shocked by its ability to skew development in their laboratory animals, even at among the lowest doses ever used in experiments, they aren't waiting for the government to ban it. In their personal lives, they can't run away from products containing it fast enough. "I would love to see it banished off the face of the Earth," Dr. Patricia Hunt, a Washington State University geneticist, said.
She began ditching her bisphenol-A-containing products after discovering that mere traces of the chemical were able to scramble the eggs of her lab mice. In humans, similar damage would lead to miscarriages and birth defects, such as Down syndrome. "I thought, 'Oh my God,'ƒ|" she said. "I'm going to throw out every piece of plastic in my kitchen."
Although it has been known, since a search for estrogenic drugs in the 1930s, to act like a sex hormone, bisphenol A has recently emerged as one extremely odd compound, perhaps the most unusual in widespread use. Research has found that it seems to turn modern toxicology on its head by being more dangerous at very low exposures than at high ones, a finding that is focusing attention on the possible health repercussions of the relatively small amounts leaching from consumer products.
Bisphenol A also has a bizarre pattern of research results, with the funding source of a study the best predictor of whether scientists find it harmful or safe. All major industry studies into bisphenol A's safety, and they number about a dozen, haven't found anything worrisome in low-dose exposures.
However, about 90 per cent of studies by independent researchers over the past decade, numbering about 150, have found adverse effects, ranging from enlarged prostates to abnormal breast tissue growth.
Bisphenol A has been used in increasing amounts since the 1950s in food and beverage containers because it doesn't impart a plastic-like taste, although traces leach out. Plastics that use it are often identified by an industry triangle symbol and the number seven.
Because it is one of the highest-volume manufactured chemicals in the world and used in so many consumer products, bisphenol A exposure in Canadians is likely to be pervasive.
Urine testing in the United States suggests that about 95 per cent of the population have been exposed, and Ottawa began a survey in March to see if a similar figure applies to Canadians, a reasonable prospect given that the same products are used in both countries. Testing elsewhere in the world has also found it present in human blood, as well as in placentas and fetal cord blood.
Manufacturers say that exposures are nothing to worry about, contending that the amounts getting into people from what they eat and drink aren't of any consequence.
"We know that human exposure to BPA is extraordinarily low, well below levels that have been shown to be safe," said Steven Hentges, spokesman for bisphenol A at the American Plastics Council, which comments on the health controversy over the chemical for four of the five North American manufacturers, GE Plastics, Sunoco Inc., Bayer AG, and Dow Chemical Co. The other producer is Hexion Specialty Chemicals.
He dismisses disease trends showing increasing numbers of hormonally linked ailments rising in tandem with bisphenol A use as "only a statistical association at best" that in no way implicates the industry's product. "You could co-relate those same disease trends with TV watching or coffee drinking or anything you want," he said.
While some companies insist that bisphenol A is harmless, others are just as adamant that it's among the biggest health hazards to which Canadians are unwittingly and routinely exposed.
For Rick Smith, executive director of Environmental Defence, a Toronto group that tracks the exposure of Canadians to pollutants, bisphenol A is the worst substance among the 200 Ottawa suspects may be dangerous. "I think bisphenol A is top of my list, even though there are others that I hate a lot," he said.
The group is so convinced the evidence already shows bisphenol A is a health hazard, it doesn't want Ottawa to wait until the assessment is finished, which could take years, to ban it, particularly in food contact uses. In March, after U.S. environmental groups found the chemical leaching from plastic baby bottles and into canned food, Environmental Defence asked the federal government to end its use, a step that if taken would make Canada the first country in the world to do so.
"If getting this chemical out of those products isn't priority No.ƒ|1, I don't know what is," says Mr. Smith, who in his personal life isn't waiting for Ottawa to act. With his five-month-old son's health in mind, he rid his home of bisphenol-A-containing baby bottles as a safety precaution.
Currently, there are no regulations limiting bisphenol A leakage from consumer products. The Canadian Food Inspection Agency doesn't monitor canned goods or bottled water for its presence and Health Canada set a provisional exposure standard in 1999, just as the controversy over its health effects was beginning. Like the chemical industry, it has long insisted that the amounts people ingest aren't harmful.
However, there have been more than a dozen studies in laboratory animals since 1999 finding adverse effects from bisphenol A at levels below Canada's standard. One study, done in 2005, found the chemical able to change breast tissue in ways that predispose them to cancer at a dose 1,000 times lower than Canada's limit.
In living things, hormones latch ď onto receptors in cells, turning vital biological processes on or off much like a switch controls a light. When cells are exposed to low doses of hormones, whatever activity they control is stimulated, but at higher doses these receptors are overwhelmed and stop their activity. That is why a hormonally active compound may have one effect at a low dose and no effect at a higher exposure.
"At low doses hormones stimulate their own receptors," said Frederick vom Saal, a University of Missouri biologist and leading academic expert on bisphenol A. "At higher doses, they inhibit their responses."
Within the plastics industry, the idea that small amounts of bisphenol A are dangerous, perhaps more worrisome than larger amounts, isn't dismissed outright, but viewed as a something still at the stage of a hypothesis in need of further proof to be validated, Mr. Hentges said.
But Dr. vom Saal, pointing to the many studies finding harm, said the industry's position "is really stunning because you have this huge independent scientific literature showing adverse effects at stunningly low doses."
Low doses come into play because hormones are active at minute, parts per trillion concentrations. (A part per trillion is the scientific equivalent of practically nothing, roughly equal to a grain of salt in a large swimming pool.) Surveys of how much bisphenol A comes out of cans and bottles into food have found parts per billion amounts, raising concerns that diet could cause exposures similar to natural hormone levels.
Like many scientists who've found health impacts from bisphenol A, Dr. vom Saal is personally so nervous about its safety that he doesn't eat canned food or use polycarbonate beverage containers any more. "We've done everything possible to try to limit our exposure to this," he said.
Dr. vom Saal helped make one of the earliest discoveries about low doses of bisphenol A, finding in 1997 that traces fed to mice caused a 30-per-cent increase in prostate size.
He's also tried to figure out why industry studies don't find the results that seem so readily apparent in the laboratories of academic scientists.
Dr. vom Saal contends that many industry experiments are flawed. In one case, he says a study funded by the plastics council and including researchers from GE, Dow, and Bayer, found no effects from low doses of bisphenol A, but used a strain of rats he says are hundreds of times less sensitive to estrogenic drugs than humans. The same study failed to use test animals that would have detected that the rats were relatively impervious to sex hormones.
The rats, known as the CD Sprague-Dawley variety, are produced by Charles River Laboratories Inc., of Wilmington, Mass., which said in a written statement that the "scientific literature is unclear and inconsistent" over whether the animals "are less estrogen sensitive than other outbred rat stocks."
Mr. Hentges defended the industry's research, saying it followed approved international guidelines and used a well regarded rat variety. He said a follow-up study using mice also failed to find adverse effects and included a test for estrogen sensitivity. Any suggestions that industry work is flawed "is just plain wrong," he said.
The contradictory findings on bisphenol A have produced a picayune scientific tit for tat between the industry and its critics on almost every aspect of each other's research. For instance, Mr. Hentges claims some academic studies are useless as predictors for human health effects because they used pumps to inject bisphenol A into animals, while human exposure is mainly oral through food.
But scientists counter that their work replicates better what occurs during fetal development, a time when most animals are uniquely sensitive to dangerous substances.
The industry says that when humans consume bisphenol A, most is converted in the gut into a form that isn't dangerous, although those worried about the substance say not all of it is dealt with in this way and diet is constantly replenishing exposures.
There are also disagreements over how potent a hormone mimic bisphenol A is. The industry calls it a weak estrogen because it is thousands of times less effective on some cell receptors. However, it is similar in strength on receptors on the surface of cells crucial for many biological functions.
Dr. vom Saal dismisses this controversy over the relative estrogenic strength of bisphenol A as mere hair splitting. "This is like saying, well Arnold Schwarzenegger is weak, relative to Superman," he said.
To date, international regulatory bodies, most recently the European Food Safety Authority in an assessment issued this year, have given the benefit of the doubt to the industry on these disputes.
Mr. Smith thinks the scientific debate over bisphenol A is part of a broad pattern that emerges whenever industries are threatened by new findings of harm from their products.
Similar disputes have occurred over smoking and cancer, the hazards of lead paint and global warming. But he said that waiting for all scientific disputes to be resolved could be disastrous, when human health is at stake.
"If we wait for absolute certainty, there is a very strong chance that a lot of people will be harmed."
Already, there have been a small number of scientific papers linking exposures to human health outcomes, such as miscarriages (women with miscarriages were found to have three times higher levels of bisphenol A than other women) and ovarian dysfunction, although the industry disputes the findings.
In March, the first U.S. class action lawsuit alleging harm from bisphenol A was launched, against five makers of baby bottles. It was filed in Los Angeles shortly after a U.S. environmental group found the hormone mimic leaching from the bottles when they are heated, something many parents do to formula or milk.
Coincidentally, one big industry player is getting out of the bisphenol A business. This year, GE announced it wanted to sell its plastic business, but the company says the sale has nothing to do with the health controversy.
Peter O'Toole, a spokesman, said the plastics business isn't growing as rapidly as other GE operations and "doesn't seem to be fitting in the current business model." He classifies any litigation risks with bisphenol A as "speculation. There have been risk assessments done on bisphenol A and there has never been evidence shown that it's harmful to human beings," he said.
Dr. vom Saal, for his part, expects that companies associated with bisphenol A will be the next tobacco industry, mired in expensive health litigation in U.S. courts. "This is a train wreck that is absolutely coming," he said.
But Mr. Hentges dismisses views that bisphenol A is about to be derailed. "He has some very unusual views," he said of Dr. vom Saal.
06/04/07, Margaret Wente, 'Zero is the new black', (Back).
‘I feel guilty whenever I buy flowers,” Envirowoman from Vancouver writes on her blog. “I think it has to do with my cruelty-fee chromosomes. Something so beautiful, having its life cut short (literally), just seems so, so wrong. I just don't feel I have the right.”
Envirowoman lists her work as investment banking. She describes herself as a plastic-free, cruelty-free, vegetarian-free chocoholic. Now that she's sworn off plastic, buying flowers presents “not just a moral challenge, but also a plastic challenge too.” After all, most flowers come wrapped in plastic. Even plants come in plastic pots. Even plants in ceramic pots, if you dig down in the dirt, are really in plastic pots.
It's hard to be good.
If you haven't thought about the moral impact of buying Mom a bunch of Easter lilies, then you are not awake. You haven't considered the tonnes of chemicals and pesticides used in the floriculture industry, or the amount of energy consumed to get those lovely blooms to your corner flower store. Better get her some chocolate instead — preferably the non-exploitive kind, without a box.
If you want to be a good environmental citizen, it is no longer enough to recycle, compost, and write a cheque to the World Wildlife Fund. You've got to strive to shrink your footprint. The ideal is to waste no energy and produce no waste. As one trend-watcher says, “Zero is the new black.”
In New York, Colin Beavan, who calls himself No Impact Man, has embarked on a year-long experiment to survive without making any net impact on the environment. His motivation, he admits, is to assuage his liberal guilt. (Okay, so there's a book and film deal too.) His goal is to produce no trash, no carbon dioxide, no toxins. To accomplish this, he and his family have given up elevators, subways, all products that come in packaging, plastics, air conditioning, TV, and toilet paper. Their 750-square-foot prewar apartment on Lower Fifth Avenue has a composter full of red wrigglers. His two-year-old daughter wears organic cotton diapers.
Mr. Beavan, who has become something of a celebrity, swears that the no-impact life is not about austerity or doing without. It's about abundance of a different, more natural kind. His family eats only food that's available within a 250-mile radius. No meat, of course. It's delicious, so long as you have a taste for cabbage and thyme tea.
“I have developed a little OCD when it comes to disposable products,” Mr. Beavan writes on his blog. No kidding. Obsessive-compulsiveness is essential for this way of life. He and his family are gradually emptying out all their plastic bottles, and won't replace them. They've switched to baking-soda toothpaste. (No box, no tube.) He shaves with his grandfather's straight razor. Now he's worrying about dental floss. But the vast green network of no-impacters usually has an answer. It turns out there's a floss called Eco-DenT, which contains no animal products and comes in a recyclable container. It's waxed by vegans.
Personal hygiene is a real challenge when you're committed to a zero-waste policy. Most people draw the line at giving up toilet paper. Not Mr. Beavan, who uses bowls of water and air drying instead. His wife, Michelle, who is part of this experiment, doesn't say what she's using instead of Tampax.
The trouble is, living the zero-impact life is more or less a full-time job, even if you don't count the time you spend blogging about it. Just getting around — by foot and bicycle — takes a lot of time. You also have to make a lot of stuff yourself, such as meals (no restaurants or take-out allowed). Since olive oil and balsamic vinegar are out, for geographical reasons, Mr. Beavan makes his own fruit-scrap vinegar. Soon, he'll start making his own castile soap, which, he claims, is a fine substitute for most personal cleaning agents.
The Beavan household still generates almost half a bag of trash a week. That makes them waste hogs compared to the couple profiled recently in The Globe and Mail's Toronto section. Sarah McGaughey and Kyle Glover got through the entire month of January completely trash-free. They are so obsessed with waste that they won't ask for a glass of water in a public place because it might come with a straw. They carry their own cup with them, or else drink tap water with their hands. (Bottled water, as we know, is heinous.) They do use plastic bags, to carry home their food, but they reuse them till they fall apart.
And yet, no matter how virtuous they try to be, it's never good enough. After they described how they dried out their plastic bags with an electric fan, they endured a storm of criticism from people who accused them of wasting energy — even though the fan uses no more energy than a 60-watt light bulb. “We kept using it, but we kind of felt guilty,” confessed Mr. Glover. So Ms. McGaughey started switching on the fan for only a few seconds — just long enough to blow the bags open so they can air dry. Mr. Glover swings them back and forth to dry them faster.
If this attention to detail strikes you as just a teensy-weensy anal, you may not be ready to join the company of the elect. You may not be ready to peel off those little stickers that come on pieces of fruit to make collages and cards for your friends. (Ms. McGaughey is.) You may not be ready to fret over the coloured strip that comes in your home-pregnancy test kit. “How can I reuse a plastic stick that has my urine on it?” Ms. McGaughey anguished. (For the record, it was positive.) Nor will your dilemmas end with death, at which point, thank God, you'll cease emitting carbon dioxide. Should you be buried or cremated? Each has environmental drawbacks. Perhaps you can be put into a tree to be ripped apart by vultures. Or perhaps your ashes can be recycled, like Keith Richards's father.
The no-impacters, it seems to me, are the modern version of religious ascetics, who practised various forms of self-denial and self-torture to prove their devotion to God. Some lived on top of poles for 40 years. Some went naked, and some ate only nuts and fruits, and some lived on air. “Those who practise ascetic lifestyles often perceive their practices as virtuous and pursue them to achieve greater spirituality,” says one authority. They believe their actions purify the soul.
As for the rest of us, we can always buy indulgences to purify the soul. These days, they're known as carbon offsets.
11/04/07, Martin Mittelstaedt, The mystery of the missing boys, (Back).
Chemical pollutants flagged in new study as possible factor in skewed sex ratio - Where are all the missing boys?
It is a question posed by a new study that has found the proportion of boys born over the past three decades has unexpectedly dropped in both the United States and Japan. In all, more than a quarter of a million boys are missing, compared to what would have been expected had the sex ratio existing in 1970 remained unchanged.
The study also says the world's most skewed sex ratio is in Canada, in a native community surrounded by petrochemical plants in Sarnia, Ont., where the number of boys born has plunged since the mid-1990s at a rate never seen.
Although the researchers do not know why boys are taking a hit, they suspect contributing causes could include widespread exposure to hormone-mimicking pollutants by women during pregnancy and by men before they help conceive children.
“We hypothesize that the decline in sex ratio in industrial countries may be due, in part, to prenatal exposure to metalloestrogens and other endocrine disrupting chemicals,” said the study, issued this week in Environmental Health Perspectives, a peer reviewed journal of the U.S. National Institute of Environmental Health Sciences.
These types of chemicals include some pesticides, dioxin and methylmercury, a pollutant from coal-fired power plants and many industrial sources commonly found in seafood. The study also flagged a host of other possible factors, including rising obesity rates, older parental age, growing stress levels, and the increasing number of children being conceived using fertility aides. Other research has shown some associations between these factors and a drop in boy births.
The study was conducted by researchers in both the U.S. and Japan, and led by Devra Lee Davis, a prominent epidemiologist and director of the Center for Environmental Oncology at the University of Pittsburgh Cancer Institute.
In an interview, Dr. Davis said that although the cause of the decline isn't known, it could be linked to the increasing number of other male reproductive problems, such as falling sperm counts and rising testicular cancer rates.
She said that males during fetal development may be more sensitive to pollutants that mimic hormones, leading to increased fetal deaths and reproductive problems later for the surviving males.
The situation in Sarnia, where nearly twice as many girls are being born than boys on the Aamjiwnaang First Nation, is internationally significant, according to the study. “To our knowledge, this is a more significantly reduced sex ratio and greater rate of change than has been reported previously anywhere,” it said.
The reserve is located in the heart of Sarnia's chemical valley, and the native community, along with researchers at the University of Rochester and the Occupational Health Clinics for Ontario Workers, are trying to find the cause of the unusual sex ratio.
Fewer boys than expected are being born in the non-aboriginal community downwind of the petrochemical plants in the area, but not to the same degree as on the reserve. The work force in Sarnia has not been studied, something that would shed light on whether pollutants are the cause.
Researchers in many countries have been reporting a drop in the ratio of boys to girls being born over the past few decades.
It is considered normal in a large population for the number of baby boys to slightly outnumber girls, by a proportion of about 105 males to 100 females. It is widely thought that more boy births are a way nature compensates for higher rates of male mortality.
But the ratio has not been static in industrialized countries, and researchers suspect that increasing numbers of male fetuses are being miscarried, a kind of sex-based culling in the womb.
In Japan, the sex ratio fluctuated with no trend from 1949 to 1970, but then declined steadily to 1999, the end of the study period there.
The decline in the number of boys in Japan equals 37 out of every 10,000 births.
In the U.S., the sex ratio also declined from 1970 to 2002. The drop in the number of boys equals 17 out of every 10,000 births.
The U.S. change was concentrated among whites, with almost no change among blacks.
(Back)
06/04/07, Margaret Wente, 'Zero is the new black', (Source).
11/04/07, Martin Mittelstaedt, The mystery of the missing boys, (Source).
07/04/07, Martin Mittelstaedt, 'Inherently toxic' chemical faces its future, (Back).
Bisphenol A is ingested by practically everyone in Canada who eats canned foods or drinks from a can or hard plastic water bottles.
Now a controversy is raging over the safety of widespread public exposure to the chemical, which is known to act like a synthetic female sex hormone.
At the heart of the intense debate over bisphenol A is that it challenges the main tenet of modern toxicology, the idea that the dose makes the poison, a principle credited to the 15th-century Swiss alchemist Theophrastus Paracelsus.
Under this principle, a two-pack-a-day smoker is more at risk of cancer than a one-pack-a-day user, and the belief that rising doses make a substance more dangerous is the basis of all government regulations that seek to set safe exposures for harmful chemicals.
It seems obvious that a high dose of a poison would be more dangerous than a lower one, but bisphenol A is creating a stir because it doesn't follow this seemingly common-sense rule. Researchers say this oddity results from the fact that bisphenol A isn't a conventional harmful agent, such as cigarette smoke, but behaves in the unconventional way typical of hormones, where even vanishingly small exposures can be harmful.
This is why some environmentalists and scientists contend that bisphenol A, which leaches in trace amounts from food and beverage packaging, is among the scariest manufactured substances in use, an eerie modern version of the vaunted lead water pipes by which ancient Romans were unknowingly poisoned.
Extrapolating from the results of animal experiments, they suspect bisphenol A has its fingerprints all over the unexplained human health trends emerging in recent decades hinting at something going haywire with sex hormones, including the early onset of puberty, declining sperm counts, and the huge increase in breast and prostate cancer, among other ailments.
But manufacturers — which include some of the world's biggest chemical companies — insist bisphenol A is harmless and say those claiming otherwise have it wrong.
Welcome to the heated controversy over bisphenol A.
Derived from petroleum, bisphenol A is the chief ingredient in polycarbonate, the rigid, translucent hard plastic used in water bottles and many baby bottles. It's also used to make the resins that line most tin cans, dental sealants, car parts, microwaveable plastics, sports helmets and CDs.
Environment Canada and Health Canada last year selected it as one of 200 substances that a preliminary review deemed possibly dangerous and in need of thorough safety assessments. The 200 were culled as the most worrisome chemicals from among about 23,000 substances in use in the 1980s and grandfathered from detailed safety studies when Canada adopted its first modern pollution laws.
Government scientists classified bisphenol A as "inherently toxic," and companies making it will be challenged by the assessment to prove that continued use is safe.
The assessment is expected to begin next month and provide a glimpse into one of the biggest public-health and scientific controversies in the world.
Some researchers with close-up views of bisphenol A are so shocked by its ability to skew development in their laboratory animals, even at among the lowest doses ever used in experiments, they aren't waiting for the government to ban it. In their personal lives, they can't run away from products containing it fast enough. "I would love to see it banished off the face of the Earth," Dr. Patricia Hunt, a Washington State University geneticist, said.
She began ditching her bisphenol-A-containing products after discovering that mere traces of the chemical were able to scramble the eggs of her lab mice. In humans, similar damage would lead to miscarriages and birth defects, such as Down syndrome. "I thought, 'Oh my God,'ƒ|" she said. "I'm going to throw out every piece of plastic in my kitchen."
Although it has been known, since a search for estrogenic drugs in the 1930s, to act like a sex hormone, bisphenol A has recently emerged as one extremely odd compound, perhaps the most unusual in widespread use. Research has found that it seems to turn modern toxicology on its head by being more dangerous at very low exposures than at high ones, a finding that is focusing attention on the possible health repercussions of the relatively small amounts leaching from consumer products.
Bisphenol A also has a bizarre pattern of research results, with the funding source of a study the best predictor of whether scientists find it harmful or safe. All major industry studies into bisphenol A's safety, and they number about a dozen, haven't found anything worrisome in low-dose exposures.
However, about 90 per cent of studies by independent researchers over the past decade, numbering about 150, have found adverse effects, ranging from enlarged prostates to abnormal breast tissue growth.
Bisphenol A has been used in increasing amounts since the 1950s in food and beverage containers because it doesn't impart a plastic-like taste, although traces leach out. Plastics that use it are often identified by an industry triangle symbol and the number seven.
Because it is one of the highest-volume manufactured chemicals in the world and used in so many consumer products, bisphenol A exposure in Canadians is likely to be pervasive.
Urine testing in the United States suggests that about 95 per cent of the population have been exposed, and Ottawa began a survey in March to see if a similar figure applies to Canadians, a reasonable prospect given that the same products are used in both countries. Testing elsewhere in the world has also found it present in human blood, as well as in placentas and fetal cord blood.
Manufacturers say that exposures are nothing to worry about, contending that the amounts getting into people from what they eat and drink aren't of any consequence.
"We know that human exposure to BPA is extraordinarily low, well below levels that have been shown to be safe," said Steven Hentges, spokesman for bisphenol A at the American Plastics Council, which comments on the health controversy over the chemical for four of the five North American manufacturers, GE Plastics, Sunoco Inc., Bayer AG, and Dow Chemical Co. The other producer is Hexion Specialty Chemicals.
He dismisses disease trends showing increasing numbers of hormonally linked ailments rising in tandem with bisphenol A use as "only a statistical association at best" that in no way implicates the industry's product. "You could co-relate those same disease trends with TV watching or coffee drinking or anything you want," he said.
While some companies insist that bisphenol A is harmless, others are just as adamant that it's among the biggest health hazards to which Canadians are unwittingly and routinely exposed.
For Rick Smith, executive director of Environmental Defence, a Toronto group that tracks the exposure of Canadians to pollutants, bisphenol A is the worst substance among the 200 Ottawa suspects may be dangerous. "I think bisphenol A is top of my list, even though there are others that I hate a lot," he said.
The group is so convinced the evidence already shows bisphenol A is a health hazard, it doesn't want Ottawa to wait until the assessment is finished, which could take years, to ban it, particularly in food contact uses. In March, after U.S. environmental groups found the chemical leaching from plastic baby bottles and into canned food, Environmental Defence asked the federal government to end its use, a step that if taken would make Canada the first country in the world to do so.
"If getting this chemical out of those products isn't priority No.ƒ|1, I don't know what is," says Mr. Smith, who in his personal life isn't waiting for Ottawa to act. With his five-month-old son's health in mind, he rid his home of bisphenol-A-containing baby bottles as a safety precaution.
Currently, there are no regulations limiting bisphenol A leakage from consumer products. The Canadian Food Inspection Agency doesn't monitor canned goods or bottled water for its presence and Health Canada set a provisional exposure standard in 1999, just as the controversy over its health effects was beginning. Like the chemical industry, it has long insisted that the amounts people ingest aren't harmful.
However, there have been more than a dozen studies in laboratory animals since 1999 finding adverse effects from bisphenol A at levels below Canada's standard. One study, done in 2005, found the chemical able to change breast tissue in ways that predispose them to cancer at a dose 1,000 times lower than Canada's limit.
In living things, hormones latch ď onto receptors in cells, turning vital biological processes on or off much like a switch controls a light. When cells are exposed to low doses of hormones, whatever activity they control is stimulated, but at higher doses these receptors are overwhelmed and stop their activity. That is why a hormonally active compound may have one effect at a low dose and no effect at a higher exposure.
"At low doses hormones stimulate their own receptors," said Frederick vom Saal, a University of Missouri biologist and leading academic expert on bisphenol A. "At higher doses, they inhibit their responses."
Within the plastics industry, the idea that small amounts of bisphenol A are dangerous, perhaps more worrisome than larger amounts, isn't dismissed outright, but viewed as a something still at the stage of a hypothesis in need of further proof to be validated, Mr. Hentges said.
But Dr. vom Saal, pointing to the many studies finding harm, said the industry's position "is really stunning because you have this huge independent scientific literature showing adverse effects at stunningly low doses."
Low doses come into play because hormones are active at minute, parts per trillion concentrations. (A part per trillion is the scientific equivalent of practically nothing, roughly equal to a grain of salt in a large swimming pool.) Surveys of how much bisphenol A comes out of cans and bottles into food have found parts per billion amounts, raising concerns that diet could cause exposures similar to natural hormone levels.
Like many scientists who've found health impacts from bisphenol A, Dr. vom Saal is personally so nervous about its safety that he doesn't eat canned food or use polycarbonate beverage containers any more. "We've done everything possible to try to limit our exposure to this," he said.
Dr. vom Saal helped make one of the earliest discoveries about low doses of bisphenol A, finding in 1997 that traces fed to mice caused a 30-per-cent increase in prostate size.
He's also tried to figure out why industry studies don't find the results that seem so readily apparent in the laboratories of academic scientists.
Dr. vom Saal contends that many industry experiments are flawed. In one case, he says a study funded by the plastics council and including researchers from GE, Dow, and Bayer, found no effects from low doses of bisphenol A, but used a strain of rats he says are hundreds of times less sensitive to estrogenic drugs than humans. The same study failed to use test animals that would have detected that the rats were relatively impervious to sex hormones.
The rats, known as the CD Sprague-Dawley variety, are produced by Charles River Laboratories Inc., of Wilmington, Mass., which said in a written statement that the "scientific literature is unclear and inconsistent" over whether the animals "are less estrogen sensitive than other outbred rat stocks."
Mr. Hentges defended the industry's research, saying it followed approved international guidelines and used a well regarded rat variety. He said a follow-up study using mice also failed to find adverse effects and included a test for estrogen sensitivity. Any suggestions that industry work is flawed "is just plain wrong," he said.
The contradictory findings on bisphenol A have produced a picayune scientific tit for tat between the industry and its critics on almost every aspect of each other's research. For instance, Mr. Hentges claims some academic studies are useless as predictors for human health effects because they used pumps to inject bisphenol A into animals, while human exposure is mainly oral through food.
But scientists counter that their work replicates better what occurs during fetal development, a time when most animals are uniquely sensitive to dangerous substances.
The industry says that when humans consume bisphenol A, most is converted in the gut into a form that isn't dangerous, although those worried about the substance say not all of it is dealt with in this way and diet is constantly replenishing exposures.
There are also disagreements over how potent a hormone mimic bisphenol A is. The industry calls it a weak estrogen because it is thousands of times less effective on some cell receptors. However, it is similar in strength on receptors on the surface of cells crucial for many biological functions.
Dr. vom Saal dismisses this controversy over the relative estrogenic strength of bisphenol A as mere hair splitting. "This is like saying, well Arnold Schwarzenegger is weak, relative to Superman," he said.
To date, international regulatory bodies, most recently the European Food Safety Authority in an assessment issued this year, have given the benefit of the doubt to the industry on these disputes.
Mr. Smith thinks the scientific debate over bisphenol A is part of a broad pattern that emerges whenever industries are threatened by new findings of harm from their products.
Similar disputes have occurred over smoking and cancer, the hazards of lead paint and global warming. But he said that waiting for all scientific disputes to be resolved could be disastrous, when human health is at stake.
"If we wait for absolute certainty, there is a very strong chance that a lot of people will be harmed."
Already, there have been a small number of scientific papers linking exposures to human health outcomes, such as miscarriages (women with miscarriages were found to have three times higher levels of bisphenol A than other women) and ovarian dysfunction, although the industry disputes the findings.
In March, the first U.S. class action lawsuit alleging harm from bisphenol A was launched, against five makers of baby bottles. It was filed in Los Angeles shortly after a U.S. environmental group found the hormone mimic leaching from the bottles when they are heated, something many parents do to formula or milk.
Coincidentally, one big industry player is getting out of the bisphenol A business. This year, GE announced it wanted to sell its plastic business, but the company says the sale has nothing to do with the health controversy.
Peter O'Toole, a spokesman, said the plastics business isn't growing as rapidly as other GE operations and "doesn't seem to be fitting in the current business model." He classifies any litigation risks with bisphenol A as "speculation. There have been risk assessments done on bisphenol A and there has never been evidence shown that it's harmful to human beings," he said.
Dr. vom Saal, for his part, expects that companies associated with bisphenol A will be the next tobacco industry, mired in expensive health litigation in U.S. courts. "This is a train wreck that is absolutely coming," he said.
But Mr. Hentges dismisses views that bisphenol A is about to be derailed. "He has some very unusual views," he said of Dr. vom Saal.
06/04/07, Margaret Wente, 'Zero is the new black', (Back).
‘I feel guilty whenever I buy flowers,” Envirowoman from Vancouver writes on her blog. “I think it has to do with my cruelty-fee chromosomes. Something so beautiful, having its life cut short (literally), just seems so, so wrong. I just don't feel I have the right.”
Envirowoman lists her work as investment banking. She describes herself as a plastic-free, cruelty-free, vegetarian-free chocoholic. Now that she's sworn off plastic, buying flowers presents “not just a moral challenge, but also a plastic challenge too.” After all, most flowers come wrapped in plastic. Even plants come in plastic pots. Even plants in ceramic pots, if you dig down in the dirt, are really in plastic pots.
It's hard to be good.
If you haven't thought about the moral impact of buying Mom a bunch of Easter lilies, then you are not awake. You haven't considered the tonnes of chemicals and pesticides used in the floriculture industry, or the amount of energy consumed to get those lovely blooms to your corner flower store. Better get her some chocolate instead — preferably the non-exploitive kind, without a box.
If you want to be a good environmental citizen, it is no longer enough to recycle, compost, and write a cheque to the World Wildlife Fund. You've got to strive to shrink your footprint. The ideal is to waste no energy and produce no waste. As one trend-watcher says, “Zero is the new black.”
In New York, Colin Beavan, who calls himself No Impact Man, has embarked on a year-long experiment to survive without making any net impact on the environment. His motivation, he admits, is to assuage his liberal guilt. (Okay, so there's a book and film deal too.) His goal is to produce no trash, no carbon dioxide, no toxins. To accomplish this, he and his family have given up elevators, subways, all products that come in packaging, plastics, air conditioning, TV, and toilet paper. Their 750-square-foot prewar apartment on Lower Fifth Avenue has a composter full of red wrigglers. His two-year-old daughter wears organic cotton diapers.
Mr. Beavan, who has become something of a celebrity, swears that the no-impact life is not about austerity or doing without. It's about abundance of a different, more natural kind. His family eats only food that's available within a 250-mile radius. No meat, of course. It's delicious, so long as you have a taste for cabbage and thyme tea.
“I have developed a little OCD when it comes to disposable products,” Mr. Beavan writes on his blog. No kidding. Obsessive-compulsiveness is essential for this way of life. He and his family are gradually emptying out all their plastic bottles, and won't replace them. They've switched to baking-soda toothpaste. (No box, no tube.) He shaves with his grandfather's straight razor. Now he's worrying about dental floss. But the vast green network of no-impacters usually has an answer. It turns out there's a floss called Eco-DenT, which contains no animal products and comes in a recyclable container. It's waxed by vegans.
Personal hygiene is a real challenge when you're committed to a zero-waste policy. Most people draw the line at giving up toilet paper. Not Mr. Beavan, who uses bowls of water and air drying instead. His wife, Michelle, who is part of this experiment, doesn't say what she's using instead of Tampax.
The trouble is, living the zero-impact life is more or less a full-time job, even if you don't count the time you spend blogging about it. Just getting around — by foot and bicycle — takes a lot of time. You also have to make a lot of stuff yourself, such as meals (no restaurants or take-out allowed). Since olive oil and balsamic vinegar are out, for geographical reasons, Mr. Beavan makes his own fruit-scrap vinegar. Soon, he'll start making his own castile soap, which, he claims, is a fine substitute for most personal cleaning agents.
The Beavan household still generates almost half a bag of trash a week. That makes them waste hogs compared to the couple profiled recently in The Globe and Mail's Toronto section. Sarah McGaughey and Kyle Glover got through the entire month of January completely trash-free. They are so obsessed with waste that they won't ask for a glass of water in a public place because it might come with a straw. They carry their own cup with them, or else drink tap water with their hands. (Bottled water, as we know, is heinous.) They do use plastic bags, to carry home their food, but they reuse them till they fall apart.
And yet, no matter how virtuous they try to be, it's never good enough. After they described how they dried out their plastic bags with an electric fan, they endured a storm of criticism from people who accused them of wasting energy — even though the fan uses no more energy than a 60-watt light bulb. “We kept using it, but we kind of felt guilty,” confessed Mr. Glover. So Ms. McGaughey started switching on the fan for only a few seconds — just long enough to blow the bags open so they can air dry. Mr. Glover swings them back and forth to dry them faster.
If this attention to detail strikes you as just a teensy-weensy anal, you may not be ready to join the company of the elect. You may not be ready to peel off those little stickers that come on pieces of fruit to make collages and cards for your friends. (Ms. McGaughey is.) You may not be ready to fret over the coloured strip that comes in your home-pregnancy test kit. “How can I reuse a plastic stick that has my urine on it?” Ms. McGaughey anguished. (For the record, it was positive.) Nor will your dilemmas end with death, at which point, thank God, you'll cease emitting carbon dioxide. Should you be buried or cremated? Each has environmental drawbacks. Perhaps you can be put into a tree to be ripped apart by vultures. Or perhaps your ashes can be recycled, like Keith Richards's father.
The no-impacters, it seems to me, are the modern version of religious ascetics, who practised various forms of self-denial and self-torture to prove their devotion to God. Some lived on top of poles for 40 years. Some went naked, and some ate only nuts and fruits, and some lived on air. “Those who practise ascetic lifestyles often perceive their practices as virtuous and pursue them to achieve greater spirituality,” says one authority. They believe their actions purify the soul.
As for the rest of us, we can always buy indulgences to purify the soul. These days, they're known as carbon offsets.
11/04/07, Martin Mittelstaedt, The mystery of the missing boys, (Back).
Chemical pollutants flagged in new study as possible factor in skewed sex ratio - Where are all the missing boys?
It is a question posed by a new study that has found the proportion of boys born over the past three decades has unexpectedly dropped in both the United States and Japan. In all, more than a quarter of a million boys are missing, compared to what would have been expected had the sex ratio existing in 1970 remained unchanged.
The study also says the world's most skewed sex ratio is in Canada, in a native community surrounded by petrochemical plants in Sarnia, Ont., where the number of boys born has plunged since the mid-1990s at a rate never seen.
Although the researchers do not know why boys are taking a hit, they suspect contributing causes could include widespread exposure to hormone-mimicking pollutants by women during pregnancy and by men before they help conceive children.
“We hypothesize that the decline in sex ratio in industrial countries may be due, in part, to prenatal exposure to metalloestrogens and other endocrine disrupting chemicals,” said the study, issued this week in Environmental Health Perspectives, a peer reviewed journal of the U.S. National Institute of Environmental Health Sciences.
These types of chemicals include some pesticides, dioxin and methylmercury, a pollutant from coal-fired power plants and many industrial sources commonly found in seafood. The study also flagged a host of other possible factors, including rising obesity rates, older parental age, growing stress levels, and the increasing number of children being conceived using fertility aides. Other research has shown some associations between these factors and a drop in boy births.
The study was conducted by researchers in both the U.S. and Japan, and led by Devra Lee Davis, a prominent epidemiologist and director of the Center for Environmental Oncology at the University of Pittsburgh Cancer Institute.
In an interview, Dr. Davis said that although the cause of the decline isn't known, it could be linked to the increasing number of other male reproductive problems, such as falling sperm counts and rising testicular cancer rates.
She said that males during fetal development may be more sensitive to pollutants that mimic hormones, leading to increased fetal deaths and reproductive problems later for the surviving males.
The situation in Sarnia, where nearly twice as many girls are being born than boys on the Aamjiwnaang First Nation, is internationally significant, according to the study. “To our knowledge, this is a more significantly reduced sex ratio and greater rate of change than has been reported previously anywhere,” it said.
The reserve is located in the heart of Sarnia's chemical valley, and the native community, along with researchers at the University of Rochester and the Occupational Health Clinics for Ontario Workers, are trying to find the cause of the unusual sex ratio.
Fewer boys than expected are being born in the non-aboriginal community downwind of the petrochemical plants in the area, but not to the same degree as on the reserve. The work force in Sarnia has not been studied, something that would shed light on whether pollutants are the cause.
Researchers in many countries have been reporting a drop in the ratio of boys to girls being born over the past few decades.
It is considered normal in a large population for the number of baby boys to slightly outnumber girls, by a proportion of about 105 males to 100 females. It is widely thought that more boy births are a way nature compensates for higher rates of male mortality.
But the ratio has not been static in industrialized countries, and researchers suspect that increasing numbers of male fetuses are being miscarried, a kind of sex-based culling in the womb.
In Japan, the sex ratio fluctuated with no trend from 1949 to 1970, but then declined steadily to 1999, the end of the study period there.
The decline in the number of boys in Japan equals 37 out of every 10,000 births.
In the U.S., the sex ratio also declined from 1970 to 2002. The drop in the number of boys equals 17 out of every 10,000 births.
The U.S. change was concentrated among whites, with almost no change among blacks.
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