Japanese scientists testing ocean water and sea sand have found widespread contamination with high levels bisphenol A, a chemical used to make plastic that's able to mimic the female hormone estrogen in living things.
Its presence in sea water comes from the breakdown of the plastic trash being dumped into the sea and from the use of the compound in anti-rusting paints applied to the hulls of ships. BPA is man-made and does not occur naturally in the environment.
The researchers took samples at more than 200 sites, mainly on the coasts around North America and Southeast Asia. They detected the chemical along the shorelines of 20 countries and in every batch of water or sand tested.
Worry over BPA water contamination is relatively new, and few standards exist to protect wildlife from becoming overloaded with the chemical or to suggest bathers would be prudent to avoid going to the beach.
But last fall, Environment Canada proposed a maximum concentration of BPA in industrial effluent. The lowest levels detected by the Japanese scientists were already at least six times higher than the limit being considered by Environment Canada, which was based in part on the ability of even trace amounts of the chemical to impair semen quality in fish.
The research results were presented last week in San Francisco at a meeting of the American Chemical Society, and one of the scientists who conducted the sampling says it shows there is widespread decomposition in the environment of the hard type of plastic, known as polycarbonate, made from BPA. Products ranging from lenses on eyeglasses to big, office-style water jugs are made from polycarbonate.
"We were quite surprised to find that polycarbonate plastic biodegrades in the environment," said one of the researchers, Katsuhiko Saido, a chemist at Nihon University in Japan.
He thought another big source was from a resin, known as epoxy and made partly from BPA, that is commonly applied onto ship hulls to prevent them from rusting out or becoming covered with barnacles. "This new finding clearly demonstrates the instability of epoxy and shows that BPA emissions from epoxy do [contaminate]the ocean," Dr. Saido said.
A spokesman for the American Chemistry Council, an industry trade group representing BPA manufacturers, was skeptical of the findings, and criticized them for being presented at a scientific conference rather than in a peer reviewed journal.
"Quite a few studies from other researchers have been published with data on BPA in seawater, freshwater and sediment. None of these researchers have reported BPA at levels even remotely close to what is claimed by the Japanese researchers. The extensive data on BPA that has been published indicates that BPA, if found at all, is present in the environment only at very low trace levels," said Steve Hentges, the spokesman.
Mr. Hentges said it is possible that epoxy resins are used on ships. Because the compounds are highly stable and durable, he said it is "unlikely that they will degrade" to form BPA.
Because BPA is able to stick to substances, the highest levels detected were in sand, at a staggering 28,000 times Environment Canada's proposed limit for water.
"What's really astonishing here is the amounts," said Frederick vom Saal, a biologist at the University of Missouri, who did not participate in the research.
Dr. vom Saal, a major authority on hormones, is worried that people going to the beach could be exposed to BPA and either absorb it through their skin while swimming or from sand. He said it was "a scary finding that the levels in the ocean could already be at levels where you would not want to swim … This is shocking."
He says regulatory authorities need to enact measures to prevent BPA from getting into the environment from the degradation of products containing it.
Many scientists have been concerned about BPA because it has a shape that allows it to fool the body's cells into viewing it as the same thing as naturally occurring estrogen. Estrogen levels in people are typically in the low parts per trillion, but the new research showed ocean concentrations were at least 10,000 times higher and started at 10 parts per billion.
Hormones are some of the most powerful biological agents in existence, the reason tiny amounts of synthetic chemicals resembling them are potentially dangerous. A part per trillion is vanishingly small - the equivalent of one second of time during a 32,000-year span. A part per billion is a second in 32 years.
The Canadian government has announced that it views BPA as a toxic substance because of concerns the chemical could contaminate wildlife and is a possible human health threat, although the government still allows its use in consumer products such as tin cans, which contain an liner made from it, based on a view that exposures aren't high enough to cause harm.
Independent researchers have linked BPA to a wide range of possible human health conditions, including obesity, diabetes, cancer (breast, prostate and uterine), cardiovascular disease and asthma, sometimes at levels below Canada's current safe exposure standard. But industry-funded studies have been unable to find harm from the chemical.
Concerns over the possible impact of the compound led the U.S. Environmental Protection Agency to this week announced it is considering whether BPA should be added to its list of chemicals of concern, following similar action already taken by Environment Canada.
The Japanese researchers found BPA in the oceans and sand in amounts ranging from 10 ppb to 50,000 ppb. Environment Canada's proposed water pollution limit for industry is 1.75 ppb.
Trace amounts of the chemical are showing up in fresh water as well. The Ontario Ministry of the Environment released details earlier this year of sampling it undertook that found the chemical in 12 per cent of treated municipal drinking water. The highest amount was 99 ppt.
BPA eventually breaks down into harmless compounds in the presence of light and oxygen. But the pollutant is constantly being replenished by a continuous supply of new plastic being added to the oceans.
Dr. Saido said with so much plastic floating around in the oceans, including a huge patch in the middle of the Pacific that is twice the size of Texas, these products "will certainly constitute a new global ocean contamination [source]for long into the future."