OAKLAND - Previous assumptions about the health risks of one of the world's most widely used flame retardants are wrong, scientists say, with new data suggesting the compound is both more toxic and widespread in humans and wildlife than thought.

The chemical, known as "Deca," is a close cousin to PCBs and the bigger brother of two flame retardants already banned in Europe and several states, including California.

A bill attempting to banish Deca from consumer products in California fell short Thursday evening in the Assembly and appeared doomed.

More than 56,000 tons of Deca were infused into consumer goods worldwide last year, chiefly TV sets. Scientists knew Deca leached out into the environment, contaminating house dust and food and, by extension, our blood and breast milk. But they thought it was largely inert, harmless and quickly passed from our bodies.

Evidence from California's Department of Toxic Substances Control and the Virginia Institute of Marine Science undermines those assumptions. What was thought to be harmless is likely not, say scientists conducting the research. Deca appears to be quickly absorbed by organisms and quickly broken down into long-lasting and far more toxic compounds.

Maine last week passed a bill banning the compound; a similar measure is already on the books in Washington state. Illinois lawmakers are also contemplating a ban.

"What's troubling is our assumptions," said Rob Hale, a professor at the Virginia Institute who led some of the research. "We long assumed these products did not leach out of plastics or get into the environment. That was etched in stone.

"Now out pops data on birds of prey ... that all point to not only does Deca get out and get into organisms, it can also be broken down into (compounds) that have all these toxic effects."

The data comes from addled eggs of peregrine falcons and other raptors in California, Washington, the East Coast and China.

The two dozen or so eggs tested so far indicate those raptors - including two falcon pairs nesting in the Bay Area - have the highest chemical loads of Deca of any living organism tested, a red flag for a species that only recently rebounded from DDT exposure in the late 1970s.

Deca is part of a family of flame retardants known as PBDEs, or polybrominated diphenyl ethers. It's the only PBDE still on the market.

Siblings Penta and Octa were banned earlier in the decade in California and Europe after scientists concluded both compounds were bioaccumulative and toxic. The largest domestic manufacturer ceased making the chemicals in 2005.

Deca escaped any ban in part because scientists couldn't find evidence of similar effects. (The names come from the number of bromine atoms attached to the molecule: 10 for Deca, eight for Octa, five for Penta. The fewer rings, the smaller the molecule and the more toxic and persistent it is for living organisms.)

Industry groups note that the chemical is astoundingly effective at stopping a very real risk - fire - in plastics. Manufacturers say they don't need much Deca to protect products; plastics with Deca can be readily recycled, unlike those with other additives; the amounts contaminating humans remains, so far, fairly minuscule; and much less is known about alternative flame retardants.

"What's the right balance?" asked John Kyte, North American director for the Bromine Science and Environmental Forum, representing Deca's manufacturers.

"Deca does not pose a threat to human health and the environment. Can I say that definitively? No I can't. But no one can for any compound.

"The bottom line is we don't want to produce - and we don't want to have on the market - a product that's not safe," he said.

The egg data, in conjunction with other ongoing research, suggests otherwise.

The values range from about 0.5 parts per million to 3.5 parts per million and are 10 to 15 times higher than what scientists find in Swedish raptors. One egg from China tested at 12 parts per million, astonishing scientists.

The levels are nearly 100 times beyond body burdens found in aquatic species such as harbor seals and terns. It is also 100 times what is commonly found in humans, although data is scant on the latter point and some evidence suggests children are more contaminated than their parents.

Such a concentration seems small: A drop or three of Deca into a swimming pool. But the molecules are many. Any drop of water from that pool would contain 31 trillion molecules of Deca.

Kim Hooper, a research supervisor in DTSC's Environmental Chemistry lab, believes researchers misread the chemical because they focused initially on aquatic species and thus never noticed a problem. Peregrines in urban areas eat pigeons and sparrows - scavengers of human society. It appears now - and for reasons little understood - that Deca accumulates in such a terrestrial food web but doesn't in the more well-studied aquatic food web.

"We haven't thought these things were getting in biota in any amounts," said Kim Hooper, who is supervising the research at DTSC. "Now that it is in biota, you say, 'What are the terrestrial wildlife we've looked at?'

"Well, the answer is essentially none."

Raptor researchers say they doubt Deca endangers the birds the way DDT or PCBs did a generation ago. Thirty years ago, California had only two peregrine nests statewide. Today there are between 200 and 300.

There's also a lot of evidence that Deca quickly breaks down in the body and the environment to smaller, more toxic compounds - such as Octa, said Heather Stapleton, an assistant professor at Duke University's Nicholas School of the Environment and Earth Sciences.

The science on this is largely settled, she said.

But not to industry, which maintains the chemical is largely inert. And that uncertainty has left lawmakers paralyzed.

Maine was one of the first states to buck the trend and ban Deca, with a bill clearing the Legislature last week. The state of Washington was earlier, with the governor in April inking into law a bill that would ban Deca once safe and suitable alternatives are found.

But in California, a bill by Assemblywoman Sally Lieber, D-San Jose, to ban Deca outright in California could only muster 30 of the 41 votes necessary to clear the Assembly Thursday.

A different bill banning a wide class of brominated and chlorinated flame retardants from mattresses, bedding and domestic furniture did clear the Assembly late Wednesday. But while Deca is subject to that ban, manufacturers say they don't use Deca in household furniture or bedding.

"We're taking on the manufacturers of all consumer products," Lieber said last week. "This is a big struggle.

"But we have to push this as hard as we can. There's no doubt in my mind that this is the biggest public health threat we're facing."