Scavengers lengthen the chain of toxins

The birds' bodies are routinely scavenged by other wild animals, further spreading the poison into the food chain. The chemicals have the "potential to cause additional mortality that may not be sustainable in populations already experiencing critical limitations," biologists from the United Kingdom's University of Leicester reported in 2005.

California's threatened San Joaquin kit fox is an example. Scientists collected carcasses of the big-eared, long-legged fox that died from various causes in Bakersfield and in an area 30 miles out in the country. Nearly all the dead foxes from Bakersfield had residues of the long-lived second-generation rodenticides, while none from the outlying desert did.

How are these rat poisons getting into plant eaters low on the food chain? There is no sure answer for now. Scientists wonder, though, if carcasses of poisoned animals are being scavenged by creatures low on the food chain. Or perhaps insects are crawling inside the bait stations. But there could be other ways, too. Elliott, the Environment Canada researcher, notes that scientists have seen voles and birds hopping inside the holes on the side of bait stations that approximate the size of the openings to their burrows or homes inside trees.

And as for deer? The seven that tested positive for rat poison in New York "apparently were exposed due to misuse and careless bait application," Erickson of the EPA reported. Elliott noted that big blue blocks of the poisoned bait are sometimes thrown out into the wild -- blue blocks that look a whole lot like the salt licks that deer are known to frequent.

Cracking down on rat poisons

Pushed by environmentalists who successfully sued in federal court, the EPA in 2008 issued rules for these rat poisons that largely take them out of the consumer market.

Pesticide manufacturers say EPA's action was overkill, but should eliminate any doubts about the products' safety for wildlife.

"There was not strong evidence to compel (EPA) to put into place the (new rules). However, they did so," said Karen Reardon, director of communications at Responsible Industry for a Sound Environment, which represents pesticide manufacturers. "We have now even further added protections for secondary wildlife exposure."

Dale Kemery, an EPA spokesman, said the agency does not track the amount of pesticides manufactured or applied. But New York State does tote up the applications. New York State Department of Conservation records requested by the Natural Resources Defense Council for use in a lawsuit to limit the rodenticides' use showed more than 20 tons a year were applied in eight New York City Zip codes in 2002. The pesticide manufacturer Syngenta International in 2004 revealed that some 10 million pounds of first- and second-generation rat poisons were sold annually in California. And in British Columbia, scientists obtained records showing large increases in their use during the 1990s.

The Western Canadian study documented a 100 per cent increase in sales of one of the rat poisons, brodifacoum, and a 24 per cent increase in another, bromadiolone, in British Columbia between 1991 and 2003.

Canada in 2006 changed the rodenticides' labels to require that they be used in dog- and child-proof bait stations that allow only rats access to the poison, or that the bait be limited to where kids and animals don't have access.

Then, in 2009, six months before release of the study of the owl poisonings, Health Canada issued stricter regulations. Their inspiration came from a contentious rule approved south of the border.

EPA cited risks decades ago

In the United States, the EPA knew by the early 1980s that the pesticides that emerged the decade before were affecting non-targeted wildlife. But it was 1999 before the agency's scientists launched a comprehensive risk analysis of the pesticides' effects on wildlife.

George W. Bush was president by the time an EPA document outlining the environmental risks of the rat poisons was ready to go out for public comment. EPA sent a draft of the document to the pesticide industry in September 2001 for what was supposed to be a 30-day technical review. The stated purpose was to allow industry officials to make technical corrections.

Instead, the agency held a series of closed-door meetings with industry officials, environmentalists charged. "There has been excessive undue influence from industry on the entire process," said the group Beyond Pesticides. "There has been little to no opportunity for any other stakeholder to provide input or even attend any of these meetings with EPA."

Reardon of the pesticide industry group said it's clear the pesticide industry didn't get special treatment from EPA because the industry opposed what the agency ended up requiring. "EPA has added additional safeguards on top of what was already required. One must conclude that EPA's actions satisfied what they believed was additional risk," she said.

In January of 2003, the agency released preliminary results for public comment. This came more than three years after the risk analysis began. It took EPA five more years, until May of 2008, to complete a regulatory review.

And then, a quarter-century after the poisoning of wildlife became well known, the agency decreed that rules to protect wildlife would go into effect more than three years later, in June 2011.

Under the new rules, use of the second-generation rat poisons by consumers will be curtailed. The sale of loose rat baits will be banned in "big box" stores like Home Depot as well as other retail outlets. However, consumers can purchase up to one pound of bait in bait "stations" that are designed to keep out kids and dogs.

Professional exterminators as well as employees of farms, warehouses and other commercial installations may continue to use the more-toxic rat poisons, and loose baits. However, they are required to use above-ground bait stations if the bait is left outdoors or in any place accessible to children, pets or wildlife.

Public health versus toll on nature

The rules represent a significant check on unsafe use of the products by consumers, said Rick Keigwin, director of EPA's Pesticide Re-evaluation Division "We wanted people who are professionals in the field, who have the training, to use these products in the appropriate way," he said.

The U.S. Fish and Wildlife Service and others pushed for EPA to disallow all outdoor uses of the rodenticides, with narrow exceptions.

EPA didn't go that far, said Laura Parsons, an EPA biologist specializing in pesticides, because of pushback from some businesses. For example, she said, "restaurants and food-service facilities felt very strongly that they needed some kind of perimeter control." The EPA's position was backed by the U.S. Department of Housing and Urban Development and the federal Centers for Disease Control and Prevention.

Professional pesticide applicators support the new "common-sense" rules, said Bob Rosenberg, vice president of the National Pest Management Association, and opposed efforts to ban outdoor use of the more-toxic products.

"Rodents are serious problem for all the reasons you know about -- public health reasons," Rosenberg said. "It's a lot better to get them outside rather than inside the structure. You want to get them before they get to the food."

Meanwhile, the multinational Reckitt Benckiser, which markets d-CON rat baits, is challenging the EPA's new rules in court in an effort to prevent them from going into effect.

The least-toxic answer, said Golden, the Fish and Wildlife Service toxicologist, is a system known as "integrated pest management." It emphasizes use of non-toxic pest-control methods, which in the case of rats translates to trapping the rats inside the house and finding ways to keep any more from getting in.

Golden predicted that poisoning of wild animals will continue.

"I wouldn't use anticoagulants in my backyard," said Golden. "These things are pervasive and are turning up in places we did not expect.... They're certainly not contained where we think they are."

Tomorrow: How Canada stacks up against U.S. laws to protect humans from accidentally being poisoned by super-toxic rodenticides.

*Correction added at 2:45 p.m., Dec. 16, 2010.