Scientists race to wipe out toxins

Genetic engineers' work on PCB-devouring enzymes could help Canada get rid of the toxins in a cheap and clean way.

Researchers at four Canadian universities have been studying four natural enzymes found in common soil bacteria that have the punch to at least partially break down 30 or 40 of the 209 compounds that infamous PCBs (polychlorinated biphenyls) are made of. They are now in the process of genetically engineering the enzymes so they'll be able to degrade the other PCB compounds.

“If you use natural bacteria, you don't have to transport contaminated soil or burn PCBs,” says biochemistry professor Lindsay Eltis from Universite Laval in Montreal. “This would cost less and there would be no toxic byproducts. . . . In essence, we hope to be able to reduce pollution cleanly and affordably.”

Mr. Eltis, and chemistry professor Victor Snieckus from Queen's University in Kingston, head a team examining two of the enzymes.

Michel Sylvestre, biotechnology professor at l'Institut national de la recherche scientifique - sante in Montreal, and Concordia

University chemistry professor Justin Powlowski lead teams working on the other two.

Over millions of years, bacteria naturally evolve and develop the ability to break down compounds. The research teams are trying to speed up this evolution through genetic engineering.

In a process called bioremediation, their altered bacteria could be unleashed into the environment and set on the prowl of toxins.

Bioremediation got its big break during the Exxon Valdez oil spill in 1989, when bacteria succeeded in cleaning up petroleum-smeared shorelines faster than all other methods -- and with no ill effects.

Current government policy for eliminating PCBs is incineration or burial. But burial is controversial since there have been dangerous leaks. Incineration also has its problems, as PCBs burned at less than 700C can yield toxic byproducts.

PCBs used to be found in everything from electric transformers to ink to cosmetics. Their use was banned in Canada in 1977, but some existing equipment such as capacitors and transformers were allowed to continue using PCBs until the end of their service life.

According to the latest figures from Environment Canada, there were still 11,458 tonnes of PCBs being used in such equipment in 1996. There was an estimated 134,889 tonnes of PCB waste in Canada in the same year.

Governments have been struggling to find ways of cleaning up the various sites still heavily contaminated with PCBs. Some remain hidden under sediment in our waterways and creep up through plants in the sea floor.

“PCBs are accumulating and they don't disappear easily,” says Mr. Sylvestre, who has worked on PCB degradation for more than 20 years.

Studies have shown high rates of cancer and miscarriages in humans exposed to high levels of PCBs.

But while researchers trumpet their research as a potentially environmentally friendly way to destroy the pollutants, environmental groups are holding back their applause.

Jo Dufay, campaign co-ordinator for the public interest group Council of Canadians, says it would be terrific if there were a safe biological method of breaking down PCBs, but she is skeptical of this approach because it relies on genetic engineering.

“When scientists splice and dice genes in a lab, they have to be careful of not creating one problem to deal with another problem,” says Ms. Dufay. “Put into the wild, altered bacteria can have devastating consequences.”

Aware that genetic engineering is controversial, researchers lament the public's reluctance to embrace new technologies.

“We know genetic engineering is still taboo,” says Mr. Eltis. “But we're not developing anything that could be dangerous in any way. I mean, it's not like we're cloning sheep here.”

Mr. Sylvestre expects it will be at least three years before the group's technology can actually be used.

The research is funded through a three-year $870,000 grant from the Natural Sciences and Engineering Research Council. The project runs until the fall of 1999, by which point the teams plan to have developed a comprehensive set of PCB-eaters.