Montreal tests show harmful effects of contaminants

Contaminants in Arctic foods have been found to cause small balls in rats and stunt their sexual growth — and this toxic cocktail could be causing the same kind of damage in human beings.

Exposure to contaminants found in the Arctic harms the fetal and reproductive development of rats, according to two studies conducted by researchers at the Montreal University Health Centre.

Rats are reliable models for human beings in laboratory tests for medications and other substances, so the studies’ troubling results could be significant for northern residents.

The contaminants that researchers in one study gave to pregnant rats contained chemicals commonly found in Arctic fish and wildlife.

Dr. Bernard Robaire, from McGill University’s pharmacology department, said he chose this particular combination of chemicals because it contained the kind of chemicals that Inuit regularly consume in a country foods diet.

These chemicals originate in paints, cleaning solvents and pesticides. Many of these substances have already been banned, but some are still in use.

They’ve travelled into the polar food chain through the water or wind, accumulating in the fat of marine mammals, birds and fish.

Researchers gave rats a souped-up amount of these toxins.

“During pregnancy, they gave them from 10 to 1000 times the average level found,” Robaire said. “Then, we looked at the effect on the fetus, such as the size of the testes.”

Robaire said tests showed genetic changes in the fetus, including testes and ovaries with genetic abnormalities. As the rats grew, researchers also noted a late onset of puberty.

Robaire said these two factors could damage fertility.

Robaire said his study focused on the reproductive system of rats, although previous studies have found these contaminants can also damage the nervous system of animals and people.

A related study conducted at the Montreal University Health Centre looked at how a compound used in marine paint, called tributyltin or TBT, affects rats.

TBT is effective in killing algae and insects on marine vessels.

But its toxic residue accumulates in sediments, especially in cold-water sediments, where, even in very small amounts, it causes reproductive damage to bottom-feeders such as oysters and mussels.

Pregnant rats receiving TBT in the study had pups showing damage to their immune systems and reproductive systems.

Without more studies, Robaire said it’s impossible to predict what happens to the reproductive systems of human beings when they consume comparable levels of these chemicals.

Unfortunately, there’s no more money in the federal Toxic Substance Research Initiative for a follow-up study that would try and relate these results to people — despite the notable impact of these contaminants on rats.

“It suggests that a study should be done on it,” Robaire said.