TORONTO — New Democrat Leader Jack Layton is slated to become the first of several prominent politicians to have their blood tested for chemical contaminants when he provides a sample on Thursday.

The testing is part of an environmental group's campaign to highlight Canadians' exposure to toxins -- especially when it comes to children.

"Canada is one of the worst polluting industrialized nations in the world,'' said Rick Smith, executive director of Environmental Defence.

"We're at a critical point.''

With Parliament currently reviewing the country's pollution laws, Smith said it's vital that political leaders are engaged in the process and show leadership on the issue.

Environment Minister Rona Ambrose, Health Minister Tony Clement and Liberal health critic John Godfrey will also give blood, while Bloc Quebecois Leader Gilles Duceppe has not responded to a request by the Environmental Defence to be tested.

The samples of blood will be tested by an independent laboratory for 102 compounds that fall into seven broad categories, ranging from pesticides like DDT and heavy metals such as mercury, to various air pollutants and flame retardants.

The results should provide a snapshot of Canadians' exposure to harmful chemicals, many found in ordinary products, which can cause cancer or other serious health issues.

Layton could not be reached Wednesday, but said in a statement that all Canadians need to understand the health hazards of pollution.

"We know that even the youngest children have these contaminants threatening their health,'' Layton said.

"It's time the federal government got serious about reducing emissions and controlling pesticide use.''

Environmental Defence issued the challenge to the politicians last month after releasing a study that found the bodies of seven children were contaminated with a range of toxic chemicals, among them PCBs and flame retardants.

The children, and six adults, were from five families in Vancouver, Toronto, Sarnia, Montreal and Quispamsis, N.B.

The study found an average of 23 known or suspected toxins -- including carcinogens, hormone disrupters and neurotoxins -- in the children.

The adults were contaminated by 32 chemicals, and had higher concentrations of some products no longer in use, such as DDT and PCBs.

In response, Health Canada promised a national study in which 5,000 people will be monitored for toxic contamination over a two-year period, starting next year.

Neither Clement nor Ambrose was available Wednesday, but a spokesman for the environment minister said she would likely be tested within a couple of weeks.

"Our government firmly believes that health and the environment are closely linked,'' said Ryan Sparrow.

"That's why we're taking steps to reduce pollution and that's why both ministers are taking the steps and these tests in order to highlight the problem.''

Smith said he hoped that testing the politicians would "put a face'' on the problem and drive home the scope of the issue.

There is no doubt toxins will be uncovered in the politicians, he said.

"The only question is how much and at what levels.