The amount of dangerous industrial contaminants seeping into Canada’s environment has risen 20 percent since 1995, according to a report by three environmental organizations that compiled data from industrial polluters. The biggest increase came in discharges into lakes and rivers, which rose 37 percent, while air and land pollution each rose 9 percent. The increase in hazardous pollutants — including lead, arsenic, asbestos, and benzene — suggests that recent cleanup efforts by government and industry have been insufficient, the report’s authors say. They called for more stringent laws to reduce the rate of chemicals released into the environment and thereby protect wildlife and human health. Since the early 1990s, Canada, like the U.S. under the Bush administration, has generally relied on voluntary agreements rather than mandatory regulations to coax industries to reduce their environmental impacts.