Montreal's public health department is warning school boards across the city not to use biodegradable cleaning products, Radio-Canada has learned.

Dr. Louis Jacques, who works for the health department, said Friday that he has studied research on such products, and is worried the very thing that makes them green could cause allergic reactions in children.

The department decided to look into the research after a health and safety employee at La Commission scolaire de Montréal, the city's largest French-language school board, brought the issue to its attention, Radio-Canada reported.

Jacques said biodegradable products contain organic enzymes that help break down detergents.

He said it's those enzymes that need further study and perhaps regulation. So far, La Commission and the Lester B. Pearson School Board, the largest English school board in Quebec, have already stopped using the products, according to Radio-Canada.

"Based on the studies that have been done among workers, we know that these products can cause asthma, rhinitis, conjunctivitis and dermatitis," Jacques said.

"But the most frequent health problem that was caused or aggravated by these products is asthma."

The health board plans to make recommendations on green products in late March.