Ontario has released a final list of pesticides that will be banned for cosmetic use and sale, including weed killer 2,4-D, starting on Earth Day, April 22.

The new regulations will prohibit the sale and use of 2,4-D in its concentrated form despite a NAFTA challenge from its manufacturer, Environment Minister John Gerretsen said Wednesday.

Dow AgroSciences, a unit of Dow Chemical, filed a $2-million notice of action against the federal government last August.

It alleges that Quebec's ban on 2,4-D violates Canada's obligations under NAFTA because it prohibits a product without any scientific basis.

Gerretsen says he won't back down from a ban that protects the health and safety of Ontario residents just because Ontario might also face a lawsuit.

Ontario passed legislation last year banning the sale and use of pesticides with exceptions granted for golf courses and farms.