South Camden, N.J., has the distinction of being one of the nation’s poorest cities — and an important East Coast laboratory for the environmental justice movement. Environmental justice advocates believe South Camden’s poverty goes a long way toward explaining why the city is home to so many plants and factory facilities, many of which spew toxic waste into the water and air. The city has the highest rate of fine airborne particulates and of infant mortality in New Jersey, and three out of five people living near one (or more) of its many plants has respiratory problems, about twice the rate as in neighboring North Camden. There are already three large environmental lawsuits pending in the city, and a fourth will be lodged soon, although only one of those suits — a claim that the state Department of Environmental Protection discriminated against residents by allowing the St. Lawrence Cement Company to open a factory in the city — directly invokes environmental justice issues.