National outrage at the poisoning of a predominantly poor and black citys water supply is bringing unprecedented attention to environmental justice issues, according to a leading researcher.

President Barack Obama declared a federal emergency in Flint, Michigan, last month in response to unsafe amounts of lead in the city's water supply and elevated levels of the neurotoxin found in children's blood. Ramped-up efforts to deal with the public health crisis came after resident complaints went unheard for months after the city switched water sources in 2014 to cut costs. They failed to properly treat the new Flint River water to prevent it from corroding lead pipes.

The long delay and continued denial before officials acted on residents' concerns has prompted questions over whether the crisis would be handled differently in a whiter, wealthier city -- over half of Flint's population is black, and 40 percent live below the poverty line. Gov. Rick Snyder (R) said the Flint water crisis is absolutely not a case of environmental racism and theres no evidence that race explicitly contributed to the water switch or the handling of complaints.

Still, activists have connected the crisis to a pattern of minority communities facing unequal exposure to environmental health risks .

The Flint water crisis stands apart from other environmental justice cases, according to Paul Mohai, a professor who founded the University of Michigan's environmental justice program. It's unique because the evidence seems so indisputable," he said, and the health consequences have an obvious cause.