Conservation groups have sued the Environmental Protection Agency and the U.S. Coast Guard for authorizing toxic oil dispersants without ensuring that these chemicals would not harm endangered species or their habitats. The groups want the EPA to immediately study the effects of dispersants on endangered and threatened species in all U.S. waters, including threatened and endangered whales, sea turtles, salmon and seabirds in the Pacific and polar bears and walruses in the Arctic. “If chemical dispersants are going to be used after an oil spill, we have to know whether they’ll hurt or kill whales, sea turtles and other wildlife.