Pesticides, heavy metals and other airborne contaminants are raining down on national parks across the West and Alaska, turning up at sometimes dangerously high levels in lakes, plants and fish.
A sweeping six-year federal study released Tuesday found evidence of 70 contaminants at 20 national parks and monuments -- from Denali in Alaska and Glacier in Montana to Big Bend in Texas and Yosemite in California.
The findings revealed that some of the Earth's most pristine wilderness is still within reach of the toxic byproducts of the Industrial Age.
"Contaminants are everywhere. You can't get more remote than these northern parts of Alaska and the high Rockies," said Michael Kent, a fish researcher with Oregon State University who co-wrote the study.
The substances ranged from mercury produced by power plants and industrial chemicals such as PCBs to the banned insecticides dieldrin and DDT. Those can cause health problems in humans, including nervous system damage, dampened immune system responses and lowered reproductive success.