State wildlife officials plan to destroy nearly a half-million farm-raised trout that became contaminated with PCBs, apparently from paint used at Montana’s largest hatchery.
The PCB-laden paint was applied more than 25 years ago to the walls of the fish tanks at the Big Springs Trout Hatchery in Lewiston, where the trout are raised to help stock lakes along the Missouri River.
PCBs, or polychlorinated biphenyls, were put to a variety of industrial uses up until the 1970s, before studies suggested they can cause cancer.
The fish to be destroyed are contaminated at levels ranging from 0.029 to 1.69 parts per million, state fisheries chief Chris Hunter said Friday.
Health guidelines indicate people can safely eat one fish meal a week at PCB levels to 0.10 ppm, and one a month at levels between 0.11 and 0.47.
The hatchery produces about half of the fish for Montana’s stocking program. Eight other hatcheries together produce the remaining half.