As far back as 1969, Monsanto knew that PCBs led to the contamination of oysters, fish and birds, yet it took another decade before the EPA was able to ban them, overriding fierce resistance from Monsanto. EPA estimates show that up to 150 million pounds of the chemicals are dispersed throughout the environment, including in the air and in water supplies. There are estimated to be an additional 290 million pounds buried in landfills.