Chemicals in the environment
Sorry, you guys asked the question and since there are so many replys without expanation I thought you would of missed the answer. I'm new here but I'm learning.
There are people who have already answered the question you have asked. The trouble is can you find the answer? For every question you can ask you can find an answer I learned in college. Studies have been done somewhere, sometime. You just have to find the answer and the web makes that possible.
PBS in the United States did a Documentary a couple of years ago. All you have to do is find it.
DownBeachBreeze