I was not aware that concern regarding lead toxicity and waterfowl started in the 50s.
"Lead Poisoning in Wild Waterfowl" was published in 1951
https://www.ideals.illinois.edu/items/17375

This is a good review in 1966
https://archive.org/details/ontariofishwildlv5n2onta/page/8/mode/2up

Nilo Farms - Olin Corp. - Winchester were early movers in the effort to avoid waterfowl losses from lead
1961
https://iopn.library.illinois.edu/journals/inhs/article/view/172
1975
R.S. Holmes, "Lead poisoning in waterfowl : dosage and dietary study: joint report of Illinois Natural History Survey and Olin Corporation, Winchester Group"

Of course the Greens, Audubon Society, etc. appropriated what was a legitimate effort on the part of sportsmen and conservationists; and here we are today.

https://sites.google.com/a/damascusknowledge.com/www/home