The lead shot ingested by ducks is most often already coated with either calcium, or iron, or a combination of those elements, which protects the ducks from much in the way of lead poisoning before the lead passes on through and out the duck. There is a certain level of mortality from all sources, which we cannot control 100%. Just as humans die from accidents, disease, old age, birth defects, intentional injuries, and other causes, animals also die from all these. A duck in the wild that lives 3 years is a very old duck. But, then a domestic cat that lives out doors has a life expectency of only 18 months.
Any one can work long enough and find a duck that has apparently died from ingested lead. But it is a very small percent, and it is well within the other mortality causes. It is NOT threatening ducks as a species, which is what the Endangered Species act was suppose to be all about. More ducks die from being wounded and not killed outright from pellets, both lead, and now non-toxic pellets, than die from lead poisoning CAUSED by ingestion of lead pellets.
Certainly there is no evidence that lead is having the same effect on Pheasant, rabbits, quail or other upland game animals.
People, particular infancts, who eat lead-based paint, something that was outlawed more than 40 years ago, had elevated lead levels in the their blood because of their age, size, and immature development. Adults that inhale lead fumes, found on indoor ranges, also can develop elevated lead levels. Ventilation is the key to removing that problem, and frequent cleaning of surfaces at the ranges, with water.
As to lead paint ingestion, most of that paint has already been removed from homes and apartments. The answer there was to have adequate supervision by the parents of such infants. Who would sit around and watch their child eating paint of any kind??? Just how stupid can parents be and have society pick up the cost?
Most birds do not hold stones or lead pellets in their craws more than a few hours, before passing them along with their stools. That is why the birds are always picking up new gravel and stones for their craws! Upland game birds have much smaller craws, and use much smaller pellets than the shot used by hunters to hunt them. The shot also falls on grass and woods covered ground, where it is much more likely to work down into the soil and be covered over, out of the reach of such birds. Birds tend to find their gravel along streams, sand bars, creeks, and rivers, and not in the middle of fields or in edge cover, or trees.
For that reason, there is no rational justification for restricting the use of lead shot for hunting upland game animals. The same goes for using lead shot at skeet, and trap, and sporting clays ranges. Yes, there are hundreds of pounds of lead put into the enviroment, but that lead is oxidized, and coated with whatever minerals are avaiable in the soil. Here in Central Illinois, and Northern Illinois it is mainly Calcium. In Southern Illinois is mainly Iron. If you have ever seen bullets for sale at the tourists shops near Gettysburg, or other battlefiled sites, the bullets all have this white crust on them. That is lead oxide, and usually has a high calcium content, as calcium is widely available in soils in this country. It is brought to the surfaces by the roots of trees; it leeches out of plant leaves, and from the bones of dead animals, and from the feces of mice that consume the bones. It sweetens the soil by neutralizing the acids that exist in the environment. My God, Galena, Illinois, was the source of almost all the lead used up until after the Civil War. there was lead all over that place because of the high lead content of soils in that area. If lead posed a serious threat to the general health of people, it would have decimated the population in that town rather quickly. The lead mines are now closed, but only because the amount of lead per ton of rock is too small to make a profit. I am sure there is plenty of lead dust and lead oxide to be found around that town.
The point being made is that lead has been around for hundreds of years, and we have seen no mass killing of people as a result of lead poisoning caused by either eating lead or breathing lead laden fumes. ZNor has it been shown to cause brain damage in other than small children. Since their source of lead was the lead based paints, that is no longer a problem in the USA. I have a friend who worked as a range officer at a police training facility. When his elevated lead levels were discovered, he was taken off the range. In about a year, his lead levels had dropped to well within normal levels, and he had suffered no ill effects. He was quite angry at being removed from the range, and assigned to classroom duties. His employer had him taken an annual blood test to check lead levels for several years afterwards, and it continued to drop each year. Neither he nor other co-workers suffered any lasting effects from breathing in lead particles at the range. They did upgrade ventilation and fans at the range, and that cured the problem for subsequent range workers.