Lead shot is very poisonous to waterbirds
Lead is the traditional metal used to make shot, the collective term for the small balls or pellets that are packed in shotgun cartridges and used for shooting wildfowl. When a shot is fired at a duck flying over a lake, some of the pellets may hit the intended target but many of them do not and they fall harmlessly into the water.
The hunter has bagged his or her duck and that may seem to be the successful outcome. However, pellets of lead lie out of sight on the bed of the lake. Over many years of many wildfowlers shooting at the lake the level of lead in the sediment at the bed of the lake obviously rises.
Lead is one of the more stable metals; under natural conditions it does not rust, corrode or rot: it generally stays intact. Some corrosion can occur as evidenced by the controversy regarding drinking water, human health and lead pipes in old houses, but lead is generally pretty corrosion-resistant.
Our brains are particularly sensitive to elevated levels of lead. Lead used to be added to petrol to improve engine performance, and to paint to decrease drying time and increase both durability and moisture resistance, but the un-leaded forms of these products is now the norm to protect human health.
Plants and animals living on a lakebed are not so lucky if their environment is polluted with lead shot from years of wildfowling at the same spot. Swans are often found dead and in the rare case where a post-mortem is carried out to determine the cause of death, lead poisoning is very often the result.
So, to protect wildlife and the environment why not substitute iron, steel or some composite material for lead when making shot? Conservation-minded wildfowling organisations are working towards un-leaded shot, but it takes time to change. Gun barrels are designed to cope with lead shot and substitutes for lead have different aerodynamic properties.
That said, good progress has been made; so good in fact that at a recent meeting of the European Chemicals Agency it was decided by the Irish government and other European Union Member States to ban the use of lead ammunition in gunshot over wetlands. In the transition period before that recent decision is transposed into law, it would be great if all hunters would voluntarily switch to non-lead alternatives for all ammunition.