Lead is a powerful neurotoxin. Formerly (up until 199x?) US motorists put millions of pounds per year into the air via their fuel. Now we find that motorists remain the largest lead-polluters in the form of discarded wheel-weights, to the tune of 3.5 million pounds a year.
There are a couple of dimensions to the problem, the advocacy site www.leadfreewheels.org focuses on the direct risk of lead poisoning to childred touching them. But beyond that they get ground to dust by passing traffic and they enter the ecosystem, e.g. as runoff polluting groundwater, or airborne as fine dust that can be inhaled or ingested.
Interesting question over at treehugger — do street sweepers pick these loose pieces of toxic waste up? And, if they do, then what happens to them?
The story of the use of lead additives in US fuel, and the industry’s wanton disregard for human health, is sickening and it haunts us to this day “Even though leaded gasoline is largely gone in North America, it has left high concentrations of lead in the soil adjacent to all roads that were constructed prior to its phaseout. Children are particularly at risk if they consume this”