Lead and Mercury: Late Lessons from Early Warnings

Ignoring early warning signs can result in serious illness. The tragic histories of lead and mercury, for example, demonstrate the harm caused when government and industry do not take action to protect public health.

The dangers of lead poisoning to workers and children were recognized in the 19th century. By the 1930s, most medical and scientific experts agreed that lead was harmful to both child and adult health. Despite this broad scientific consensus, manufacturers added lead to paint, and later to gasoline, blocking attempts by public health officials to stop them.

Decades later scientists demonstrated that lead can damage a developing fetus or child at very low levels. We now know that lead damages the brain, lowering IQ and causing learning disabilities and behavioral problems. More than one million children in the U.S. today have enough lead in their blood to cause brain damage. Recent research suggests that lead may cause harm at levels even lower than the current, officially recognized “safe” threshold. Millions of additional children are likely being harmed. Government agencies estimate that it could cost $16.6 billion per year from 2001 to 2010 to inspect and clean up lead paint hazards in houses that have not yet been cleaned up.

Mercury has also been known to cause damage to the nervous system since the 19th century, when it was widely used in the felt industry (“Mad Hatters’ Disease”). Since the 1950s it has been known that when women eat fish highly contaminated with mercury, their children are at risk for mental retardation, seizures and other serious problems. Yet trash incinerators and coal-burning power plants continue to emit tons of mercury, which builds up in the food chain to contaminate fish. The result is that many fish species are now unsafe to eat.

Women of childbearing age and small children have been warned to no longer eat tuna steaks, shark, swordfish, or any fish from Massachusetts ponds and rivers. Eating these fish increases the risk of permanent harm (such as learning and attention problems) to the developing fetus or young child. In spite of this damage to an important food source, the industries that emit mercury continue to lobby against mercury reductions. Now 1 out of 10 women of child-bearing age have mercury levels that exceed the advised safe limit, putting untold numbers of future children at risk for learning and attention problems.