Lead is a soft and highly toxic elemental metal found naturally in the environment. It is usually extracted from ore deposits along with copper, silver and zinc. Australia is the world's leading producer of lead, followed by the United States and China.
Although lead is naturally occurring, most of it found in the environment today got there from a range of earlier commercial and industrial uses by people. It has been widely used in cables, pipes, paints and pesticides.
Historically, the major sources of lead emissions to the air have been motor vehicles and industry. There is dramatically less toxic lead in our air now than there was in the late 1970s, when the use of leaded gasoline was phased out across the country - virtually eliminating lead emissions from cars, trucks, buses and boats.
Today, metal processing plants are the most significant remaining sources of lead in the air, although solid waste combustion facilities, some power plants, companies that make lead-acid batteries and general aviation fuels that still contain lead also produce lead emissions.
Health Effects of Lead & Who is Most at Risk
People can be exposed to lead not only through the air we breathe, but also by drinking water that passes through lead-soldered plumbing, consuming lead-tainted food, or ingesting lead-contaminated soil or chips of leaded paint.
Lead accumulates in our blood, bones, muscles and fat. Infants and young children are especially sensitive, even to very low levels of lead. Specifically, lead exposure causes:
- Damage to organs such as the kidneys, liver and brain, as well as the central nervous system.
- Seizures, mental retardation, behavioral disorders, memory problems and mood changes.
- High blood pressure and increased heart disease, particularly among men.
Exposure to lead also may contribute to anemia, osteoporosis (brittle bone disease) and reproductive disorders.
Infants and young children are at greatest risk from the health effects of lead poisoning. Even at low levels, lead can damage the brains and nervous systems of developing fetuses and young children, resulting in learning deficits and lower IQs.
Environmental Effects of Lead
Lead in our water and soil can be a result of corrosion of lead or lead-soldered water pipes, corrosion of leaded paints or deposition of lead emissions from the air. Because it is an element, lead cannot break down in the environment nor be transformed into some other, less harmful material. Once present in the environment, it also can be extremely difficult and expensive to clean up.
From soil and water, lead accumulates in organisms and entire food chains. Lead poisoning can affect the health of shellfish and many other forms of aquatic life, and also disrupt the body functions of phytoplankton, which produce oxygen and provide food that are both vital to fish and larger sea animals.
Lead also can affect the chemistry and fertility of soil, particularly near highways and farmlands, where high concentrations may be present.
In October 2008, the U.S. Environmental Protection Agency (EPA) toughened its health-based primary National Ambient Air Quality Standard (NAAQS) for lead in the air by 90 percent, from 1.5 micrograms per cubic meter (ug/m_) to 0.15 ug/m_ averaged over a "rolling" three-month period.
The new secondary standard for protection of crops, vegetation and buildings was set at the same level. These were the first changes to the NAAQS for lead that EPA had imposed in 30 years.
Long-Term Lead Trends
Decades of monitoring show that across Massachusetts, lead levels in the air we breathe have been extremely low for many years - well below the NAAQS that was in effect before October 2008. Our state is expected to easily meet the newer, more stringent standard.