California Air Resources Board Identifies Inorganic Lead as a Toxic Air Contaminant
For immediate release
SACRAMENTO – After a thorough health effects evaluation, the California Air Resources Board (ARB) today made inorganic lead the 19th substance to be identified as a toxic air contaminant. The ARB found inorganic lead, forms of the metal which do not contain carbon, to be an airborne toxic without an identifiable safe threshold level.
ARB Chairman John Dunlap said, "Reducing Californians' health threat from lead is one of the state's biggest air pollution success stories. Identifying inorganic lead as a toxic is another important step in protecting our children from the potential health damage associated with airborne lead."
The primary public health risk from inorganic lead is its effects on the nervous systems of children. In high concentrations, children can even suffer irreversible brain damage and death. ARB experts consider the risks to children to be the most important because a significant number of children in California experience elevated levels of lead in their blood.
In adults, the health risks can include increased blood pressure and related cardiovascular problems and possibly cancer. California's greatest outdoor exposure to lead is currently from inorganic forms.
The majority of California's inorganic lead emissions are less than 10 microns in diameter, about one fifth the size of a human hair, and the particle size that can easily be inhaled and deposited into lung tissue. While small particles comprise most inorganic lead emissions, the ARB is also concerned about larger size particles that can be deposited into drinking water or food supplies. According to ARB data, between 175 and 182 tons of inorganic lead are emitted into California's air each year. For most Californians, airborne lead contributes to only a small percentage of their overall exposure to this toxic material. However, in areas where blood lead levels are already high, even due to other sources, it may be necessary to take further actions to reduce lead emissions. Now that it has been identified as a toxic air contaminant, California law requires the ARB to develop a risk management plan for exposure resulting from airborne inorganic lead. During the past 20 years, a number of efforts have been taken by state and local air quality agencies that have cut the public's exposure risk from all forms of lead by over 95 percent.
Between 1978 and 1987, the phase-out of leaded gasoline had cut its use by 90 percent and reduced the overall inventory of airborne lead by nearly 95 percent. The ARB completed its phase-out of lead from on-road gasoline in 1992 and since that time ambient concentrations of all forms of lead have been cut in California's atmosphere.
Currently, aircraft fuel is the primary source of inorganic lead emissions contributing about 149 tons of the metal to the state's lead inventory each year. The next largest source of inorganic lead is metal melting facilities which emit about 6 tons of inorganic lead to California's air per year.
In total, Californians are exposed to about 390 tons of lead in blowing dust each year. Lead emissions of all forms are emitted from a number of sources that include: paints, tires, fuels for off-road vehicles, such as aircraft, marine, construction and farm equipment. Inorganic lead is also found indoors, however, most indoor exposure is from particles that migrate from outside, although some exposure still occurs in older buildings which were coated with lead-based paints. While those paints were banned in residences in 1978, it can still be found in some homes. Also, lead-based paints are still allowed in industrial, military and marine settings.