Hunt for Truth – Alternative Sources of Lead Information

LEAD PAINT

Lead based paints contain a highly soluble form of lead compounds. Historically, lead paint was used due to its superior durability and appearance over non-lead paints. The use of lead paint was widespread in the twentieth century, in both residential and industrial applications, and continues to this day despite the fact that it was banned in 1978 for residential uses because of concerns regarding lead poisoning of children.

Today legacy lead based paints continue to be a serious issue because of the very large quantity remaining in the environment. Older buildings containing lead paint exist throughout the U.S. Additionally, large amounts of soil and dust contain elevated levels of soluble lead from the breakdown of old leaded paints. In this regard, lead paint is a significant source of lead exposure to humans and wildlife. In fact, many avian species have been observed consuming leaded paint fragments from numerous sources.

A study conducted on Midway Island concluded that the Laysan albatross was experiencing population level decline from exposure to leaded paint (Finkelstein et al, 2003). The source of exposure was determined to be lead paint flaking from old military buildings at bases on the island. The birds were consuming these fragments and feeding them to their fledglings, causing as many as 10,000 deaths per year in this one colony.

Another noted avian exposure to lead based paint in the environment was discovered at Pinnacles National Monument in California. California condors 317 and 318 (all birds are numbered by the Condor Recovery Program), were observed ingesting lead paint fragments from the North Chalone Fire Lookout Tower. In turn, these parents fed the regurgitated lead paint fragments to their fledgling (550). Condors 317, 318 and 550 were all tested and found to have elevated blood-lead levels, while 550 had to be evacuated to the Los Angeles Zoo for intensive chelation treatment for lead poisoning.

Despite the known health effects from the highly soluble form of compounded lead in paint, lead paint is still used for road base paint on highways throughout the U.S. Because of the superior quality and durability of lead paint, the Department of Transportation uses leaded paints for striping highways. The current lead paint used on highways has been diluted since the passage of the 1978 lead paint ban, nevertheless this soluble lead compound remains in use in our environment. Though lead paint is no longer widely used in the U.S., lead based paint remains prevalent in our environment and continues to poison humans and wildlife. 

LEADED GASOLINE

The industrial use of tetramethyl/tetraethyl lead additives in gasoline was widespread throughout the U.S. from 1929 to 1996, when it was banned in use for on-road vehicles. Lead was used as a fuel additive due its ability to boost fuel octane ratings and thereby reduce “engine knock,” which can cause severe damage to an engine.

During the time period when lead was widely used in gasoline, over 13.2 billion pounds of extremely toxic, minute particles (particulate matter <10 µ) of lead were released into the environment. This highly soluble lead residue remains in the environment in very large quantities, especially in urban areas and around highways where the lead levels in soil range from 10-100 times greater than background levels.

Presently, leaded gasoline is still used in the automotive racing and the aviation industries, which continue to release highly soluble industrial lead into the atmosphere. Legacy leaded gasoline, though largely banned, continues to be a major source of lead exposure to humans and animals alike. Indeed, large urban centers such as New Orleans have reported over 3000 ppm lead in soils around residential areas. Further, contaminated soils along roadways are a significant source of lead exposure to wildlife that scavenge and ingest road-kill. Additionally, animals that take frequent dust baths are susceptible to dermal exposure to lead compounds. 

LEADED PESTICIDES

Legacy leaded pesticides that were commonly used in agricultural areas present another source of lead exposure to humans and animals. Lead arsenate was the most widely used arsenic based pesticide to control the gypsy moth around the late 1800’s in the U.S. The successful application of lead arsenate against the gypsy moth, and the easy manufacturing process that allowed farmers to prepare it at home, resulted in widespread use of lead pesticides across the U.S.

Largely used on fruit crops, this pesticide began to be phased out of use once it was realized that washing the fruit vigorously did not remove lead residues. It was eventually abandoned when DDT became available in 1948. Lead arsenate can persist in the environment for a very long period of time. Studies conducted as late as 1998 showed high concentrations of lead remaining in soil where this pesticide was previously applied.

There is a strong correlation between the use of lead pesticides and lead poisoning of raptors, such as golden eagles, bald eagles and hawks, because of the fact that lead pesticides were once very prevalent in agricultural use, especially on orchards in Washington. (Department of Washington Fish and Wildlife Report, Feb. 12, 2001) Due to its high solubility, lead arsenate can leach into the ground, groundwater and surface waters (Columbia River) and migrate to soils downstream. Thus, ground squirrels living in burrows in and around orchards are very likely to be exposed to lead in the soil. Because ground squirrels have been shown to be a major diet item of hawks and golden eagles, this situation provides a plausible exposure pathway due to lead in the soil.

Lead pesticides illustrate yet another abundant source of highly soluble compounded lead in the environment and a potential for lead exposure to humans and wildlife. 

MICROTRASH

The term microtrash generally refers to small items of human trash consisting of things like coins, bottle caps, beverage tabs, nuts, bolts screws and glass shards. Wildlife that have a propensity to scavenge objects for sources of calcium, such as the California condor, are prone to collecting and eating microtrash.

Depending on the type of microtrash consumed, wildlife can exhibit symptoms including abdominal perforations, infections and heavy metal poisoning. Condors have been observed collecting and consuming microtrash in very high levels, with one instance where a pound of coins, bottle caps, metallic objects and glass were found in the gizzard of a condor fledgling. Microtrash ingestion accounts for almost 75% of nest failures in the California condor and because many of these items contain lead, microtrash is a likely source of exposure to lead for scavengers. 

MINING WASTE

Tailings, chat and other waste from mining operations have contributed significantly to the exposure of humans and wildlife to high levels of lead. The waste, commonly referred to as “chat” from dry mining operations or “tailings” from wet operations, is usually a dust, or a sand and gravel like substance that contains very high concentrations of heavy metals (e.g. lead, mercury, zinc, etc.). This waste is often left in piles or ponds at or around the operative or abandoned mining sites.

This mining waste is considered hazardous waste. In one instance, the mining town of Picher, Oklahoma, was declared uninhabitable due to the high levels of lead in the area associated with residual waste piles. In California alone, there are estimated to be between 39,000 to 47,000 abandoned mines, with 4,300 of these presenting significant risks to the environment, and many being declared EPA Superfund sites due to the extent of environmental hazards posed by the toxic waste (California Department of Conservation, 2000).

In California, the Black Bob Mine in Los Padres National Forest is an abandoned gold mine with significant amounts of lead and arsenic in the tailings. The Black Bob Mine is located within the California condor zone where the endangered species is located. The lead tailings are situated at the tributary to Salt Wash Creek, immediately upstream from the Wild lands Conservancy. The U.S. Forest Service has acknowledged that the tailings are contaminated and have already removed 205 cubic yards of waste, but more waste remains. Wildlife in the area, including the California condor, are exposed to lead in both the soil and water and are at risk from either ingesting grit or water, or dermal absorption from dust baths.

Old mining operation sites have released significant amounts of lead into the environment, and continue to be a source of lead exposure to humans and wildlife alike.