Mercury in Automotive Systems - A White Paper 960409

Mercury is a naturally occurring element and therefore neither created nor destroyed, but pushed and pulled throughout the biosphere. Mercury released in vapor form to the atmosphere can be transported and redeposited via atmospheric deposition.

Recent international, federal and state regulatory initiatives have been directed toward effective use management and minimization of toxic substances in manufacturing and commerce. The concern is that these substances bioaccumulate in the food chain, posing a threat to human health and the environment. The most significant human health exposure to mercury is the dietary intake of fish and fish products, since mercury biomagnifies in aquatic species.

The Michigan Environmental Science Board (MESB), a task force formed by the state of Michigan, has found a small margin of safety between background (i.e., natural) levels of mercury exposure and concentrations that can cause harm to humans. At the national level, the U.S. Environmental Protection Agency has established the National Mercury Task Force to address mercury concerns from all sources and to make recommendations to the EPA Administrator. In Minnesota, legislation recently enacted requires a number of actions regarding mercury, including removal of switches from scrapped automotive vehicles. These efforts at the state and federal levels are indicative of growing concerns about mercury and the need to address anthropogenic (man-made) sources.

While recent studies have shown a decline in the use of mercury in some products, product designers and engineers need to recognize these concerns and that the decisions they make early in the design process can have a substantial impact on our environment. The time to control mercury is in component specification, not when it is present at low concentrations in Automobile Shredder Residue. Life cycle, design for the environment and pollution prevention principles incorporated at the beginning of the product design, along with the other important tradeoffs that need to be considered, can result in continued competitive products in the marketplace while minimizing potential adverse impacts to our environment.

In automotive applications, for example, mercury switches used in lighting, antilock brake systems, and active ride control result in a calculated 9.8 metric tons per year of elemental mercury. These same switches incorporated in the product in the beginning ultimately are disposed at the end of the vehicle life. While this paper does not focus on the current fate of these switches, it is fair to say that the ultimate fate of mercury could be released to the environment. Automotive engineers can, in the design/decision process, reduce use and/or eliminate mercury with viable, environmentally benign alternatives. This proactive effort and design philosophy will substantially reduce sources of anthropogenic mercury emissions.

Based upon the findings in this white paper, the Design and Manufacture for the Environment committee recommends the following actions:

1. Academia, Regulatory and other Agencies perform additional studies regarding the significance of mercury loading to the ecosystem through Automotive Shredder Residue (ASR). Survey all industries to further quantify mercury emissions to the environment.
2. Product Engineers apply life cycle principles to any new components in vehicles that utilize mercury. This would include pollution prevention, possible elimination, and reduced use of mercury in automotive products.
3. Manufacturing/Industrial engineers develop containment strategies to existing mercury articles exiting the automotive market. “Containment” is defined as designs and procedures used to insure that a product does not release mercury into the air, water or land.