Hazardous Waste Health Article

HAZARDOUS WASTE

All human activities generate some form of waste. In its most general sense, the term "hazardous waste" comprises toxic chemicals, radioactive materials, and biologic or infectious waste. Hazardous waste poses a threat to workers through occupational exposure and to the public through exposure in homes, communities, and the general environment. Exposure may occur near the site of generation, along transportation corridors, and near the ultimate disposal sites. Most hazardous waste results from industrial processes that yield unwanted intermediates, products that fail quality control, and spilled material.

Hazardous waste management is divided into two main areas: currently generated waste, which is regulated under the Resource Conservation and Recovery Act (RCRA) of 1976, and waste at abandoned sites, which is regulated under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980. The Environmental Protection Agency (EPA) has jurisdiction and responsibility for managing the "cleanup" of hazardous waste sites. The Agency for Toxic Substances and Disease Registry (ATSDR), a branch of the Centers for Disease Control and Prevention (CDC), evaluates and assists communities that have been exposed to hazardous waste.

Under RCRA, industries assume responsibility for all of the waste they generate. They may manage it on-site or ship it off-site. In the latter case they retain responsibility, even when it has reached a legal disposal site. This is termed "cradle-to-grave" responsibility. Under CERCLA (also known as the Superfund Act), states may petition the EPA to have a hazardous waste site listed on the National Priorities List. This makes the site eligible for federal cleanup assistance in the event that a responsible party is not identified or does not accept responsibility.

Under RCRA, solid waste is defined as hazardous if its "quantity, concentration, or physical, chemical, or infectious characteristic" leads to death or serious illness or otherwise poses a "substantial present or potential hazard to human health or the environment, when improperly treated, stored, transported, or disposed of, or otherwise mismanaged." Under the Toxic Substances Control Act, more than 55,000 individual chemicals can fit the definition of a hazardous waste.

The main types of hazardous wastes are depleted raw materials, reaction products, tank residues, filter cake, precipitates, and spent solvents. They may be disposed of in liquid or solid form, either contained or uncontained. Wastes must be listed on a manifest, hauled by a licensed hauler, and disposed of at an approved hazardous waste site.

It is estimated that hazardous chemical wastes have been stored at more than 50,000 sites in the United States alone, although only 1,500 are listed on the National Priorities, or Superfund, List. To be listed, a site must be assessed using the EPA Hazard Ranking System. Once the site is identified, a preliminary site assessment is performed to determine if there is a potential hazard. If a hazard exists, there may be emergency remediation, but typically the second phase is a remedial investigation/feasibility study that categorizes a site and identifies remediation options. Remediation may range from an enclosure and warning signs to complete removal of waste, capping, and treatment of groundwater.

The Hazard Ranking System yields three scores, involving: (1) the possibility of offsite migration; (2) the likelihood of human receptors coming in contact with contaminated air, water, soil, or organisms; and (3) the explosivity or fire hazard posed by the material.

The ten substances most often identified at Superfund sites are: trichloroethylene, toluene, benzene, lead, chloroform, polychlorinated biphenyls (PCBs), tetrachloroethylene, phenol, trichloroethane, and chromium. The receptor populations include not only neighbors living adjacent to industrial sources or waste sites, but emergency responders, public safety officials, regulatory agency personnel, and hazardous-waste remediation workers.

Pathways of exposure include: direct contact with contaminated soil from playing or working on or adjacent to a waste site, consumption of contaminated groundwater, inhalation of vapors or dust from a site, and consumption of contaminated food stuffs.

MICHAEL GOCHFELD

(SEE ALSO: Agency for Toxic Substances and Disease Registry; Benzene; Environmental Determinants of Health; Environmental Protection Agency; Hazardous Waste; Landfills, Sanitary; Lead; Municipal Solid Waste; Nuclear Waste; Occupational Safety and Health; PCBs; Pollution; Toxic Substances Control Act; Toxicology)

BIBLIOGRAPHY

Gochfeld, M. (1995). "Hazardous Waste." In Textbook of Occupational and Environmental Medicine, eds. L. Rosenstock and M. Cullen. Philadelphia, PA: W. B. Saunders.

Gochfeld, M., and Burger, J. (1995). "Assessment and Mediation of Hazardous Waste Sites." In Environmental Medicine, ed. S. Brooks et al. St. Louis, MO: Mosby.