The Department of Toxic Substances Control (DTSC) collects data on each shipment of hazardous waste in, into, and out of California.

The volume of federal hazardous waste has decreased, the volume of other hazardous waste recycled has increased, and the volume of remediation waste has increased. At the same time, the number of businesses regulated and the number of shipments per year have increased significantly.

Federal hazardous waste, defined by the federal Resources Conservation and Recovery Act (RCRA), has decreased almost 40% since 1984. This waste is generally considered to be more hazardous than other hazardous waste, which is defined and regulated under state authority. The volume of other non-federal hazardous waste has increased almost 40%, and most of this increase is due to the increased recycling of used oil. These wastes are now collected and recycled into useful products rather than disposed into landfills, wastewater systems, or illegally. Remediation waste has increased significantly, which is an indication of the progress in identifying and cleaning up contaminated sites. At the same time, the number of businesses regulated has increased dramatically, from approximately 20,000 in 1984 to 300,000 in 1993. The number of hazardous waste shipments has also grown from under 50,000 in 1984 to over 400,000 in 1993.