Evaluation of the Limiting Permissible Concentration Concept in Ocean Dumping Assessments

The U.S. Ocean Dumping Regulations and Criteria (40 CFR 220-229) limit the types, amount, and release rates of waste into the marine environment. Materials to be considered for ocean dumping must be assessed by a technical evaluation of their potential environmental impact. Based on bioassay results, a limiting permissible concentration (LPC) is established that shall not be exceeded beyond the disposal site boundaries during initial mixing, and shall not be exceeded at any point in the marine environment after initial mixing. The LPC determination is made up of three critical variables: initial mixing considerations, acute toxicity threshold, and the use of an application factor to protect against chronic effects. Thus, the LPC is not a constant value, but is affected by laboratory results and dumping practices.