Chemical codes: a methodology for generic risk assessment of wastes

Abstract

Over half of the 10 13 kg of solid waste generated in the United States each year is classified as ‘nonhazardous industrial waste’ and is regulated under Subtitle D of the Resource Conservation and Recovery Act (RCRA). The common designation of ‘nonhazardous’ is misleading because these wastes often contain the same toxic and carcinogenic compounds found in Subtitle C ‘hazardous industrial wastes’. This research developed a quantitative method to determine the toxic risk of Subtitle D wastes. Also, we used trial and error to devise a waste classification scheme, which resulted in an algorithmic classification of waste streams into nine categories based on component properties. These two types of analyses were applied to a ‘training set’ of 2605 waste streams and a total of 8000 waste streams. Fewer than 10% of waste streams ( 163 2605 = 6.3% in the training set, 571 8000 = 7.1% of all waste streams) had low toxic scores, and might be termed ‘nonhazardous’. Of the remainder, about two-thirds (63%) of both the training set ( 1549 2422 ) and total set ( 4703 7429 ) were moderately toxic. The rest are of the most concern because they are large-volume (> 10 000 kg/month) and high relative toxicity waste streams. Together, over 90% of the Subtitle D waste streams which are commonly termed ‘nonhazardous industrial waste’ were found to be toxic.