The Reclaimed Substances Category is comprised of several subcategories, each with a varying number of substances. The subcategories included are: 1) Residual Hydrocarbon Waste; 2) Naphtha Hydrocarbon Waste3) Naphthenic Acids 4) Disulfide Oil; and 5) Acids and Caustics from Petroleum Refining.  

1. Residual hydrocarbon wastes and 2. Naphtha hydrocarbon wastes are both Reclaimed Petroleum Hydrocarbons. These wastes were originally grouped together in the same category; however in the final submission of the category assessment documents, the sponsor separated them into two categories: (1) Reclaimed petroleum hydrocarbons; residual hydrocarbon wastes from petroleum refining category and (2) Reclaimed petroleum hydrocarbons; naphtha hydrocarbon wastes from petroleum refining category. The members of the reclaimed petroleum hydrocarbons; naphtha hydrocarbon wastes are represented by the fuel oil, residual, wastewater skimming (CASRN 68956-48-9) and petroleum products, C5 – C12, reclaimed, wastewater treatment (CASRN 68956-70-7). The members of the reclaimed petroleum hydrocarbons; residual hydrocarbon  are represented by the residual hydrocarbon waste streams from petroleum refining which include hydrocarbons C = 20, petroleum wastes (CASRN 68476-53-9); petroleum wastes (CASRN 68477-26-9); and clay-treating filter wash residues, petroleum (CASRN 68918-73-0). 

3. Naphthenic acids are a naturally occurring, complex mixture of cycloaliphatic carboxylic acids recovered from petroleum distillates. Naphthenic acids are extracted from kerosene and diesel streams in the refinery to improve the performance characteristics and storage properties of the finished products. Accordingly, from a petroleum industry perspective, the naphthenic acid streams are wastes; however, in some cases streams containing naphthenic acids can be treated to produce refined naphthenic acids which can be used as intermediates in the production of other substances. The major uses of substances derived from refined naphthenic acids are oil-soluble metal soaps for driers and other catalysts, wood preservatives, tire cord adhesion promoters, and as amine derivatives for corrosion inhibitors. 

4. Disulfide oil, or DSO, is produced  as a byproduct of the petroleum refining process.  DSO is a product of mercaptan removal from selected C4 to C5 light hydrocarbon streams by a process known as sweetening, since it removes the sour smelling sulfides from crude petroleum. The mercaptans are extracted from this feedstock in an entirely closed system referred to as a Merox®unit, which can be designed to operate with any of a variety of petroleum streams including liquefied petroleum gas, naphtha, or any other hydrocarbon fraction. DSO is also well suited for the application of a “read across” approach for predicting the health and environmental impacts of DSO, where modeling might not meet data needs. To the extent possible, the American Petroleum Institute (API) has information assembled information for the primary disulfide constituents of DSO. 

5. Acids and caustics from petroleum refining are represented by four separate types of reclaimed substances; all four substances are a product of petroleum refining. Three of the solutions are caustic and contain high levels of sodium hydroxide; whereas a single solution is an acidic mixture with high levels of sulfuric acid. Each substance contains a wide variety and an ever varying amount of organic constituents extracted from individual petroleum fractions. The three caustic substances in this category are generated when different petroleum streams are purified or “sweetened” to remove undesirable constituents such phenols, cresols and mercaptans. The forth substance, acidic sludge, is a byproduct of petroleum alkylation and contains a high percentage of sulfuric acid along with various hydrocarbons and suspended sediment. 

To meet the HPV Challenge, the Testing Group has thoroughly evaluated the substances within the broad Reclaimed Substances category and has made all of the reliable human health and ecological hazard data available to the public.

1. The Category Assessment Document (CAD) for Residual Hydrocarbon Wastes submitted to EPA by API which includes the final chemical hazard characterization and considers any new testing and analysis carried out for substances within the category.
2. The Robust Summary for Residual Hydrocarbon Wastes submitted to EPA by the American Petroleum Institute (API) which summarizes the available reliable data on physic-chemical properties, environmental fate and transport pathways, ecotoxicity, and human health toxicity.
3. The EPA Screening-Level Hazard Characterization for Residual Hydrocarbon Wastes which summarizes EPA’s views on the available data for the category and on the need for additional studies to fill data gaps.
4. The API Petroleum HPV Testing Group’s response to the EPA Screening-Level Hazard Characterization for Residual Hydrocarbon Wastes.

1. The Category Assessment Document (CAD) for Naphtha Hydrocarbon Wastes submitted to EPA by API which includes the final chemical hazard characterization and considers any new testing and analysis carried out for substances within the category.
2. The Robust Summary for Naphtha Hydrocarbon Wastes submitted to EPA by the American Petroleum Institute (API) which summarizes the available reliable data on physic-chemical properties, environmental fate and transport pathways, ecotoxicity, and human health toxicity.
3. The EPA Screening-Level Hazard Characterization for Naptha Hydrocarbon Wastes which summarizes EPA’s views on the available data for the category and on the need for additional studies to fill data gaps.
4. The API Petroleum HPV Testing Group’s response to the EPA Screening-Level Hazard Characterization for Naptha Hydrocarbon Wastes.

1. The Category Assessment Document (CAD) for Naphthenic Acids submitted to EPA by API which includes the final chemical hazard characterization and considers any new testing and analysis carried out for substances within the category.
2. The Robust Summary for Naphthenic Acids  submitted to EPA by the American Petroleum Institute (API) which summarizes the available reliable data on physic-chemical properties, environmental fate and transport pathways, ecotoxicity, and human health toxicity.
3. The EPA Screening-Level Hazard Characterization for Naphthenic Acids which summarizes EPA’s views on the available data for the category and on the need for additional studies to fill data gaps.
4. The API Petroleum HPV Testing Group’s response  to the EPA Screening-Level Hazard Characterization for Naphthenic Acids.

1. The API Response  to EPA Comments on Disulfide Oil (DSO) Assessment. 
2. The Disulfide Oil (DSO) HPV Data Review & Assessment with Annexes
3. The EPA Screening-Level Hazard Characterization for Disulfide Oil which summarizes EPA’s views on the available data for the category and on the need for additional studies to fill data gaps.
4. The API Petroleum HPV Testing Group’s response to the EPA Screening-Level Hazard Characterization for Disulfide Oil.

1. The Category Assessment Document (CAD) for Acids and Caustics from Petroleum refining submitted to EPA by API which includes the final chemical hazard characterization and considers any new testing and analysis carried out for substances within the category.
2. The Robust Summary for Acids and Caustics are the two SIAR documents for sodium hydroxide and sulfuric acid.
3. The EPA Screening-Level Hazard Characterization for Acids and Caustics is not currently available.
4. The API Petroleum HPV Testing Group will respond to the  EPA Screening-Level Hazard Characterization for Acids and Caustics when it becomes available.