Characterization of the toxicological hazards of hydrocarbon solvents

Abstract

Hydrocarbon solvents are liquid hydrocarbon fractions derived from petroleum processing streams, containing only carbon and hydrogen atoms, with carbon numbers ranging from approximately C5-C20 and boiling between approximately 35-370°C. Many of the hydrocarbon solvents have complex and variable compositions with constituents of 4 types, alkanes (normal paraffins, isoparaffins, and cycloparaffins) and aromatics (primarily alkylated one-and tworing species). Because of the compositional complexity, hydrocarbon solvents are now identified by a nomenclature ("the naming convention") that describes them in terms of physical/ chemical properties and compositional elements. Despite the compositional complexity, most hydrocarbon solvent constituents have similar toxicological properties, and the overall toxicological hazards can be characterized in generic terms. To facilitate hazard characterization, the solvents were divided into 9 groups (categories) of substances with similar physical and chemical properties. Hydrocarbon solvents can cause chemical pneumonitis if aspirated into the lung, and those that are volatile can cause acute CNS effects and/or ocular and respiratory irritation at exposure levels exceeding occupational recommendations. Otherwise, there are few toxicologically important effects. The exceptions, n-hexane and naphthalene, have unique toxicological properties, and those solvents containing constituents for which classification is required under the Globally Harmonized System (GHS) are differentiated by the substance names. Toxicological information from studies of representative substances was used to fulfill REACH registration requirements and to satisfy the needs of the OECD High Production Volume (HPV) initiative. As shown in the examples provided, the hazard characterization data can be used for hazard classification and for occupational exposure limit recommendations. Introduction Scope and purpose of the documentThe present document summarizes information on the physical/ chemical properties and toxicological hazards of hydrocarbon solvents and provides examples of the ways in which the information on hazard characterization can be used for hazard classification and to set occupational exposure limits. Many of the toxicological studies were published separately, but the results are summarized herein and referenced in the appendices.Hydrocarbon solvents are liquid hydrocarbon fractions that are primarily produced by the distillation of petroleum feed stocks or their synthetic analogs (e.g., Fischer-Tropsch derived materials), sometimes followed by additional processing steps such as solvent extraction, hydrodesulfurization, or hydrogenation. 1 Most hydrocarbon solvents are complex substances with variable compositions and are best described as UVCB 2 (unknown and variable composition) substances, but some are single constituent (mono-constituent) substances. The complex and variable nature of these solvents is the consequence of their manufacturing processes. In short, most hydroca...

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