API TR 403-1995: Toxicology Report on Petroleum Substances – Scope and Application in Health Risk Assessment

Introduction

API TR 403-1995 is a technical report issued by the American Petroleum Institute (API) under the categorization of a Hearth Department report and a toxicology report. Published in 1995, this document provides critical toxicological data and risk assessment guidance related to petroleum substances, particularly those encountered in upstream and downstream operations. While not a compliance standard in itself, API TR 403-1995 serves as an authoritative reference for industrial hygienists, toxicologists, safety engineers, and environmental regulators when evaluating the potential health effects of exposure to petroleum streams and combustion by-products.

Scope of API TR 403-1995

API TR 403-1995 focuses on the toxicological properties of selected petroleum fractions and combustion products that are relevant to hearth and furnace operations. The scope includes:

• Identification of chemical constituents typically found in petroleum-derived fuels and emissions
• Review of acute and chronic toxicity data for these constituents
• Assessment of exposure pathways relevant to occupational settings (inhalation, dermal, ingestion)
• Derivation of reference exposure levels and health-based screening criteria
• Guidance for interpreting toxicological data within the context of process safety and industrial hygiene programs

The report is intended to support risk management decisions for facilities involved in refining, combustion, and the handling of petroleum products. It is especially relevant for operations where petroleum substances are burned in hearths, furnaces, or boilers, as emissions may contain a mixture of hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), metals, and other potentially hazardous compounds.

Technical Requirements and Data Presented

Chemical Characterization

The report organizes petroleum substances into categories based on boiling point ranges and chemical composition. It provides tabular summaries of key compounds such as benzene, toluene, ethylbenzene, xylene (BTEX), n-hexane, polycyclic aromatic hydrocarbons (PAHs), and selected metals. For each compound, toxicological parameters are listed, including:

• CAS Registry numbers
• Occupational exposure limits (OSHA PELs, ACGIH TLVs)
• Acute toxicity (LD50, LC50)
• Chronic non-cancer and cancer endpoints
• Reference doses (RfD) and reference concentrations (RfC) when available

Note: Values shown above are illustrative examples of the type of data compiled in API TR 403-1995 and may not reflect the exact figures in the original report. Always consult the primary document for definitive data.

Hazard Identification and Risk Characterization

The report includes a systematic approach for evaluating the toxicological hazards of petroleum emissions from industrial hearths. It discusses the influence of combustion conditions (temperature, air-to-fuel ratio, residence time) on the formation of toxic by-products such as carbon monoxide, nitrogen oxides, sulfur dioxide, and PAHs. A key technical requirement is the application of dose-response assessments specific to petroleum mixtures rather than single compounds, which is highlighted in the report as more representative of real-world exposure scenarios.

Implementation Highlights

API TR 403-1995 is best utilized as a foundational reference document integrated into a facility’s existing health and safety management system. Key implementation strategies include:

• Exposure Assessment: Use the report’s chemical profiles to prioritize monitoring and sampling programs for workplace air and emissions.
• Air Permitting: Provide toxicological justification for emission limits or risk-based permit conditions, particularly when demonstrating that off-site exposure concentrations are below health-protective levels.
• Product Safety Data Sheets: Supplement MSDS/SDS information with additional chronic toxicity data when required by internal product stewardship policies.
• Training: Incorporate summary tables into training modules for operators and maintenance staff who work near hearth units or petroleum handling areas.

Compliance Notes and Regulatory Use

API TR 403-1995 is not a mandatory standard and does not have the force of regulation. However, it can be referenced in regulatory contexts, particularly in OSHA’s General Duty Clause or EPA’s risk management programs, as evidence of an employer’s awareness and appropriate evaluation of chemical hazards. The following compliance considerations apply:

• OSHA: The report can assist in meeting the Hazard Communication Standard (29 CFR 1910.1200) by providing toxicological data for classification and labeling of petroleum mixtures.
• EPA: Under the Clean Air Act, state and local agencies may accept risk assessments that rely on data from API TR 403-1995 for emissions from process heaters and boilers.
• International Use: While developed in the U.S., the report has been cited by European and Asian regulators as a supplementary source for petroleum toxicology (e.g., REACH dossier preparation).

Conclusion

API TR 403-1995 remains a valuable historical consolidation of petroleum toxicology data, especially for applications involving hearth and combustion operations. Its systematic presentation of physical-chemical properties, toxicity endpoints, and exposure guidance allows risk assessors to quickly access relevant information. While modern updates and supplemental documents have since been issued by API and other organizations, TR 403-1995 continues to provide foundational context for understanding the inherent hazards of petroleum substances. For any facility still referencing this report, it is essential to supplement it with current regulatory requirements and the most up-to-date scientific literature.