Toxic equivalency factors (TEFs) for polycyclic aromatic hydrocarbons (PAHs)

Area of Science:

• Environmental Science
• Toxicology
• Risk Assessment

Background:

• Polycyclic Aromatic Hydrocarbons (PAHs) are prevalent at hazardous waste sites, necessitating remediation.
• Toxicity criteria are lacking for many PAHs, complicating accurate risk assessment.
• Current EPA methods assume all carcinogenic PAHs have potency equal to benzo[a]pyrene (B[a]P), potentially overestimating risks.

Purpose of the Study:

• To evaluate existing approaches for assessing the relative potency of different PAHs in site-specific risk assessments.
• To present a modified approach for more accurate risk assessment of PAH mixtures.

Main Methods:

• Review and evaluation of current methodologies for PAH relative potency assessment.
• Development and proposal of a modified risk assessment approach.

Main Results:

• The assumption that all carcinogenic PAHs are as potent as B[a]P likely leads to risk overestimation.
• Existing approaches for considering PAH relative potency vary.
• A modified approach is proposed to better reflect current knowledge.

Conclusions:

• A more nuanced approach to PAH risk assessment is needed.
• The proposed modified method offers a more accurate reflection of PAH relative potency.
• Site-specific risk assessments can be improved by considering PAH-specific toxicities.