Advancing the science on chemical classes

Area of Science:

• Environmental Science
• Toxicology
• Regulatory Science

Background:

• Chemical hazard identification and risk assessment are typically performed individually for each substance.
• Grouping chemicals into categories offers an underutilized strategy for enhancing regulatory efficiency.

Purpose of the Study:

• To review existing national and international chemical grouping approaches.
• To define criteria for chemical grouping based on decision context and scientific properties.
• To explore the utility of a decision tree framework for chemical classification.

Main Methods:

• A comprehensive review of current chemical grouping methodologies.
• Analysis of decision-making contexts (e.g., risk assessment, policy) and scientific considerations (e.g., physical-chemical properties).
• Case study utilizing ortho-phthalates to identify and organize cross-agency frameworks.

Main Results:

• Structural similarity is the predominant method for chemical grouping among regulatory bodies.
• Toxicity to specific organs or biological functions is also employed in some grouping strategies.
• A decision tree approach, incorporating inter-agency regulatory information, can enhance chemical risk management.

Conclusions:

• Chemical class-based approaches can streamline the reduction of exposure to multiple hazardous substances, thereby lowering health risks.
• A decision tree framework can aid in selecting chemicals for a class based on the specific regulatory context.
• Implementing a decision tree approach can facilitate more efficient and coherent chemical risk management across agencies.