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Health effects classification and its role in the derivation of minimal risk levels: immunological effects

H G Abadin1, C-H S J Chou, F T Llados

  • 1Division of Toxicology and Environmental Medicine, Agency for Toxic Substances and Disease Registry, Atlanta, GA, USA. HAbadin@cdc.gov

Regulatory Toxicology and Pharmacology : RTP
|December 30, 2006
PubMed

Insights

The Agency for Toxic Substances and Disease Registry (ATSDR) establishes minimal risk levels (MRLs) for environmental contaminants. Fifteen MRLs focus on chemicals where the immune system is the most sensitive target for toxicity.

Area of Science:

  • Environmental Health
  • Toxicology
  • Immunotoxicology

Background:

  • The Agency for Toxic Substances and Disease Registry (ATSDR) develops health-based guidance values called minimal risk levels (MRLs).
  • MRLs represent daily exposure levels unlikely to cause adverse noncancer health effects.
  • These values are derived from human data or sensitive animal studies.

Purpose of the Study:

  • To identify chemicals with the immune system as the most sensitive target of toxicity.
  • To report on the derivation of MRLs for these immunotoxic chemicals.
  • To discuss the rationale and critical studies used in developing MRLs based on immunological endpoints.

Main Methods:

  • Systematic review of toxicological databases to identify sensitive endpoints.
  • Prioritization of human studies, or the most sensitive animal species and relevant endpoints.
  • Selection of critical studies for MRL derivation based on immune system toxicity.

Main Results:

  • ATSDR has derived 346 MRLs to date.
  • Fifteen MRLs have been established for 11 chemicals targeting the immune system.
  • Chemicals include benzene, PCBs, dioxins, and organotins, among others.

Conclusions:

  • The immune system is a critical target for toxicity for several environmental chemicals.
  • ATSDR's MRLs provide crucial guidance for assessing risks associated with chemical exposures.
  • Methodology for deriving MRLs based on immunotoxicity is established and applied.

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