Arsenic: opportunity for risk assessment.

Area of Science:

• Environmental Health
• Toxicology
• Carcinogenesis

Background:

• Arsenic is a known human carcinogen found in food and water.
• Regulatory standards for arsenic have existed for nearly a century, based on a presumed safe intake threshold.
• Modern US regulatory approaches often conflict with established arsenic standards for carcinogens.

Purpose of the Study:

• To investigate the existence and implications of a safe threshold dose for arsenic exposure.
• To explore the molecular mechanisms by which arsenic induces cancer.
• To support regulatory standards for arsenic through the study of arsenical skin disease.

Main Methods:

• Quantitative analysis of recent epidemics of arsenicism.
• Gene induction studies to understand arsenic's carcinogenic pathways.
• Survey of arsenical skin disease as a potential monitoring tool.

Main Results:

• Epidemics confirmed a dose-response threshold for both non-cancerous skin lesions and arsenic-induced cancers.
• Arsenic acts as a general gene inducer, activating pathways involved in cell proliferation and viral activation, classifying it as an indirect carcinogen.
• Background arsenic levels below current drinking water standards have not been linked to disease.

Conclusions:

• A safe threshold for arsenic intake exists, supporting classical toxicological principles.
• Arsenic's role as an indirect carcinogen is supported by its gene-inducing properties.
• Arsenical skin disease serves as a valuable indicator for public health surveillance and regulatory enforcement.