Is there a link between arsenic in drinking water and skin cancer?

Link Between Arsenic in Drinking Water and Skin Cancer

There is a significant link between arsenic exposure in drinking water and skin cancer, with inorganic arsenic being classified as carcinogenic to humans by the World Health Organization and US National Toxicology Program. 1

Evidence for Arsenic-Skin Cancer Connection

• Chronic exposure to arsenic-contaminated drinking water is associated with increased risk of skin lesions and skin cancers, even at levels previously considered safe 2
• The most common arsenic-induced skin cancers are Bowen's disease (carcinoma in situ), basal cell carcinoma (BCC), and squamous cell carcinoma (SCC) 3
• Studies in the United States have found associations between arsenic-contaminated water and skin cancer, sometimes occurring at arsenic concentrations below 10 μg/L (the EPA maximum allowable concentration for municipal water) 4
• Arsenic exposure is linked to characteristic skin manifestations including:
  • Skin hyperpigmentation and hyperkeratosis (hallmark signs of chronic exposure) 3
  • Multiple and recurrent lesions, often on sun-protected areas of the body 3

Mechanisms of Arsenic Carcinogenesis in Skin

• Arsenic tends to accumulate in the skin, making it a target organ for carcinogenic effects 3
• Possible mechanisms of arsenic carcinogenesis include:
  • Oxidative stress and chromosomal abnormalities 3
  • Altered growth factors and cell cycle disruption 3
  • P53 dysfunction leading to G2/M cell cycle arrest and DNA aneuploidy 3
  • Impaired immune function with decreased Langerhans cells in lesions 3

Risk Factors and Susceptibility

• Individual arsenic methylation capacity plays a significant role in susceptibility to arsenic-induced skin disorders 5
  • Individuals with higher percentages of methylarsonic acid (MMA) and lower dimethylarsinic acid (DMA) in urine have 5.5 times higher odds of developing skin disorders 5
• Arsenic may act as a co-carcinogen with UV radiation, enhancing tumorigenicity 6
  • This interaction may explain why arsenic-induced skin cancers are less common on sun-exposed areas 3, 6

Public Health Implications

• Arsenic contamination in drinking water is a global public health issue 3
• Testing of drinking water sources in high-risk areas is recommended, particularly for private wells which are not regulated by EPA standards 1, 4
• In areas with high arsenic levels, alternative water sources (e.g., bottled water) are advised 1
• Common household water filters are generally not effective at removing arsenic 1

Monitoring and Prevention

• Individuals with arsenic exposure should be monitored for skin lesions, which can be precursors to skin cancer 2
• Those with arsenic-induced Bowen's disease should undergo more aggressive cancer screening for lung and urinary bladder cancers 3
• Maintaining good folate status may be important for arsenic elimination from the body 1

Understanding this link is critical not only for skin cancer prevention but also for comprehending arsenic carcinogenesis in other organs, as skin manifestations often serve as visible biomarkers of systemic arsenic toxicity.