A recent study on the effects of environmental arsenic at the University of Oklahoma Health Sciences Center indicates that arsenic in drinking water can both stimulate the growth of cancerous tumors and cause them to spread faster, the Water Quality Association (WQA) reports.
While researchers still do not know whether arsenic in drinking water increases the overall incidence of tumors, the study shows that arsenic levels as low as four parts per billion can stimulate blood vessel growth, and levels as low as 10 ppb cause tumors to expand. Many previous studies have linked arsenic ingestion and cancer - especially skin and bladder cancers.