Assessed arsenic in drinking water in Bangladesh for WHO in 1997 and classified it as a public health emergency.
Showed that with exposure to water containing around 800-900 ug/L of arsenic, more than 1 in 10 adult deaths may be due to arsenic-caused diseases, perhaps the highest environmental health risk ever reported in a large population.
Provided substantive evidence that arsenic is a potent cause of human bladder cancer and lung cancer.
Discovered biologically plausible major reductions in breast cancer mortality during high exposure to inorganic arsenic in drinking water which could not be attributed to bias or confounding.
Showed that epidemiological and human experimental data do not support the hypothesis that methylation protects against low dose arsenic effects.
Identified a dose-response relationship between arsenic exposure and bladder cell micronuclei, a genotoxic marker of effect, and changes in the frequency of micronuclei after exposure to arsenic is reduced.
Identified the dose-response relationship between arsenic concentration in well water in India and the occurrence of keratoses and hyperpigmentation.
Completed two bladder cancer case-control studies, one in Argentina and one in California/Nevada, showing modest increases in bladder cancer related to potential exposure to arsenic in wells, but only in smokers.
Identified the first evidence that arsenic in drinking water may be a cause of childhood liver cancer, in the age range 10-19 years.
Found evidence that arsenic in drinking water my cause chronic respiratory disease including reduced lung function in adults.
Found the first evidence suggesting that arsenic in drinking water might be a cause of increased mortality from tuberculosis.
Conducted the first epidemiological studies (in Chile and India) indicating that arsenic in drinking water may cause bronchiectasis.
Demonstrated that lung cancer risks related to arsenic are similar when based on absorbed dose, whether arsenic is ingested or inhaled.
Identified the first epidemiological evidence that exposure to arsenic in utero and early life increases mortality in young adults, including deaths from lung cancer, kidney cancer, acute myocardial infarction and bronchiectasis.
Identified the first epidemiological evidence that exposure to arsenic in utero and early life increases nonmalignant pulmonary disease in adults.
Found evidence of reduced cognitive function in children exposed to arsenic in India.
Mapped out the 50-year latency patterns for arsenic causing lung cancer, bladder cancer, kidney cancer and myocardial infarction in Chile.
Found evidence of increased respiratory symptoms in children in Bangladesh exposed to arsenic in utero and early life.
Discovered novel preliminary evidence that people with elevated body mass index (BMI)–especially those with elevated BMI in early life–have markedly higher risks of arsenic-related cancers such as lung and bladder cancer.
Found increased lung, bladder and kidney cancer mortality even 40 years after arsenic exposure reduction, suggesting arsenic in drinking water may involve one of the longest cancer latencies for a human carcinogen.