Arsenical Cancers, Arsenical Keratosis, Arsenical Melanosis, Arsenic Exposure, Arsenicosis, Arsenic Poisoning, Arsenic Toxicity
Conditions
Keywords
arsenical melanosis, arsenical melanoses, arsenical keratosis, arsenical keratoses, arsenical cancer, arsenic cancers, arsenic, arsenicosis, arsenic exposure, arsenic toxicity, arsenic poisoning, drinking water, selenium, selenite, sodium selenite
Brief summary
Context: Approximately 100 million people throughout the world consume water contaminated with arsenic at levels above carcinogenic thresholds, including 40 million in Bangladesh alone, with up to one-fourth of deaths attributed to arsenic exposure in the worst-affected regions. There are no proven therapies for treating chronic arsenic toxicity or for preventing arsenical cancers. Selenium has been known to counter arsenic toxicity in a variety of animal models. The investigators have recently shown in animals and humans that this effect is mediated by the formation of \[(GS)2AsSe\]- , the seleno-bis(S-glutathionyl) arsinium ion, which is then rapidly excreted via the hepatobiliary system. Concurrently, two Phase II studies in China and Bangladesh have suggested clinical benefit to selenium supplementation in arsenicosis patients. Objective: To assess whether daily selenium supplementation counters arsenic toxicity in patients exposed to drinking water arsenic. If proven effective, selenium supplementation might be safely and cost-effectively implemented in the worst-affected localities.
Interventions
DRUGsodium selenite
200 micrograms (µg) of selenium in the form of sodium selenite; capsule form consumed once daily with breakfast.
DRUGplacebo
dicalcium phosphate capsule matching the selenium capsule in appearance; consumed once daily with breakfast
Sponsors
National Cancer Institute (NCI)
American Cancer Society, Inc.
Texas Tech University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Caregiver, Investigator)
Eligibility
Sex/Gender
ALL
Age
12 Years to 55 Years
Healthy volunteers
No
Inclusion criteria
* Resident of Bangladesh in an arsenic-affected region (Chandpur) * Age between 12 and 55 * Exposure to arsenic in home drinking water greater than 50 ug/L. * Arsenical melanosis on the torso confirmed by epiluminescence microscopy
Exclusion criteria
* Recent history or plans to consume selenium-containing supplements * Anticipated change in home drinking water supply during study period
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| changes in arsenical melanosis | 0 weeks (baseline), 24 weeks, and 48 weeks (end) | Arsenical melanosis was recorded in 4 quadrants of each patients' torsos using the Dermlite epiluminescence microscopy system. The images were then scored in a blinded, randomized fashion by a dermatologist. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| changes in blood arsenic levels | week 0, week 24 and week 48 | The levels of arsenic in patients' blood was measured to determine whether intervention had a differential effect. |
| changes in urinary arsenic levels | week 0, week 24 and week 48 | The levels of arsenic in patients' urine was measured to determine whether intervention had a differential effect. |
Countries
Bangladesh
Outcome results
None listed