Exposure to a high selenium environment in Punjab, India: Biomarkers and health conditions.
Level 4 - case-series / case-control
Cross-sectional observational study
PubMed 31862262 · doi:10.1016/j.scitotenv.2019.134541
What was done
Researchers collected blood, hair, and nail samples from 680 adult volunteers (267 men, 413 women) living across seven villages in a known seleniferous region of Punjab, India. Selenium concentrations were measured across all biological specimens. Participants completed questionnaires assessing dietary intake, lifestyle characteristics, potential exposure sources, and various adverse health conditions.
What was found
Serum and hair selenium concentrations were highly correlated with each other, whereas correlations with nail selenium were weaker. Hair and nail selenium levels were positively associated with the intake of local pulses, vegetables, and cereals, while serum selenium showed limited association with local food intake. Higher serum and hair selenium levels were linked to increased prevalence of selenosis symptoms, including hair and nail abnormalities and loss, garlic breath odor, nausea and vomiting, exertional breathlessness, chest pain, edema, worm infestation, and spontaneous abortion. No association was found with dermatitis or loss of appetite. The abstract does not provide exact numeric effect sizes, biomarker concentrations, or statistical confidence intervals.
Why it matters
This study provides field evidence on human biomarker behavior and toxicity profiles resulting from chronic environmental overexposure to selenium, suggesting that blood and hair are better biomonitoring markers than nails for selenosis.
Limits
The study is cross-sectional, preventing causal determination. The abstract omits numerical values, effect sizes, and biomarker concentrations, while noting statistical imprecision in effect estimates. Health conditions and dietary intake were gathered via self-reported questionnaires, introducing potential recall and misclassification bias.
Cited by
- supports Excessive selenium intake can cause hair loss and brittle nails.