Mercury air, urine monitoring and health effects on occupationally exposed dental healthcare workers in Delhi, India.

Air samples were area samples, not personal breathing-zone samples, and none covered an entire eight-hour shift, so they cannot be used to decide whether workers exceeded the occupational limit. Air and urine monitoring were done at only one healthcare establishment, while the survey covered 22 establishments, so the exposure measurements may not represent all sites. The survey was cross-sectional and used self-reported symptoms, so it cannot show that mercury caused the reported symptoms. The paper describes convenient sampling for the survey and also says 632 workers were randomly selected, so the selection method is unclear. People with tuberculosis, cancer, chronic heart, lung, or kidney disease, pregnant women, and lactating women were excluded, so the results do not cover those groups. Natural ventilation from open windows and fans was present during air sampling, and closed-window conditions were not estimated, so air concentrations could differ in less ventilated rooms. The conclusion says clinic mercury may be above safe levels, but the reported air samples were below the occupational limit and the urine samples were mostly below the reference range. The paper lists multiple objectives rather than a single primary outcome, so no result should be treated as the main finding.

The authors declared no conflict of interest, and the paper states that no organized funding source was used.

Do not conclude that dental workers were overexposed to mercury or that mercury caused their symptoms. The air samples were below the occupational limit, were not full-shift personal breathing-zone samples, and the symptom associations came from a cross-sectional survey.