Kasraei Sh, Mortazavi H, Vahedi M, Bakianian Vaziri P, Assary MJ. Blood Mercury Level and Its Determinants among Dental Practitioners in Hamadan, Iran. Journal of Dentistry (Tehran). 2010 Spring;7(2):55-63.
Dentists breathe and handle mercury vapor and particles whenever they place or remove amalgam. A 2010 cross-sectional study from Hamadan, Iran, measured blood mercury in every practicing dentist in the city and asked which office habits tracked with higher levels—useful real-world data for anyone designing safer amalgam workflows, whether in a busy general practice or a teaching clinic.
What the study found
All 43 dental practitioners in Hamadan completed a questionnaire and provided a 5 ml venous blood sample analyzed by cold-vapor atomic absorption. Mean blood mercury level (BML) was 6.3 µg/L (abstract; full text reports average 6.43 µg/L, SD 1.31, range 4.15–8.93). Men averaged 6.73 µg/L; women 5.13 µg/L.
The authors judged BML higher than standards, citing an allowable maximum of 3 µg/L from their referenced restorative-materials literature. Factors positively associated with BML included age, years in practice, working hours per day, amalgam placements per day, amalgam removals per week, seafood intake, years in the current office, powdered amalgam use, diamond burs for removal, dry sterilization of amalgam-contaminated instruments, and deficient air ventilation.
Statistically, working hours per day (r = 0.529, P < 0.001) and amalgam restorations per day (r = 0.474, P = 0.002) correlated significantly with BML; regression confirmed those two as significant predictors. Descriptive patterns also pointed higher among dentists using dry sterilization or diamond burs for removal, though not all subgroup contrasts reached significance. Only one participant reported using high-vacuum suction during amalgam work—underscoring how uncommon robust evacuation was in this cohort.
Why it matters for SMART
SMART focuses on removal-day protection, but Kasraei’s map of workplace determinants shows why daily office hygiene and ventilation belong in the same conversation. More placements, longer hours, dry heat sterilization, diamond-bur removal, and poor ventilation tracked with higher blood mercury—exactly the exposures SMART practices try to cut with water, high-volume evacuation, PPE, air filtration, and careful waste handling. For patients, choosing a mercury-aware team is not only about the dam and suction on removal day; it is about a culture of mercury hygiene that protects the people who work in the room every week.
Practical takeaways
- Ask about suction and water — High-volume wet technique matters during placement and removal.
- Prefer encapsulated amalgam (or better, mercury-free materials) — Powder/reservoir systems were linked with higher BML signals.
- Avoid dry sterilization of amalgam-contaminated instruments — Dry heat was associated with higher blood mercury.
- Ventilate the operatory — Deficient air movement was on the authors’ risk list; SMART also emphasizes room filtration.
- Limit occupational dose — Workload (hours and amalgam count) drove the strongest statistical links.
Bottom line: Among all Hamadan dentists, average blood mercury exceeded the authors’ cited 3 µg/L benchmark, and longer hours plus more daily amalgam work were the clearest predictors—evidence that structured mercury hygiene and safer removal protocols protect the dental team as well as patients.