Toxicokinetics of mercury after long-term repeated exposure to thimerosal-containing vaccine.
The preservative thimerosal contains ethyl mercury (EtHg). Concerns over possible toxicity have re-emerged recently due to its presence in (swine and other) flu vaccines. We examined the potential accumulation of mercury in adults given repeated injections of a thimerosal-preserved vaccine for many years. Fifteen female patients were recruited from an outpatient clinic running a clinical trial with repeated injections (1 ml every 3-4 weeks) of a staphylococcus toxoid vaccine containing 0.01% thimerosal to treat chronic fatigue syndrome. Fifteen untreated female patients with the same diagnoses served as controls. Blood samples were taken before injecting the vaccine, 1 day later, about 2 weeks later, and just before the next injection. In the 15 controls, samples were taken twice. Blood was analyzed for total mercury and EtHg. The toxicokinetics were assessed for each patient separately as well as with a population-based pharmacokinetic model. Total mercury in blood increased on Day 1 in all treated patients (median: 0.33, range: 0.17-1.3 μg/l), as did EtHg (median: 0.14 μg/l, range: 0.06-0.43 μg/l). After a few weeks, levels were back to normal and similar to those in controls. Levels of methyl mercury (MeHg; from fish consumption) were much higher than those of EtHg. After exclusion of an outlier, the mean half-life in a population-based model was 5.6 (95% CI: 4.8-6.3) days. The results indicate that mercury from thimerosal is not accumulated in blood in adults. This is in accordance with short half-lives and rapid metabolism of EtHg to inorganic mercury.
Department of Occupational and Environmental Medicine, Sahlgrenska Academy, University of Gothenburg, SE 405 30 Gothenburg, Sweden. lars.barregard@amm.gu.se
Lars
L
Barregard
Dinko
D
Rekić
Milena
M
Horvat
Lisa
L
Elmberg
Thomas
T
Lundh
Olof
O
Zachrisson
D000328:Adult; D000368:Aged; D002986:Clinical Trials as Topic; D005260:Female; D006207:Half-Life; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D008628:Mercury / Q000097:blood* / Q000633:toxicity; D008767:Methylmercury Compounds / Q000097:blood / Q000633:toxicity; D008875:Middle Aged; D011310:Preservatives, Pharmaceutical / Q000737:chemistry / Q000493:pharmacokinetics*; D013208:Staphylococcal Toxoid / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics*; D013849:Thimerosal / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics*; D013997:Time Factors
D008767:Methylmercury Compounds; D011310:Preservatives, Pharmaceutical; D013208:Staphylococcal Toxoid; D013849:Thimerosal; D008628:Mercury