Autism and Mercury: The Pediatrics thimerosal study

Title: Mercury Levels in Newborns and Infants After Receipt of Thimerosal-Containing Vaccines
Authors: Michael E. Pichichero, MDa, Angela Gentile, MDb, Norberto Giglio, MDb, Veronica Umido, MDb, Thomas Clarkson, PhDc, Elsa Cernichiari, MSc, Grazyna Zareba, PhDc, Carlos Gotelli, PhDd, Mariano Gotelli, PhDd, Lihan Yan, MSe and John Treanor, MDa
Source: PEDIATRICS Vol. 121 No. 2 February 2008, pp. e208-e214

The famous Thimerosal study from the American Academy of Pediatrics journal finally was released this morning. This short review could not possibly do justice to the major controversy about mercury and autism, so I will limit the commentary to the results of THIS STUDY ONLY. Given that Thimerosal is commonly used in vaccines in other countries outside of the US and Europe, the researchers teamed with a research group in Argentina to examine how infants and toddlers process Thimerosal when injected as part of their standard vaccination procedures. The researchers examined newborns, 2 month old babies, and 6 month old babies. The infants received a birth dosage of BCG and HBV vaccines that contained 32.5 ug of mercury (ethyl mercury). The 2-months-olds received the first dosage of diphtheria-tetanus-whole-cell pertusis and Hib, the first dosage of polio, and the second dosage of HBV, providing a total of about 40-50 ug of mercury. Finally the 6-month-olds received the additional dosage of diphtheria-tetanus-whole-cell pertusis, Hib, and HBV for a total mercury intake also between 40-50 ug. Then the researchers examined mercury levels in the blood, stool, and urine 1, 3, 5, 11, 21, and 30 days after the vaccinations. The 1/2 life of mercury was found to be 3.7 days in new born, 2 days for 2-month olds, and 2.2 days for 6-months olds. Blood mercury levels returned to baseline by day 11 after the vaccination. The 1/2 life refers to the time it takes for the drug to reach 1/2 of its original value (max in the first cycle). Why is this significant? Because part of the argument against the use of Thimerosal in vaccines was based on the effect of Methylmercury in adults. Methylmercury has a 1/2 life of about 50 Days with studies reporting as long as 180 days! This long 1/2 life of Methylmercury means that the person is exposed to levels of mercury for extended periods of times (weeks), which has many potential side effects. The argument made by the authors of this study is that the 1/2 life of Ethyl Mercury as found in children is only about 3 days, significantly reducing the exposure to mercury in these babies. Now, the authors correctly state that this study does not address the "toxicity" of thimerosal, so it could be argued that exposure to ethyl mercury even for a short period of time (3-4 days)could be enough to cause maturational changes in the brain leading to permanent impairments.