one microgramme, around 15% of the average daily mercury intake in the US for adults and 2.5% of the daily level considered tolerable by the WHO. The action sparked concern that thiomersal could have been responsible for autism. The idea is now considered disproven, as incidence rates for autism increased steadily even after thiomersal was removed from childhood vaccines. Currently there is no accepted scientific evidence that exposure to thiomersal is a factor in causing autism. Since 2000, parents in the United States have pursued legal compensation from a federal fund arguing that thiomersal caused autism in their children. A 2004 Institute of Medicine (IOM) committee favored rejecting any causal relationship between thiomersal-containing vaccines and autism. The concentration of thiomersal used in vaccines as an antimicrobial agent ranges from 0.001% (1 part in 100,000) to 0.01% (1 part in 10,000). A vaccine containing 0.01% thiomersal has 25 micrograms of mercury per 0.5 mL dose, roughly the same amount of elemental mercury found in a can of tuna. There is robust peer-reviewed scientific evidence supporting the safety of thiomersal-containing vaccines. MMR vaccine In the UK, the MMR vaccine was the subject of controversy after the publication in The Lancet of a 1998 paper by Andrew Wakefield and others reporting case histories of twelve children mostly with autism spectrum disorders with onset soon after administration of the vaccine. At a 1998 press conference, Wakefield suggested that giving children the vaccines in three separate doses would be safer than a single vaccination. This suggestion was not supported by the paper, and several subsequent peer-reviewed studies have failed to show any association between the vaccine and autism. It later emerged that Wakefield had received funding from litigants against vaccine manufacturers and that he had not informed colleagues or medical authorities of his conflict of interest: Wakefield reportedly stood to earn up to $43 million per year selling diagnostic kits. Had this been known, publication in The Lancet would not have taken place in the way that it did. Wakefield has been heavily criticized on scientific and ethical grounds for the way the research was conducted and for triggering a decline in vaccination rates, which fell in the UK to 80% in the years following the study. In 2004, the MMR-and-autism interpretation of the paper was formally retracted by ten of its thirteen coauthors, and in 2010 The Lancets editors fully retracted the paper. Wakefield