UC Davis LogoStudy experts at the UC Davis MIND institute claim that after regulating a number of issues, usually developing children and children with autism have identical levels of mercury in their blood streams. Mercury is said to be a heavy metal found to unfavorably influence the developing nervous system. This was alleged from a large population based study.

The study is believed to be the most painstaking investigation to date of blood-mercury levels in children with autism. The experts warned that the study is not an assessment of whether mercury plays a function in causing the disorder.

Lead study author Irva Hertz-Picciotto, an internationally known MIND Institute researcher and professor of public health sciences, commented, “We looked at blood-mercury levels in children who had autism and children who did not have autism. The bottom line is that blood-mercury levels in both populations were essentially the same. However, this analysis did not address a causal role, because we measured mercury after the diagnosis was made.”

The study was performed as part of the Northern California-based Childhood Autism Risks from Genetics and the Environment (CHARGE) study, of which Hertz-Picciotto is the principal investigator. The CHARGE study is claimed to be a big, inclusive, epidemiologic investigation intended to recognize features connected with autism and find out hints to its origins. CHARGE study participants comprised of children between 24 and 60 months who are detected with autism, plus children with other developmental disorders and naturally developing controls.

The study looked at an extensive assortment of sources of mercury in the participants’ surroundings, counting fish consumption, personal-care products like nasal sprays or earwax removal products, which may have mercury and the kinds of vaccinations they were given. The study also evaluated whether children who have dental fillings made of the silver-colored mercury-based amalgam and who grind their teeth or chew gum had more blood-mercury levels. Actually, it was seen that those children who both chew gum and have amalgams did have more blood-mercury levels.

But eating fish like tuna and other ocean fish and freshwater fish is thought to be the major and most important forecaster of blood-mercury levels. Data on most likely sources of mercury i.e. fish consumption and dental amalgams were gathered by interviews with the study subjects’ parents. Information on vaccines was available from the child’s vaccination and medical records. Some children lately had a vaccine containing mercury, and their blood-mercury levels did not increase.

The study examined about 452 subjects. Out of them, around 249 were detected with autism, around 143 were growing normally and roughly 60 suffered from other developmental delays like Down syndrome. In the beginning, children with autism seemed to have considerably lesser blood-mercury levels as compared to normally growing children. But children with autism are inclined to be fussy eaters and, in this study, they consumed less fish. When adjusted for their lower levels of fish consumption, their blood-mercury concentrations were approximately similar as those of children with normal growth and very alike to those found in a countrywide representative sample of 1- to 5-year-old children.

As not much is known about the causes of autism, the experts intend to look at everything from household products to medical treatments, diet and supplements, and even infections. Moreover, they may investigate communications among several factors.

Hertz-Picciotto remarked, “Just as autism is complex, with great variation in severity and presentation, it is highly likely that its causes will be found to be equally complex. It’s time to abandon the idea that a single ‘smoking gun’ will emerge to explain why so many children are developing autism. The evidence to date suggests that, without taking account of both genetic susceptibility and environmental factors, the story will remain incomplete. Few studies, however, are taking this kind of multi-faceted approach.”

Hertz-Picciotto mentioned the CHARGE study is casting a wide net, dealing with a collection of experiences that begin in the home or the broader surroundings, as well as genes and gene expression.

The study appears in the Journal Environmental Heath Perspectives.