Four researchers from government and academia told a panel of U.S. senators on Aug. 3 that exposures to environmental toxins are a likely cause of autism in genetically predisposed individuals.
"ASDs [Autism Spectrum Disorders] could result from a variety of factors, including combinations of genes, environmental exposures and gene-environment interactions," EPA's Assistant Administrator for Research and Development and Science Advisor Paul Anastas said in a written version of his remarks to the Senate Environment and Public Works' Subcommittee on Children's Health.
Each expert delivered overviews of research into the connection between neurodevelopmental disorders like autism and exposure to toxic chemicals, especially "heavy metals" like mercury, lead and arsenic. None, however, suggested that children who regressed into autism after receiving massive environmental exposure to mercury and aluminum in childhood vaccines were being or should be studied. Aluminum is also a known neurotoxin.
'Autism and the Indiana Environment Blog'
But in a soon-to-be-released book The Age of Autism: Mercury, Medicine, and a Manmade Epidemic, authors Dan Olmsted and Mark Blaxill take the medical research establishment to task for this myopic view of autism and vaccines, arguing that mercury has contributed to a range of illnesses and conditions since its first use in medicine in the late 15th century.
"Too many vaccines too early may be a part of the toxic picture," they argue in the book's introduction. While mercury has been removed from some childhood vaccines, they note, it still exists in many, including flu shots routinely given to pregnant women and children.
"Today's hearing will look at the latest research on potential environmental factors that may harm the health of our children, including their ability to think, learn, and interact with families and other people in society." - Sen. Barbara Boxer, Environment and Public Works chair
In the book's forward, author David Kirby, who wrote the 2005 bestselling book Evidence of Harm: Mercury in Vaccines and the Autism Epidemic: A Medical Controversy, noted that one in six children today are born with mercury levels in their blood high enough to cause neurodevelopmental deficiencies later in life.
"These poor kids are born already set up for neurological failure," he wrote. "Many of them are already at the exact toxic tipping point when it comes to prenatal and neonatal exposures to toxic metals. So why on earth would we inject them with vaccines containing organic ethylmercury and aluminum salts beginning on day one, and repeated at regular intervals over the next couple of years?"
The Senate hearing, called "State of Research on Potential Environmental Health Factors with Autism and Developmental Disorders," opened with Subcommittee Chair Amy Klobuchar, D-Minn., noting that 1.5 million children have been diagnosed with an ASD in America today. "That means there will be more kids with autism than juvenile diabetes," she said, "yet there is still so little known about the disease, its causes or treatments."
Environment and Public Works Committee Chair Barbara Boxer, D-Calif., explained the purpose. "Today's hearing will look at the latest research on potential environmental factors that may harm the health of our children," she said in her opening statement, "including their ability to think, learn, and interact with families and other people in society."
Presaging the testimony that was to come, Klobuchar offered a primer on why toxic chemicals like mercury, which Kirby calls the "second deadliest element on earth after plutonium," are suspected culprits in the steadily increasing incidence of autism.
"As we know, children are more susceptible to environmental dangers than adults," she said. "Children consume more food and water, touch more dirt because they are closer to the ground and are exposed to toxins easier than adults. Because their immune systems are still developing, kids are more likely to become sick when exposed to environmental risks."
"There will be more kids with autism than juvenile diabetes, yet there is still so little known about the disease, its causes or treatments." - Sen. Amy Klobuchar, Subcommittee on Children's Health chair
Anastas said that, because of their extraordinary complexities, prenatal and early postnatal brain and nervous system development can be disrupted by environmental exposures at much lower levels than would affect adults.
"We are learning that there are critical windows of susceptibility, both prenatally and in early childhood," he said, "during which the effects of exposures to environmental contaminants, depending on dose and timing, can be significantly more severe and can lead to permanent and irreversible disability."
Linda Birnbaum, director of the National Institute of Environmental Health Sciences (NIEHS), said her agency spent $9.3 million on autism in fiscal year 2009, more than half -- $4.9 million -- from President Barack Obama's American Reinvestment and Recovery Act (ARRA), also known as the "Stimulus."
"ARRA provided a key opportunity to increase NIH support for autism research," Birnbaum told the subcommittee, citing four grants as examples.
One will look at air pollution from traffic and genes that process pollutants to see if they are different in children with autism and if those genes interact with pollution.
Another will determine whether polyfluoroalkys are found at higher levels in newborns who are later diagnosed with autism. Widely used in stain-resistant coatings, food packaging and fire-fighting foams, these chemicals are known to interfere with hormones, Birnbaum said.
"Environmental influences on brain development, behavior and other neurological outcomes of public health concern are a rapidly growing area of environmental health sciences." - Linda Birnbaum, National Institute of Environmental Health Sciences director
The third will analyze a variety of chemicals, including pyrethroid pesticides, flame retardants (polybrominated diphenyl ethers, or PBDEs) and plasticizers (bisphenol A and phthalates) that are widely dispersed in the environment but haven't been adequately studied for their possible connections to autism.
A fourth will seek to identify genes whose effects on ASDs may vary depending on pregnant mothers' exposures to cigarette smoke, alcohol, medications and infections.
"Environmental influences on brain development, behavior and other neurological outcomes of public health concern are a rapidly growing area of environmental health sciences," Birnbaum said.
Anastas said that since 2002, EPA has invested $10.8 million in "extramural dollars" to support autism research through the Centers for Children's Environmental Health and Disease Prevention Research and $1 million through an "intramural program" for work in neurodevelopmental toxicology.
"EPA Intramural Research at EPA's National Health and Environmental Effects Research Laboratory (NHEERL) focuses on susceptibility to chemicals, the factors underlying this susceptibility, chemical mechanisms of action and the relevance of effects detected by testing to human health," he said. "EPA scientists are assessing the potential for environmental chemicals to alter processes essential for development of the nervous system, including how nerve cells grow, divide, make connections and communicate with each other."
EPA labs also test suspected neurodevelopmental toxicants in rodents for effects on learning, memory, sensory function and behavior, Anastas added. Many of these endpoints are affected in autism, although no well-accepted animal models of autism exist.
"We know that prenatal and early childhood exposures to chemicals such as methylmercury, lead, PCBs and arsenic can affect development of the nervous system and lead to developmental disability." - Paul Anastas, EPA Assistant Administrator for Research and Development
To date, he said, NHEERL scientists have tested more than 200 pesticides for developmental toxicity using cells in culture and zebrafish. With this data, they are developing the capacity for computer modeling of the toxicity of environmental chemicals.
"Researchers at NHEERL and the National Center for Computational Toxicology are creating databases and approaches to predict the toxicity of new and untested chemicals," Anastas said.
The University of California at Davis Center for Children's Environmental Health is studying possible genetic and environmental risk factors that may contribute to the incidence and severity of childhood autism, Anastas continued. "Part of the research focuses on how chemicals that are known to be toxic to the developing nervous and immune systems could contribute to atypical development of social behavior in children," he said.
The UC Davis center is also studying nearly 1,400 families in the first, large-scale, epidemiologic investigation of the underlying causes of autism, the Childhood Autism Risk from Genetics and the Environment (CHARGE) study, he said.
Heavy metals are one of the exposure classes being investigated in the CHARGE study, Anastas said, as well as the potential relationship between exposure to flame retardants and autism. "There has been some concern because PBDEs can affect development of the nervous system," he said, "and in animal studies can affect behavior such as hyperactivity. They can also have hormone-disrupting effects, particularly on estrogen and thyroid hormones."
Other neurodevelopmental disorders of concern, Anastas said, include attention deficit disorder and ADHD, learning disabilities, sensory deficits and developmental delay.
"We have learned that many of the molecular and cellular systems that are associated with autism are the very same ones that are the target of environmental chemicals currently of concern to human health because of their widespread use." - Isaac Pessah, UC Davis Children's Environmental Health and Disease Prevention director
"These disorders can cause lifelong disabilities, and the causes are likely to include both environmental and genetic factors," he said. "We know that prenatal and early childhood exposures to chemicals such as methylmercury, lead, PCBs and arsenic can affect development of the nervous system and lead to developmental disability. Depending on the level and timing of exposure, these exposures can produce either obvious developmental disability or subclinical brain injury."
UC Davis's Isaac Pessah, a professor of toxicology who directs the Children's Environmental Health and Disease Prevention there, said the vast majority of public and private resources has, and continues, to support work on the genetic side of the equation. But these studies have shown that genes alone cannot predict the majority of autism cases, the patterns of impairments or their severity. Nor can they predict success for current treatment modalities.
"We have learned that many of the molecular and cellular systems that are associated with autism are the very same ones that are the target of environmental chemicals currently of concern to human health because of their widespread use," he said. "Further research is needed on modifiable factors that contribute to causing or protecting against autism."
Pessah said more than 80,000 "commercially important chemicals" are now in production, and it's important to know which promote developmental neurotoxicity consistent with the immunological and neurological impairments identified with autism.
"It is clear that there is a critical need to identify which chemicals in the environment that influence the same biological pathways known to be affected in autism," he said. "Limiting exposure to these chemicals is the only way to mitigate or prevent autism in susceptible individuals."
Bruce Lanphear, a senior scientist at the Child & Family Research Institute at the Cincinnati Children's Hospital Medical Center, noted that one in six American children have developmental problems, "from a subtle learning disability to overt behavioral disorders, such as attention deficit hyperactivity disorder (ADHD) or autism."
And exposures to common environmental toxins, such as lead, tobacco, PCBs and mercury, have consistently been linked with higher rates of intellectual impairment or behavioral problems, such as conduct disorder and ADHD.
"Too many vaccines too early may be a part of the toxic picture." - The Age of Autism: Mercury, Medicine, and a Manmade Epidemic, by Dan Olmsted and Mark Blaxill
The Cincinnati Children's Hospital has confirmed earlier reports implicating lead in the development of some behavioral disorders in children, he said. "We estimated that one in five cases of ADHD in U.S. children was due to childhood lead exposure. We also found joint effects of prenatal tobacco exposure and childhood lead exposure."
While all four presenters mentioned heavy metals in general and mercury in particular as likely contributors to the development of ASDs, they were silent on the role that mercury exposure from childhood vaccines has played in the autism epidemic of the late 20th and early 21st centuries.
Olmsted and Blaxill, however, trace the earliest known cases of autism directly to exposure to mercury in the 1930s, when its commercial use skyrocketed in agriculture, forestry and medicine, including vaccines.
Olmsted is an award-winning journalist whose experience includes stints as an original staff writer and editor at USA Today, senior editor at United Press International in Washington, and editor and reporter at daily papers in Illinois and New York.
Blaxill is the father of a daughter with autism who regularly speaks and writes on autism. He has published scholarly articles in several journals, including the International Journal of Toxicology, the Journal of Autism and Developmental Disorders and NeuroToxicology. He has also peer reviewed articles on autism for the New England Journal of Medicine, Pediatrics, the American Journal of Epidemiology and the International Journal of Toxicology.
Both are editors at the daily online news service Age of Autism.
Apparently the first to ever do so, Blaxill and Olmsted identified the first 11 cases of autism ever recorded in scientific literature by Johns Hopkins psychiatrist Dr. Leo Kanner in 1943. They reviewed their records, interviewed family members and met two of the actual study subjects. They found mercury exposure in the occupational and medical histories of each.
"Leo Kanner's original cases, linked only by this overlooked association with mercury, suggest that from the very beginning autism was an environmentally induced illness," the authors wrote, "-- a toxic injury rather than something inherited or inculcated."
Steven Higgs can be reached at .
- Read and watch the Senate hearing
- The Age of Autism: Mercury, Medicine, and a Man-made Epidemic, by Dan Olmsted and Mark Blaxill, will be released Sept. 14, 2010.