Our Mission: We are igniting a movement that inspires parents to protect young children from harmful chemicals. Donate ยป
Charity Navigator 4 Star CharityBlog
Autism: Its the Environment, Not Just Doctors Diagnosing More Disease
Marla Cone, Environmental Health News
Monday, July 27, 2009
California's sevenfold increase in autism cannot be explained by changes in doctors' diagnoses and most likely is due to environmental exposures, University of California scientists reported.
The scientists who authored the new study advocate a nationwide shift in autism research to focus on an array of potential factors in the environment that babies and fetuses are exposed to, including pesticides, viruses and chemicals in household products.
"It's time to start looking for the environmental culprits responsible for the remarkable increase in the rate of autism in California," said Irva Hertz-Picciotto, an epidemiology professor at University of California, Davis who led the study.
Throughout the nation, the numbers of autistic children have increased dramatically over the past 15 years. Autistic children have problems communicating and interacting socially; the symptoms usually are evident by the time the child is a toddler.
More than 3,000 new cases of autism were reported in California in 2006, compared with 205 in 1990. In 1990, 6.2 of every 10,000 children born in the state were diagnosed with autism by the age of five, compared with 42.5 in 10,000 born in 2001, according to the study, published in the journal Epidemiology. The numbers have continued to rise since then.
To nail down the causes, scientists must unravel a mystery: What in the environment has changed since the early 1990s that could account for such an enormous rise in the brain disorder?
For years, many medical officials have suspected that the trend is artificial -- due to changes in diagnoses or migration patterns rather than a real rise in the disorder.
But the new study concludes that those factors cannot explain most of the increase in autism.
Hertz-Picciotto and Lora Delwiche of the UC Davis Department of Public Health Sciences analyzed 17 years of state data that tracks developmental disabilities, and used birth records and Census Bureau data to calculate the rate of autism and age of diagnosis.
The results: Migration to the state had no effect. And changes in how and when doctors diagnose the disorder and when state officials report it can explain less than half of the increase.
Dr. Bernard Weiss, a professor of environmental medicine and pediatrics at the University of Rochester Medical Center who was not involved in the new research, said the autism rate reported in the study "seems astonishing." He agreed that environmental causes should be getting more attention.
The California researchers concluded that doctors are diagnosing autism at a younger age because of increased awareness. But that change is responsible for only about a 24% increase in children reported to be autistic by the age of five, according to the report.
"A shift toward younger age at diagnosis was clear but not huge," the report says.
Also, a shift in doctors diagnosing milder cases explains another 56% increase. And changes in state reporting of the disorder could account for around a 120% increase.
Combined, Hertz-Picciotto said those factors "don't get us close" to the 600% to 700% increase in diagnosed cases.
That means the rest is unexplained and likely caused by something that pregnant women or infants are exposed to, or a combination of genetic and environmental factors.
"There's genetics and there's environment. And genetics don't change in such short periods of time," Hertz-Picciotto, a researcher at UC Davis' M.I.N.D. Institute, a leading autism research facility, said in an interview Thursday.
Many researchers have theorized that a pregnant woman's exposure to chemical pollutants, particularly metals and pesticides, could be altering a developing baby's brain structure, triggering autism.
Many parent groups believe that childhood vaccines are responsible because they contained thimerosal, a mercury compound used as a preservative. But thimerosal was removed from most vaccines in 1999, and autism rates are still rising.
Dozens of chemicals in the environment are neurodevelopmental toxins, which means they alter how the brain grows. Mercury, polychlorinated biphenyls, lead, brominated flame retardants and pesticides are examples. While exposure to some -- such as PCBs -- has declined in recent decades, others -- including flame retardants used in furniture and electronics, and pyrethroid insecticides -- have increased.
Household products such as antibacterial soaps also could have ingredients that harm the brain by changing immune systems, Hertz-Picciotto said.
In addition, fetuses and infants might be exposed to a fairly new infectious microbe, such as a virus or bacterium, that could be altering the immune system or brain structure. In the 1970s, autism rates increased due to the rubella virus.
The culprits, Hertz-Picciotto said, could be "in the microbial world and in the chemical world."
"I don't think there's going to be one smoking gun in this autism problem," she said. "It's such a big world out there and we know so little at this point."
But she added, scientists expect to develop "quite a few leads in a year or so."
The UC Davis researchers have been studying autistic children's exposure to flame retardants and pesticides to see if there is a connection. The results have not yet been published.
"If we're going to stop the rise in autism in California, we need to keep these studies going and expand them to the extent possible," Hertz-Picciotto said.
Funding for studying genetic causes of autism is 10 to 20 times higher than funding for environmental causes, she said. "It's very off-balance," she said.
Weiss agreed, saying that "excessive emphasis has been placed on genetics as a cause. "The advances in molecular genetics have tended to obscure the principle that genes are always acting in and on a particular environment. This article, I think, will restore some balance to our thinking," he said.
Some issues related to whether the increase is merely a reporting artifact remain unresolved. There could be other, unknown issues involving diagnosis and reporting, scientists say.
The surge in autism is similar to the rise in childhood asthma, which has reached epidemic proportions for unexplained reasons. Medical officials originally thought that, too, might be due to increased reporting of the disease, but now they acknowledge that many more children are asthmatic than in the past. Experts suspect that environmental pollutants or immune changes could be responsible.
Autism has serious effects, not just on an individual child's health but on education, health care and the economy.
"Autism incidence in California shows no sign yet of plateauing," Hertz-Picciotto and Delwiche said in their study.
Marla Cone is the Executive Editor of Environmental Health News, which compiles media and original reporting on health and environmental topics.
For further discussion on this topic, please see Honorary Board Member Dr. Harvey Karp's recent blog on The Huffington Post.
Note: This was first published on Environmental Health News, one of Healthy Child's trusted sources of information. It is reprinted with permission.
Posted by Sandy on 08/06 at 08:29 AM
Has anyone tried looking into the use of epidurals during childbirth as a possible cause?
Posted by Carrie on 08/06 at 08:52 AM
I have been disappointed in this website’s refusal to bring up the topic of vaccines as a source of toxins for our children. To dance around it so as not to offend…whom? is not courageous but disappointing.
Posted by Roxanne on 08/06 at 08:02 PM
I had the same thought about epidurals today…...Any studies done?
Posted by Dr. Seriah Rein on 08/12 at 11:22 AM
While thimerosal has been eliminated (due to overwhelming evidence of toxicity to the developing nervous systems of infants and young children), it has not been eliminated from all vaccines or from flu shots, which still contain mercury. Furthermore, mercury is not naturally excreted; therefore, mercury build-up within the body becomes a serious problem.
Mercury amalgam fillings (which are 50% mercury, an element more toxic than arsenic) continue to vaporize in the mouth of the patient throughout his/her lifetime. Research has documented, therefore, that the pregnant mother with mercury amalgam fillings is, likewise, passing on the mercury to her developing child. Passing the fetal barrier is one of the reasons pregnant women are warned to avoid mercury-containing foods (present in greater quantities in the larger fish, such as tuna.) At the time a vaccination containing mercury is given, it is added to the already present mercury load - capable of doing neurological damage and tipping the child towards autism or lesser degrees of such.
I am aware that DAMS International (Dental Amalgam Mercury Solutions) provides a wealth of information to the public on how to avoid continued mercury exposure during dental care and reliable information on safe and natural detoxification of mercury from the body. They are in St. Paul, Minnesota.
It is folly to overlook this environmental hazard. Instead, it would be wise to take personal initiative to educate and protect yourself and your loved ones from the ravages of mercury toxicity, which is more prevalent than can be imagined, exacting its toll on the human body from fetal development on throughout life - named by many researchers as a strong suspect in the development of Alzheimer’s Disease and numerous other diseases.
Posted by dentistas on 08/25 at 12:19 AM
The surge in autism is similar to the rise in childhood asthma, which has reached epidemic proportions for unexplained reasons. Medical officials originally thought that, too, might be due to increased reporting of the disease, but now they acknowledge that many more children are asthmatic than in the past. Experts suspect that environmental pollutants or immune changes could be responsible.
Posted by Niki on 08/30 at 08:39 PM
I love the fact that two people thought of epidurals. I think they are responsible for much more than deadening pain during labor.
Posted by Susan on 07/31 at 08:38 AM
I recently came across your blog and have been reading along. I thought I would leave my first comment. I don’t know what to say except that I have enjoyed reading. Nice blog. I will keep visiting this blog very often.
Susan