[Pharmwaste] Autism epidemic not caused by shifts in diagnoses; environmental factors likely

[DeBiasi,Deborah]

http://www.environmentalhealthnews.org/ehs/news/autism-and-environment

Autism epidemic not caused by shifts in diagnoses; environmental factors
likely 

Changes in doctors' diagnoses cannot explain the sevenfold increase in
autism since 1990, a new California study shows. Environmental factors
are probably to blame. 

By Marla Cone
Editor in Chief
Environmental Health News
January 9, 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 Thursday.

 
Epidemiology 

Annual incidence rates of autism in California 
      The scientists who authored the new study advocate a nationwide
shift in autism research to focus on 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.

 
Epidemiology.  
  
   

 

  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.    "It's time to start looking for the
environmental culprits responsible for the remarkable increase in the
rate of autism in California."
                ...Irva Hertz-Picciotto

 

   
   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.

   Mothers of autistic children were twice as likely to use pet flea
shampoos, which contain organophosphates or pyrethroids, according to
one study that has not yet been published. Another new study has found a
link between autism and phthalates, which are compounds used in vinyl
and cosmetics. Other 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.

Deborah L. DeBiasi
Email:   dldebiasi at deq.virginia.gov
WEB site address:  www.deq.virginia.gov
Virginia Department of Environmental Quality
Office of Water Permit Programs
Industrial Pretreatment/Toxics Management Program
PPCPs, EDCs, and Microconstituents
Mail:          P.O. Box 1105, Richmond, VA  23218 (NEW!)
Location:  629 E. Main Street, Richmond, VA  23219
PH:         804-698-4028
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