Empirical Data Show Autism is On the Rise. Is it Logical to Blame the Toxins of the 1970s?
By Cynthia Nevison, Ph.D., SafeMinds Board Member
When I was pregnant with my first son in 2007, I read that a boy in the U.S. had a 1 in 91 chance of being diagnosed with an autism spectrum disorder. A good friend was a special education teacher who attended national meetings to keep up with the latest research. She told me she’d noticed a definite increase in the number of autistic kids over the course of her career (The odds today, as most of you already know, are so much worse: 1 in 42 boys, 1 in 189 girls). My friend said that nobody really knew what was causing the increase in autism, but that the leading theory involved an upsurge of nerdy men marrying nerdy women.
When my baby was born, I was smitten. He arrived ten days past his estimated due date, weighed 7 pounds 1 ounce; he had peach fuzz on his head and deep blue eyes. He was so sweet and adorable—and so helpless and dependent on me to make wise choices for him.
A close relative, who had been stricken with polio as a boy, had died of a neurodegenerative disease at age 69. Though he recovered from polio, my family always suspected his later disease may have been caused by his boyhood illness. So I went to my son’s 2-month well baby visit glad that he would be getting DTaP and polio shots. I was surprised, however, at how many other vaccines were recommended. I left the doctor’s office feeling uneasy about injecting such a small baby with so many bioactive substances at once.
I knew there had been a controversy surrounding vaccines and, although I’d heard the link with autism had been thoroughly discredited, I decided I needed to inform myself about the issue before I went back to the doctor for my son’s 4-month visit. I earned my Ph.D. in atmospheric science from Stanford University and had 18 years of experience in scientific research when my son was born. I was very interested in making an evidence-based decision on this issue.
I was shocked and dismayed by what I learned:
- That autism was often accompanied by devastating gastrointestinal problems.
- That in November 1999 CDC data revealed that babies with the highest early vaccine mercury exposure had a 7.6-fold increased risk of getting autism compared to those with zero exposure. Instead of making this information public, the CDC held an off-site meeting at the Simpsonwood retreat and conference center with doctors and vaccine manufacturers to decide how to manipulate the data to make these inconvenient results go away.
I read David Kirby’s Evidence of Harm, subscribed to the SafeMinds newsletter, and had a second baby in 2009. When my second son was 9 months old the doctors were unhappy with his weight gain and diagnosed him with an eating disorder. I grew disillusioned with standard medicine during the stressful year that followed. We saw an eating therapist who told me to distract my son into eating with zany behavior and a nutritionist who gave me a list of junk foods to fatten him up. My little boy was also subjected to a number of traumatic, often botched blood draws that achieved little or nothing. It was I, with the help of a new, holistic doctor, who finally improved my son’s appetite by giving him zinc and other mineral supplements. With my second son’s eating problems I became even more grateful to SafeMinds for giving me information about children’s health that wasn’t being covered in the mainstream media.
In 2011, when SafeMinds advertised for a volunteer with an atmospheric science background, I sent them my resume and began a study looking at geographical correlations between autism and atmospheric mercury. Although I found a statistically significant correlation, I eventually became skeptical of my own study. It didn’t really make sense. The time trend in atmospheric mercury over the U.S. had been flat since at least the mid 1990s and seemed inconsistent with the sharply increasing trend I’d plotted in the autism data. In addition, the diagnosed autism rate in China, the world’s biggest coal burner and mercury emitter (and a country with horrendous air pollution), was lower than in the U.S.
Around this same time, in 2012, Philip Landrigan and colleagues published an autism research strategy that included a list of the top 10 compounds suspected of causing autism.
Having studied and taught a survey course in environmental chemistry, I recognized immediately that 3 of the first 5 compounds on their list had been banned or sharply curtailed in the 1970s. But I had little idea about the trends in some of the other compounds. So I decided to do a study, based around Landrigan’s list, to answer 2 major questions:
1) What is the time trend in autism in the United States and how much of the apparent rise is real rather than due simply to better diagnosis?
2) How does that rise in autism, if it really exists, compare to the time trends in each of the chemicals in Landrigan’s top 10 list?
My findings have been published this week in the peer-review journal Environmental Health.
The main points that I have uncovered are:
- Diagnosed autism prevalence has risen dramatically in the U.S over the last several decades and continued to trend upward as of birth year 2005.
- The increase in autism is mainly real, with only about 20-25 percent attributable to increased autism awareness/diagnoses, and has occurred mostly since the late 1980s.
- In contrast to the upward trend in autism, children’s exposure to most of the top 10 toxic compounds has remained flat or decreased over this same time frame.
- The environmental factors with time trends that correlate positively to autism include 2 vaccine-related indices: cumulative aluminum adjuvant exposure and cumulative total number of disease-doses by 18 months; polybrominated diphenyl ethers (used as flame retardants); the herbicide glyphosate (used on GM crops); and maternal obesity.
- Figure 1. Autism prevalence vs. birth year for California IDEA data, derived using two independent methods: 1) Constant-age tracking of 9 year-olds over 20 years of annual reports from 1991-2010 (red) and 2) Age-resolved snapshot from the most recent report in 2010 (blue). The slope of each curve over the same birth year interval, 1993-2001, is estimated with a least squares linear fit. The snapshot fit (grey) spans ages 9-17 in the 2010 report. The constant-age tracking fit spans report years 2002-2010. The snapshot:tracking slope ratio over the 1993-2001 birth year interval is 0.80, suggesting that 80% of the tracked increase is real. (Reprinted from Environmental Health 2014, 13:73 doi:10.1186/1476-069X-13-73) Note: due to underascertainment among 5 and 6 year-olds, the age-resolved snapshot curve decreases after birth year 2003. However, constant-age tracking of 5 year-olds suggests that autism is still increasing in birth years 2004-2005.
Of course, correlation does not mean causation, so this last point should be interpreted with caution. It also should not be taken as a comprehensive list. There are many other environmental factors I would have liked to have included in my paper, but was not able to reconstruct their trends, including prenatal ultrasound, the use of acetaminophen (Tylenol), and antibiotics. Trends in key nutrient levels like vitamin D, zinc, and magnesium may also be important.
The vaccine index correlations, on their own, would mean little, but become more significant when you consider that thousands of parents are reporting autistic regression in their children following severe adverse reactions to vaccines. The severe, obvious reactions are the exception, not the rule, among autistic kids, but these cases are real and have been conceded and compensated under U.S. law.
With children’s well-being at stake, we should be leaving no stone unturned until we get to the bottom of these parental reports. Instead, we have dismissed them with statistics and called it Science, despite knowing that in some cases those statistics were deliberately manipulated.
It’s also not enough for epidemiologists to show that most kids can tolerate the current vaccine schedule without developing autism. That’s already obvious, but it doesn’t prove there’s not a vulnerable subset of children who can’t.
The director of the NIEHS recently described air pollution as a probable “real agent involved in the increasing prevalence of ASD.” Her comments were based on the multiple epidemiological studies that have found correlations between autism and air pollution. I’ve read those studies and have been surprised that none has recognized that air quality has been improving in the U.S. over recent decades, beginning with the 1970 Clean Air Act. Can we logically expect that further reductions in air pollution will reverse the upward trend in autism?
We owe it to our children to exert ourselves to what John F. Kennedy once described as the “discomfort of thought” and to consider the whole body of scientific evidence.
It’s time to stop resting on what JFK called the comfort of myths.
Myth #1: We are not failing to protect children against autism, rather, autism has been there all along and we’re just succeeding in diagnosing it better.
Myth #2: We can account for the upward autism trend with comfortable explanations like air pollution, which nobody likes, or with “throw-up-our-hands-and-do-nothing” explanations based on a vague convergence of multiple toxins.
Because of the “convergence of many toxins” paradigm, the mainstream scientific community has led parents to believe that we cannot know what causes autism and therefore we cannot prevent it. It’s hard to dismiss this paradigm. The many chemicals in our environment at best are not helping our kids and certainly are contributing to their overall body burden of toxins. But we also should be skeptical of these kinds of vague explanations. If they were true, would autism have such a distinct time trend, with an inflection point in the late 1980s? Especially considering that many of the worst toxins were in decline at that point? Also, despite hand-waving arguments to the contrary, there is no evidence that autism existed prior to the 1930s.
The “we can’t know” attitude also absolves scientists and doctors of responsibility for prevention, and suggests the only thing we can do is diagnose autism as early as possible in order to do behavioral intervention.
The unfortunate truth is that the environmental influences causing autism may at the same time be medically useful, even lifesaving. Rather than the current approach of blanket denial, wouldn’t it be better to confront the situation honestly and come up with solutions that promote a more optimal health outcome for children as a whole?
Parents deserve better and more honest information about how to protect their children, not only from autism, but also from the other chronic conditions that afflict so many kids these days: asthma, ADHD, and severe food allergies, many of which, like autism, are fundamentally disorders of the immune system.
Some members of the environmental health community once showed true courage in taking on powerful industries, like the lead industry, that were poisoning children’s brains
We need such leaders again to challenge the illogic of past and current explanations for the rise in autism, from nerdy parents to air pollution, to end the denial of inconvenient truths, and to act to protect innocent children.