ALAMEDA – At two years old, Olivia Brune has wispy blonde hair, a button nose and, if you’re kind enough to stack some blocks for her, a mischievous smile.
She loves sliced pear, her mommy and daddy, and kicking over block towers.
And though she doesn’t know it yet, her odds of getting breast cancer a half century from now are higher than her mother’s and – to a certain extent – may already be dialed into her body.
Sure, exercise and diet will remain important throughout Olivia’s life. But a growing number of scientists working on one of the trendiest topics in environmental health report that for all of us, a portion of our susceptibility to various ailments may be established by chemical exposures our mothers and even grandmothers experienced while pregnant.
In Olivia’s case, this could mean her susceptibility to asthma, cancers, infertility and other afflictions is influenced by trace amounts of synthetic industrial chemicals her mother, Mary, encountered during pregnancy.
It’s part of a surprising series of findings by scientists researching environmental pollutants. The findings are turning normal notions of what’s toxic and what’s not on their head.
Many of these chemicals, known as “endocrine disruptors,” act like hormones at very low doses. They appear in every niche of American life: Bisphenol-A is used to line food cans in the supermarket; phthalates help soften nail polish, lotions, cosmetics and plastic; pesticides protect the nation’s crops. They also are found in tiny amounts in our bodies.
The science is still new and unorthodox. Regulators, manufacturers and a good number of scientists remain skeptical that their presence at such levels has any significant consequence to our health.
In fact, many natural compounds, particularly in foods such as soy, are as biologically active as these synthetic hormones, yet they pose no threat.
But a growing cadre of scientists report subtle and often unexpected toxic effects from these compounds. Interestingly, the most intriguing research comes not from toxicologists trained to spot such trends, but from epidemiologists, chemists, biologists and medical doctors.
-Mixing chemicals together creates effects far greater than simply the sum of the individual chemicals.
Earl Gray, a research biologist with the U.S. Environmental Protection Agency in North Carolina, finds altered sexual development in the male offspring of animals fed a mix of plastic additives known as phthalates at levels not considered harmful individually. Tyrone Hayes, an endocrinologist at the University of California, Berkeley, finds similar effects with pesticide mixtures. In both cases, levels are not far from those that exist in our bodies.
-Timing of our exposures is crucial.
The cancer rates of adult mice exposed to a known brain mutagen show almost no difference compared with those of unexposed mice, scientists at the National Center for Toxicology Research found in a recent experiment. But smaller doses given to mice both as adolescents and in the womb somehow primed their brains for cancer as adults.
Scientists at the National Institute of Environmental Health Science find the same effect with PCBs and DDT: Both are toxic at any age, but the real damage comes from prenatal exposure.
Most toxicologists, however, aren’t looking at the unborn or very young. To assess a chemical’s carcinogenity, the government’s standard protocol requires mature laboratory animals.
-Effects also may not be huge – and thus often slip below the radar screen of those looking for cancer or other signs of gross mutation.
Researchers at the University of California, Davis, showed earlier this summer that exposure to smog at an early age dooms individuals to a lifetime of decreased lung function. The result isn’t cancer or even, for many, a noticeable problem. But it does leave a larger slice of the population more susceptible to asthma and other respiratory ailments.
-According to an even more controversial finding, certain natural and synthetic chemicals alter our epigenome – the program controlling when and how genes switch on and off.
Researchers working independently at the University of California, San Francisco, and at Children’s Hospital Oakland both find evidence that this epigenome, like our genes, is passed to succeeding generations.
It remains the “black box” of modern genetics. Some scientists suspect that environmental contaminants can tweak that program.
And so, when the time comes to fight off prostate or breast cancer, our body – and the bodies of our children and grandchildren – never activate the very protein designed to fight off the tumor.
-Equally puzzling: Even at extraordinarily high doses, many endocrine disruptors don’t cause harm – translated, in the world of toxicology, as cancer or a gene mutation.
But at one-millionth the dose, Frederick vom Saal, a biologist at the University of Missouri, finds that bisphenol-A triggers slight developmental problems: reduced reproductive development or larger birth weight. That, in turn, ever so slightly tweaks one’s odds of having fertility problems or being obese or reaching puberty early.
The effect is not limited to bisphenol-A.
In many cases, particularly with hormone-mimicking chemicals, researchers find effects in their laboratory experiments at part-per-trillion concentrations. Many of these chemicals, meanwhile, are considered safe at levels thousands or even millions of times higher.
To put that in perspective: UC Berkeley researchers find that the urine of a farmworker applying the herbicide Atrazine to crops can be poured into a swimming pool with some tadpoles, and the male frogs morphing from those tadpoles a few weeks later would all be chemically castrated.
“This is a major paradigm shift in the field,” vom Saal said.
“Every assumption – every single assumption – that goes into determining whether the level of an endocrine-disrupting chemical is safe is false.”
Call it a working hypothesis.
Dr. David Martin has spent his adult life looking at cancer. A pediatric oncologist at Children’s Hospital Oakland Research Institute, he is at the forefront of research showing factors such as diet can have health consequences years and even decades later and can, in fact, be passed to succeeding generations.
But he describes as pure speculation the notion that hormonelike pollutants disrupt finely tuned cell-differentiation programs and trigger cancer. After 30 years of looking, he said, he has yet to see any evidence that levels found in today’s environment pose a threat to our health.
Speculation that they do cause harm, Martin added, leads to “public panics over all sorts of compounds” and for no good reason.
What Martin and fellow researchers have discovered he said, is that a woman’s diet can influence her granddaughter’s health, and that arsenic, given while the baby is in womb, somehow triggers cancer much later in life.
But to dig deeper – to link environmental exposures while young to ailments later in life or in future generations – is a “very complex problem.” To simply run the tests necessary to establish a transgenerational link for a known carcinogen such as arsenic would cost Children’s Hospital Oakland $250,000 a year for five years, a steep price in today’s funding environment, he said.
“It’s very easy for me to see how a hormone or something that mimics a hormone could have effects that could lead eventually to cancer,” he said.
So are federal and state regulators.
Last year, as state lawmakers grappled with a ban on bisphenol-A and other plastic additives known as phthalates, they sent a letter to the U.S. Food and Drug Administration seeking guidance.
Does the FDA, they asked, consider products made with bisphenol-A safe for use with food or beverages?
Yes, replied George Pauli, the agency’s associate director of science and policy. The agency is aware of studies stating the compound acts like estrogen at low doses, he wrote. “However, based on all the evidence available at this time, FDA sees no reason to change its long-held position that current uses with food are safe.”
The Legislature never passed the ban.
San Francisco has run into similar difficulty with its first-in-the-nation ban on bisphenol-A and phthalates in toys. It went into effect Friday. Industry has already filed a lawsuit, saying evidence of harm was insufficient at best.
“Yes, it’s well-known that BPA (bisphenol-A) is weakly estrogenic,” said Steve Hentges, director of polycarbonate plastics for the American Plastics Council. “But many things are.
If you follow that logic, you would ban all sorts of things – like food.”
It is easy to sow doubt. The tobacco industry established that years ago.
Scientists are naturally skeptical. Manufacturers often have considerable financial incentive to keep products on the market – or show, even if they are banned, that the question of harm is inconclusive.
And so it is easy, researchers and policy advocates say, for industry to fund a study that muddles the issue – finding no problems where others see harm – and drag the debate on for years.
Consider bisphenol-A, a compound developed as a synthetic hormone in 1936 and used today in food cans and shatter-proof plastic sports drinks and baby bottles.
Of 163 studies by university and government researchers, 149 found some deleterious effect, vom Saal found. Yet of 13 industry-funded studies, none found any adverse impact.
The result? Regulators call the evidence inconclusive and urge further study.
Meanwhile, manufacturers continue to sell their product. In bisphenol-A’s case, that’s 6 billion pounds a year.
“There’s a whole industry that exists to manufacture doubt. They understand how regulatory agencies work,” said David Michaels, a former assistant secretary for environment, safety and health in the Energy Department who now heads the Project on Scientific Knowledge and Public Policy at George Washington University.
“You could make the case that if there wasn’t a multibillion-dollar industry using Atrazine” – the most widely used herbicide in the world – “the EPA would not be hesitant to regulate it more strongly.”
Back in Alameda, Mary Brune didn’t know about any of this a year and a half ago. She was just a mother, arriving home from work and plopping in front of the television to nurse 6-month-old Olivia. On came a nightly news report about the discovery of perchlorate, the active ingredient in rocket fuel, in 100 percent of the human breast milk samples from 19 states.
“I didn’t know at the time what perchlorate was, and I had no way of knowing if it was in my milk, but I was pretty much outraged,” she said.
She formed Making Our Milk Safe with three friends, all new mothers. Today the group has mothers in 34 states fighting to ban endocrine-disrupting compounds and to spur the development of biomonitoring programs aimed at tracking contaminants in our bodies.
“There’s something happening silently under the surface that 25 years from now we’re going to say, ‘How did we not see this coming?'” Brune said.
“As a parent, you do what you can. I can’t control what happened when Olivia was in my womb, but I can control her exposure to harmful chemicals by choosing safer products when possible.
“I don’t think there should be mass hysteria about this new research,” she added.
“But I do think there should be a collective call for action on the part of government and manufacturers to sort out the safety issue.”