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Safe and Useful Chemicals Under Attack, Again, as Endocrine Disruptors
By Gilbert Ross, M.D.
A recent "health" column in USA Today ("'Everywhere chemicals' in plastics alarm parents," Oct. 30) attempts yet again to scare the public -- especially parents of young children -- about the alleged "endocrine-disrupting" effects of common chemicals, specifically bisphenol-A (BPA) and phthalates. The specific phthalate attacked, the vinyl plasticizer DEHP, is found in many healthcare products, including intravenous tubing and bags, and some instruments used in surgery. BPA is found, most familiarly, in plastic water bottles and baby bottles, but also in various consumer products such as the coating inside food cans and dental fillings.
The authors of this alarmist article point towards "mounting evidence" that these chemicals "may trigger hormonal changes." Their evidence comes entirely from high-dose rodent studies, and of course from the fact that almost all Americans have trace levels of a wide variety of chemicals detectable in their bodies. What many don't know -- and this article certainly wouldn't help them learn -- is that the mere presence of a chemical does not mean that it is harmful. A well-known dictum of toxicology is "the dose makes the poison."
These products have been ubiquitous in our environment for decades and have proven useful in many products. Although there has never been any evidence of human harm from any of them, so-called "environmental" activists persist in trying to get rid of them. A variety of government panels -- both here and abroad -- have evaluated BPA, and none have banned or restricted their use. ACSH did a study of DEHP in 1999, and our blue-ribbon panel concluded that there was no cause for concern about adverse effects on humans from typical exposure to this chemical.
It is sad and disappointing to see a widely-read newspaper like USA Today print alarmist screeds masquerading as "health" columns -- but until scientists who know better speak out against the anti-technology activists and the "endocrine disruptor" zealots, these are the headlines we're likely to keep seeing.
Gilbert Ross M.D. Executive and Medical Director of the American Council on Science and Health (ACSH.org, HealthFactsAndFears.com).
Anne (November 8, 2007)
While BPA may not have been banned, phthalates have. Europe has been in the process of banning certain phthalates for the last few years, and California is leading Americans in doing the same. (http://www.usatoday.com/news/health/2007-10-15-toxic-toys_N.htm).
High-dose rodent studies are not the only source of information for phthalate human toxicity. Studies have come out that were able to correlate phthalate levels in mothers and their babies with sexual development effects seen in the children that were expected from phthalates.
The large question with phthalates and BPA especially is not what it will do to you or I now, but what it will do to babies as they grow and develop. The thought that newborn "premies" receiving IV tubes are delivered a high dose of phthalates when they are at their weakest, or that infants are exposed to BPA every time they have a bottle, should be enough for people to realize the need to restrict these chemicals.
Anne (November 8, 2007)
The reference for the study on phthalates in humans is as follows:
Swan, Shanna H. et al. Decrease in anogenital distance among male infants with prenatal phthalate exposure. Environmental Health Perspectives Volume 113, Number 8, August 2005
Ron Bailey (November 16, 2007)
Anogenital distance is an interesting concept. I discuss it's relevance in my Reason column "Of Penises and Pesticides" at URL: http://www.reason.com/news/show/116485.html
See below:
"Pesticides May Affect Penis Size, " runs the headline in the London Free Press. The first paragraph alarmingly reports that "A renowned U.S. scientist who has documented fertility and sex changes—including decreasing penis size—due to environmental contamination says he wouldn't apply pesticides on his own lawn."
Whose sexual organs was the renowned scientist talking about? Alligator penises. Specifically, the penises of some American alligators that grew up in Florida's most polluted lake. In 1980 a massive industrial pesticide spill drained into Lake Apopka, contaminating it with high levels of pesticides with anti-androgenic activity. The toxins clearly had deleterious effects on wildlife. The renowned scientist cited in the article is University of Florida researcher Louis Guillette, who also apparently asserted, "This is important because it is not just an alligator story. It is not just a lake story. We know there has been a dramatic increase in penile and genital abnormalities in baby boys."
One sometimes gets the impression from some scientists and activists that pesticides are just pure evil developed by wicked corporations for the purpose of poisoning people, not substances devised to protect crops or eradicate disease-carrying vermin. In any case, since it turns out that activists were wrong when they claimed that pesticides were causing a cancer epidemic, then surely the chemicals must be doing something else vile. How about hitting men where it really hurts? That'll get their attention!
But is it true there has been a "dramatic increase" in penile abnormalities? The evidence is equivocal. A major scientific review in 2005 found that male congenital anomalies had increased from 7 per 1000 in 1988 to 8.3 per 1000 in 2000. Interestingly, the same study found that the higher a family's socio-economic status, the higher the risk that a boy would be born with penile abnormalities. Another study found higher than expected rates of male genital deformities among newborns in some parts of the Netherlands. Specifically, researchers found a correlation between a father's exposure to pesticides and the probability of cryptorchidism (failure of one or both of the testicles to descend into the scrotum) in his newborn son. There was no correlation between paternal and maternal pesticide exposure and the incidence of hypospadias (a genital defect in which the urethra opens on the underside of the penis rather than at the end).
On the other hand, there is a plethora of studies that find no recent increase in penile defects. For example, in 2003 a California study lasting 13 years and funded by the March of Dimes found "there was no evidence for an increase in prevalence "of hypospadias. And a 2004 Scottish study in the British Medical Journal reported that "A new linked register of congenital genital anomalies in Scotland suggests that over a decade, the birth prevalence of genital anomalies has changed little. " Ditto for Finland and New York State. And a 2005 study in Washington State study found "the prevalence of hypospadias in Washington State did not increase significantly between 1987 and 2002."
Even a 2005 study specifically trying to correlate exposure to organochlorines with male genital abnormalities found none. In that study, researchers compared the levels of pesticide residues in the blood serum of women whose boys were born with malformations with women whose boys were not did. They reported, "Our study does not provide epidemiologic support for a causal adverse relationship between DDT or DDE and cryptorchidism or hypospadias."
But there is another puzzle—exposures to many of the most suspect pesticides have been declining for decades. A 2002 study of synthetic chemical residues in human breast milk supported by an activist group, the Natural Resources Defense Council, concluded, "Over the past few decades, levels of the organochlorine pesticides, PCBs, and dioxins have declined in breast milk in countries where these chemicals have been banned or otherwise regulated." A report from the American Council on Science and Health in New York which receives some industry support asserts that the residues of many organochlorine pesticides found in human tissues declined by 90 percent. So if exposure to pesticides is declining, why would male genital abnormalities be going up?
The Washington State study points to one possibility. It found one factor that correlated with an increased incidence of hypospadias�maternal age. In 2001, another study by Columbia University urologist Harry Fisch also found that the incidence of hypospadias increased with maternal age. As Fisch notes the number of live births to women over age 35 has increased from 6 percent in 1980 to over 12 percent today. The comprehensive 2005 study that found an increase in hypospadias noted that it also correlated with higher socio-economic status which tends to be linked with higher maternal age.
As far as I know, no one has done a study comparing the penis sizes of newborn boys and pesticide exposure. However, researchers at the University of Rochester in New York reported in 2005 that the distances between the anal openings and the scrotums (anogenital distance or AGD) of boys whose mothers had relatively higher levels of plasticizers known as phthalates in their urine were less than those whose mothers had lower levels of phthalates. This effect had been previously observed in rodent pups that had been exposed to phthalates prenatally in the lab. But keep in mind that none of the 134 boys in the Rochester study had malformed genitals.
Not surprisingly, some in the industry disagreed, arguing, "Because little is known about AGD in human infants and its variation, no conclusion can be drawn whether the reported values are normal or abnormal. The range of AGD values seen among study subjects likely represents typical biologic variation that would be expected to occur among normal study subjects." Curiously, the Rochester researchers responded, "First, because all infants in our study appeared normal, [industry scientists] infer that there is no evidence of an adverse effect. However, the absence of evidence of an effect in infancy does not preclude serious adverse effects in later life. "
One could also say that the absence of evidence for an armada of gigantic purple space squid massing behind the moon for an invasion of the earth doesn't mean that they won't show up later—but never mind. Perhaps the Rochester study will be replicated and eventually show that phthalates are responsible for actual deleterious effects on the health and fertility of people, or perhaps its findings will dissipate in the light of further research just as those that initially supported the notion of a synthetic chemical cancer epidemic did.
Make no mistake about it—massive occupational exposure in the 1970s and 1980s to some pesticides had tragic health effects such as causing infertility in hundreds of agricultural workers. But so far, the effect of low level exposures to pesticides and other synthetic chemicals on human male genitalia does not appear to have been "dramatic" and may not exist at all. Dueling ambiguous scientific studies bring to the fore a hard policy question: How much time and resources do we (government, industry and consumer) want to spend in chasing what have so often turned out to be phantom risks? In the meantime, spraying a lawn for dandelions and fire ants doesn't seem like taking much of a risk with one's manhood to me.
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