Thyroid by Shutterstock.com
- Let's hope the relentless anti-science drumbeat doesn't result in a chemical regulatory crisis. @JonEntine
- The NRDC is not exactly known for scientific nuance reports @JonEntine.
- A review of the evidence suggests that the NRDC is far off the mark in its report on phthalates.
As Jon Entine of the Genetic Literacy Project reports, the NRDC is not exactly known for scientific nuance. So, there was little surprise when blogger Mae Wu took to the cyberwaves recently to plug an NBC Dateline story promoting the alleged dangers of “endocrine disrupting” chemicals.
According to Wu, we should all be shocked—yes shocked—that an NBC producer and her family found trace chemicals in their urine—microscopic amounts of BPA, triclosan and phthalates—all of which are approved and not harmful as commonly used, according to the Environmental Protection Agency.
But that didn’t stop NBC and Wu from hyping what amounted to chemophobia. The scare tactic in this case was insinuating that the presence of common chemicals in our urine is dangerous. Journalists who do not understand risk analysis make this mistake all the time—ignorantly more than likely by NBC, as the reporter had no background in toxicology or science in general, but cynically by NRDC, whose unstated mission it seems is to scare people about chemicals.
What NBC and Wu never disclosed is that the presence of chemicals in our urine is neither unusual nor, in almost all cases, anything to be remotely concerned about. Miniscule traces of substances found in our urine can sometimes be meaningful but it’s usually just data noise—an artifact of high tech ultra sensitive biomonitoring devices; the dose and exposure time, not the presence of a chemical, determines its toxicity.
NBC found tiny amounts of BPA, a chemical investigated and approved numerous times by the Environmental Protection Agency—most recently one year ago in a direct rebuke of an NRDC suit. The Centers for Disease Control and Prevention (CDC) has previously found traces of BPA in the urine of more than 90% of adults and children. That sounds frightening but not to a scientist. How scientists and journalists frame this often-stated fact is a good barometer of their understanding of toxicological risk—whether they genuinely wrestle with complex science or are mouthpieces, intentionally or not, for a predetermined, chemophobic perspective
Yes, we encounter BPA, phthalates and dozens of other common chemicals every day; and yes, they show up in our urine. It’s estimated that more than 160 chemicals can be detected in human urine, many of which are potentially dangerous if consumed at high enough doses over a long enough period of time. However, our liver regularly detoxifies chemicals from the environment and food, which is why we don’t keel over from drinking coffee, which has dozens of “killer” chemicals.
The CDC has repeatedly stated that while biomonitoring “can … help scientists plan and conduct research on exposure and health effects,” the presence of a chemical—whether BPA, triclosan, a phthalate or some other substance targeted by advocacy groups—does not mean that it’s harmful … or cause(s) an adverse health effect,” the CDC has written.
In the case of BPA, the FDA, reflecting the emerging scientific consensus that there is far more smoke than fire on the issue of so-called endocrine disruption, concluded, “[O]ral BPA administration results in rapid metabolism of BPA to an inactive [and therefore harmless] form.” The same mechanism is in place to detoxify many other so-called endocrine disrupting chemicals. The same is true for phthalates and triclosan, the other chemicals demonized by both NBC and the NRDC.
Phthalates in the crosshairs
Wu makes hash of the genuine scientific knowledge about all three chemicals. To dissect her shoddy reporting, I’ll just focus on one—the class called phthalates. Phthalates are plasticizers used to increase the flexibility and durability of a product. There are dozens of different types, but nine major ones used in thousands of consumer and industrial applications including, cosmetics, cables, flooring, medical devices and children’s vinyl backpacks and toys. NRDC’s website lumps them all together indiscriminately:
Phthalates are known to interfere with the production of male reproductive hormones in animals and likely to have similar effects in humans. Their effects in animal studies are well recognized and include lower testosterone levels, decreased sperm counts and lower sperm quality. Exposure to phthalates during development can also cause malformations of the male reproductive tract and testicular cancer. Young children and developing fetuses are most at risk.
A review of the evidence suggests that NRDC is far off the mark when it casually writes that phthalates are “likely to have similar effects in humans.” No study—not one—has shown that. Few chemicals on the market today have undergone as much scientific scrutiny as ph thalate esters. Activists and industry groups pitted against each other in the debate have no shortage of studies they can invoke as ammunition. But one thing is clear: almost all of the evidence cited by anti-chemical campaigners is based on research linking phthalates to reproductive problems in rodents exposed to dose levels far higher than any human might face.
The NRDC’s misstatements about phthalates are compounded by the fact that, like many activist organizations, it willfully confuses different types of the chemical. Scientists draw distinctions between so-called low molecular weight ones—DEHP, BBP, DBP and DIBP— and high weight ones such as such as DINP, DIDP and DPHP. The low weight phthalates are slightly more volatile and can release minute amounts of off gasses—though not at toxic levels. As in the case of BPA, science bodies around the world have found low phthalates taken into the body are safely metabolized. Nonetheless, some regulatory bodies have voted in precautionary bans based entirely on rodent studies.
The long-term regulatory fate of the high phthalates is less sure. The chemical is ubiquitous, used in PVC/vinyl products as well as in hoses, shoe soles, sealings and many industrial processes. From a chemical perspective, high-weight phthalates are tightly bound, more stable and more resilient than low phthalates. They’ve been found safe time and again. Under pressure from activist groups, the US Consumer Product Safety Commission (CSPC) research organization known as the Chronic Hazard Advisory Panel or CHAP is expected to issue an updated scientific review soon. Pending the results of the CHAP review, there now exists a temporary ban on any child-care article that contains more than 0.1 percent of DINP, DIDP or DPHP.
It’s purely precautionary and unwarranted based on the death of evidence. The CDC offers a comprehensive list of links to a slew of scientific research on the chemical—none of which point to any serious human consequences. There is no cumulative buildup and the chemical is metabolized quickly by the body and excreted, noted Antonia M. Calafat of the CDC. “There is no consensus at present whether the phthalates are causing adverse health effects in humans,” added.
Two state of the art reports involving monitoring humans make hash of the NRDC’s fear mongering. A comprehensive study conducted in 2004 by the Children’s National Medical Center and the George Washington University School of Medicine showed no adverse effects in organ or sexual functioning in adolescent children exposed to phthalates as neonates. The same team evaluated infants in a 2010 study and reconfirmed the negative findings. Another more recent study has shown that even high levels of phthalates showed no effect on the genital development of marmosets, let alone humans—activist claims to the contrary.
Precautionary concerns prompted the Australian government to undertake yet another review released just last year of the most common high phthalate plasticizer, DINP. The National Industrial Chemicals Notification and Assessment Scheme (NICNA) crunched data provided to them by the US CSPC, which had had prepared it for the CHAP analysis. NICNA’s findings: “Current risk estimates do not indicate a health concern from exposure of children to DINP in toys and child care articles even at the highest (reasonable worst-case) exposure scenario considered.” That hat means even pregnant women or children are not in harms way. The scientists added: “No recommendations to public health risk management for the use of DINP (the most common “high phthalates”) in toys and child care articles are required based on the findings of this assessment.”
Trace phthalates not dangerous
Rather than reviewing the contextualized evidence about chemicals on its website or in its blogs, the NRDC merely sneers. In her post, Wu also pumped a recently released University of Washington study finding micro-traces of phthalates in people who ate an organic diet, claiming it showed that “even when you do the ‘right’ thing, it is exceedingly difficult to eliminate phthalate exposure.“ That’s true, but as scientists stress time and again exposure does not equate with danger.
The report cited by the NRDC appeared in Nature in February. Pediatrics professor Sheela Sathyanarayana and her team measured the exposure of 10 families—an absurdly low number for a study of this kind—to phthalates and BPA. They supplied half the families with fresh, local and organic foods that didn’t come into contact with plastic during preparation or storage. They then measured phthalate and BPA metabolites in the participants’ urine—something scientists including at the CDC say is relatively useless in determining toxic exposure—before, during and after the diet changes.
The results were contradictory, as often happens with such small sample sizes. Bizarrely, the new organic diet substantially increased exposure to one type of phthalate, DEHP, suggesting the study was probably contaminated, raising questions about all the data and its conclusions. The researchers then tested the phthalate concentrations in the foods fed to the participants. They found that dairy products (butter, cream, milk, and cheese) and spices (ground cinnamon, cayenne pepper and ground coriander) had minute amounts of DEHP.
Besides the small sample size—one might need tens or even hundreds of subjects for the study to have much validity—the research was dogged by other problems. The results are an outlier when compared to other exposure studies. The use of spot urine samples with such small group sizes is not a rigorous approach. Additionally, as the authors note, they didn’t present the corrected values for creatinine, which otherwise allows researchers to correct for urine concentration—how dilute is it depending on how much water one drinks. That throws the entire study in doubt. They also didn’t analyze the diet in a rigorous way. The phthalates could be a biomarker of dietary fat consumption, which means they could have been eating a higher than typical amount of dietary fat or significantly more food.
So what should we take away from this study? According to the NRDC’s Sara Jannsen, another NRDC staffer who blogged when this data was first released, everyone should be on red alert. “As demonstrated in this study, the current levels of exposure are not safe,” she wrote.
I contacted the lead researchers to see whether her study agreed with the NRDC’s assessment. “The premise of our study was to see if we could reduce phthalate and BPA concentrations with either an educational handout or food replacement – not to examine health outcomes,” Sathyanarayana wrote me.
I then asked the professor about her use of the word “contamination” to describe the presence of phthalates in the food. Among scientists, the word is a technical term that points to intermingling, and does not speak to whether something is actually “polluting” or “dangerous,” which is the exaggerated way activists interpret that term.
Entine: “There appears to be an assumption running through [your article] that the presence of a chemical = contamination (used in the pejorative rather than the descriptive sense) = harm which then justifies regulatory intervention of some unstated nature. Is that in fact the argument you are making?”
Sathyanarayana: “No, I was not making that argument.”
So, here we have a problematic study hyped erroneously by science-challenged activists only to be picked up by science-absent television journalists only to be recycled back to the public by anti-chemical activists. At the center of this fiasco: the NRDC.
Any wonder we have a science education crisis in our country? Lets’ hope that the relentless anti-science drumbeat doesn’t result in a chemical regulatory crisis as well.