Superficial science in new nano sunscreen report

Richard Denison, Ph.D., is a Senior Scientist.

I hate to say it, but Friends of the Earth, Consumers Union, and the International Center for Technology Assessment (ICTA) have done a disservice to good science and policy with their new superficial report Manufactured Nanomaterials and Sunscreens: Top Reasons for PrecautionThere are all kinds of legitimate safety questions yet to be answered about the use of nanoscale ingredients in sunscreens, a few of which are briefly discussed in the report.  But virtually all of them apply equally to the alternative chemicals used in other sunscreens as well, a fact that the report’s authors conveniently duck.

Instead, the authors cite the usual litany of effects seen in various studies of nanomaterials, most of them associated with inhalation or ingestion – exposure pathways the relevance of which they never question in their apparent haste to warn consumers off of applying nano-containing sunscreens to their skin.  They cite the “small size” of nanomaterials as the driving concern, failing to recognize that the organic molecules used in other sunscreens are typically far smaller – not to mention specifically designed to be absorbed into the skin.

Like the authors, I’m all for thorough testing, labeling and demonstration of safety of nanoscale ingredients in sunscreens and other consumer products.  But those needs extend well beyond nanoscale materials to all ingredients.  A less selective rendition of the facts about the safety of sunscreens would better serve these causes – and consumer protection.

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  1. Jennifer Sass
    Posted August 20, 2009 at 12:11 pm | Permalink

    Dear Richard,
    As always, your insights and expertise is welcomed. I do not, however, share your opinion in this case. You make two major points:
    First, that sunscreens contain all sort of other nasty chemicals that pose health threats. True. However, the point of the report is that there is no good reason to include an added potential risk from nanomaterials. Nanomaterials do not improve the efficacy of sunscreens, so why have them? Let consumers make informed choices by labelling sunscreens and other products where the ingredients are “nano” scale.

    Second, the issue of route of exposure. There is mounting evidence from well-designed independent laboratory studies (referenced in the above report) that the small sample of nanomaterials that have been tested can penetrate skin that is flexed or damaged, such as sunburnt skin. Once through the skin, there is plenty of evidence that nanomaterials can circulate in the blood stream throughout the body. True that only a small subset of nanomaterials have been tested in this way, but this is already raising red flags. Shouldn’t we presume that the untested materials will act like the tested ones, unless we have good evidence otherwise?

    Respectfully from your no-nano-sunscreened, floppy-hat wearing colleague,

  2. Posted August 20, 2009 at 2:24 pm | Permalink

    There is a danger here that cautioning against a newer technology on the basis of a whole string of “ifs” ends up implicitly condoning more familiar technologies that nevertheless are far from safe. While there are questions that remain unanswered over the safe use of nanomaterials in sunscreens, the overwhelming balance of current information is in their favor. Some degree of judgment is needed here, precisely because the science is not conclusive (when is it ever?). But I would certainly not shy away from well-executed nanoparticle-based sunscreens based on the current state of knowledge.

    That said, I would agree that more research is needed to double check the safety of these products. And it’s important that the active nanoscale ingredients in sunscreens are fully identified, so that purchasers can make informed decisions.

    But informed decision-making also relies on access to clear, unbiased information.

    I actually thought that the FOE etc. report read reasonably well. But I have to wonder whether, if condensed into a product ingredient label, it would be any more informative than current labels that eschew any mention of “nano.”

  3. Posted August 20, 2009 at 4:00 pm | Permalink

    Jen and Andrew:
    Thanks for engaging on this. My main concern with the FoE report, which Andrew touches on, is that it fails to acknowledge that the decision facing consumers is NOT as easy or simple as avoiding the “added potential risk from nanomaterials” in sunscreens. That’s because the alternatives that do not contain nanomaterials have their own risks and uncertainties.

    By necessity, then, a sound analysis must be comparative. The report fails entirely on that score: It dismisses without even citing a significant number of studies (still far from conclusive) that indicate nano metal oxides do NOT show significant skin penetration; and instead cites a few studies on entirely different nanomaterials. I am NOT arguing the latter studies are irrelevent, but surely neither are the former.

    A less superficial report could have raised legitimate concerns about both nanomaterials and other equally untested and underassessed substances used in sunscreens, concluding that sunscreen safety cannot be determined — thereby highlighting the serious deficiencies of our regulatory system.

    Or it could have applied a weight-of-evidence approach that fairly and forthrightly examined ALL of the available information to reach the most defensible conclusion as to sunscreen preference that is possible in light of the serious data gaps.

    This report did neither.