Anti antimicrobials - time to get serious about triclosan and triclocarban

I thought I was “antibacterial” savvy. For years I’ve read labels on antiperspirants and soaps before tossing them into the shopping cart. It wasn’t until I joined a consumer products working group, whose current focus is the dynamic duo of antibacterials, triclosan and triclocarbon, that I found I should also be checking my toothpaste. That’s right, listed right there on the ingredients for Colgate toothpaste was triclosan.

So why the outrage, what’s so bad about these products? Most experts including physicians groups and an FDA panel agree that these antibacterials, originally used in hospitals, aren’t really necessary for the average consumer. Unless there’s a reason to be ultra-clean, there’s nothing like a good hand washing with plain old soap.

Then there are the environmental implications of washing this stuff down the drain. As discussed a while back on this site, these chemicals tend to make their way through sewage treatment plants, persisting in soil and water. But that’s not all folks. Back when I wrote about antimicrobials I focused on the release and impact of these things into the environment. But now I read that triclosan is detectable in breast milk. And although the author concludes that concentrations are below those that might be cause for concern, here we have a chemical that 1) doesn’t seem to do much good 2) gets into the environment and stays there and 3) gets into breast milk. Hmmm.

The breast milk study, by A.D. Dayan, found “No triclosan was detected in 2 samples, it was barely detectable in 9 and the concentration ranged from about 100 to about 2100 μg/kg lipid in the other 51 milk samples.” With the majority of samples testing positive it’s curious that Dayan ponders the results, adding the following “caveats” for how and why these samples might contain the antibacterial:

"Possible contamination at the time of collection.• For example, might the mother have used a triclosan-containing soap to wash her breasts shortly before donating the milk? When did she last use a medicated deodorant, dentifrice or dusting powder?• Was the milk sample collected early or late in lactation after parturition because the body’s fat stores change with time, possibly affecting systemic exposure to any lipophilic material stored in fat?• When was the sample collected in each episode of lactation, i.e. was it ‘fore-milk’, which is more watery, or a later, hind-milk sample with a higher fat content?• Was the sample collected after a period during which the mother had not breast fed or expressed milk? Even a necessarily brief period without milk expression may make the first sample of milk then obtained more concentrated than usual.”

Skepticism is fine – what would science be without some healthy skepticism. But in this case I can’t help but be skeptical in the opposite direction – if there’s no clear benefit of the stuff – why risk exposing the most vulnerable population? Besides none of these caveats lessen the implication that breast fed infants of these women would likely be exposed at some point.

Now, a study by Bruce Hammock (from the University of California, Davis) and others, published in Environmental Health Perspectives suggest that use of these products may in fact, do more harm than good. Reporting that while triclocarban enhanced activation of steroid hormone dependent genes, triclosan was found to be antagonistic in assays designed to evaluate interaction with steroid hormone dependent activity, the authors suggest caution when it comes to triclosan and triclocarbon concluding:

“These observations have potentially significant implications with regard to human and animal health since exposure may be directly through dermal contact or indirectly through the food chain. These screening studies revealed that further investigations into the biological and toxicological effects of TCC [triclocarban], its cabanilide analogs, and TCS [triclosan] are urgently needed."

Perhaps one route, rather than relying on the consumer to read, read, read is to encourage producers to remove the stuff - or to encourage the EPA to cancel all non-medical uses - which is exactly what several environmental and public health organizations are suggesting according to an article in Water and Wastewater News.

But for now, until their campaigns are successful, it’s time to take cleanliness into our own hands and keep reading those labels.

Who's screening sunscreens?

A while back I wrote about sunscreens here and here. But that was already over a year ago - and as anyone who is confused by he says and she says in science knows - the reports just keep on rolling. Just yesterday the New York Times Science Section published an article by Tara Parker-Pope calling sunscreen safety into question, and based in large part on an Environmental Working Group (EWG) report on the stuff. In short, it seems that the EWG is concerned about chemicals like oxybenzone (or BP-3 )which are absorbed by the blood and can be detected in urine - the problem is - health impacts are unknown (although a recent news article in Environmental Health Perspectives reports that in animal studies BP-3 " effects in liver, kidney, and reproductive organs, and studies by other groups have shown endocrine-disrupting effects,") and some claim EWG's rating system for sunscreens lacks scientific rigor. Either way, there just aren't enough studies - though one would wonder maybe why consumers are allowed to slather products on themselves and their young ones when "there aren't enough data."

According to Parker-Pope, "Of nearly 1,000 sunscreens reviewed, the group recommends only 143 brands. Most are lesser-known brands with titanium and zinc, which are effective blockers of ultraviolet radiation. But they are less popular with consumers because they can leave a white residue." But many of the titanium and zinc sunscreens don't leave a residue, and the reason they don't is that titanium and or zinc in "micronized." In other words - really small - sometimes nanosized.

Those who remember smearing the white stuff on their noses in the summer - most likely were using zinc that scattered not only the undesirable UV light but also visible light (hence the clown effect.) Today's micro or nano zinc allow visible light to pass through them and so appear clear, while still scattering the sun’s shorter and harmful ultraviolet rays. Cool right?

Maybe. My friend Cal Baier-Anderson, blogging over at Environmental Defense just posted about a study initiated following an "...observation that installers of metal roofs who used these sunscreens inadvertently transferred the product onto the roofs. In places where the workers’ skin had touched the painted metal surfaces, the paint showed accelerated weathering. Why? Because the particular type of nanoscale TiO2 in the sunscreen (the anatase crystal form) is photoactive – when it absorbs UV light, it releases free radicals that speed up the oxidation of the underlying paint."

Cal wondered if the same might happen to our skin - inadvertently accelerating the weathering of our skin just as we are trying to stop any further damage. For more on the topic check out Cal's entry Nano on a Hot Tin Roof (rusted!) and her other entry on nanoproducts and sunscreen Burning Questions.