A question from a nonprofessional

[kelemvor]

I meant to add this my link for the study above. So there are some other studies such as the one I referenced, but I'll also agree with tbone that a lack of oxybenzone doesn't necessarily make sunscreen "safe."

Including it also doesn't necessarily make sunscreen unsafe.. unless there's some hidden study that we don't all know about.

Sounds like there was one where the folks doing the study added some toxic chemical to oxybenzone therefore invalidating the study entirely, and another by a reputable marine lab but funded by a sunscreen company.

The study including the addition of a toxic chemical concluded that the concoction was dangerous to coral at 100% concentrations. The other concluded oxybenzone was not dangerous to coral. I think in the absence of some actual science showing a problem I've got no more concerns about using normal sunscreen when diving.

 

[Seaweed Doc]

The "mixed it with a toxic chemical [DMSO} and thus invalidated" argument makes sense if no control is done and if a variety of oxybenzone concentrations aren't attempted.

However, using a control of DMSO alone (that is, with no oxybenzone) shows no effect of the supposed second toxin.

For an example, see::

Downs, C. A., Kramarsky-Winter, E., Segal, R., Fauth, J., Knutson, S., Bronstein, O., ... & Pennington, P. (2016). Toxicopathological effects of the sunscreen UV filter, oxybenzone (benzophenone-3), on coral planulae and cultured primary cells and its environmental contamination in Hawaii and the US Virgin Islands. Archives of environmental contamination and toxicology, 70(2), 265-288.

 

[kelemvor]

The "mixed it with a toxic chemical [DMSO} and thus invalidated" argument makes sense if no control is done and if a variety of oxybenzone concentrations aren't attempted.

However, using a control of DMSO alone (that is, with no oxybenzone) shows no effect of the supposed second toxin.

For an example, see::

Downs, C. A., Kramarsky-Winter, E., Segal, R., Fauth, J., Knutson, S., Bronstein, O., ... & Pennington, P. (2016). Toxicopathological effects of the sunscreen UV filter, oxybenzone (benzophenone-3), on coral planulae and cultured primary cells and its environmental contamination in Hawaii and the US Virgin Islands. Archives of environmental contamination and toxicology, 70(2), 265-288.

Thanks! For others who also wish to read the details, you can obtain it here: https://repository.library.noaa.gov/view/noaa/13720

 

[Schwob]

Hawaii to ban certain sunscreens harmful to coral reefs

 

[kelemvor]

So, having read the details behind the study. It's mostly pretty good. However, there is what I consider a critical error that invalidates much of the study. This error appears to be the primary factor cited by the "reef safe" people. Oxybenzone (Benzophenone-3) is positively buoyant. Why does that matter? Unless you actually rub Oxybenzone directly onto the coral, it doesn't come into contact with coral. Even if you slather on a thick coating onto your body and dive just a few inches above the coral it will not contact the coral. Even if you briefly contact the coral I'd expect very little of the Oxybenzone to stick to the coral. Further, Oxybenzone (Benzophenone-3) is biodegradable. That means it's going to break down rather than create a permanent oil slick waiting to attach to something and sink down onto the reef. C.A. Downs et alia had to compound Oxybenzone with another chemical to make the test possible.

So, what I learned is that if Oxybenzone (Benzophenone-3) somehow finds its way onto a coral in mass then that coral is doomed. I also learned that it's almost impossible for Oxybenzone (Benzophenone-3) to come in contact with coral unless you go force the situation with an unusual chemical mix or a heck of a lot of mechanical effort.

That critical distinction is likely why the Mote Marine study apparently showed no problems with a particular brand of Oxybenzone based sunscreen. I can't seem to find the paper for that study, just news articles (mostly on sponsored sites) summarizing results into normal English.

Like many laws, the Hawaiian lawmakers hearts are in the right place. I think they've been mislead. I think there's an above average chance that businesses with a vested interest in selling sunscreen sans Oxybenzone were involved in lobbying for the law.

 

[scorpiofish]

I know I am late to this discussion, but I don't frequent the board as much as I used to. I've been involved in the manufacture/and or formulation of sunscreens since 1991 and been scuba diving since 1992. I am passionate about both, but more so about diving. The original Italian study on sunscreen actives and coral was so flawed I just ignored it. Here are the flaws in the coral damage theory.

1) Un-dispersed Benzophenone-3 (BP3) in powder form has a specific gravity SG of 1.2. It is not water soluble. If you drop it the ocean, it will fall to the bottom. But, in the actual product, the BP3 has been dispersed in oil, roughly .9 SG. The final product may sink or float depending on the oil content. Even if the lotion had an SG of 1.04 and sank, as it the emulsion broke down, the oil droplets with BP3 would float away. In order for the BP3 to kill coral, it had to be "held" onto the coral.

2) Dosage. My pool is 27,000 gallons, or about 100,000 kilograms. If I slather my body with 2 oz. of SPF (.060 kilos) with a 3% BP3 content, then .0018 kilos of BP3 could end up int the pool. Let's say I jammed 20 naked divers fully lathered in SPF, then we are still talking about .036 kgs of BP3 in 100,000 kgs of water. Also, i) No diver in a wetsuit will be wearing 2 oz. of sunscreen on their exposed body, ii) 20 divers in 27,000 gallon area is ridiculously overstated, iii) if the sunscreen is highly water resistant, it contains a polymer that traps the BP3 on the skin for 80 minutes of immersion (every formula gets tested).

BTW, we no longer use Oxybenzone/Benzophenone-3. It has other issues, real or imagined. However the same "kills coral" issue has been raised with other chemical sunscreen agents. If you want to use sunscreen in the ocean, and think the science isn't the junk it is, I recommend the following:

1) Use a highly water resistant version. Again, each formula is tested for FDA drug approval by immersing a persons are in water for 80 minutes. They are then zapped again to ensure that the original SPF rating holds up.

2) Today's formulas have UVA protection (which has nothing to do with the SPF rating, which is UVB). The ingredients that prevent UVA damager are either Avobenzone, Zinc Oxide, and to a lesser extent Titanium Dioxide. Avobenzone is a chemical like Oxybenzone and has that evil ending ...benzone. Zinc is physical blocker and has been proven not to damage the reef. So, choose a sunscreen that uses Zinc Oxide instead of Avobenzone. I hate Avobenzone anyway because it isn't as stable in formulation and the protection falls off faster. The problem with Zinc Oxide is that as you go up in percentage, the pastier it goes on, as in whiteface.

As per these new laws and rules, just more "feel good" measures that won't make a difference, kind of like the straw laws. Real laws that would make a difference would be higher penalties and stricter enforcement of littering laws. Less crap would make it into the ocean.