An Honest Mistake. When Zinc Based Sunscreens Go Wrong.
I awoke this morning to a story on Forbes entitled ‘The Failure of Jessica Alba’s Honest Company Sunscreen Explained’ and immediately wanted to find out more as sunscreen failure has to be a brand owner (and formulators) worst nightmare. After looking over some of the feedback on Amazon, especially comments that have come back in over this summer (Northern Hemisphere) I have to say there is no getting away from the fact that this product is causing some problems, even though official comment from the company states that complaints were running at less than 1% of sales. Apparently the sunscreen was re-formulated for this season after people feeling it was too greasy before so this may well be the first summer for the new, ‘improved’ formula which now contains Zinc Oxide (non nano apparently) at 9.3% down from 20% in the old formula.
The original article I read on Forbes can be accessed here. It gives a reasonable review of the situation but does miss a couple of broader issues out and gets a couple of bits wrong, bits I want to discuss here.
But first I thought I’d also draw your attention to a pretty good article explaining the reliability of AMAZON reviews. Apparently there are people who review products they haven’t even tried just because they don’t like the ‘sound’ of them. Worth keeping in mind…..
This is a zinc-only SPF 30
Non-Nano Zinc Oxide 9.3%
Beeswax*, Butyloctyl Salicylate, Butyrospermum Parkii (Shea) Butter*, Calendula Officinalis Flower Extract*, Chamomilla Recutita (Matricaria) Flower Extract*, Cocos Nucifera (Coconut) Oil, Helianthus Annuus (Sunflower) Seed Oil, Hydrogenated Vegetable Oil, Jojoba Esters, Methyl Dihydroabietate, Olea Europaea (Olive) Fruit Oil*, Prunus Armeniaca (Apricot) Kernel Oil, Silica, Simmondsia Chinensis (Jojoba) Seed Oil*, Tocopherol
Claims (Direct from the brand website)
- Naturally derived, unscented, broad-spectrum (UVA and UVB) SPF mineral sunscreen – everything you need, nothing you don’t
- Easy to apply, non-greasy, non-whitening (non-nano!) zinc oxide sunscreen provides safe, effective sun protection for the entire family
- Zinc oxide is the ONLY active sunscreen ingredient – NO synthetic chemical sunscreens
- Water resistant – tested effective for up to 80 minutes
- Shake well before use!
- Hypoallergenic • Non-Nano • Mineral-Based • Biodegradable • Reef-Friendly • Water Resistant (80 minutes) • pH Balanced
About the formula.
The first thing that strikes me here is the low-level of zinc oxide. Zinc Oxide is a great sunscreen active but it is very hard to get more than 1.5 SPF units per 1% Zinc out of it and to be honest, even that is pushing it. Sunscreen zinc can be anything from say 10 nanometers in diameter (a true nano particle) up to 200 nanometers.
Zinc in the 10-100 nanometers diameter range goes on clear and gives you the highest SPF per % rating. This formula claims to have 9.3% zinc and an SPF of 30. That means that each % of zinc is giving over 3 SPF units which is pretty damn amazing. I’ll not say ‘impossible’ as I am happy to admit to not knowing everything but without a second filter to work synergistically with this SPF performance, especially for a filter that claims NON-NANO is nothing short of miraculous.
Zinc that sits between 101-200 nanometers is what we call MICRONISED zinc. This is still clear and is NON-NANO. It typically gives an SPF of between 0.8-1.2 SPF units per %. 9.3% Zinc would be expected to achieve an SPF of between 7.44-11.16 SPF under normal circumstances.
So what is going on?
Supporting Cast Additives.
Well sunscreens don’t just rely on filters alone, filter efficacy can be boosted in many ways including the use of film formers (to boost surface adhesion), great pigment wetting agents (of the type of technology we use in lipsticks to get a better colour payoff), the use of anti-inflammatory agents (to slow down our reddening response. The use of these is somewhat controversial as it may give an artificially high SPF) and/or the use of other ingredients that have some UV protective features but aren’t listed as sunscreen actives (Raspberry seed oil, seabuckthorn, shea butter etc. Although these typically only have a very small impact on an SPF test).
I can see a couple of ingredients in this formula that would help to boost SPF performance in one or more of the ways described above.
OK so I made that term up BUT one thing that is possible is for a manufacturer to use non-nano zinc in their recipe but process it in a way that de-aggregates it by using roll mills and other highly energetic processes to pound it down and therefore increase its potential to give a higher SPF. Here is one article demonstrating that this is possible. Now I’m thinking that if this was going on the finished formula SHOULD be marketed as containing nanoparticles but it would be difficult to know that this was going on unless the manufacturer of the formula disclosed it. It is highly unlikely that the Honest range has its own factory and even knows how its products are made.
Other things in the formula of note.
I did notice that the second ingredient after beeswax is Butyloctyl Salicylate – a synthetic ester of salicylic acid that is used to help disperse pigments (in colour cosmetics and sunscreens). It makes sense to have this in here and this ingredient may well be one that boosts the SPF but I did wonder how that got to pass the ‘Honest’ definition of ‘naturally derived’, especially as it would be present in a decent amount being the second ingredient in (outside of the declared active). In addition to that chemically this ingredient is in the same family as the ‘chemical’ sunscreen actives that are used in ‘regular’ sunscreens which makes it’s use all the more intriguing.
I also found the ingredient Methyl Dihydroabietate interesting – it is spelled incorrectly on the website, the Dihydro should be Dehydro but as I’m rubbish at spelling I’ll not harp on about that. This is another highly functional emollient or spreading agent but this time it is naturally derived. These di-terpenes can come from pine resin or from Algae (very exciting, I love Algae chemistry). See here for more info.
But really that’s it with the formula. It’s all oil based so there is no emulsifier, no preservative and nothing else weird to note. I would expect this to feel relatively heavy and greasy but again, that isn’t unusual for an oil based zinc product and that doesn’t usually stop die-hard zinc fans. The silica in the formula would most likely have to be labelled as nano should this formula get into Europe but that’s another story……
Other things I picked up on after reading the Forbes article.
- 80 minutes water resistance. This may be so in the test but I wouldn’t be putting that on the packet as people with very sensitive skin probably won’t make it that long in a real life environment. It is always safer to tell customers to over-apply a product than to rely on the best case lab scenario in your marketing.
- Shake the bottle claims are not allowed for Australian sunscreens but they are allowed in other countries. The ‘shake before use’ claim works best for ultra-low viscosity products that contain a ball within the pack to help agitate the fluid and re-combine any that has split. I can’t imagine that this product has a low enough viscosity to make this a possibility given its beeswax, silica and shea butter. Plus there is hydrogenated oil in there to thicken it. However, I could be wrong as I haven’t seen it. The reason we can’t have ‘shake’ SPF products here is because they are un-reliable.
- I tend to agree with the comments from Billy J. Gurley in as much as it looks like the zinc could have settled. Sunscreen products need to have their SPF tested in a third-party lab before going on the market. However, it is possible to make a sample, get it tested, have it pass and then place the product onto the market without doing stability testing. In fact, here in Australia the TGA allow you to run your stability testing parallel to your launch – so it doesn’t have to be completed before hand – as long as should anything go wrong in testing you inform the TGA and pull the product. I’m not sure on how it works in the USA. A sensible protocol for SPF products is to test SPF after an initial 3 month accelerated stability (equivalent to one year real-time) then re-test the product again in the middle and end of the shelf life and compare results. Assays of active can also be taken during the shelf life to make sure your sunscreen active is still present evenly throughout the product. It is entirely possible that this sort of testing hasn’t been done as completely as it could have been and in the final consumer packaging as the above protocol isn’t a legal requirement and different companies take different views of it all. It is also possible that it has been tested thoroughly and that the current problems are batch specific but either way it needs reviewing.
In Summing up.
I have said it before and will say it again, Zinc based sunscreens are not easy to get right no matter how much money you have to throw at them. Not only that but the instructions of how to use a sunscreen product must also be crystal clear and not downplay the risks of over-exposure to sun nor up-state the efficacy of a product.
I hope this situation gets resolved soon as it is clear to me that people want honest, simple products but more than that, they need them to work.