When you’re in the supermarket or drugstore and you’re staring at the dozens of different sunscreens for sale, you probably pay attention to the sun protection factor (SPF) and the brand, but do you pay attention to the kind of container?

As silly as it sounds, new research shows that the type of bottle you choose can make a big difference, especially when you’re buying sunscreen for a child to use.

How can such a small thing make such a big difference? I contacted Abbey-Rose Diaz, MASc, who was a postgraduate researcher in the School of Public Health at Queensland University of Technology in Australia when she conducted this study, to find out.

SUNSCREEN SHOWDOWN

Hamilton and her colleagues had good reason to be interested in this topic. Australia has the world’s highest rate of skin cancer. Over a period of three weeks, researchers asked 87 children, ages five to 12, to apply sunscreen every day using a different dispenser each week—either a pump, a squeeze bottle or a roll-on (which is applied like liquid deodorant). Pressurized spray sunscreen, sticks and wipes weren’t tested. The exact same sunscreen was inside all three types of dispensers. What researchers wanted to learn: How much sunscreen would the kids actually use from each type of dispenser—and would it be enough to really protect them from sunburn and cancer?

The results? The kids applied more sunscreen per square centimeter of skin when using a pump bottle (0.75 mg per square centimeter of skin) than when using a squeeze bottle (0.57 mg) or a roll-on (0.22 mg).

Hamilton explained that the small difference between the pump and the squeeze bottle was not statistically significant, but the larger difference between those two bottles and the roll-on was. The big problem with the roll-on was that it takes multiple passes with this sort of container to get much sunscreen out, and when you aren’t using your hands to spread sunscreen around, it’s harder to know where you’ve missed. In fact, one child ran the roll-on over her face and body and pronounced herself finished—without realizing that not a single drop of sunscreen had come out! This finding makes me wonder if sprays and wipes are equally ineffective, since you don’t apply those directly with your hands, either. But more research will need to be done to answer that question.

PUMP IT UP

So, if you buy pump-bottle or squeeze-bottle sunscreen for your children, are they good to go? Not so fast. In the second part of Hamilton’s study, she looked at how much sunscreen the kids applied in relation to their body sizes—this would tell her whether they had put on enough for adequate sun protection. And the results were quite disheartening.

The benchmark thickness used by sunscreen manufacturers worldwide to test the SPF of a product is 2mg/cm². In other words, unless we apply the product at that thickness, we are not getting the full level of sun protection. While the youngest kids (ages five and six) applied sunscreen more thickly, on average, than the older children (ages seven through 12), all ages applied significantly less than the 2 mg/cm² test amount. The average sunscreen thickness from all dispensers was 0.48 mg/cm², which is about one-quarter of the thickness required to reach the sunscreen’s SPF. So even when kids used a pump or squeeze bottle, they still weren’t applying nearly enough sunscreen. These findings were published in Archives of Dermatology this past January.

So using a pump or squeeze dispenser is only the first step. It’s also critical to make sure that your kids know how much sunscreen to apply…where to apply it…and when to reapply it. Realistically—kids being kids—this might not all happen when you aren’t there to monitor it. But here’s one trick from Australia—equip each of your kids with a teaspoon measure. The Cancer Council Australia’s rule of thumb is that adults should apply a teaspoon of sunscreen to each limb, another teaspoon each to the front and back of the torso, and a half-teaspoon each to the ears, neck and face. Children should apply a proportion of this amount that’s relative to their size. It should all be done again every two hours. The lengthy process may annoy your child, but putting up with the groans now will absolutely pay off later.