New research published on 1/21/20 shows that all six of the chemical UV filters in sunscreens are absorbed through the skin and enter into the blood after one use. 

The battle between local and state governments, sunscreen manufacturing lobbies, environmentalists, and dermatologists is ongoing regarding the ban of some active chemical ingredients (UV filters) in sunscreens based on studies claiming that these ingredients harm coral reefs. Now sunscreen studies are focusing on humans.

Below, I share the timeline concerning human safety of sunscreen active ingredients and give you my personal and professional opinion as a dermatologist about the current state of sunscreen controversies.

History of sunscreens from the 70's to today

The currently approved sunscreen filters were “grandfathered” into the system in the 1970s.

In the United States, sunscreen is considered an over-the-counter (OTC) drug, which is a drug available to consumers without a prescription. The Federal Food, Drug, and Cosmetic Act authorizes the Food and Drug Administration (FDA), an agency within the Department of Health and Human Services, to ensure that OTC drugs, such as sunscreens, are safe and effective in order to be marketed in the United States.

As skin cancer awareness has increased, so has the use of sunscreen; larger body surfaces are covered for many days and when following guidelines, in large quantities with frequent re-application.
 

Due to increased sunscreen usage and studies regarding human safety of certain chemical UV filters, the FDA became concerned about systemic absorption.

Hence in its new proposed (not final) guidelines that were published in February 2019, the FDA recommended GRASE designation (generally recognized as safe and effective) only for two mineral filters (zinc oxide and titanium dioxide) and requested certain studies for the remaining chemical filters that are approved in the US.

One of these studies is the Maximum Usage Trial (MUst) which essentially measures levels of the chemical filters in the blood after extensive sunscreen use.

The FDA completed MUst testing of four chemical filter ingredients (oxybenzone, avobenzone, octocrylene, and ecamsule) using commercially available sunscreens to determine whether these active sunscreen ingredients are absorbed into the blood. 

In this preliminary study published in a peer-reviewed journal in May 2019, involving healthy volunteers, the application of four commercially available sunscreens under the maximal use conditions resulted in plasma concentrations that exceeded the threshold established by the FDA. (Oxybenzone was absorbed very quickly and at the highest level.)

Subsequently, on 1/21/2020 the results of a follow-up randomized clinical trial by the FDA was published in JAMA Dermatology. They studied the absorption and plasma concentration of additional chemical UV filters used in US sunscreens, including homosalate, octisalate and octinoxate.

The study included again the previously studied and most commonly used filters, oxybenzone and avobenzone as well as octocrylene.

The study concluded that all 6 of the tested ingredients were absorbed in the blood at concentrations that surpassed the FDA threshold for potentially waiving additional safety studies for sunscreens.

The studies conducted by the FDA did not address toxicity of these chemicals.

A Look at the Study
 

48 healthy participants took part in a randomized clinical trial between January and February 2019. The participants were asked to apply one of the four types of sunscreen products – lotion, aerosol spray, nonaerosol spray, and pump spray - to 75% of their bodies.  

 
They applied sunscreen once on day 1, and four times on day 2-4 at two-hour intervals (to mimic what would happen if somebody spent a full day on the beach in swimwear and followed sunscreen application guidelines by applying sunscreen on the full-body every two hours).

The results in the study showed that all six of the active ingredients administered via the 4 different sunscreen formulations, were consistently absorbed and had concentrations that surpassed the FDA threshold for “potentially waving some of the additional safety studies for sunscreens.” JAMA Study
 
With each day of application, the concentration of the six chemicals in the bloodstream increased. Interestingly, even after stopping the use of sunscreen, on day seven, the concentration still remained above the safety levels established by the FDA. Most importantly, two chemicals – homosalate and oxybenzone – were still above the safety thresholds on day 21.
 
While no serious drug-related events were reported, 14 participants developed a rash from the applications.  In some people, there is an interaction between the UV light and a sunscreen ingredient that can lead to a reaction of the skin called photocontact dermatitis. In addition to fragrances and preservatives, chemical sunscreens are more likely to cause skin rashes than mineral UV filters. 

What about other chemical filters used outside of the US?

While there are no true broad-spectrum chemical filters available in the United States (zinc oxide is considered to be a broad-spectrum mineral filter), there are several so-called “second generation” broad-spectrum chemical filters that have been used for years in other countries. Companies that manufacture some of these sunscreen ingredients have sought to bring these ingredients to the U.S. market.

Sponsors and manufacturers submitted applications for approval to the FDA for eight chemical sunscreen filters (including second-generation broad-spectrum chemical filters) between 2002 and 2009. None of these filters have been approved up to date. (One of the main reasons was the lack of systemic absorption studies.)

Environmental and Human Impact

Now enter into this heated topic, the studies about coral safety showing deleterious effects of certain chemical filters on the coral reefs and marine habitat. It often reminds me of the battle about climate change. There is true data for both but enter opposing interests, money, and politics, interpretations vary vastly.

There is no doubt that in the laboratory environment, oxybenzone and octinoxate (the two ingredients studied most extensively) have harmful effects on the coral. Now we know that they also enter the blood. Questions arise about whether the concentration is high enough around the reefs to incite real harm and whether coral bleaching is rather attributable to rising sea temperatures and other environmental pollutants. 

Similarly, based on the new studies, there is no question now that the most common chemical sunscreen filters are absorbed into the blood. We need to study however whether they are harmful or not at the concentrations that were detected.

Considering that a very large fraction of US sunscreens contain these chemical filters, manufacturers are understandably worried about the financial consequences of a ban and the cost of reformulation of new sunscreens. They argue that these very efficacious filters have been used for many decades, hence they should be regarded as safe.

Dermatologists, like myself, are worried that the public will hear “sunscreen is the new margarine” or “sunscreens are not safe” and will stop using them, thus creating a new epidemic of skin cancers.

In addition, banning oxybenzone and octinoxate will eliminate some very efficacious UV filters and due to lack of availability of the second-generation broad-spectrum filters, the ban will significantly reduce choices for cosmetically more pleasing sunscreen varieties. Many dermatologists who are loudly against the ban, however, interestingly warn parents not to use any sunscreens with chemical filters on children.

In my personal opinion, holding onto “old” filters such as oxybenzone (it is hardly used in Europe anymore) is not the right approach. Money and effort by manufacturers and other stakeholders should be spent on obtaining unbiased data on the safety and formulation of new, safe and efficacious sunscreen products.

Meanwhile, in the United States, my recommendation is to be sun smart; use sun-protective measures, including hats, glasses, clothing, and sunscreens that only contain mineral filters.

Just as you should look at the ingredients label of the food you eat, start to look at the label of the sunscreen you put on your body!