Sunscreens | Find Out if Yours Could CAUSE Skin Cancer


There are two primary types of sunscreens – chemical agents and physical blocks.

“Physical blocks” sit on the surface of the skin. Typically these are not absorbed and have been shown to be non-reactive with UV light. Since they are not absorbed there is no concern about them building up in the body, being stored in fat or reacting with other chemicals.

(The jury is still out on micronized sunscreens and whether the nano-particles are absorbed.)

Early sunscreens that were used in the 1940’s were made of zinc oxide. More recently, physical block sunscreens have been made with titanium dioxide.

The very factor that makes both of these physical blocks safe – that they are not absorbed – also makes them cosmetically unappealing. Think – white paste – like we used to see across the noses of surfers.

So, in the 1980’s some enterprising chemists introduced several chemicals that could be applied in an unobtrusive layer that would absorb sunlight rather than reflect it.

The problem was that these chemical agents were only tested for safety in the lab – not on the skin.

Risks of Chemical sunscreens 

Today the vast majority of commercially available sunscreens are “chemical agents” and they may be more harmful than beneficial.

The risk comes from ingredients that are known endocrine disruptors – meaning they increase your risk of cancer and interfere with your normal hormone production and/ or function.

Most of the chemicals in sunscreens don’t have toxic effects when first applied. However, once exposed to sunlight, reactions occur between the sunscreen’s active and inactive ingredients and the epidermis (skin).

Chemical sunscreens don’t sit on top of the skin but are absorbed, meaning the ingredients can have a systemic effect.

  • They block Vitamin D synthesis
  • They are endocrine disruptors – acting as a hormone
  • They increase free radical formation – which causes DNA mutations in the skin

The Great Migration

We know that most of the major active ingredients in sunscreens have the ability to absorb across the skin and migrate into the blood. One experiment found benzophenone-3, OMC and 4-MBC were all detected in plasma one to two hours after one application. Participants continued to excrete the chemicals many days after the last application, which suggests they may accumulate in fatty tissues in the body.

Even more alarming is that these chemicals have been found in breast milk at concentrations known to have estrogenic effects.

A large proportion of the active ingredients in sunscreens can also act as penetration enhancers that speed up the absorption of other chemicals through the skin and into the blood.

In a number of studies, sunscreens have enhanced the absorption of pesticides such as DEET, paraquat, parathion and malathion and industrial solvents, all known carcinogens.

Here’s a list of some of the key chemicals to avoid:

The irony here is that these chemicals, which tested safe in the lab, increase free radical production … when exposed to sunlight.

Parabens are a type of endocrine disruptor – it mimics estrogen and interferes with testosterone. According to a research review in the Journal of Applied Toxicology parabens have been linked to an increase risk in breast cancer as well as interfering with the male reproductive system and increasing the risk of malignant melanoma.

Retinyl palmitate has been shown to increase the rates of cancer when it is exposed to UV-A rays.


UV filters like octinoxateoxybenzone, benzophenone, Padimate A, causes phototoxic reactions, meaning it reacts with UVA to produce symptoms widely resembling sunburn in some individuals.

Padimate O when exposed to sunlight, generates free radicals that cause strand breaks on DNA. An experiment with Padimate O found that it produces singlet oxygen (free radicals) when exposed to light and increased indirect DNA damage by a factor of 75 over sunlight exposure alone.

Avobenzone – upon exposure to UV light generates free radicals.

PABA was one of the first commercially used UVB sunscreens. The FDA limits PABA content to a maximum of 15%; in Europe the limit is 5%. PABA is prohibited as a sunscreen ingredient in Canada due to its ability to affect DNA in human cells. PABA has been found to form potent free radicals when exposed to UV light.

Oxybenzone – is rapidly oxidised to become a potent free radical and linked with cell damage. It has estrogenic properties. In addition to hives and dermatitis, oxybenzone also causes degradation of the epidermis – your primary protective layer.

A study by the CDC found that 97 per cent of the 2,500 people tested had oxybenzone in their urine. An earlier study found oxybenzone being excreted many days after the last application, which suggests a tendency to accumulate in fatty tissues in the body.

Benzophenone, along with menadione, form free radicals which can initiate a chain reaction that will cause damage to anything it comes in contact with, including cell DNA. A 2012 study published in the Environmental Science & Technology found exposure to benzophenone is linked to an increased risk of endometriosis.

Check you sunscreen

Let me know in the comments below if you find any of these chemicals in your sunscreen.


This is the second in a series of three articles on Sun and Your Skin.

Part One: Healthy Skin Rethink – Tanning is Better Than Sunscreen

Part Three: Healthy Skin | Preventing Sun Damage (good sunscreens)



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