The hidden side of clinical trials

Watch the AllTrials TEDx talk on YouTube

Learn more

Evidence matters to the public

Join us on 1st November at Parliament to make the case

Learn more

Plant Science Panel

Insecticides, biofuels, GMOs …

Learn more

'The Ugly Truth'

by Tracey Brown, director of Sense About Science

Learn more

Publications and resources

Harmful chemicals in make-up and household products

In October 2007, the Daily Mail ran a story (“Is Your Make-Up Killing You?”) based on a two-part Channel 4 documentary called How toxic are you? which claimed to show that chemicals from make-up are stored in the body and that chemicals in baby products are absorbed into babies.


Dr Gary Moss (School of Pharmacy, University of Hertfordshire) researches specifically how drugs and other chemicals penetrate the skin barrier and the implications for safety in pharmaceuticals and cosmetics. He responds here.


Summary of his main points:

  • There is currently no scientific debate about the safety of chemicals used in cosmetics and in the home, in the amounts in which they are used. All of these ingredients have been tested and are regulated
  • The “beauty-obsessed sisters” who were used as case-studies are hardly typical subjects—they are an extreme case when considering the common use of cosmetic products and are not representative of most people
  • The claim that women absorb 5lb of chemicals from cosmetics every year is flawed. In general external chemicals cannot freely pass across the skin because the stratum corneum (the thin, outermost layer of the skin) has evolved to provide protection from chemicals that people are routinely exposed to
  • “Skin irritant” is used in an utterly non-scientific, emotive and inappropriate context. Remember, water can be classified as a skin irritant under appropriate circumstances
  • Domestic cleaning products contain surfactants (similar to soap), and may cause damage to the stratum corneum barrier of the skin. However, because your skin replaces itself very quickly, eight days without exposure to these chemicals is unlikely to make any difference


Full comments from Dr Gary Moss:


There is currently no scientific debate or controversy about the safety of chemicals used in cosmetics and in the home, in the amounts in which they are used. All of these ingredients have been tested and are regulated.

How Toxic Are You?” and its “findings” are a misrepresentation of what is known about how chemicals interact with the body and is not scientific. Scientific studies need to be robust, and whilst the case studies in this documentary may serve to instill baseless fear, it has added nothing scientifically worthwhile for its viewers. It do not appear to use appropriate controls, and inappropriately use terminologies associated with chemical classifications. The language is emotive and inappropriate (e.g. to paraphrase: filling one’s lungs with plastic from hairsprays: this assumes that the aerosol produced by the spray has the correct physical properties to even get into the lung, a process which has been the subject of much research in, for example, asthma product development for years) and shows a fundamental lack of understanding of the processes associated with the absorption of chemicals by the human body. It is also interesting that the solutions seem to be found among the “organic” or “alternative” cosmetic ranges. Have similar tests been conducted on such products to ensure their long-term safety? In addition, the “beauty-obsessed sisters” who were used as case-studies are hardly typical subjects—they are an extreme case when considering the common use of cosmetic products.
As a scientist with experience of how drugs and other chemicals penetrate the skin barrier (percutaneous absorption), the claim that women absorb 5lb of chemicals from cosmetics every year is flawed and cannot be calculated by an extrapolation of the blood and urine analyses. It is commonly perceived that drugs can freely pass across the skin. This is a mistake that is commonly repeated but is seldom the case, because the stratum corneum, the thin, outermost layer of the skin, has evolved to provide protection from external chemicals that people are routinely exposed to. The transdermal route promises much but, in pharmaceutical terms, has actually delivered relatively little. Creams, ointments, and so on are often applied not to healthy skin but to sites where the skin has been damaged. In this case, there may be a greater issue of exposure to the chemicals in the product, in the sense that they have a better chance of passing into the tissues and bloodstream than if these products were applied to intact skin.
But in the case of cosmetics, which are normally supposedly applied to intact, healthy skin, it is unlikely that the components will penetrate it. (This is mainly, but not exclusively, due to three things; their physicochemical properties, how long the skin is exposed to them, and the nature of the formulation). These products are usually washed off in the morning and then replaced. Simply put, these molecules do not cross the skin barrier in significant amounts. Very few chemicals actually do—one of the reasons for the lack of success of transdermal drug delivery. Regular removal by the body keeps these levels well below toxic thresholds. The programme makers should be aware of the ADME process—absorption, distribution, metabolism and excretion, and look at this issue holistically.
The subject of hormone disruption is also an extremely emotive one. While the makers of this programme can clearly differentiate between leave-on and rinse-off products, once again, they seem unaware of the fundamentals of absorption through the skin. While some chemicals may pass across the skin, the rate at which this happens, the physicochemical nature of the substances applied to the skin and the rate of clearance—both from the site where it is applied and from the blood—all combine to make this a very complicated model. Unfortunately, this grey area—not being able to answer “yes” or “no” to a question such as “do chemical penetrate the skin” is something which is not well expressed in the media. Do chemicals penetrate the skin? If they do, is the amount and rate of penetration, as well as the location, likely to provide a toxic level of the chemical in the body? How does the body respond to the presence of the chemical? How does the body get rid of it? How much will be absorbed and retained by the body? What happens when this happens? All these questions—considered together—will give a true indication, in a properly representative clinical study relative to a suitable control study, of the toxicological profile.
The lack of understanding shown of product classifications is also worrying. Do the programme makers understand why something might be classified as an irritant? Are they aware of the conditions under which such an assessment is made? Remember, water can be classified as a skin irritant under appropriate circumstances. Therefore, the uneducated bandying-around of the term “skin irritant” is utterly non-scientific and used in an emotive and inappropriate context. Further, the often repeated scare story—the association of parabens with breast cancer is emotive and pointless—other than to get “cosmetics” and “breast cancer” in the same programme. This is highly irresponsible.
“How Toxic Are You?” also discusses domestic cleaning products. These contain surfactants (similar to soap, for example), and may cause damage to the stratum corneum barrier of the skin. However, because your skin replaces itself very quickly, eight days without exposure to these chemicals is unlikely to make any difference.
 
Overall, the results in this documentary are based on an extreme case, do not appear to have suitable controls and do not appear to understand the holistic nature of the absorption, distribution, metabolism, and excretion (ADME) process. Therefore the way in which the programme-makers have presented them to other, more typical consumers of these products might not be comparable or fair. In short, I would have no confidence that their results, and subsequent claims, have any proper scientific validity—the programme consists of bad science and pointless scaremongering.

Author: Sense About Science

Document type: For The Record

Published: 16 October 2007


Back · New resources search