Surfactants Are Everywhere, aka Stop Being Terrified of Chemicals

28 May 201826 May 2018

This post was originally published on the now sadly defunct awesome website The Toast in 2014. A reader suggested that I repost it on Lab Muffin… which I thought I did, but apparently that was all a fever dream. Here it is!

There’s soap in your mayonnaise!

As a scientist with a degree in chemistry, the surge in chemophobia over the last five years has been both baffling and frustrating.

While there are plenty of toxic substances that we should be well frightened of, there are also many safeguards against their use – by and large, the chemicals you encounter in your day-to-day life are benign, even the ones with the scary unpronounceable names and the ones made from substances that can literally chew your face off (sodium chloride, I’m looking at you). But it’s incredibly easy to fall into the trap of common-sense-based marketing. Scientific literature is not exactly reader-friendly, and scientists have a long history of alienating themselves from Normal People.

There’s one particularly painful tactic which anti-chemical lobbyists love to use, and that is the faulty generalization. You’ve no doubt seen it enough times already…

“I had the flu vaccine and still got the flu, therefore vaccines don’t work.”
“This chemical gave rats cancer in a study, we need to take it out of our shampoo/food/clothing!” (Despite the fact that the rats used in these sorts of studies are specifically bred to grow tumors like they’re going out of style, and to receive the amount the rats did, you’d have to mainline a swimming pool’s worth of shampoo/food/clothing every week.)
“Mineral oil comes from crude oil, therefore you’re rubbing petrol on your face! Use our natural, organic face cream instead, because you know exactly what’s in it.” (Which is ironic, since natural products are notoriously variable in composition.)
“It contains chemicals! Chemicals are bad.” (Except for the million or so chemicals that you unwittingly use every day to stay alive, like oxygen and water and neurotransmitters, one of which is pretty much MSG dissolved in water.)

To demonstrate how easy it is to make these grand leaps from benign facts to chemophobic, scaremongering argumentum ad Natural News, let me introduce you to my lovely assistant, surfactants, one of my favourite categories of chemicals (yes, chemists all have their favourite chemicals, it’s a disease.)

Chemicals can be roughly divided into two broad categories. On one side are the hydrophiles, which dissolve readily in water, and are highly charged, which lets them interact favourably with other highly charged things – common examples are water, salt, and ethanol (drinking alcohol.) On the other side there are lipophiles, which are oily, and tend to be weakly charged or neutral. The two don’t interact favourably enough to hang out together in a happy stable mix, and despite any amount of violent shaking, they invariably separate and go to their respective sides.

Video: Why pH matters for AHAs and acids in skincare

18 November 202118 April 2017

I’ve been a little frustrated with what scientific concepts I can get through in words and crudely drawn illustrations on this here blog. When I teach at my day job, I do a lot of hand-waving, emphatic underlining, symbolic gesturing and smashing together of whiteboard markers, and not having the ability to show movement sometimes feels a bit like I …

Should You Be Avoiding Parabens? The Science

12 February 20239 February 2017

Much like “organic” and “all-natural”, “paraben-free” is one of those phrases you’ll see displayed prominently on increasing numbers of skincare and beauty products. What are parabens, what health effects do they have, and should you be avoiding them? Here’s the science behind the marketing.

(I’ve written a much simpler rundown of parabens here, if you want a quicker overview.)

What are parabens?

Parabens are a family of preservatives commonly used to control the growth of microbes in cosmetics, toiletries, food and pharmaceuticals. They are esters of para-hydroxybenzoic acid, a naturally occurring chemical found in many fruits and plants. Their chemical structures and actions are very similar, with the “R” group changing as shown below.

The most commonly used parabens are methylparaben, ethylparaben, propylparaben and butylparaben, although many others (isopropyl-, isobutyl-, pentyl-, phenyl-, benzyl-) have been used in products as well. Different parabens work best under different conditions and act against different microbes, so you’ll often see them used in combination to enhance the preservative effect.

Parabens were developed in the 1920s and these days, they’re the most widely used preservatives in cosmetics, appearing in over 85% of products. Parabens are popular for good reason: they’re inexpensive, effective in very small amounts, work well in most products, and act against a wide range of nasty microbes. They have a very long record (almost 100 years) of safe use. The only reliably linked harmful health effect is allergy, which occurs in a tiny fraction of people, and it’s often only a problem on broken skin.

Why do parabens have a bad reputation?

Despite all these advantages, parabens have become well known as a “nasty” in the last 10 years. This came about when a few studies appeared which led people to question whether parabens were really as safe as they seemed:

Skincare Products I Hate and Do Not Recommend

23 January 2017

I’ve done a lot of posts on skincare products I love… now, for something a bit different, here are some that I really hate and would only recommend to people I don’t like. So if I ever recommend these to you… it’s not me, it’s you. I just don’t see our relationship working out.

Coffee Scrubs

Coffee scrubs are made from coffee grounds, which is literally the stuff you chuck into the bin after making coffee. Now I’m sure there’s a little bit of work involved in making sure it doesn’t mould away in the packet, but essentially you’re buying rubbish at $30 for a small bag.

How can they charge this much, you ask? Well, it’s because they usually claim to get rid of cellulite. This is a bald-faced lie, because apart from the fact that you can’t actually get rid of cellulite, one application of the amount of caffeine required to make cellulite look a little better equates to 2.1 kg of coffee grounds, left on your skin for hours. Any improvement you get is probably mostly a combination of massage, exfoliation and placebo, which really shouldn’t cost that much.

Coffee scrubs are also messy as hell – unlike sugar and salt scrubs, they don’t dissolve in water so gritty black specks will lurk in unexpected places forever. I’m still finding bits of coffee grounds under my soap despite rinsing my entire shower down with vinegar the one time I tried one.

I suppose there’s nothing really harmful about coffee scrubs, really. What pisses me off is mostly just the SHEER AUDACITY of charging so much for a product that’s worse than salt mixed with a bit of oil (about $1.10 a kg, if you shell out for the nice oil). It’s more expensive than a whole bunch of other great exfoliants, and it’s basically bagged up garbage. I wish I’d thought of it.

What you should use instead: Salt + oil, or a leave-on anti-cellulite caffeine cream.

Apricot Scrubs with Shell Bits

First off, physical exfoliation is not the devil. It’s a great thing to use in conjunction with chemical exfoliants. But apricot scrubs containing ground walnut shell… that’s a different matter entirely.

As far as I can tell with my trusty literature review tools, there isn’t any evidence that they cause microtears which harbour bacteria (and I have no idea how that rumour started, but if you know anything about it I’d love to hear from you!), and there are many beneficial products and procedures with harder particles (hello microdermabrasion). But maybe half of the “skincare-naive” people who ask me about their skin problems have this on their bathroom shelf, and they use way too much pressure when scrubbing, and do it way too often (for some reason people feel the need to use it once a day). This sort of treatment usually starts by giving you a nice glow, but it’s unsustainable and quickly leads to sensitive, dehydrated, compromised skin that feels rough and is prone to breakouts. Of course, the obvious thing to do is to use more of the product to get that nice glow back, but it’s a downward spiral from there.

I don’t think St Ives deserves to be sued, but I also wouldn’t lose any sleep if apricot scrubs disappeared. (Also, why are they all called apricot scrubs instead of walnut scrubs?)

What to use instead: Any gentler physical exfoliant: konjac sponges, sugar scrubs, cleansing brushes. If you don’t already have an exfoliation routine in place, I’d recommend setting one up.

Soaps for the Face

True or “natural” soaps that is, made from lye or caustic potash and fats or oils. This includes products like African black soap and Castille soap. Soap is bad news for your face for a couple of reasons:

It’s impossible for soap to work at a pH lower than around 9.5, which is unfortunate because your face has a pH of 4-6, and high pH will disrupt your skin’s ability to stay intact
Soap’s structure (straight tail, small head group) makes it awesome at messing up the proteins in your skin

Some people with tolerant skin will be able to handle soap on their face, and most people can use it on tougher body skin with no big dramas, but a lot of companies that sell soap as facewash go for the “gentle, great for sensitive skin, BECAUSE IT’S NATURAL” angle.

NO.

If your skin is sensitive, soap is not great for it (dehydration, breakouts and roughness galore), and soap isn’t much more natural than gentler cleansing ingredients anyway. Soap is fats and oils which have been reacted to turn it into something else entirely, much like how plastic is made by reacting dead dinosaurs.

What you should use instead: A gentle face cleanser that’s formulated with surfactants made for mildness. Check out this gentle cleansing guide for tips on how to pick a good product and some suggestions.

Hypoallergenic Natural Products Loaded with Essential Oils

On a similar note, the “gentle, great for sensitive skin, BECAUSE IT’S NATURAL” brigade are also really fond of jamming essential oils into products to somehow make them less reactive. Which is entirely the wrong direction to go, because fragrance is one of the things that people with sensitive skin are frequently sensitive to, and guess what – essential oils are fragrant (and plant extracts usually are too). In fact, many synthetic fragrances are just essential oils with some chemicals taken out. That’s why a whole bunch of “natural” skincare products have a list of chemicals at the end of their ingredients, like linalool, benzyl alcohol, geraniol and coumarin – these ingredients known to cause allergies in susceptible people are usually hidden in essential oils and plant extracts, but EU regulations require that they be listed.

What is hyaluronic acid and how does it work in skincare and makeup?

30 December 201627 December 2016

What Is Hyaluronic Acid?

Hyaluronic acid (HA), along with its cousin sodium hyaluronate, is an immensely popular ingredient in skincare and makeup. It’s also naturally found in the body. Most of it dwells in the extracellular matrix, the scaffold which holds up the cells of your skin. Hyaluronic acid is found in both the epidermis and the deeper dermis, where it’s important in hydration, metabolic processes, skin repair, and protection against free radical and UV damage.

Hyaluronic acid is a glycosaminoglycan, a class of chemicals that can hold onto water very efficiently, due to its very polar nature. 1 gram of hyaluronic acid can hold onto 6 litres of water – that’s 6000%! Hyaluronic acid keeps skin firm and plump this way. It’s been thought that decreased hyaluronic acid levels led to the thinner and drier look of aged skin. However, the research currently suggests that the amount of hyaluronic acid in the skin doesn’t actually decrease with age, but it does redistribute with both natural and environmentally-induced skin aging.

What Does Hyaluronic Acid Do in Skincare?

In skincare, hyaluronic acid is mostly used for its incredible ability to hold onto moisture: it’s included in moisturisers and serums as a humectant ingredient. Humectants hydrate the skin, and since one of the effects of dehydrated skin is fine lines and wrinkles, this can make your skin look dramatically younger and less tired. Another popular and cheaper humectant moisturiser is glycerin, but glycerin can feel sticky and heavy. Hyaluronic acid is frequently combined with glycerin to make it feel lighter on the skin.

The hyaluronic acid used in skincare isn’t all the same. It’s usually divided into different sizes: there’s high molecular weight hyaluronic acid, which has a larger molecular size, and low molecular weight hyaluronic acid, which is formed by chopping it into smaller fragments. “Sodium hyaluronate” usually indicates smaller fragments than “hyaluronic acid”, but even within those names there are a range of molecular sizes. The main significance of the different sizes is that smaller molecules are able to penetrate the skin better than larger molecules, which means that low molecular weight hyaluronic acid can hydrate deeper than high molecular weight hyaluronic acid, which holds onto water at the surface of the skin.

All About Bee Venom and Honey in Skincare

21 October 2016

Honey and bee venom have been used in folk medicine for thousands of years, but they’ve made a recent resurgence in skincare. Here’s the science behind these ingredients. Honey in Skincare Honey is formed from nectar and pollen by bees through a process of partial digestion (don’t think too hard about it if you want to enjoy honey ever again). …

Free Acid Calculator for Exfoliants at Specific pH Levels

14 August 20182 June 2016

Free Acid Calculator for pH and Exfoliants

Since writing this post on the influence of pH on exfoliating acid skincare ingredients, I’ve had a lot of questions on how much active free acid there is in specific formulations. The calculation is a bit fiddly to do every time, so I’ve developed an easy spreadsheet to help you predict the free acid content for a product, if you know the amount of the acid ingredient in it, and its pH. This might also be useful if you’re into making your own acid products, or messing around with the strengths of pre-made products.

Refresher on Acids and pH

pH is a measure of how acidic or basic something is – a lower pH is more acidic, which means there’s a higher concentration of H⁺ ions.

AHAs and BHAs (alpha and beta hydroxy acids) are common exfoliating ingredients. They’re acids, which means they can exist in two forms:

as the free acid, which means it has no charge
as the ionised or dissociated form, which means it’s lost a H⁺ and it has a negative charge (this is also called its conjugate base)

The two forms can interconvert. Here’s what they look like for glycolic acid:

The ionised form has a difficult time getting through skin’s oily lipid layer and into the skin where it can act. The free acid form is a lot more oil-soluble, so it penetrates a lot more easily. (In some circumstances, if the ionised acid is non-polar enough, it can still penetrate through skin.)

Do Coffee Scrubs Work Against Cellulite?

15 October 201926 March 2016

Coffee scrubs are making a big comeback. With brands like Frank claiming that the caffeine in coffee scrubs can reduce cellulite, it sounds too good to be true. So are messy coffee scrubs worth it? What is Cellulite? Cellulite, also called lipodystrophy, is a change in how the fat under your skin is shaped, making it look lumpy or dimply …