Few things are ever black or white, and the science can always be questioned, as it should be. People have expressed concern about sulphates in hair care products. Now I'm not a scientist, but I can read what the science says. Based on what I've read, there is nothing to suggest you need to throw out your hair shampoo due to cancer risks. This is backed up by the American Cancer Council. There might be some other concerns you should consider, but it doesn't look like cancer is one of them. However let me go into this a little deeper, don't just take my opinion on face value. Please research the topic for yourself also. If you find something contradictory, let me know. I don't want to spread wrong information, as there are enough people doing that already. Please understand this is a complicated topic, and the rabbit hole goes deep. There might not be any cancer evidence, but are there grounds to avoid sulphates in your hair shampoo? Hopefully you'll understand more at the end of this.
You can find sulphates in many products ( even toothpaste ), as there is at least a 100 different types. Sulphate is a man-made chemical. It's the compound they use in shampoo to get the oil off your hair and skin. It's an emulsifier so it combines water and oil, and cleans all the film from your hair and scalp. It's this ingredient that gives you the foaming action, and it's also found in cleaning products. Sodium Lauryl Sulfate (SLS), Sodium Laureth Sulfate (SLES) appears to be the main versions used in hair shampoo.
Sulphate is partly made up of Sulphur, which comes from petrolatum. Sulphur also occurs naturally, and is the 3rd most abundant mineral in your body according to Dr Mercola. Petrolatum is also known as petroleum jelly. Now petrolatum or petroleum jelly has been "linked" to breast cancer. Columbia University found breast tissue in ladies with breast cancer was 2.6 times more likely to contain PAH's or polycyclic aromatic hydrocarbons. These are common contaminants in Petrolatum. According to science, correlation does not mean causation. We must be careful not to jump to conclusions. There are many questions that need to be answered about that study and results before we draw our final conclusion. I talk to a lot of ladies and many want to avoid "man-made chemicals", especially sulphates as there has been much hype about it. There is an assumption that all things man-made are bad, and that's not always true. Broccoli is often described as a "super food" yet it doesn't grow in nature. In fact it's made man from a plant called Brassica Oleracea. Many of the healthy greens you eat have been modified from this plant. So humans are capable of making something good from time to time.
Ok back to sulphates, which are not the same as sulphites. Sulphites can be found in wine. Why do people think sulfates cause cancer? Maybe because sulphates are derived from petrolatum which has been somehow linked to cancer? From what I've read there was only one study found by the National Industrial Chemicals Notifications and Assessment Scheme, to have been done on the topic. It found sodium lauryl sulphate (SLS) was not carcinogenic in dogs. There have been other studies that say there MAY be a connection but they were using SLS levels that far exceeded normal human use.
Let's also remember that sulphates were introduced into shampoo in the early 1930's. It's safe to say most people have been washing their hair with shampoo that contains the compound. Actually if we want to be honest about it, you've been bathing in sulphates all your life via many products. Soap and toothpaste are examples. Sulphate free shampoo has only gained in popularity in the past decade or so. That gives us 80 years of human "experimentation". If sulphates in hair shampoo were carcinogenic we should see a big jump in cancer rates right? This is a graph of cancer rates for ladies since the 1930's.
I don't see anything concerning. Lung cancer is likely because of smoking, and I doubt the small increase in ovary or pancreas cancer is caused by washing your hair. Breast cancer rates are actually going down so any possible loose link doesn't seem to hold water.
Sulphates irritate the skin
This is true. It can also damage the eyes in very young children. Sulphuric acid is used to create sulphates. So it can be nasty in high or prolonged exposure. Having said that, should we run for the hills and throw out all products that contain sulphates? If you think yes, then consider the following. My partner added cinnamon to the oats we fed a baby girl. Naturally she got some on her face, and afterwards developed a rash. Turns out cinnamon is also a skin irritant. Oregano oil is used to "burn" moles off the skin. It's also a skin irritant, to put it mildly. These are natural, edible products but will also cause skin or eye damage, so are they evil? They are useful if used responsibly. We know sulphates have a nasty side to them, but if used responsibly they can be helpful.
Do sulphates dry out hair?
As we've already learned, sulphate acts as an emulsifier, which strips your hair of oil. Does this dry your hair out? Well I guess that depends on the state of your hair. Damaged hair, and hair with too much static build up will be more susceptible to drying out. This is because the hair cuticle opens up and exposes the insides of the hair strand.
If you strip your hair of oil and then use a normal hair dryer, there is a chance you are going to turn your hair into spinifex. We need to wash our hair and remove oil because all the dust and pollution gets trapped in this film. Sulphate free shampoo also removes oil, but some say not as well. So why bother with it? Natural hair shampoo does the same thing as normal shampoo, just not as well and you usually pay more for it. We have no evidence to suggest that sulphates cause cancer, so there are few reasons to use sulphate free shampoo. I understand that people want to use more "natural" or "organic" products. We get all the of LA BIOSTHETIQUE natural range, which is a lovely product.
You could argue that by definition crude oil, the stuff petrol comes, is also organic and natural. Crude oil comes from small animals and plants that died and fell to the sea floor. These were then covered by mud and over many years crude oil is formed. ( That's the short version ) Sometimes it's good to put things into perspective because humans have a tendency to get carried away.
Sadly our options are limited at this point, because water doesn't clean oily hair. Oily hair looks and feels horrible in a short period of time. My advice is to ensure your hair isn't left too dry after using a shampoo. You can easily fix that with a good moisturising conditioner or oil treatment. It's important to do that as this will prevent your hair from getting a static charge. Hair without a static charge seals and doesn't get dried out from shampoo or blow drying. It will also keep your hair colour looking vibrant for longer.
There is more information on hair static and what to do about it on the styling appliances page. So should you avoid sulphates in shampoo? It's up to you, but I don't see any reason to worry about it too much. If you are going to ban sulphates then there are lots of products you will need to reconsider. No point just avoiding the shampoo. Of course things might change in the future if the facts change and new discoveries are made. There are also no observable signs that sulphates are an issue either. There are plenty things that you're exposed to on a daily basis, that are likely to be of greater concern.