Parabens are used as preservatives in personal care products to stop bacteria growing. Parabens are xenoestrogens, they have a chemical structure similar to estrogen, which means they mimic the effects of estrogen in the body, interfering with the body's natural hormone production. Any substance that interferes with the body's endocrine system in this way is called an endocrine disruptor.

Parabens are absorbed through the skin and build up in the body. Parabens have been found in breast tissue, and are linked to hastening the growth of breast cancers.

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Parabens, if mixed with some ethanolamine compounds can cause a process called nitrosation, in which nitrosamines are formed. Nitrosamines are formed when nitrates react with a secondary or tertiary amine. Most nitrosamines are reasonably anticipated to be human carcinogens (Source: US Department of Health and Services National Toxicology Program (NTP)).

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What to look for on the label:

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• benzylparaben

• butylparaben

• propylparaben

• methylparaben

• ethylparaben

• isobutylparaben

• Isopropyl paraben

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No safe level of exposure could be identified for Butylparaben and as such it was recently placed on the European Chemicals Agency Candidate List.

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Click here for further reading on EDCs

​Ethanolamine compounds are comprised of alcohols and amino acids, and are used in personal care products as emulsifying agents, fragrances and pH adjusters.

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Ethanolamines, if mixed with parabens are of greater concern due to likelihood of nitrosation. Exposure to nitrosamines can lead to cancer.

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What to look for on the label:

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• MEA monoethanolamine (MEA)

• DEA diethanolamine (DEA)

• TEA triethanolamine (TEA)

• TEA-lauroyl, acetamide MEA

• Lactamide MEA

• Cocamide DEA

• Cocamine MEA

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DEA has been associated with hormone disruption, cancer, liver tumors, accumulation in the liver and kidney causing organ toxicity. DEA and Cocamide DEA are reasonably expected to be mutagenic substances.

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Inhalation of MEA is toxic, and produces athsma like symptoms. As such MEA and Cocamide MEA should not be used as an ingredient in cosmetic products in which N-nitroso compounds are formed or in formulations that will be aerosolised.​

Phthalates are endocrine-disrupting chemicals that alter the functioning of the endocrine system, causing hormonal imbalances, reproductive issues, and cancers. Particularly harmful to pregnant and breastfeeding women due to developmental and reproductive toxicity. 

The National Toxicology Program (NTP) reports that diethylhexyl phthalate (DEHP) is reasonably anticipated to be a human carcinogen.

What to look for on the label:

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• Phthalate,

• Diethyl Phthalate (DEP)

• Dibutyl phthalate (DBP)

• Diethylhexyl Phthalate (DEHP)

• Di-(2-ethylhexyl) phthalate (DEHP)

• Di isononyl  phthalate (DINP)

• Di-isodecyl phthalate (DIDP)

• Benzyl butyl phthalate (BBP)

• Fragrance (with the exception of fragrance that is derived from essential oils).

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A recent Harvard study shined a light on the insidious effect of Phthalates on women of childbearing age: After controlling for other known risk factors, including phthalate exposure during pregnancy, scientists found that high levels of exposure to two (particular) phthalates tested was associated with a 50 percent to 70 percent increased relative risk of preterm birth. i.e. Exposure to phthalates even before conception, can cause preterm birth.

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Click here for further reading on EDCs.

The list of potential effects on humans is long for SLS: skin and eye irritation, dry skin, eczema, mouth ulcers, liver and gastrointestinal toxicity to name some.

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Note SLS is different to Sodium Laureth Sulfate, which is an ethoxylated chemical, refer to Ethoxylated chemicals below.

Penetration enhancer that disrupts the surface of skin cells so that other chemicals can get in more easily. If on the label with ingredients such as ethoxylated chemicals can be particularly dangerous.

Ethoxylation is the process of reacting ethylene oxide with other substances. This process can create residual amounts of harmful chemicals that may remain in the product and cause the consumer to be exposed.  The harmful chemicals that can remain in the product subsequent to the ethoxylation process are: small amounts of 1,4-dioxane, and residual ethylene oxide. Both are known carcinogens. If these were not removed from the product before it is offered for sale, these harmful substances would remain in the product when used by the consumer and could potentially cause cancer after prolonged use.

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What to look for on the label:

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• Ethylene glycol

• Ethylene Oxide

• PEG (polyethylene glycol)

• PPG (polypropylene glycol)

• PEG laurate

• PEG-60 almond glycerides

• Sodium laureth sulphate

• Ceteth-5 steareth-21

• Ceteareth-20

• PEG-20 stearate

• Oleth-10 phosphate

• Octoxynol-9

• Polysorbate

• PEG-8 stearate

• Glycereth-26

• PEG-40

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Phenoxyethanol

A popular preservative widely used in personal care products, particularly since the fall from grace of parabens, Phenoxyethanol is deemed safe only up to a maximum concentration of 1% (for adults, 0.4% for children). Adverse systemic effects have been observed in toxicological studies on animals when levels of exposure was higher than 1%, including DNA mutations. Overexposure is thought to depress the nervous system. Repeated long term exposure is linked to organ failure.

Carcinogenic

See Exothylated chemicals (above)

Aminomethyl Propanol and Aminomethyl Propanediol are substituted aliphatic alcohols used as PH adjusters in personal care products.

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What to look for on the label:

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• Aminomethyl propanol

• Aminomethyl propanediol

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Although these ingredients are primary amines that are not substrates for N-nitrosation, they may contain secondary amines as impurities in finished products that may undergo N-nitrosation. These ingredients should not be included in cosmetic formulations containing N-nitrosating agents.

Source: International Journal of Toxicology

Sodium Lauroyl Isethionate is created by combining fatty acids with isethionic acid. Isethionic acid is created by combining sodium bisulfite and ethylene oxide. i.e. Isethionic acid is an exothylated chemical. Traces of ethylene oxide and1,4-dioxane, both carcinogenic, can remain in the product after exothylation.

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Sodiuum Lauroyl sarcosinate or SLSA, is a penetration enhancer. Can be dangerous depending on use, if mixed with other chemicals, increasing their absorption into the body. SLSA also has contamination potential, may contain nitrosamines. Most nitrosamines are reasonably expected to be carcinogenic.

Cocamidopropyl betaine is a commonly used surfectant, used in many products to make lather. It is a synthetic fatty acid that is derived from coconuts, making it particularly popular in products that are marketed as natural. However, it is known to be a skin and eye irritant. Classified as unsafe in products left on skin and not washed off.

Triclosan is commonly used in toothpastes and soaps, and is an endocrine disrupting bioaccumulative irritant, that is restricted in cosmetics in Canada and Japan.

High doses have been shown to cause a decrease in the level of thyroid hormones, affecting thyroid hormone-associated gene expression. Triclosan has also been shown to disrupt postembryonic development.

Sources: EWG Skin Deep

US Food and Drug Association

A widely used ingredient particularly in sunscreens, as well as other personal care products, Oxybenzone is an ultraviolet light absorber and filter. This ingredient is also a penetration enhancer that helps other ingredients penetrate the skin more readily. Watch for other nasty ingredients as well if you see Oxybenzone on the label, as you will be more prone to absorbing more of other nasties when Oxybenzone is present.

Oxybenzone is also suspected to be an endocrine disruptor.

Isothiazolinones are preservatives used in personal care products to limit bacterial growth. Toxic when inhaled, ingested or applied to skin, Isothiazolinones can emit formaldehyde (a carcinogen) at low temperatures. They are thought to be toxic to the nervous system, and are a common cause of contact allergic skin reactions.

A mixture of chloromethylisothiazolinone and methylisothiazolinone was found to cause inhalational injury to airways of children. This mixture has also been linked to pulmonary toxicity in rats. Source: US Library of Medicine, National Institute of Health.

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"Allergy to methylisothiazolinone is extremely common. The European Scientific Committee on Consumer Safety reviewed the literature and in July 2015 banned the use of MI in Europe in all-new leave-on products and lowered the concentration for rinse-off products; the concentration is now so low that it no longer functions as a preservative, and probably will not be used" Source: DermNet NZ

Note, methylisothiazolinone is sometimes erroneously called methylisothiazoline

Halogenated solvents are solvents which contain a halogen such as chlorine, bromine or iodine.

What to look for on the label:

• Dichloromethane, or Methylene Chloride

• Trichloroethylene

• Perchloroethylene

Builds up in fat tissue and cannot be metabolised

Fragrance is one of the most common causes of allergic skin rashes and reactions and can also trigger headaches and athsma.

Labels will often list "Fragrance" or "Parfum" which can mean any of various chemicals. According to the International Fragrance Association (IFRA) who published a list of chemicals its members use to make consumer products, there are over 3100 ingredients used under the name 'fragrance'.

Carcinogen and allergen, toxic if swallowed, is toxic in contact with skin, causes severe skin burns and eye damage, is toxic if inhaled, may cause cancer, is suspected of causing genetic defects and may cause an allergic skin reaction Source: EU candidate list.

Preservative

There is strong evidence BHA is an endocrine disruptor as reported by the European Commission on Endocrine Disruption.

Aluminium Chloride is used as an active ingredient in anti-perspirant deodorants. Not enough research has been done to conclusively prove the danger to human health that is associated with the use of aluminium chloride. It is linked to an increased risk of breast cancer, and also has been linked to Alzheimer's disease after high concentrations of this substance were found in the brains of Alzheimer's patients. It is best avoided, and assumed to be unsafe until proven otherwise.

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Mineral salts of ammonium alum or potassium alum are contained in crystal deodorants. Whilst these are marketed as a more natural alternative, Ammonium Alum is classified as expected to be toxic or harmful, and suspected to be an environmental toxin and be persistent or bioaccumulative by the Environment Canada Domestic Substance List

Limited or incomplete evidence of cancer. Data gaps prevent classification as a carcinogen, as reported by the World Health Organisation International Agency for Research on Cancer IARC.

May be a teratogen in high doses. Known to cause birth defects in high doses in studies on mice.

Subject of much controversy due to likely ability to penetrate very deeply into the body and potentially cause health issues. Further studies are required to understand the safety and health risks associated with the use of nanomaterials in skincare.

Not to be confused with Polyethylene Glycol (PEG), refer to ethoxylated chemicals above.

Propylene Glycol is a penetration enhancer, may cause excess absorption of undesirable chemicals if mixed. Can cause serious health conditions, including liver and heart damage and damage to the central nervous system if a sufficient amount is absorbed by the body. Found to provoke allergic reactions in patients with eczema and other skin allergies.