The complete guide to synthetic preservatives present in liquid bottled products

When it comes to synthetic preservatives, it's no secret that many personal and cleaning liquid products are home to a range of questionable chemicals. Liquid bottled products such as shampoo are usually 80% or more water. This creates the need for a preservative system to stop the growth of mould and bacteria.

Here are some common synthetic preservatives and their potential side effects:


The synthetic preservative with a bad reputation. This is due to a study that found concentrations of methylparaben in breast tumours. While this research didn't definitively prove that parabens can cause cancer, it did lead to many buyers looking for products without paraben preservatives. The U.N. Environment Programme has also identified parabens as endocrine-disrupting chemicals. 

Other names:

  • Germaben II
  • Methylparaben
  • Propylparaben
  • Butylparaben


This stuff isn't just used to embalm dead bodies, formaldehyde is used as a preservative in some liquid personal care products too. It's officially listed as a carcinogen which means it's known to cause cancer.

Other names:

  • Methanal
  • Germall Plus
  • DMDM Hydantoin
  • Imadozolidinyl Urea
  • Diazolidinyl Urea


This preservative was named the 2013 Allergen of the Year. Methylisothiazolinone is widely used as a preservative in personal care products and has been credited with causing an epidemic of allergic contact dermatitis.

Other names:

  • Kathon
  • Methylisothiazolinone
  • Methylchlorisothiazolinone
  • Benzisothiazolinone
  • Chloromethylisothiazolinone
  • Octylisothiazolinone
  • Fragrance
  • Parfum


Phthalates are a known carcinogen and endocrine disruptor. They're used to soften and increase the flexibility of plastic and vinyl. Phthalates also appear in many personal care products, often disguised under the general term "fragrance" or "parfum."  

Other names:

  • Diethyl phthalate
  • Butyl benzyl phthalate
  • Di-(2-ethylhexyl) phthalate
  • Di-n-butyl phthalate
  • Di-isononyl phthalate
  • Parfum
  • Fragrance
  • Soft plastic e.g. shampoo bottles can leach phthalates into liquid products. 


This preservative has taken the place of parabens after they became an unpopular additive. Phenoxyethanol may cause central nervous system damage in infants so it's best to avoid it if you're pregnant, breastfeeding or using it on babies and toddlers. 

Other names:

  • 2-Phenoxyethanol
  • Euxyl K® 400 
  • PhE
  • Optiphen
  • Optiphen Plus

Often combined with the following ingredients as Phenoxyethanol isn't broadly effective on its own:

  • Caprylyl glycol
  • Sorbic acid/potassium sorbate
  • EDTA

BHA (butylated hydroxyanisole)

This synthetic antioxidant is used as a preservative in lipsticks and moisturisers. BHA is listed as a possible human carcinogen and endocrine disruptor. BHA may be bad for the environment because of its toxicity to aquatic organisms and potential to bioaccumulate.

BHT (butylated hydroxytoluene)

Similar to BHA, BHT is also a cosmetic synthetic preservative. Long-term exposure to high doses of BHT is toxic in mice and rats causing liver, lung, thyroid and kidney problems. BHT can also act as a tumour promoter in certain situations.

Organic acids

As consumers begin looking for products without synthetic preservatives, many brands have begun using "natural" organic acids. Consumers consider these to be “natural alternatives,” but they are often made synthetically.

Other names:

  • Benzoic Acid/Sodium Benzoate
  • Sorbic Acid/Potassium sorbate
  • Levulinic Acid
  • Anisic Acid
CONCENTR8ED eco bars plastic-free, palm oil-free, toxic chemical-free, low tox living, natural beauty, natural cleaning


Synthetic preservatives are needed in products because of their high water content. The easiest way to ditch these synthetic preservatives is to choose products with little to no water. Our entire eco bar range is synthetic preservative-free with little to no water. Try eco bars today and stop paying for water.