Babassuamidopropalkonium chloride Derived from Babassu oil, this is a ‘quaternary ammonium’ (see Quaternary ammonium compounds under ‘Q’ here), which works well to fight frizz and static in hair products.

Babassuamidopropyltrimonium methosulfate Synthesised from the fatty acids in Babassu oil; See Quaternary ammonium compounds under ‘Q’ here.

Barium sulfate Also known as ‘Blanc fixe’ or listed as CI 77120 and a salt of barium, which is an earth metal, used generally as a white colouring. Many members of the Barium family are skin irritants, and cause rashes; this ingredient is not an approved colourant for use in the USA.

Behenyl alcohol – also known as Docosanol, a mixture of fatty alcohols derived from Behenic acid, which is a minor component of vegetable oils and animal fats. It’s often used to stabilise products or make them more opaque.

Behenamidopropyltrimonium methosulfate A synthetic emulsifying wax, generally used in hair products.

Behentrimonium chloride A synthetic preservative. See also Quaternary ammonium compounds under ‘Q’ here.

Behentrimonium methosulfate Used in hair conditioners and relaxers, facial moisturisers and age-defying treatments and antiperspirants. See also Quaternary ammonium compounds under ‘Q‘ here.

Bentonite A white clay, found primarily in the USA and Canada; it’s non-toxic, but can clog pores.

Benzoic acid Preservative that naturally occurs in cherry bark, cherries, anise, tea and cassia bark, which is also approved for limited use in food production. In common with many preservatives, benzoates (including benzoic acid) have been linked with problems such as eczema or asthma; they are very ‘active’ – ie effective at preventing bugs from breeding. Benzoic acid can be mildly irritating but tends to feature in formulations in small quantities, way down the ingredients list; most people have no problem with this ingredient but if you have a history of asthma or urticaria (hives), you may want to avoid it.

Benzyl alcohol Used in perfumes and as a preservative, it’s also a topical antiseptic and can be highly irritating, in some cases. It occurs naturally in many plants – including jasmine and hyacinth – but can also be synthesised from petrochemicals.

Benzyl benzoate Occurs naturally in Balsam Tolu and Balsam Peru (which are resins), it can be used as a plasticiser in nail polish and a fixative for perfumes. It’s considered to have extremely low toxicity for humans, but you should avoid contact with eyes or mucous membranes, which can be irritated by this ingredient.

Benzyl salicylate Another name for salicylic acid, this is a fixative ingredient in perfumery, and often used in sunscreens, too. For some individuals, this ingredient can be irritating and trigger rashes – but everyone’s different…

Betaine Derived from beets and other vegetables, with no known toxicity. A form of betaine – coco-betaine (short for cocamidopropyl betaine) is proving very useful to formulators as an alternative to foaming ingredients like Sodium lauryl sulfate in shampoos and body washes.

BHT Short for Butylated hydroxytoluene; a preservative and antioxidant used in foods and drinks as well as cosmetics (although prohibited as a food additive in the UK). This synthetic ingredient has been known to cause allergic reactions.

Bisabolol Derived from camomile, with soothing, anti-inflammatory properties.

Bifida ferment lysate Milk-derived ingredient which is a product of Bifida, a ‘friendly bacteria’ found in the human digestive system, used in cosmetics as a skin conditioner.

Biosaccharide gum A gum which comes from Sorbitol, which works well as a skin conditioner.

Bis-diglyceryl polyacyladipate-2 What a mouthful! Basically, a synthetic substitute for lanolin. It is often listed with the words (vegetable oil) in brackets, as here – but in reality, it’s a highly adulterated form of vegetable oil. Adipic acid – a main constituent of this ingredient – can be irritant to skin and eyes, as well as mucous membranes, depending on your vulnerability to sensitivity and the levels in a formulation.

Bismuth oxychloride (CI 77163) This occurs naturally in the earth’s crust, is approved as a colourant ingredient and also referred to (in beauty ‘slang’) as ‘synthetic pearl’. It can trigger allergic reactions in some individuals.

Blue 1 Lake (CI 42090) Derived from aluminium, it’s approved as a colour additive by the US FDA (Food and Drink Administration), and is also used in food and drinks. (Also known as ‘Brilliant Blue’.)

Boron nitride Boron occurs naturally in the earth’s crust, and is used in food supplements. Boron nitride, however, is made from boron and nitrogen, and is used in colour cosmetics. In high quantities (much higher than you’ll find in cosmetics), it can be hazardous to health when breathed in.

Brassica campestris/Aleurites fordi oil copolymer A wax blend made of rapeseed oil (non-GM) and Chinese Wood oil; has strong water-resistant properties.

Butylene glycol A synthetic ingredient often used as a ‘humectant’. Considered safe for use in food, and by the Cosmetic Ingredient Review of the Cosmetic, Toiletry and Fragrance Association for use in cosmetics.

Butylparaben One of the ‘contentious’ paraben family of preservatives, widely used for its anti-fungal action. Few ingredients trigger such violent debate as parabens. We have always taken a precautionary approach, although it appears that several of the studies that link parabens with breast cancer, for instance, were flawed (or at least flimsy). What is clear is that some parabens can be irritating to skin. The bottom line is that we would welcome much more research into this thorny subject. There are, meanwhile, many alternatives to parabens appearing in formulations as manufacturers find creative ways to avoid using them – partly a response to the fact that so many products are now declaring themselves to be ‘paraben-free’.

Butyl methoxydibenzoylmethane Also known as Avobenzone and Parsol 1789, a synthetic ingredient primarily designed to absorb UVA and used in suncare products. Question marks have been raised over this and some other chemical sunscreen ingredients.

Butylphenyl methylpropional A synthetic fragrance ingredient which has been found to be a skin irritant. Tests also showed that in high concentrations, application of BM to animals’ skin caused sperm damage. The concentrations used, however, far exceed anything you’ll be exposed to in regular daily use. (We do not condone animal testing in any way.)