Chemical nasty: Kathon CG - Toxic Beauty

Isothiazolinone-derived biocides, such as Kathon CG (primarily consisting of methylisothiadzolinone and methychlorisothiazolinone) are commonly used as anti-microbials in cosmetics and industrial settings. In occupational situations isothiazolinone-derived agents have caused chemical burns, contact dermatitis and skin sensitization.

Kathon CG, often used in cosmetic formulations such as moisturizers, body and sun tanning lotions and some shampoos, surfactants and conditioners, is a potent skin sensitizer and frequent cause of contact dermatitis in Europe, mainly occurring through the use of moisturizers containing the substance on slightly damaged skin. A study addressing the sensitization to preservatives in 811 Italian children with atopic dermatitis or other eczema found 4.9 per cent demonstrated a reaction to kathon CG.

A 1992 Cosmetic Ingredient Review (CIR) safety assessment of methylisothiazolinone and methychloroisothiazolinone found them to be highly toxic to rats when administered orally and moderately toxic when applied to the skin> Pregnant rabbits were force fed the compound, which was shown to be embryotoxic (adversely) affecting the growth development of the embryo) and fetotoxic to the fetus in the womb0. It also caused dose-dependent skin irritation in human volunteers.

It is just not just skin irritation that is a problem with Kathon CG; it may also have a harmful effect on brain cells; this is called neurotoxicity. methylisothiazolinone was linked to neuron cell death in a study on rat brain cells conducted in 2002 by the Department of Neurobiology, University of Pittsburgh School of Medicine. The study's authors concluded that 'there is no question that in addition to the many known cases of occupational exposure to these compounds [i.e. isothiazolinones]. a significant portion of the general population is being constantly exposed to low levels of these compounds, which are potent neurotoxins.

Some cosmetics may contain formaldehyde as a preservative in small concentrations, or release formaldehyde as a degradation product. Formaldehyde is a carcinogen and a common contact allergen, sensitizer and respiratory irritant. Almost 20 per cent of the population may have a strong reaction to low concentrations of formaldehyde (0.25 ppm). Preservatives that are formaldehyde releases include diazolidinyl urea. DMDM hydantoin, imidazolidinyl urea, quaternium-15, 2-bromo-2nitropropane-1.3-diol (bronopol), sodium hydroxymenthylglycinate and benzylhemiformal.

Reference: Toxic Beauty: Dawn Mellowship