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Methyldibromo glutaronitrile

Reports of contact dermatitis
A definite increase
Comment

Bandolier rarely visits the world of consumer products, but was prompted by a reader asking whether there was any known association between methyldibromo glutaronitrile and skin rash and itching. The answer is that there is, and the problem seems to be increasing.

Methyldibromo glutaronitrile is a preservative used in many cosmetics, shampoos, creams, and even some forms of toilet paper. It was introduced into Europe in the mid-1980s and in the early '90s into the USA. It comes by many other names, including the trade names Euxyl K 400, Tektamer 38, Merquat 2200, as well as other chemical names. The introduction of methyldibromo glutaronitrile was to replace preservatives known to be associated with a relatively high incidence of contact dermatitis in the range of 2-3%.

Reports of contact dermatitis


The literature is rather well-endowed with case reports of contact dermatitis involving methyldibromo glutaronitrile, as well as several case series. These studies have been conducted in patients referred to dermatology clinics with skin or other complaints. Testing involves reasonably standard tests of patches of chemicals at one or more concentrations, and skin reactions judged to be irritant or allergic based on appearance and time course. Irritant reactions were those that tended to fade over 48-96 hours, and allergic reactions remained stable or increased in intensity.

Some of the reports are not immediately available, but a summary of the larger studies is in Table 1. In the early 1990s, methyldibromo glutaronitrile was associated with contact dermatitis in about 1% of patients, but this appears to have increased in Europe and the USA.

Table 1: Positive tests for methyldibromo glutaronitrile

Country

Period of testing

Number of subjects

Percent positive

USA 1996-1997 163 4.9-7.9
USA 1994-1996 3,074 2.0
Holland 1994 2,943 4.0
Holland 1994 528 2.8
Germany 1990-1994 11,422 2.3
Italy 1991-1994 3,455 2.8
Italy 1991 2,057 1.2

A definite increase


Two longitudinal studies support the increase of sensitivity to methyldibromo glutaronitrile. Most important is an on-going study in 16 centres in 11 European countries examining the seven most commonly used preservatives [1] tested in patients with contact dermatitis. Levels of sensitivity for six of the preservatives remained constant over the period 1991-2000. Two ran at sensitivity levels of about 2% and the others at 1% or below. For methyldibromo glutaronitrile there was a sustained increase from under 1% at the start of this period to over 3.5% by the end (Figure 1). Another longitudinal survey in a London dermatology institute recorded large increases in sensitivity to methyldibromo glutaronitrile in the late 1990s [2].

Figure 1: Percentage of tests positive for methyldibromo glutaronitrile sensitivity in 16 centres in European countries in patients with contact dermatitis



Comment


A survey of a random selection of skin creams in Denmark in about 1999 showed only about 1 in 20 containing methyldibromo glutaronitrile [3]. A brief survey of Bandolier's local pharmacy seems to have many more products containing methyldibromo glutaronitrile. Skin creams, shampoos, shower gels, tanning creams, cucumber eye lotions, and protection creams are cosmetic products containing methyldibromo glutaronitrile. But it can also be found in industrial cleansers and a range of different materials.

Labelling should tell you whether or not it is present, but a survey [3] showed that while declared preservatives were within their permissible limits, some preservatives can be present, but not declared. So far this seems not to be the case with methyldibromo glutaronitrile.

References:

  1. JD Wilkinson et al. Monitoring levels of preservative sensitivity in Europe. A 10-year overview (1991-2000). Contact Dermatitis 2002 46: 207-210.
  2. JP McFadden et al. Increased rate of patch test reactivity to methyldibromo glutaronitrile. Contact Dermatitis 2000 42: 54-55.
  3. SC Rastogi. Analytical control of preservative labelling on skin creams. Contact Dermatitis 2000 43: 339-343.
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