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  • Patch testing with 2.0% (0.60 mg/cm 2) formaldehyde instead of 1.0% (0.30 mg/cm 2) detects significantly more contact allergy.

Patch testing with 2.0% (0.60 mg/cm 2) formaldehyde instead of 1.0% (0.30 mg/cm 2) detects significantly more contact allergy.

Contact dermatitis (2012-10-06)
Ann Pontén, Kristiina Aalto-Korte, Tove Agner, Klaus E Andersen, Ana M Giménez-Arnau, Margarida Gonçalo, An Goossens, Jeanne D Johansen, Christophe J Le Coz, Howard I Maibach, Thomas Rustemeyer, Ian R White, Magnus Bruze
ABSTRACT

The currently used patch test concentration for formaldehyde is 1.0% (wt/vol) in water. However, clinical experience and previous studies suggest that 1.0% might be insufficient for detecting an optimized number of clinically relevant cases of contact allergy to formaldehyde. To validate earlier patch test results for comparison of 1% (wt/vol) and 2% (wt/vol) formaldehyde in water, and to investigate co-reactivity with quaternium-15. In 12 dermatology clinics, 3591 patients were routinely patch tested simultaneously with 2.0% (wt/vol) (0.60 mg/cm(2)) and 1.0% (wt/vol) (0.30 mg/cm(2)) formaldehyde. Micropipettes were used for delivering the exact dosage of the allergen. Significantly more patients reacted to 2.0% formaldehyde than to 1.0% (3.4% versus 1.8%, p < 0.001). Overall, there were no sex differences between those reacting positively to 2.0% and 1.0%. Of 25 quaternium-15-positive patients, 4 (0.1%) reacted positively without reacting to formaldehyde. On the basis of the results of this multicentre study, as well as of previous studies, it can be suggested that 2.0% (wt/vol) in water formaldehyde should be used in routine patch testing in the baseline series.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Hexamethylenetetramine, ReagentPlus®, 99%
Sigma-Aldrich
Hexamethylenetetramine, ACS reagent, ≥99.0%
Sigma-Aldrich
Hexamethylenetetramine, meets analytical specification of Ph. Eur., BP, 99-100.5% (calc. to the dried substance)
Sigma-Aldrich
Hexamethylenetetramine, puriss. p.a., reag. Ph. Eur., ≥99.5% (calc. to the dried substance)
Methenamine, European Pharmacopoeia (EP) Reference Standard
Supelco
Hexamethylenetetramine