THRESHOLD FOR OCCLUDED FORMALDEHYDE PATCH TEST IN FORMALDEHYDE-SENSITIVE PATIENTS - RELATIONSHIP TO REPEATED OPEN APPLICATION TEST WITH A PRODUCT CONTAINING FORMALDEHYDE RELEASER

Our purpose was to investigate the eliciting threshold concentration o f formaldehyde in formaldehyde-sensitive individuals in the occluded a nd non-occluded patch test, and to evaluate the relationship to repeat ed open application test (ROAT) with a product containing a formaldehy de releaser. 20 formaldehyde-sensitive patients and a control group of 20 healthy volunteers were included in the study. Occluded and non-oc cluded patch tests with formaldehyde solutions from 25 to 10,000 ppm, and ROAT for 1 week with a leave-on cosmetic product containing on ave rage 300 ppm formaldehyde, were carried out simultaneously on each sub ject. In the occluded patch test, 1/2 of the 20 patients only reacted to 10,000 ppm formaldehyde, 9 reacted to 5,000 ppm, 3 reacted to 1,000 ppm, 2 reacted to 500 ppm and 1 reacted to 250 ppm. No definite posit ive reactions were observed in the non-occluded patch test or in the R OAT. No positive reactions were observed in the control group to any o f the test procedures. We concluded that the threshold concentration f or occluded patch test to formaldehyde in formaldehyde-sensitive patie nts was 250 ppm. The threshold in occluded patch test corresponded to the degree of sensitivity. Definite positive reactions in the ROAT wer e not seen, either indicating that they are unlikely to happen with th e type of product used or that the exposure time was too short. (C) Mu nksgaard, 1997.