Scapular reactivity to contact irritants: application-time and area variations.

ABSTRACT

Twenty-two diurnally active, fair-skinned, male volunteers were repeatedly patch tested with 10, 15 and 20% lapyrium chloride (LC) and 0.3 and 0.5% sodium lauryl sulfate (SLS) for 5 consecutive days. A series of 5 patches containing SLS and LC were placed vertically once daily for 6 h on different sites of the scapula paravertebral, lateral and medial. The sites of application were randomized over subjects for patch testing once a day per area at either 08%, 16% or 00%. Each patch was left in place 6 h; scoring of each site, using a 13-point scale, was done 2, 10 and 18 h after removal. The cutaneous reactivity varied in a statistically significant manner according to the time and area of patch application. For each day except the first, LC scores exhibited highest and lowest responses at 16% and 00%, respectively. For SLS, a statistically significant application-time difference in reactivity was detected only for the readings of day 2 when scores were highest at 00% and lowest at 16%. Intraregional variations in scapular reactivity were also exhibited. Strongest reactions to LC occurred in the center of each scapula; weakest reactions were elicited on either the lateral or paravertebral sites. For SLS, statistically significant intraregional differences in reactivity were detected only for the second day of patching, with strongest responses near the spinal column and weakest near the axilla.