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The differences in human cumulative irritation responses to positive and negative irritant controls from three geographical locations.
A retrospective analysis was conducted to evaluate whether studies from three geographically diverse locations have similar response profiles to the positive and negative controls in a standard 14-day cumulative irritation study (1). The positive irritant control (0.1% sodium lauryl sulfate, SLS) and the negative control (0.9% sodium chloride, saline) data from seventeen 14-day cumulative irritation studies were reviewed. The studies were compiled from three locations representing dry/hot, humid/hot, and dry/cold environments (Scottsdale, Arizona; St. Petersburg, Florida; and Winnipeg, Manitoba, respectively). Irritation scores were generated by trained skin graders from a total of 442 subjects studied between 1999 and 2005. Cumulative irritation scores were reviewed and compared between study locations. The irritation scores for the positive and negative controls were not significantly different between locations. Temperature and relative humidity (RH) variation did not correlate significantly with overall irritation. However, the dryer climate (i.e., negative or low dew point) had a tendency to induce a higher overall irritation level for both positive and negative controls.
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