The potential of 3
sunscreens (
p-aminobenzoic acid, 4-isopropyldibenzoylmethane and
homosalate) and 2 known human photoallergens (
musk ambrette and tetrachlorosalicylanilide) to cause
photoallergy,
phototoxicity, and/or contact sensitization was determined using a guinea pig
photoallergy model, as previously described by Harber and associates. The model was slightly modified by employing 6 exposures over 2 weeks and using Hill Top Chambers for application of the test material. Contact
photoallergy was detected in guinea pigs treated with
musk ambrette or tetrachlorosalicylanilide (
TCSA), although with
TCSA, a lower incidence of
contact sensitivity and
phototoxicity was also detected. The results of studies conducted with
sunscreens showed that
p-aminobenzoic acid was photoallergenic, whereas
homosalate and 4-isopropyl-dibenzoylmethane (
Eusolex 8020) were not. However, contact sensitization, and to a lesser degree primary irritation, was detected with
Eusolex 8020 at the concentrations employed in this study. The results of these studies suggest that this guinea pig model is a suitable model for assessing the photoallergic potential of various compounds, including the
sunscreens tested in this study.