Taking these supplements in large quantities may, therefore, increase the accumulation of porphyrins, which can theoretically raise the risk of photosensitivity in certain individuals, especially those with dysfunctional alleles of ABCG2. Ingestion of chlorella tablets has induced phototoxic dermatitis in some individuals with unknown ABCG2 genotypes: Pa and its ester were identified as photosensitizing agents present in the tablets [17]. This evidence concerns the gene ABCG2 and phototoxic dermatitis.