Hydroquinone

Hydroquinone is used as a developing agent in photography and as
an antioxidant in rubber and food. Tinnitus (ringing in the
ears), dizziness, headache, nausea, vomiting, dyspnea, erosion of
the gastric mucosa, edema of internal organs, cyanosis,
convulsions, delirium, and collapse may result from the ingestion
of a large amount of hydroquinone in humans. Hydroquinone is
also a skin irritant in humans. Chronic (long-term) occupational
exposure to hydroquinone dust can result in eye irritation,
corneal effects, and impaired vision. No information is
available on the reproductive, developmental, or carcinogenic
effects of hydroquinone in humans. There was some evidence of
carcinogenic activity in orally-exposed rodents. Increased skin
tumor incidence has been reported in mice treated dermally. EPA
has not classified hydroquinone for carcinogenicity.