PUVA is a special treatment using a photosensitizing drug and timed artificial-light exposure composed of wavelengths of ultraviolet light in the UVA spectrum. The photosensitizing drug in PUVA is called psoralen. Both the psoralen and the UVA light must be administered within one hour of each other for a response to occur. These treatments are usually given in a physician's office two to three times per week. Several weeks of PUVA is usually required before seeing significant results. The light exposure time is gradually increased during each subsequent treatment. Psoralens may be given orally as a pill or topically as a bath or lotion. After a short incubation period, the skin is exposed to a special wavelength of ultraviolet light called UVA. Patients using PUVA are generally sun sensitive and must avoid sun exposure for a period of time after PUVA. Common side effects with PUVA include burning, aging of the skin, increased brown spots called lentigines , and an increased risk of skin cancer , including melanoma . The relative increase in skin cancer risk with PUVA treatment is controversial. PUVA treatments need to be closely monitored by a physician and discontinued when a maximum number of treatments have been reached.
The Tribune said then that "other doctors find what he's doing unethical and potentially dangerous, and federal regulators, who learned about this experiment last week, have warned him that he might have violated the law." One fellow abortion researcher explicitly told the paper he considered what Hausknecht was doing "downright unethical." Even a representative of the Population Council, the non-profit which later created Danco, the company Hausknecht now works for, then called his work "extremely risky" and told the Tribune "I hope his malpractice insurance is paid up."