Which one of the following was not initially associated with PCBs?

Minamata disease is primarily associated with methylmercury poisoning, which resulted from the consumption of fish contaminated with mercury in Minamata Bay, Japan. This public health tragedy took place in the 1950s and 1960s and is specifically linked to neurological and sensory impairments caused by mercury exposure, rather than polychlorinated biphenyls (PCBs).

On the other hand, Yusho disease (linked to rice oil contaminated with PCBs) and Yu-cheng disease (linked to PCBs in cooking oil) are both directly tied to the consumption of food products contaminated with these compounds. Chloracne, a skin condition resembling severe acne, is a well-documented health effect resulting from PCB exposure. Therefore, since Minamata disease is not associated with PCBs, it is appropriate to identify it as the correct answer in this context.