What toxic substance has been banned by the Consumer Product Safety Commission since 1978?

The correct answer is lead. Lead was widely used in paint and other products, particularly in residential settings, due to its durability and pigmentation properties. However, it became clear that lead exposure posed serious health risks, particularly to young children, including developmental delays and neurological impairment. In response to these dangers, the Consumer Product Safety Commission (CPSC) banned the use of lead-based paints in household products in 1978. This regulation was a significant step towards protecting public health, particularly focusing on reducing lead poisoning incidents resulting from lead in paint.

While asbestos, copper, and mercury are also hazardous substances that have regulations surrounding their use, they were not banned by the CPSC in the same way lead was. Asbestos has faced stricter regulations but not a complete ban; copper remains in use with certain limitations; and mercury, despite its dangers, is still present in some products, albeit controlled. Therefore, lead is uniquely recognized as having been banned specifically in the context of household paint and products, making it the correct answer to this question.