deleterious - harmful
Something ‘deleterious’ is damaging and unhealthy, typically in a subtle or unexpected way. In other words, it’s ill effects may not be seen immediately, but will manifest in time and be very difficult if not impossible to reverse or treat. For that reason, this formal word has extremely negative connotations.
Smoking has a deleterious effect on people. Many can seem fine for years before eventually suffering major health complications.
Our company is committed to producing fully recyclable products and packaging that will help reduce the deleterious impact of plastic on the environment.
Some residents are worried that recent cuts to the local police force will be deleterious to the community.