Deleterious - {adjective}
1. injurious to health: deleterious gases.
2. harmful; injurious: deleterious influences.
Synonyms:
pernicious, hurtful, destructive; noxious.
Antonyms:
beneficial
Example Sentences:
1. Overwork can be deleterious to one's health.
2. Though and improved diet was beneficial, it could not overcome the deleterious effects on the disease.