harmful

injurious to physical or mental health

• “noxious chemical wastes”
• “noxious ideas”

able or likely to do harm

causing or capable of causing harm

• “too much sun is harmful to the skin”
• “harmful effects of smoking”

constituting a disadvantage

contrary to your interests or welfare

• “adverse circumstances”
• “made a place for themselves under the most untoward conditions”

tending to cause great harm