Baneful (adjective)

Having a harmful or deadly effect; causing injury or destruction.

Origin:

From old english 'bana' meaning killer or destroyer.

Examples:

1. The baneful effects of tobacco on health have been well documented.
2. The baneful influence of the gang was felt throughout the community.
3. The baneful consequences of global warming are becoming more apparent every day.
4. The baneful impact of pollution on the environment is a growing concern.
5. The baneful effects of the toxic chemicals in the water were evident in the sickened wildlife.