1. the quality or state of being harmful, damaging, or having a negative effect on health, well-being, or performance
Usage: abstract noun; formal register

Examples

• The deleteriousness of smoking on lung health is well documented.
• Scientists warned about the deleteriousness of prolonged screen time for children's development.
• The deleteriousness of the new policy became apparent within weeks.
• Excessive sugar consumption has a deleteriousness that affects both physical and mental health.
• The report highlighted the deleteriousness of pollution in urban environments.
• Despite warnings about its deleteriousness, the practice continued in some regions.