A negative factor related to farming the land, particularly in the context of growing food for a growing population, could be deforestation. This is because expanding agricultural land often leads to the clearing of forests, which can have significant environmental impacts, including loss of biodiversity, disruption of ecosystems, and contribution to climate change.
While air pollution, mining accidents, and unemployment are also important issues, they may not be as directly tied to the act of farming itself compared to the impact of deforestation on land use and environmental sustainability.