Pervasive yet differential. These descriptors fit numerous twenty-first-century phenomena affecting human and more-than-human vitality, from the COVID-19 pandemic to climate crisis and toxic exposure. While individual immunity varies, no population is fully immune to COVID-19. No one is fully protected from impacts accompanying global warming. No one is untouched by the countless vectors for toxicity, even beings in Earth’s remotest regions. Yet experiences of toxic threats, like experiences of the COVID-19 and climate crises, are not uniform across individuals, communities, and ecosystems. For this reason, the framework of the toxic offers the health humanities a crucial intervention into social injustices correlated to gender, wealth, geography, race, and ethnicity. We cannot sufficiently understand and redress health disparities keyed to these identity positions without accounting for industrial and petrochemical toxins. The toxic is at the nexus of identity, health, and environment and also rests at the nexus of varied epistemologies, from positivist science to environmental justice and queer and feminist materialisms. It demonstrates the value of entangling epistemologies that might otherwise conflict with one another.