This book highlights the dangers of toxic chemicals, with a particular focus on hydrogen sulfide (SH₂), a noxious gas often emitted from landfills. It explores waste management, degradation processes, and the release of toxins like SH₂ into the environment. Through an analysis of lexiviates, this book demonstrates how these fluids contaminate soil and groundwater, seriously affecting public health. The text also discusses the acute and chronic effects of SH₂ exposure, associated pathologies, and the importance of appropriate safety measures for landfill workers. In conclusion, it proposes strengthened policies and innovative techniques for sustainable waste management, aimed at reducing the risks associated with toxic substances and protecting human and environmental health.