The Incinerating of waste can also cause problems, because plastics tend can produce toxic substances, such as dioxins, when they are burn. Gases from incineration may cause the air pollution and contribute to acid rain, while the ash from incinerators may contain heavy metals and other toxins. Direct ecological: Is a Inevitable consequences of the practice of solid waste disposal in landfills are gas and leach ate generation can due primarily to microbial decomposition, climatic conditions, refuse characteristics and land filling operations.