Helena Louhelainen's master's thesis examined chemical exposure risks for workers treating liquid hazardous waste at Lahti's liquid hazardous waste treatment plant in Finland. The study analyzed the composition of different waste streams processed at the plant, including oil-contaminated fluids and acid and alkali-based wastes. Laboratory tests and on-site measurements identified various volatile organic compounds, metals, and gases released into the air during treatment. Major chemical hazards included some carcinogenic, mutagenic, and reprotoxic substances like benzene and benzo(a)pyrene in oil waste waters. Gases in plant air that can cause death at high levels included hydrogen sulfide, cyanide, nitrogen dioxide and chlorine