Contaminants in Soil and WaterHeavy Metals and Pesticides
Heavy Metals
Metallic chemical elements that are toxic at low concentrations• Mercury (Hg)• Cadmium (Cd)• Arsenic (As)• Chromium (Cr)• Lead (Pb) • Uranium (U)
Mercury PoisoningEnvironmental Source:•Consumption of seafood with mercury in the flesh (bio-accumulation)•Inhaling contaminated air from coal power plants
Human Health Impacts:•Peeling skin, hair and teeth loss, memory impairment
Mad Hatter diseaseSkin peeling from fingertips
Arsenic Poisoning
Environmental Source•Contaminated groundwater– Natural arsenic leaches into water– byproduct of oil extraction
•Food grown in contaminated soil– Rice in the USA can have arsenic levels of 260 parts
per billion
Human Health Impacts•Scaling skin, Headaches/confusion, hair loss, convulsions, lung/skin cancers
Lead Poisoning
Environmental Source•Lead in household items– Paint, gasoline, pipes, pesticides in soil, batteries
Human Health Impacts•Cognitive deficits, kidney failure, reproductive problems, memory loss, depression
PesticidesDDT•Dichlorodiphenyltrichloroethane
DDTDeveloped to kill insects responsible for spreading diseases like malaria (WWII)– Chemist who developed DDT won Nobel Prize in
Medicine 1948
•Post-war used as insecticide on farms, at home, in residential urban areas
DDT Health Impacts
Listed as a Toxic chemical• Poisonous to wide range of animals, not just intended
target “pests”
In humans:• Linked to diabetes• Birth defects• Developmental problems in children• Parkinson’s disease• Possibly carcinogenic (causes cancer)
DDT Safety Symbol
Symbol for “Environmental Pollutant” listed by European Chemicals Agency
Rachel Carson “Silent Spring”• Written in 1962,
first account of the far-reaching dangers of DDT
• Huge backlash from chemical industry
• Led to DDT being banned in USA, 1972