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