What is it?
Heavy metals are naturally occurring elements that accumulate in the body over time and have no safe threshold of exposure. Lead was used in paint and plumbing until relatively recently and remains a hazard in older homes. Mercury is released from certain fish, old thermometers and dental amalgam fillings. Arsenic contaminates groundwater in many regions and can be present in rice, treated wood and some herbal supplements. Cadmium is found in cigarette smoke, some fertilisers and certain ceramics.
What it does to your body
Neurotoxicity
Lead causes irreversible cognitive impairment, lower IQ and behavioural problems in children at any measurable level. There is no safe blood lead concentration.
Kidney damage
Cadmium and mercury are directly nephrotoxic at chronic low-level exposure, contributing to kidney disease in the general population.
Cardiovascular disease
Lead is associated with hypertension and increased cardiovascular event risk at low blood levels found in the general population.
Reproductive harm
Lead and mercury cross the placenta and disrupt foetal brain development, with lasting consequences for cognitive and behavioural development.
Cancer
Arsenic is a Group 1 carcinogen, linked to skin, bladder and lung cancer. Cadmium is classified as a Group 1 carcinogen for lung cancer.
How widespread is the problem?
CDC data shows 500,000 US children aged 1 to 5 have blood lead levels above the reference value. WHO estimates 1 in 3 children globally has blood lead levels high enough to cause neurodevelopmental damage. Mercury from fish consumption is the primary ongoing dietary exposure source for adults in developed countries.
Where it hides in your home
Key research
WHO Lead Exposure Global Burden Assessment
WHO estimated lead exposure causes 21.7 million years of healthy life lost annually, predominantly through cardiovascular disease and cognitive impairment in children.
CDC Blood Lead Reference Value Update
CDC lowered the blood lead reference value to 3.5 micrograms per decilitre, acknowledging that no level is safe and more children need intervention.
IARC Arsenic Classification Group 1
IARC classified arsenic and inorganic arsenic compounds as Group 1 carcinogens, with sufficient evidence for skin, lung and bladder cancer.
Heavy metals bind to bone and soft tissue, creating a long-term reservoir. Lead deposited in bone has a half-life of approximately 10 to 30 years. Reducing ongoing exposure is the priority. Chelation therapy is a medical intervention for acute poisoning but is not recommended for typical environmental exposure levels.