Heavy Metals at Home: Lead, Arsenic, Cadmium, and Mercury

The conversation about lead in homes almost always starts with paint — which makes sense, because lead paint is the largest residential lead hazard in the United States. But it's worth beginning with the scale of the problem, because most homeowners significantly underestimate how common it is.

The EPA estimates that approximately 37 million homes in the US still have lead-based paint — more than a quarter of the country's housing stock. Homes built before 1978, when lead paint was banned for residential use, are the concern. And within that category, homes built before 1940 have the highest concentrations — lead was used lavishly as a pigment in the early 20th century, producing durable, bright colours that still coat walls, trim, windows, and doors across millions of older homes today.

Lead paint that is in good condition — intact, not chipping, not on friction surfaces — is not an immediate hazard. It's lead paint in deterioration, or lead paint that gets disturbed by renovation work, that creates the inhalation and ingestion exposure that causes harm. The distinction between stabilised and disturbed lead paint is the fundamental dividing line between a manageable situation and an active health hazard.

The other critical context: lead removal is not a DIY project. Improper disturbance of lead paint releases lead dust at concentrations that can cause acute poisoning and contaminate an entire home. The EPA's Renovation, Repair and Painting (RRP) rule requires certified contractors for renovation work in pre-1978 homes.

Lead is the most studied residential heavy metal hazard — but it's not the only one. Arsenic, cadmium, and mercury also have residential exposure pathways that are worth understanding.

Arsenic in household products Chromated copper arsenate (CCA) was the standard preservative for pressure-treated wood used in decks, playground equipment, and landscaping until 2004. Homes with CCA-treated decks built before that date may have residual arsenic in the wood surface that can transfer to hands during contact. Children playing on old playground equipment with CCA-treated wood or using CCA-treated lumber in sandbox construction have higher urinary arsenic levels than those without this exposure.

Older pesticide formulations also contained arsenic — fruit orchards treated with lead arsenate pesticides historically, and some older homes with gardens in formerly agricultural land, may have elevated arsenic in the soil.

Cadmium Found in some older ceramic glazes, some phosphate fertilisers, and cigarette smoke. Cadmium is a kidney toxicant and carcinogen; it accumulates in the body over decades. In a home context, the most relevant sources are old painted ceramics used for food and drink, and smoking in enclosed spaces.

Mercury Compact fluorescent light bulbs (CFLs) contain small amounts of mercury. Broken CFLs require specific cleanup procedures (not vacuuming, which disperses mercury vapour) — the EPA has published cleanup guidelines. Older thermometers, thermostats, and some switches contain elemental mercury and should be disposed of through hazardous waste collection, not household waste. Fish consumption (particularly tuna, swordfish, and high-trophic species) is the most significant mercury exposure route for most people, but this is dietary rather than residential.

Heavy metals in homes enter the body primarily through two routes: inhalation of dust and particles, and ingestion.

The dust pathway Lead and arsenic don't stay where they're applied. Lead paint that deteriorates or is disturbed generates dust — particles small enough to be invisible but concentrated enough to cause poisoning when inhaled or ingested. Lead paint dust settles on all horizontal surfaces, accumulates in carpet, and collects on window sills and floor cracks where windows generate friction. Toddlers who crawl on floors and put hands in mouths receive a direct ingestion dose from contaminated floor dust.

The same pathway applies to arsenic from CCA-treated wood (residue on surfaces) and to cadmium from ceramic glazes that chip or leach into food.

Testing your dust Lead dust testing kits for home use are available at hardware stores — a surface wipe sample that changes colour if lead is present above a threshold. These provide qualitative confirmation but not quantitative measurement. For quantitative results relevant to children's health, XRF testing (X-ray fluorescence, used by professionals) or laboratory analysis of dust wipe samples provides accurate concentration data.

The ingestion-via-soil pathway Children who play in gardens around older homes may be exposed to lead in soil from the exterior paint that has weathered and settled over decades. Soil near the foundation of a pre-1978 home is the highest-risk area. Testing soil lead levels — particularly in play areas — is advisable before a child regularly plays there.

Heavy metal hazards in homes are manageable — the key is knowing what you have, not disturbing it inappropriately, and maintaining physical barriers between the hazard and the people in the home.

The renovation rule: call a professional first For any renovation in a pre-1978 home that involves sanding, scraping, or demolishing surfaces that may contain lead paint — including repainting, window replacement, door sanding, and floor refinishing — the EPA's RRP rule applies. Work must be performed by certified contractors using lead-safe practices. This isn't bureaucratic caution: improper sanding of lead-painted trim spreads lead dust throughout a home in concentrations that can cause blood lead elevation in children within days.

Maintaining intact lead paint If lead paint is in good condition: • Inspect it twice a year for chipping, peeling, or chalking • Keep friction surfaces (window sashes, door edges) well-lubricated and in good repair — these generate the most lead dust • Clean surfaces with damp cloths rather than dry dusting, which redistributes rather than removes lead particles

Soil and outdoor hazard management: • Create a physical barrier over lead-contaminated soil in play areas: grass, mulch, or paving • Wash children's hands before eating after outdoor play near older homes • Leave shoes outside or in an entry — they track in soil-based contaminants

PollutionProfile's Home Toxin Audit helps you identify which specific heavy metal risks may apply to your home based on its construction date, and guides you through the testing and remediation steps appropriate for your situation.