Lead in paint, dust, and water
Unlike most environmental concerns, lead has unambiguous, evidence-based action levels — and they keep getting tighter. The CDC has lowered the blood-lead reference level four times since 1991. The actionable advice in many homes is the same it was decades ago. The testing is more accessible now than ever.
The two-sentence summary
For children, "there is no safe level of lead in blood" (CDC, AAP, WHO). For most US homes built before 1978, exposure risk is testable and remediable, but the only way to know whether your specific home matters for your specific child is to measure: dust wipes, paint, water.
Why pre-1978
Lead in residential paint was federally banned in 1978 (Consumer Product Safety Act, 1977). About 87% of housing built before 1940 contains lead-based paint somewhere. The share drops with each decade — about 69% (1940-59), 24% (1960-77), then essentially 0% after 1978 (HUD 2011 American Healthy Homes Survey). The lead is fine while it's intact and painted over. It becomes a problem when it chips, deteriorates, or is disturbed by a renovation that doesn't follow EPA Renovation, Repair, and Painting (RRP) rules.
Where the exposure usually comes from
Not from chewing paint chips, mostly. The dominant exposure pathway in modern US homes is lead dust on horizontal surfaces — window sills, floor near window troughs, baseboards, the rug in the doorway. Friction surfaces (window sashes that ride up and down, doors that swing past their jambs) shed lead-paint chips into fine dust, which kids ingest via hand-to-mouth.
The other significant exposure path is lead service lines in drinking water — homes built before about 1986 may have lead in the service line connecting the water main to the home, in interior plumbing, or in solder. Acidic water + stagnant water (first-draw morning samples) make the worst case.
How we test
Paint (XRF)
Inspector uses an XRF (X-ray fluorescence) gun on painted surfaces — window casings, door jambs, baseboards, sills. Result is mg/cm². EPA TSCA §401 action level: 1.0 mg/cm² (or 0.5% by weight) qualifies as lead-based paint.
Dust wipes
Wipes are taken per EPA TSCA §403 protocol, single-sample per surface, sent to a National Lead Laboratory Accreditation Program (NLLAP) lab.
| Surface | EPA action level |
|---|---|
| Floor (interior) | 10 µg/ft² (lowered 2021) |
| Window sill | 100 µg/ft² |
| Window trough | 400 µg/ft² |
The 2021 floor lowering (from 40 to 10 µg/ft²) reflects updated CDC blood-lead reference levels and changed a lot of homes from "clear" to "needs attention."
Water
First-draw (morning, before any tap use) cold-water sample from the kitchen tap is the most-sensitive way to detect lead in plumbing. Flushed (after 30+ seconds of running) is the most sensitive way to detect lead in the service line specifically. EPA Lead and Copper Rule revisions: 10 µg/L (10 ppb). The earlier action level (15 µg/L) is no longer the current threshold for individual sample concern.
Blood lead reference levels (for context)
The CDC blood-lead reference value (the level above which a child is considered to have higher exposure than 97.5% of US children 1-5) is currently 3.5 µg/dL (since 2021). It was 5 µg/dL from 2012-2021, 10 µg/dL through 2012, 25 µg/dL in 1991, 60 µg/dL in 1978. The number keeps dropping because each generation of research shows neurocognitive effects at lower exposures.
There is no safe blood lead level in children.
When to test
- Pre-1978 home with children under 6 or pregnant occupants.
- Before any renovation in a pre-1978 home — RRP rules apply either way, and a pre-renovation baseline + post-renovation clearance is the strongest record.
- A child in the household has had an elevated blood lead level (any value above CDC reference); the home is one of several possible sources to rule in or out.
- Pre-purchase, for any home built before 1978.
- Pre-pregnancy, for the home you'll bring a newborn into.
When NOT to test (yet)
- The home was built after 1978 AND the water system isn't on lead service lines (your utility can confirm via the new lead-and-copper inventory requirement, effective 2024). Risk is very low and testing is rarely the next move.
- You're about to gut-renovate a pre-1978 home. Plan for RRP-rule remediation up front; the pre-renovation test is useful but the post-renovation clearance test is mandatory.
What we report
- XRF readings per surface (mg/cm², pass/fail vs 1.0).
- Dust wipe results per location (µg/ft², pass/fail vs the current EPA TSCA §403 thresholds).
- Water lead in µg/L for first-draw and flushed samples.
- Inspector's plain-English interpretation: which surfaces matter, which to address first, whether RRP-rule abatement is required, whether the water result indicates a service- line vs interior-plumbing source.
- If applicable: referral guidance toward EPA-certified Lead Abatement contractors (separate credential from RRP).
What a positive result usually means
- Lead-based paint detected (XRF > 1.0 mg/cm²): the paint is there. The intervention depends on its condition. Intact paint can be encapsulated. Friction surfaces (sashes, jambs) need RRP-rule attention. Renovation requires an EPA-certified RRP renovator.
- Dust wipe over the floor action level: immediate attention. HEPA-vacuum + wet-clean the affected area. Re-test 7-14 days later. Address the source surface (typically a friction surface dispersing dust).
- Water lead > 10 µg/L first-draw: very likely interior plumbing or fixtures. Water lead > 10 µg/L flushed: more likely service-line contribution. Your utility may be required to replace the service-line portion they own under the Lead and Copper Rule revisions.
Selected references
- Centers for Disease Control. Blood Lead Reference Value. Updated 2021.
- EPA. 40 CFR Part 745 (Lead-Based Paint).
- EPA. Lead and Copper Rule Revisions. Final Rule 2021; revised 2024.
- HUD. American Healthy Homes Survey, 2011.
- AAP Council on Environmental Health. Prevention of childhood lead toxicity. Pediatrics 2016.