At a glance
| Chemical family | Heavy metal — soft, dense, malleable bluish-gray metallic element (Pb, atomic number 82); bioaccumulates in bone with 20-30 year skeletal half-life |
| CAS number | 7439-92-1 (elemental); various CAS for compounds (lead acetate 301-04-2, lead carbonate 598-63-0, lead chromate 7758-97-6, others) |
| Classification | IARC Group 2A (inorganic lead compounds, probably carcinogenic to humans, Monograph Volume 87, 2006); IARC Group 3 (organic lead compounds); CDC Blood Lead Reference Value (BLRV) 3.5 µg/dL (October 2021 MMWR, current as of 2026); EPA Lead and Copper Rule Improvements (2024) — 10 µg/L water action level, full lead service line replacement within 10 years; HUD lead-safe housing standards for federally-assisted housing |
| Where you encounter it | Lead paint in homes built before 1978 (US residential ban); lead-contaminated dust from deteriorating paint at windows, doors, floors; lead in drinking water from pre-1986 plumbing solder, brass fixtures, and lead service lines (highest in first-draw morning water after pipes sit overnight); lead in soil near older homes, former industrial sites, and leaded-gasoline-era roadways; imported ceramics, candle wicks, certain cosmetics (kohl/surma, sindoor), some children's toys and jewelry; lead-based ammunition residues; aviation gasoline near small airports (100LL avgas still contains tetraethyl lead) |
| Sleep micro environment relevance | High in pre-1978 housing — bedrooms have window-well dust, baseboard accumulation, and carpet reservoirs holding lead-paint chips and fines. Children's bedrooms are particularly relevant because hand-to-mouth behavior amplifies dust ingestion. Lead in drinking water reaches the kitchen rather than the bedroom directly but affects total body burden |
| Activated carbon capture | Not applicable — lead is a heavy metal contaminant of dust, surfaces, and water rather than a vapor-phase VOC. Air filtration with HEPA reduces airborne lead particles; certified NSF/ANSI 53 water filters reduce lead in drinking water; activated carbon as designed for VOC capture is not the relevant capture technology for lead. Inferred from general heavy-metal capture engineering distinctions; lead-specific residential capture is filtration-based, not adsorption-based |
What it is
Lead — chemical symbol Pb (from Latin plumbum), CAS 7439-92-1, atomic number 82 — is a soft, dense, bluish-gray heavy metal that has been mined and used by humans for at least 7,000 years. What changed in the twentieth century was the scale of distribution: leaded gasoline (US used 1923-1996), lead-based paint (banned for US residential use 1978), lead solder in food cans (US phase-out 1980s) and water pipes (US ban 1986). The leaded-gasoline era in particular distributed lead globally into soils, dusts, and human body burdens at concentrations that produced measurable population-level cognitive effects.
Lead's biological behavior is dominated by two facts: it bioaccumulates in bone with a half-life of 20-30 years, and it readily crosses the placenta and developing blood-brain barrier. The bone reservoir releases lead back into circulation during periods of high bone turnover — pregnancy, lactation, menopause, fracture healing, immobilization — meaning a single blood lead measurement captures current exposure plus recent bone release, not lifetime cumulative dose. The blood half-life is approximately 30 days; the bone half-life is two to three orders of magnitude longer. The developmental neurotoxicity that drives the residential health concern operates during critical brain-development windows — particularly the prenatal period and the first two years of life — when even small disruptions to neural pathway formation produce persistent functional differences.
Where you encounter it
From lead paint in pre-1978 housing
The US banned residential lead-based paint at the end of 1978. Homes built before then almost certainly contain lead paint, typically under newer paint layers. Approximately 24 million pre-1978 housing units in the United States contain significant lead-paint hazards. Intact lead paint behind newer paint layers poses lower immediate risk than chipping, peeling, chalking, or friction-impact surfaces (windows, doors, stair edges) that release lead-paint dust into the indoor environment. The dust pathway dominates childhood exposure: settled dust on floors, windowsills, and toys is ingested through hand-to-mouth behavior, particularly in children under three.
From drinking water
Lead enters drinking water from corrosion of plumbing materials installed before the 1986 ban on lead solder and lead-containing brass fixtures, and from the estimated 9 million lead service lines (the pipe connecting a building to the public water main) still in use across the United States. The EPA Lead and Copper Rule Improvements (LCRI, finalized October 2024) require water systems to replace 100% of lead service lines within 10 years and lowered the lead action level from 15 µg/L to 10 µg/L. Regulatory First-draw morning water — water that has been sitting in pipes overnight — has the highest lead concentration of any sample during the day; running cold water for 30 seconds to two minutes before drinking flushes the standing water.
From soil, imported goods, ammunition, and aviation gasoline
Lead-contaminated soil is meaningful in three scenarios: yards around pre-1978 homes (where exterior lead paint weathered into the soil), areas near former industrial sites, and zones near major roadways from the leaded-gasoline era. Soil lead transfers indoors via shoes and pets, accumulating in carpet dust. Some imported ceramics — particularly hand-painted pieces and traditional craft products — contain lead glazes that leach into acidic and hot foods. Certain imported cosmetics (kohl, surma, sindoor) have been documented to contain lead. Some imported candy wrappers, plastic mini-blinds, and children's costume jewelry have similarly been associated with lead exposures. Lead-based ammunition deposits lead in homes of hunters and shooters through handling and clothing-borne residue. Aviation gasoline (100LL avgas) for small piston-engine aircraft still contains tetraethyl lead — the only remaining widespread use of leaded fuel in the US — and produces measurable lead deposition near general-aviation airports.
What the research says
Developmental neurotoxicity — the foundational evidence
Lanphear and colleagues 2005 in Environmental Health Perspectives conducted the international pooled analysis of seven prospective cohort studies that established the dose-response between childhood blood lead and intellectual function below 10 µg/dL — the threshold that had previously been considered "safe." The pooled analysis showed the steepest cognitive decline per unit blood lead occurred in the lowest exposure range, not the highest, with an estimated 6.2-point IQ decrement for an increase from less than 1 µg/dL to 10 µg/dL. Peer-reviewed Jusko, Henderson, Lanphear and colleagues 2007 in Epidemiology demonstrated cognitive effects at blood lead concentrations below 10 µg/dL in the Rochester cohort, reinforcing the absence of an identified threshold. Peer-reviewed
The benchmark dose work
Budtz-Jørgensen, Bellinger, Lanphear and Grandjean 2013 in Risk Analysis conducted the benchmark dose modeling of the pooled international cohort data, deriving lower confidence limits on the dose producing a one-IQ-point loss in the range of 0.1 to 1.0 µg/dL — concentrations below the limit of reliable quantification with routine clinical assays. Peer-reviewed The benchmark dose finding underpinned the CDC's 2021 update of the Blood Lead Reference Value from 5 µg/dL to 3.5 µg/dL, which itself is a statistical screening threshold (the 97.5th percentile of US children's blood lead distribution) rather than a health-based safety standard.
The CDC Blood Lead Reference Value update
CDC's MMWR publication of October 28, 2021 formally lowered the BLRV from 5 µg/dL to 3.5 µg/dL based on NHANES data from 2015-2018. Regulatory The reference value is not a health-based standard — CDC has explicitly stated that no safe blood lead level in children has been identified — but rather a population-statistical threshold for identifying children with blood lead higher than most US children. The clinical and public-health implication is that any avoidable lead exposure during childhood is worth avoiding; the urgency of source remediation scales with the measured concentration, but the message is not "below X is safe."
IARC carcinogenicity classification
The IARC Monograph Volume 87 (2006) classified inorganic lead compounds as Group 2A (probably carcinogenic to humans), upgraded from the previous Group 2B classification based on consistent observational evidence in occupationally exposed populations. Regulatory Organic lead compounds (tetraethyl lead and related) were classified as Group 3 (not classifiable) on grounds of inadequate evidence. Cancer is a secondary concern relative to developmental neurotoxicity at typical residential exposures, but the carcinogenicity classification reinforces the regulatory framework around occupational and high-environmental exposures.
Adult cardiovascular and other effects
Lead is associated with hypertension, cardiovascular mortality, and renal effects at chronic adult exposures. The cardiovascular dose-response extends to current US adult blood lead distributions, with population-attributable risk estimates suggesting a meaningful fraction of US cardiovascular mortality is attributable to lifetime lead exposure. The ATSDR Toxicological Profile for Lead documents the full health-effect inventory with the regulatory framing. Regulatory The WHO lead-poisoning factsheet provides the global health perspective on residential and occupational lead exposure. Regulatory
What helps reduce exposure
For pre-1978 homes: wet-clean instead of dry-sweep. Dry sweeping aerosolizes lead-paint particles. Damp mopping with disposable cloths, HEPA-filter vacuuming, and wet wiping of windowsills and floors capture lead-bearing dust without re-entraining it into the air — the single highest-impact household practice for lead-paint-era homes.
Address chipping paint using lead-safe practices. The EPA Renovation, Repair and Painting (RRP) rule requires that contractors working in pre-1978 housing or child-occupied facilities be RRP-certified. Improper renovation in pre-1978 homes by non-RRP-trained workers is a documented source of pediatric blood lead elevation — often producing more exposure than passive aging of intact paint.
For drinking water: run cold water 30 seconds to 2 minutes before use after pipes have been still; use NSF/ANSI 53 certified filters. First-draw morning water has the highest lead concentration. Cold water only for drinking and cooking — hot water dissolves more lead from pipes. NSF/ANSI 53 is the specific certification for lead reduction; generic activated-carbon pitcher filters without that certification are not validated.
Remove outdoor shoes at the door, and wash hands — especially children's — before eating and bed. Soil-tracked lead is meaningful in pre-1978 housing yards. The hand-to-mouth dust ingestion pathway in young children is broken by frequent hand-washing.
For children: get blood lead tested per AAP guidance. Universal screening at ages 12 and 24 months for Medicaid-enrolled children; risk-based screening for others. The result actionably informs whether further intervention is warranted.
What does NOT help
- Boiling water. Concentrates rather than removes lead — as water evaporates, dissolved lead stays in the smaller remaining volume.
- Standard activated-carbon pitcher filters without NSF/ANSI 53 certification. The certification matters; the marketing language doesn't.
- Painting over lead paint without abatement. Sealing intact lead paint behind a fresh layer is the EPA's "encapsulation" strategy and can be appropriate; doing so over chipping or deteriorating paint without proper preparation just hides ongoing dust release.
- "Lead-free" labels on imported items without third-party verification. Enforcement of import labeling varies. Third-party testing (XRF screening, certified laboratory analysis) is the actionable verification for items of concern.
- Chelation therapy at non-clinical blood lead levels. Chelation is a medical treatment for severe lead poisoning, supervised by physicians and reserved for very high blood lead levels (typically >45 µg/dL in children per CDC guidance). At residential exposure levels, source removal and time are the appropriate interventions; chelation has its own risks and is not appropriate as a consumer self-treatment.
- Removing all dust without addressing the source. Frequent cleaning helps but does not substitute for fixing the underlying lead-paint condition. The two work together; cleaning alone in a home with active paint deterioration is a treadmill.
Open research questions
- The shape of the dose-response below the current limits of routine clinical quantification (~1 µg/dL) — Lanphear's pooled analysis suggests the dose-response is non-linear with the steepest effect at the lowest exposures, but characterizing it below routine assay sensitivity requires analytical methods most clinical labs don't run. Speculation re: shape below ~1 µg/dL; established above
- Cumulative lifetime dose versus current blood lead level as predictor of adult cardiovascular and renal outcomes — the bone-lead reservoir is the better integrator of lifetime exposure, but bone lead measurement requires K-shell X-ray fluorescence and is research-grade rather than clinical. Inferred from established lead pharmacokinetics; clinical translation requires K-XRF availability
- Transgenerational effects of bone lead released during pregnancy — maternal bone lead crosses the placenta. The effect of grandmother-era leaded-gasoline exposure on present-day grandchildren is a plausible but inadequately characterized pathway. Speculation
- Comparative effectiveness of different remediation strategies — encapsulation vs full abatement vs window/door replacement vs HEPA-cleaning protocols — in real-world residential settings has not been studied with the depth that the foundational exposure-effect work has. Speculation
Citations
- Ruckart PZ, Jones RL, Courtney JG, LeBlanc TT, Jackson W, Karwowski MP, Cheng P-Y, Allwood P, Svendsen ER, Breysse PN (2021). Update of the Blood Lead Reference Value — United States, 2021. Morbidity and Mortality Weekly Report, 70(43):1509-1512. cdc.gov/mmwr Regulatory — current BLRV 3.5 µg/dL
- International Agency for Research on Cancer (2006). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 87: Inorganic and Organic Lead Compounds — inorganic lead Group 2A, organic lead Group 3. Lyon: IARC. inchem.org/iarc/vol87 Regulatory
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for Lead. atsdr.cdc.gov/ToxProfiles/tp13.pdf Regulatory
- US Environmental Protection Agency (2024). Lead and Copper Rule Improvements (LCRI) — final rule. epa.gov Regulatory — 10 µg/L action level; 10-year lead service line replacement
- Lanphear BP, Hornung R, Khoury J, Yolton K, Baghurst P, Bellinger DC, Canfield RL, Dietrich KN, Bornschein R, Greene T, Rothenberg SJ, Needleman HL, Schnaas L, Wasserman G, Graziano J, Roberts R (2005). Low-Level Environmental Lead Exposure and Children's Intellectual Function: An International Pooled Analysis. Environmental Health Perspectives, 113(7):894-899. DOI 10.1289/ehp.7688 Peer-reviewed
- Jusko TA, Henderson CR, Lanphear BP, Cory-Slechta DA, Parsons PJ, Canfield RL (2008). Blood lead concentrations <10 µg/dL and child intellectual function. Epidemiology, 19(1):8-15. DOI 10.1097/01.ede.0000288388.26707.c9 Peer-reviewed
- Budtz-Jørgensen E, Bellinger D, Lanphear B, Grandjean P; International Pooled Lead Study Investigators (2013). An International Pooled Analysis for Obtaining a Benchmark Dose for Environmental Lead Exposure in Children. Risk Analysis, 33(3):450-461. DOI 10.1111/j.1539-6924.2012.01882.x Peer-reviewed
- World Health Organization. Lead Poisoning and Health — Fact Sheet. who.int Regulatory
- US Environmental Protection Agency. Renovation, Repair and Painting Program (RRP Rule) — lead-safe work practices for pre-1978 housing. epa.gov/lead/rrp Regulatory
- US Department of Housing and Urban Development. Lead-Based Paint Poisoning Prevention in Certain Residential Structures — 24 CFR Part 35 (the "Lead Safe Housing Rule"). hud.gov Regulatory
Frequently asked questions
What blood lead level is dangerous?
The CDC has identified no safe blood lead level in children. The agency's Blood Lead Reference Value (BLRV), updated to 3.5 µg/dL in October 2021 (down from 5 µg/dL), is a screening threshold used to identify children with blood lead levels higher than most US children — it is explicitly not a health-based standard. Lanphear's international pooled analysis demonstrated cognitive effects in children at blood lead concentrations below 10 µg/dL, with the steepest dose-response in the lowest exposure ranges. The honest framing is that any avoidable lead exposure during childhood is worth avoiding, with the urgency of remediation scaling with the measured concentration.
How do I know if my home has lead?
Homes built before 1978 (when the US banned residential lead-based paint) almost certainly contain some lead paint, typically buried under newer paint layers. The risk depends on the paint's condition — intact paint behind newer coats poses less immediate risk than chipping, peeling, or chalking surfaces. EPA-certified lead inspectors and risk assessors can test paint, dust, soil, and water. Lead test swab kits provide useful screening but are not definitive. The most actionable test for households with young children is a child's blood lead level — the AAP recommends testing children at ages 12 and 24 months in high-risk settings.
Does boiling water remove lead?
No — boiling water concentrates lead rather than removing it. As water evaporates during boiling, dissolved lead remains in the smaller volume of liquid. The right interventions for plumbing-sourced lead are running cold water for 30 seconds to 2 minutes before drinking (after pipes have sat still overnight), using cold water for cooking and infant formula preparation (hot water dissolves more lead from old plumbing), and certified point-of-use filters — specifically those bearing NSF/ANSI Standard 53 certification for lead reduction. Standard activated-carbon pitcher filters without that specific certification are not validated to reduce lead.
At what age should children be tested for lead?
The American Academy of Pediatrics recommends blood lead testing for all children enrolled in Medicaid at ages 12 and 24 months. For other children, testing is recommended in high-risk situations — pre-1978 housing, deteriorating paint, recent renovation work, refugee or immigrant status, or other CDC-defined risk factors. Many state and local health departments have additional or universal testing requirements. Talk to your pediatrician — testing is straightforward, typically a fingerstick capillary screen confirmed by venous draw if elevated.
How long does lead stay in the body?
Lead has two very different biological half-lives depending on where it ends up. Lead in blood and soft tissues clears with a half-life of approximately 30 days. Lead stored in bone — which is where the majority of total body lead resides after years of exposure — has a half-life of 20 to 30 years. The bone reservoir releases lead back into blood during periods of high bone turnover (pregnancy, lactation, menopause, fracture healing, immobilization). This is why current blood lead levels do not capture cumulative lifetime exposure and why a single blood lead measurement is a poor estimator of total body lead burden in adults.
Is lead in vintage dishware safe?
Many vintage ceramics — particularly hand-painted and brightly colored pieces from before the 1990s, and some imported ceramics from any era — contain lead glazes that can leach into food, especially with acidic foods (tomato sauce, vinegar-based dressings, citrus juices) and hot foods. Lead test kits provide useful screening. The conservative practice is to use vintage and uncertified imported ceramics for display rather than food service, and to use NSF-certified or third-party-tested modern ceramics for daily eating and drinking.
Can lead exposure be reversed?
Stopping the exposure source reduces ongoing accumulation, and lead in blood and soft tissues clears over months. The neurodevelopmental effects of childhood lead exposure are not fully reversible — the developmental window during which the brain is most susceptible to lead is a one-way door. Chelation therapy is a medical treatment for severe lead poisoning at very high blood lead levels; it is not appropriate or effective at typical residential exposure levels and should never be self-administered. Source removal and time are the primary interventions for moderately elevated levels in otherwise healthy individuals.
Related compounds
Embr Sleep is a sleep environment company researching the chemistry of the bedroom. See the methodology page for how this Atlas tags claims by evidence strength. For broader context on residential contamination pathways, see non-toxic bedroom; for soil and drift exposure framing relevant to lead and other persistent contaminants, see farm family sleep.
Last reviewed 2026-05-25. If you find a factual error, contact us.