Lead Pb

spore: profile
id: lead
spore_version: 0.2
family: low-melting-metals-and-solders
name: Lead
abbreviation: Pb
role: dense soft metal (radiation shielding, solder, battery plates)
category: metals
type: heavy-metals
summary: >
  Lead is a very dense, soft metal that melts at 327.5 degC. It absorbs X-rays and gamma rays strongly per gram (NIST mass
  attenuation coefficient 0.07102 cm2/g at 1 MeV), and tin-lead solder melting at 183 degC has long been used on circuit boards,
  but lead is a reproductive toxicant, is limited to 0.1% in most new EU electronics and was listed as a REACH Candidate List
  substance in 2018. NASA still prefers tin-lead finishes on space electronics because lead-free pure tin grows conductive whiskers.
best_for: "Compact radiation shielding per volume, and tin-lead solder and finishes that resist tin whiskers (NASA requires at least 3% Pb in tin finishes unless a mitigation is approved)"
weakest_at: "Toxicity (reproductive toxicant, no known safe blood level per WHO), softness (Young's modulus 16 GPa) and mass; regulation has removed it from most consumer electronics"
identity:
  formula: Pb
  cas: "7439-92-1"
  source: pubchem-lead
  where: PubChem compound record CID 5352425, CAS and EC identifiers section (CAS 7439-92-1; EC 231-100-4 as ECHA entry)
tags:
  environments: []
  stresses: [total-radiation-dose]
  applications: [radiation-shielding, electronics-and-chips, batteries]
properties:
  - benchmark: density
    label: Density, solid lead
    value: 11.34
    unit: g/cm3
    scope: material
    conditions: {form: "elemental lead, grade and purity not stated", reference_listing: "ILO-WHO International Chemical Safety Card as quoted by PubChem"}
    method: Value listed in a PubChem compilation of agency records
    status: ground
    note: PubChem also lists 11.3 at 25 degC (US DOE PAC database) and 11.3437 at 61 degF (CAMEO Chemicals, quoting NTP 1992, no unit stated). WebElements gives 11340 kg/m3.
    source: pubchem-lead
    where: Experimental Properties > Density (ILO-WHO ICSC entry)
  - benchmark: density_xcom_assumed
    label: Density assumed in the NIST attenuation tables
    value: 11.35
    unit: g/cm3
    scope: material
    conditions: {use: "material constant assumed for elemental medium in the NIST X-ray attenuation evaluation", Z: 82}
    method: Input constant of the NIST mass attenuation coefficient tables
    status: calculated
    note: The page states that some density values in Table 1 are only nominal. Lead is not among those it names (Z = 85 and 87).
    source: nist-xray-tab1
    where: Table 1, row Z = 82 (Pb), density column
  - benchmark: melting_point
    label: Melting point
    value: 327.5
    unit: degC
    scope: material
    conditions: {form: "elemental lead", pressure: "not stated", reference_listing: "ILO-WHO International Chemical Safety Card as quoted by PubChem"}
    method: Value listed in a PubChem compilation of agency records
    status: ground
    note: PubChem also lists 327.462 degC (US DOE PAC database) and 621.5 degF (CAMEO, OSHA).
    source: pubchem-lead
    where: Experimental Properties > Melting Point (ILO-WHO ICSC entry)
  - benchmark: boiling_point
    label: Boiling point
    value: 1740
    unit: degC
    scope: material
    conditions: {form: "elemental lead", pressure: "not stated for this entry", reference_listing: "ILO-WHO International Chemical Safety Card as quoted by PubChem"}
    method: Value listed in a PubChem compilation of agency records
    status: ground
    note: PubChem also lists 1749 degC at 760 mmHg (US DOE PAC database).
    source: pubchem-lead
    where: Experimental Properties > Boiling Point (ILO-WHO ICSC entry)
  - benchmark: youngs_modulus
    label: Young's modulus
    value: 16
    unit: GPa
    scope: material
    conditions: {form: "elemental lead, temperature, purity and test method not stated"}
    method: Value listed on the WebElements physical-properties page (compilation, underlying measurement not given)
    status: ground
    note: A compilation value, not a datasheet for a stated grade. Lead creeps at room temperature, so a modulus alone does not describe sustained loading.
    source: webelements-pb
    where: Lead physical properties page, Young's modulus
  - benchmark: shear_modulus
    label: Shear (rigidity) modulus
    value: 5.6
    unit: GPa
    scope: material
    conditions: {form: "elemental lead, temperature and purity not stated"}
    method: Value listed on the WebElements physical-properties page
    status: ground
    source: webelements-pb
    where: Lead physical properties page, shear modulus
  - benchmark: bulk_modulus
    label: Bulk modulus
    value: 46
    unit: GPa
    scope: material
    conditions: {form: "elemental lead, temperature and purity not stated"}
    method: Value listed on the WebElements physical-properties page
    status: ground
    source: webelements-pb
    where: Lead physical properties page, bulk modulus
  - benchmark: poissons_ratio
    label: Poisson's ratio
    value: 0.44
    unit: dimensionless
    scope: material
    conditions: {form: "elemental lead, temperature and purity not stated"}
    method: Value listed on the WebElements physical-properties page
    status: ground
    source: webelements-pb
    where: Lead physical properties page, Poisson's ratio
  - benchmark: brinell_hardness
    label: Brinell hardness
    value: 38.3
    unit: MN/m2
    scope: material
    conditions: {form: "elemental lead, load, ball size and purity not stated"}
    method: Value listed on the WebElements physical-properties page, unit as written there
    status: ground
    note: Written by the page in MN m-2, not as an HB number, and the test conditions are not given.
    source: webelements-pb
    where: Lead physical properties page, Brinell hardness
  - benchmark: thermal_conductivity
    label: Thermal conductivity
    value: 35
    unit: W/(m.K)
    scope: material
    conditions: {form: "elemental lead", temperature: "not stated on the page"}
    method: Value listed on the WebElements physical-properties page
    status: ground
    source: webelements-pb
    where: Lead physical properties page, thermal conductivity
  - benchmark: cte
    label: Coefficient of linear thermal expansion
    value: 28.9
    unit: ppm/K
    scope: material
    conditions: {form: "elemental lead", temperature: "not stated on the page"}
    method: Page gives 28.9 x 10^-6 per K; written here as ppm/K, same number
    status: ground
    source: webelements-pb
    where: Lead physical properties page, coefficient of linear thermal expansion
  - benchmark: electrical_resistivity
    label: Electrical resistivity
    value: 2.1e-7
    unit: ohm.m
    scope: material
    conditions: {form: "elemental lead", temperature: "not stated on the page"}
    method: Page gives 21 x 10^-8 ohm m; written here as 2.1e-7 ohm m, same quantity
    status: ground
    source: webelements-pb
    where: Lead physical properties page, electrical resistivity
  - benchmark: mass_atten_60keV
    label: Mass attenuation coefficient at 60 keV
    value: 5.021
    unit: cm2/g
    scope: material
    conditions: {photon_energy: "0.06 MeV", medium: "elemental lead, Z = 82", quantity: "mu/rho (total attenuation, narrow beam)"}
    method: NIST XCOM-based tabulation of X-ray mass attenuation coefficients
    status: calculated
    note: Tabulated from theory and data, not measured on a specific lead sample. Narrow-beam coefficient; thick-shield buildup is not included.
    source: nist-xray-z82
    where: Table 3, Lead (Z = 82), row 6.00000E-02 MeV, mu/rho column
  - benchmark: mass_atten_100keV
    label: Mass attenuation coefficient at 100 keV
    value: 5.549
    unit: cm2/g
    scope: material
    conditions: {photon_energy: "0.1 MeV", medium: "elemental lead, Z = 82", quantity: "mu/rho (total attenuation, narrow beam)"}
    method: NIST XCOM-based tabulation of X-ray mass attenuation coefficients
    status: calculated
    note: This energy is just above the lead K absorption edge (88.0045 keV), which is why the coefficient is higher than at 80 keV (2.419 cm2/g, same table).
    source: nist-xray-z82
    where: Table 3, Lead (Z = 82), row 1.00000E-01 MeV, mu/rho column
  - benchmark: mass_atten_500keV
    label: Mass attenuation coefficient at 500 keV
    value: 0.1614
    unit: cm2/g
    scope: material
    conditions: {photon_energy: "0.5 MeV", medium: "elemental lead, Z = 82", quantity: "mu/rho (total attenuation, narrow beam)"}
    method: NIST XCOM-based tabulation of X-ray mass attenuation coefficients
    status: calculated
    source: nist-xray-z82
    where: Table 3, Lead (Z = 82), row 5.00000E-01 MeV, mu/rho column
  - benchmark: mass_atten_1_25MeV
    label: Mass attenuation coefficient at 1.25 MeV
    value: 0.05876
    unit: cm2/g
    scope: material
    conditions: {photon_energy: "1.25 MeV", medium: "elemental lead, Z = 82", quantity: "mu/rho (total attenuation, narrow beam)"}
    method: NIST XCOM-based tabulation of X-ray mass attenuation coefficients
    status: calculated
    note: 1.25 MeV is close to the mean of the two cobalt-60 gamma lines; the same table gives 0.07102 cm2/g at 1 MeV and 0.04606 cm2/g at 2 MeV.
    source: nist-xray-z82
    where: Table 3, Lead (Z = 82), row 1.25000E+00 MeV, mu/rho column
  - benchmark: lead_k_edge_energy
    label: Lead K absorption edge
    value: 88.0045
    unit: keV
    scope: material
    conditions: {medium: "elemental lead, Z = 82", edge: "K"}
    method: Edge energy as tabulated in the NIST mass attenuation coefficient table (0.0880045 MeV)
    status: calculated
    note: At the edge the table jumps from 1.910 to 7.683 cm2/g (mu/rho).
    source: nist-xray-z82
    where: Table 3, Lead (Z = 82), rows at 8.80045E-02 MeV (K)
  - benchmark: solder_melt_sn63pb37
    label: Melting point, eutectic tin-lead solder Sn63Pb37
    value: 183
    unit: degC
    scope: material
    conditions: {alloy: "Sn63Pb37 (63% tin, 37% lead)", form: "wire, bar, paste or preform", note: "single melting point, no range listed"}
    method: Manufacturer alloy temperature chart
    status: ground
    note: Chart is dated 17 Nov 2004. The same chart lists Sn60Pb40 at 183 to 190 degC.
    source: kester-alloy-chart
    where: Solder Alloys and Available Forms table, Tin-Lead, row Sn63Pb37, melting range column
  - benchmark: solder_melt_sac305
    label: Melting range, lead-free solder Sn96.5Ag3.0Cu0.5 (SAC305)
    value: 217
    value_high: 220
    bound: range
    unit: degC
    scope: material
    conditions: {alloy: "Sn96.5Ag3.0Cu0.5 (tin, 3.0% silver, 0.5% copper)", form: "wire, bar, paste or preform"}
    method: Manufacturer alloy temperature chart
    status: ground
    source: kester-alloy-chart
    where: Solder Alloys and Available Forms table, Lead-Free, row Sn96.5Ag3.0Cu0.5
  - benchmark: solder_melt_sn10pb90
    label: Melting range, high-lead solder Sn10Pb90
    value: 268
    value_high: 302
    bound: range
    unit: degC
    scope: material
    conditions: {alloy: "Sn10Pb90 (10% tin, 90% lead)", form: "wire, bar, paste or preform"}
    method: Manufacturer alloy temperature chart
    status: ground
    note: Lead-rich solders of this kind (85% lead or more) are the subject of RoHS Annex III exemption 7(a).
    source: kester-alloy-chart
    where: Solder Alloys and Available Forms table, Tin-Lead, row Sn10Pb90
  - benchmark: pb_in_pcb_mobile_phones
    label: Lead in printed circuit boards of older mobile phones
    value: 3747
    unit: ppm
    scope: material
    conditions: {sample: "30 mobile phones (non-smartphone), boards removed from the phones", digestion: "aqua regia leach of cryo-milled board powder, residue fused with LiBO2", basis: "per mass of board"}
    method: Disassembly, milling, acid leach and fusion, then elemental analysis (instrument not named on the page read)
    status: ground
    uncertainty: not stated on the page read
    note: Value as quoted in the abstract (the statistic, mean or median, is not specified on the page read). The paper compares phones by type, not by manufacture year on the page read, so the link to RoHS is the authors' reading that Pb is lower in newer phones, not a direct before/after test.
    source: holgersson2018
    where: Abstract (Pb concentrations by product group)
  - benchmark: pb_in_pcb_smartphones
    label: Lead in printed circuit boards of smartphones
    value: 260
    unit: ppm
    scope: material
    conditions: {sample: "30 smartphones", digestion: "aqua regia leach of cryo-milled board powder, residue fused with LiBO2", basis: "per mass of board"}
    method: Disassembly, milling, acid leach and fusion, then elemental analysis (instrument not named on the page read)
    status: ground
    uncertainty: not stated on the page read
    note: About 14 times lower than the older mobile phones in the same study (3747 / 260, calculated here). Internet routers in the same study contained 3413 ppm.
    source: holgersson2018
    where: Abstract (Pb concentrations by product group)
corrosion:
  - environment: Water
    headline: "Lead is listed as practically insoluble in water, but this record has no corrosion rate."
    effect: "The ILO-WHO Chemical Safety Card quoted by PubChem lists lead as practically insoluble in water, and CAMEO Chemicals and NIOSH list it as insoluble. No corrosion rate, acid, atmosphere or soil test was opened, so no corrosion behaviour is claimed. The WHO notes that lead can reach drinking water through plumbing with lead pipes or solders."
    rating: unknown
    source: pubchem-lead
    where: Experimental Properties > Solubility; WHO fact sheet, exposure sources
risks:
  hazards:
    - text: "ECHA C&L Inventory, as aggregated by PubChem for lead (EC 231-100-4): signal word Danger; pictograms GHS07, GHS08, GHS09. Hazard codes with the share of notifying companies that gave them: H360 may damage fertility or the unborn child 84.4%; H362 may cause harm to breast-fed children 44.3%; H372 causes organ damage through prolonged or repeated exposure 50.5%; H373 may cause organ damage 34.4%; H332 harmful if inhaled 38.4%; H302 harmful if swallowed 36.2%; H410 very toxic to aquatic life with long-lasting effects 61.9%; H400 very toxic to aquatic life 57.9%. 91 notifications; 127 of 2,477 reports (5.1%) state the substance does not meet GHS hazard criteria. Notified classifications vary with impurities and additives."
      ghs: [GHS07, GHS08, GHS09, H360, H362, H372, H373, H332, H302, H410, H400]
      source: pubchem-lead
      where: GHS Classification section (ECHA C&L Inventory)
    - text: "WHO fact sheet on lead poisoning (updated 10 June 2026): 'There is no known safe blood lead concentration.' Children absorb more lead than adults from the same dose and can suffer permanent harm to brain development; lead stored in bone can be released in pregnancy and reach the fetus. IHME estimates more than 3.5 million deaths and more than 71.5 million DALYs attributed to lead exposure in 2023."
      ghs: []
      source: who-lead
      where: Key facts; Impacts on health; Global burden
    - text: "Workplace limits quoted by NIOSH: OSHA PEL 0.050 mg/m3 and NIOSH REL 0.050 mg/m3 (8-hour time-weighted average, as Pb, 29 CFR 1910.1025); IDLH 100 mg/m3 (as Pb)."
      ghs: []
      source: niosh-npg
      where: Pocket Guide to Chemical Hazards, Lead, exposure limits
  failure_risks:
    - mode: Tin whiskers when lead is removed from tin finishes and solder
      trigger: "Electroplated pure tin (a lead-free finish) on parts such as relays; incubation from days to years"
      consequence: "NASA's site reports at least three on-orbit commercial satellites completely failed from tin-whisker short circuits, and lists GALAXY VII, SOLIDARIDAD 1 and GALAXY IIIR as complete losses, and OPTUS B1, DBS-1, PAS-4 and DirecTV 3 as partial losses, in relays described as pure tin plated. The site says whiskers have reached several millimetres, rarely over 10 mm, and reported growth rates range from 0.03 to 9 mm per year."
      severity: high
      source: nasa-whisker-failures
      where: Whisker Failures page, satellite table; background page Q1, Q3 and Q5
    - mode: Toxic exposure during handling, soldering and recycling
      trigger: "Fume or dust from molten lead, battery recycling and mining"
      consequence: "The WHO reports that exposure to contaminated soil and dust from battery recycling and mining has caused outbreaks of mass lead poisoning, including child deaths in some countries."
      severity: high
      source: who-lead
      where: Exposure sources and impacts sections
  side_effects:
    - text: "Lead in a tin finish is widely believed to inhibit whisker growth, although NASA says the reasons remain somewhat of a mystery; its Sampson 2010 slide rates Sn-Pb as 'Greatly Reduced Whisker Tendencies' against 'Significant Whisker Tendencies' for pure tin. Tin-lead whiskers have been reported but are much smaller than pure-tin ones."
      affects: "Reliability of electronics once lead is removed"
      source: nasa-whisker-bg
      where: Background page Q4 and Q6; Sampson ETW 2010 slide 7
  handling:
    - text: "NASA mitigation guidelines for tin whiskers: avoid pure tin and write the prohibition into procurement; verify plating composition after delivery because GSFC found parts specified 'No Pure Tin' that were pure tin and had whiskers; solder-dip with tin-lead (limited success, thermal shock precautions); replate with tin-lead or nickel; conformal coat or foam encapsulate (a 2 to 3 mil coating contained growth in GSFC experiments); evaluate application-specific risk."
      source: nasa-whisker-bg
      where: Background page Q6
    - text: "NASA parts policy as summarised in a 2010 NEPP talk: policy is in NPD 8730.2 (3 November 2008); it requires traditional tin-lead solders except when justified by technical need such as high melting point, treats SAC and other new alloys as needing exceptional rationale, and requires all tin-based platings and protective finishes to have at least 3% Pb (no pure tin) unless a persuasive rationale is given or a mitigation strategy supported by data is approved by NASA."
      source: nasa-sampson2010
      where: Slide 9, The NASA Pb-free Policy
    - text: "RoHS (Directive 2011/65/EU): Article 4(1) requires electrical and electronic equipment placed on the market not to contain the substances in Annex II; Annex II sets lead at 0.1% (by weight, in homogeneous materials). Annex III exemption 7(a) covers lead in high melting temperature type solders (lead-based alloys containing 85% by weight or more lead); 7(b) covers lead in solders for servers, storage and storage array systems and network infrastructure equipment for switching, signalling, transmission and network management. Equipment categories and expiry dates of exemptions were not checked."
      source: eurlex-rohs
      where: Article 4(1); Annex II; Annex III points 7(a) and 7(b)
    - text: "REACH: ECHA added lead (EC 231-100-4, CAS 7439-92-1) to the Candidate List on 27 June 2018 as toxic for reproduction. Suppliers of articles containing more than 0.1% lead by weight, per individual article, must give recipients safe-use information, and producers or importers had to notify ECHA within 6 months. REACH Annex XVII entry 63, as amended by Regulation (EU) 2015/628, limits lead to 0.05% by weight in mouthable articles supplied to the general public (with exclusions such as articles under RoHS)."
      source: ipc-svhc
      where: IPC article (Candidate List date, reason, 0.1% threshold); Regulation 2015/628, entry 63 paragraphs 7 to 10
  mitigations:
    - text: "Use tin-lead finishes with at least 3% lead by weight, which NASA's background page treats as acceptable, accepting that RoHS, REACH and workplace rules then apply to the lead."
      source: nasa-whisker-bg
      where: Background page Q6
uses:
  - application: electronics-and-chips
    device: "Printed circuit boards of mobile phones (lead in solder, measured in boards from 30 mobile phones and 30 smartphones)"
    example: "Board lead averaged 3747 ppm in older mobile phones and 260 ppm in smartphones, and the study says lead is lower in modern smartphones."
    source: holgersson2018
    where: Abstract
  - application: electronics-and-chips
    device: "Tin-lead solder and tin-lead plated finishes on space electronics (NASA parts policy)"
    example: "NASA's 2008 policy asks for traditional tin-lead solder and at least 3% Pb in tin finishes unless a mitigation is approved, because of tin whiskers."
    source: nasa-sampson2010
    where: Slide 9
  - application: batteries
    device: "Lead-acid batteries: starting-lighting-ignition (SLI), standby power for computer and telecommunications networks, and motive power"
    example: "USGS estimates lead-acid batteries were 67% of US apparent lead consumption in 2025."
    source: usgs-mcs2026
    where: Lead, Domestic Production and Use
  - application: radiation-shielding
    device: "Shielding in displays and other equipment (the USGS notes flat-panel displays no longer require lead shielding)"
    example: "NIST tabulates the shielding strength of lead per gram of material at photon energies from 1 keV to 20 MeV; no spacecraft shield design was opened for this profile."
    source: usgs-mcs2026
    where: Substitutes paragraph; NIST data in properties
documents:
  - {title: "WebElements: Lead, the essentials", type: database, url: "https://winter.group.shef.ac.uk/webelements/lead/", year: 2026}
  - {title: "WebElements: Lead, crystal structure", type: database, url: "https://winter.group.shef.ac.uk/webelements/lead/crystal_structure.html", year: 2026}
  - {title: "NIST X-ray mass attenuation coefficients, Table 3, Lead (Z = 82)", type: database, url: "https://physics.nist.gov/PhysRefData/XrayMassCoef/ElemTab/z82.html"}
  - {title: "NIST X-ray mass attenuation coefficients, Table 1 (material constants)", type: database, url: "https://physics.nist.gov/PhysRefData/XrayMassCoef/tab1.html"}
  - {title: "USGS Mineral Commodity Summaries 2026: Lead", type: report, url: "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lead.pdf", year: 2026}
  - {title: "NASA Goddard tin and metal whisker site: background and mitigation guidelines", type: report, url: "https://nepp.nasa.gov/whisker/background/index.htm"}
  - {title: "NASA Goddard tin whisker site: whisker failures (satellites)", type: report, url: "https://nepp.nasa.gov/whisker/failures/index.htm"}
  - {title: "Sampson: Lead-free Electronics, Impact for Space Electronics (NEPP ETW 2010)", type: report, url: "https://nepp.nasa.gov/workshops/etw2010/talks/09_Sampson_NEPP_ETW2010%20Lead%20free.pdf", year: 2010}
  - {title: "Sampson: Developing a NASA Lead-Free Policy for Electronics, Lessons Learned (NTRS 20080039268)", type: paper, url: "https://ntrs.nasa.gov/citations/20080039268", year: 2008}
  - {title: "Directive 2011/65/EU (RoHS recast)", type: standard, url: "https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32011L0065", year: 2011}
  - {title: "Commission Regulation (EU) 2015/628 amending REACH Annex XVII entry 63 (lead)", type: standard, url: "https://www.legislation.gov.uk/eur/2015/628/data.html", year: 2015}
  - {title: "Holgersson et al.: metal content of small-size WEEE printed circuit boards, part 1", type: paper, url: "https://research.chalmers.se/en/publication/502981", year: 2018}
  - {title: "WHO fact sheet: Lead poisoning", type: report, url: "https://www.who.int/news-room/fact-sheets/detail/lead-poisoning-and-health", year: 2026}
  - {title: "Kester Alloy Temperature Chart (Rev 17Nov04)", type: datasheet, url: "https://hallaweb.jlab.org/tech/Detectors/public_html/manuals/data_sheets-manuals/J-L/K/kester/Alloy%2520Temperature%2520Chart%2520(17Nov04).pdf", year: 2004}
supply:
  - subject: Lead
    abundance: "USGS: identified world lead resources total more than 2 billion tons. World mine production was 4,600 thousand tons in 2024 and an estimated 4,500 thousand tons in 2025 (lead content); world reserves 95,000 thousand tons. Largest 2025 estimates: China 1,900, Australia 480, Peru 290, Russia 260, Mexico 200, India 220 (thousand tons)."
    producers:
      - {country: China, year: 2025}
      - {country: Australia, year: 2025}
      - {country: Peru, year: 2025}
      - {country: Russia, year: 2025}
      - {country: India, year: 2025}
      - {country: United States, year: 2025}
    critical_lists:
      - {list: "US Final 2025 List of Critical Minerals (USGS, published 7 Nov 2025; lead added)", listed: true}
    recycling: "USGS: an estimated 1 million tons of secondary lead was produced in the US in 2025, equal to 70% of apparent domestic consumption, nearly all recovered from old scrap, mostly lead-acid batteries. US net import reliance for refined lead was 33% in 2025. The last US primary lead refinery closed in 2013."
    substitutes:
      - "Plastics in cable covering and cans"
      - "Tin in solder for potable water systems"
      - "Lead-free solders in electronics"
      - "Flat-panel displays that do not require lead shielding"
      - "Steel and zinc in wheel weights"
    source: usgs-mcs2026
    where: Lead chapter, Salient Statistics, Recycling, Events Trends and Issues, World Mine Production and Reserves, Substitutes
gaps:
  - "Tensile strength, yield strength, elongation and creep of lead were not found in an opened source: the Metallographic.com page was offline, Matmatch could not be reached, and the NRC PDF opened was an unreadable scan. No mechanical strength value is entered; the stiffness values come from the WebElements compilation, which gives no test conditions."
  - "The REACH Candidate List entry for lead (listed 27 June 2018, toxic for reproduction, Article 57c, EC 231-100-4) could not be read on ECHA's own pages (HTTP 403 on the candidate list, news release and brief profile). The date and reason were read in an IPC industry article; ECHA's news release was only seen as a search result. Annex XIV (authorisation) status was not checked."
  - "The consolidated text of REACH Annex XVII entry 63 was not opened. Only Commission Regulation (EU) 2015/628, which added paragraphs 7 to 10 (0.05% by weight for mouthable articles supplied to the public), was read, and later amendments were not checked."
  - "RoHS: Directive 2011/65/EU Annex II (lead 0.1%) and Annex III exemptions 7(a), 7(b) and 7(c)-I were read in the EUR-Lex text, but expiry dates and later delegated amendments to the exemptions were not checked, so current exemption status is unknown."
  - "The Holgersson 2018 study was read through its abstract and the Chalmers publication page; the instrument, uncertainty, the sample years, and any before/after-RoHS comparison were not read. The 'sharp decline after RoHS' claim is therefore not established here; the paper only reports lower lead in smartphones than in older mobile phones. A Greek PCB study of 24 phones (2002 to 2011) could not be opened (bot protection)."
  - "No lead corrosion rates (atmosphere, acids, soil, water chemistry) and no space-environment data (atomic oxygen, UV, thermal cycling, outgassing, vacuum evaporation) were found for lead."
  - "No attenuation data were entered for the electron, proton or neutron radiation of space, and no secondary-radiation (bremsstrahlung) or weight-per-dose shield comparison was found; the NIST values are photon coefficients only. NIST mu_en/rho values exist in the same table but were not entered."
  - "No spacecraft shielding use of lead was sourced; the radiation-shielding use entry rests on the NIST data and a USGS remark only."
  - "Crystal structure, lattice parameter, specific heat, vapour pressure at melt and electrical conductivity versus temperature were not sourced."
  - "No PubChem or ECHA registration tonnage, REACH Annex XVII entry 63 exemptions for lead in solders, or IARC classification were read (the IARC lookup returned an error)."
  - "US lead-acid battery share fell from an estimated 86% (MCS 2025, year 2024) to 67% (MCS 2026, year 2025); USGS does not explain the change on the page read, so only the 2026 edition is used."
sources:
  webelements-lead-main:
    title: "Lead - 82Pb: the essentials (WebElements, relative atomic mass)"
    url: https://winter.group.shef.ac.uk/webelements/lead/
    year: 2026
    kind: database
    license: "WebElements, free online reference"
  webelements-lead-crystal:
    title: "Lead - 82Pb: crystal structure (WebElements)"
    url: https://winter.group.shef.ac.uk/webelements/lead/crystal_structure.html
    year: 2026
    kind: database
    license: "WebElements, free online reference"
  pubchem-lead:
    title: PubChem compound record, Lead (CID 5352425)
    id: "CID 5352425; CAS 7439-92-1; EC 231-100-4"
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Lead
    year: 2026
    kind: database
    license: public domain (NCBI)
  nist-xray-z82:
    title: "X-Ray Mass Attenuation Coefficients, Table 3: Lead (Z = 82) (NIST Physical Measurement Laboratory)"
    id: "NIST Standard Reference Database 126, elemental media table"
    url: https://physics.nist.gov/PhysRefData/XrayMassCoef/ElemTab/z82.html
    year: 2004
    kind: database
    license: US government work
  nist-xray-tab1:
    title: "X-Ray Mass Attenuation Coefficients, Table 1: Material constants assumed in the evaluations (NIST)"
    id: "NIST Standard Reference Database 126, Table 1"
    url: https://physics.nist.gov/PhysRefData/XrayMassCoef/tab1.html
    year: 2004
    kind: database
    license: US government work
  webelements-pb:
    title: "WebElements: Lead (82Pb) physical properties"
    id: "winter.group.shef.ac.uk/webelements/lead/physics.html"
    url: https://winter.group.shef.ac.uk/webelements/lead/physics.html
    year: 2026
    kind: web
    license: linked not reproduced
  kester-alloy-chart:
    title: Kester Alloy Temperature Chart
    id: "Kester, Rev 17Nov04"
    url: "https://hallaweb.jlab.org/tech/Detectors/public_html/manuals/data_sheets-manuals/J-L/K/kester/Alloy%2520Temperature%2520Chart%2520(17Nov04).pdf"
    year: 2004
    kind: datasheet
    license: manufacturer document, linked not reproduced
  holgersson2018:
    title: "Analysis of the metal content of small-size WEEE printed circuit-boards part 1: Internet routers, mobile phones and smartphones"
    id: "doi:10.1016/j.resconrec.2017.02.011 (Resources, Conservation and Recycling 133, 300-308)"
    url: https://research.chalmers.se/en/publication/502981
    year: 2018
    kind: paper
    license: publisher article, linked not reproduced
  usgs-mcs2026:
    title: Mineral Commodity Summaries 2026, Lead (USGS)
    id: "USGS MCS 2026, Lead chapter"
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lead.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  nasa-whisker-bg:
    title: "NASA Goddard tin whisker site: Background and FAQ (Q1 to Q6)"
    id: "nepp.nasa.gov/whisker/background/index.htm"
    url: https://nepp.nasa.gov/whisker/background/index.htm
    year: 2026
    kind: report
    license: public domain (NASA)
  nasa-whisker-failures:
    title: "NASA Goddard tin whisker site: Whisker Failures"
    id: "nepp.nasa.gov/whisker/failures/index.htm"
    url: https://nepp.nasa.gov/whisker/failures/index.htm
    year: 2026
    kind: report
    license: public domain (NASA)
  nasa-sampson2010:
    title: "Lead-free Electronics: Impact for Space Electronics (M. J. Sampson, NEPP Electronic Technology Workshop, 22-24 June 2010)"
    id: "NEPP ETW 2010, talk 09"
    url: "https://nepp.nasa.gov/workshops/etw2010/talks/09_Sampson_NEPP_ETW2010%20Lead%20free.pdf"
    year: 2010
    kind: report
    license: public domain (NASA)
  nasa-sampson2008:
    title: Developing a NASA Lead-Free Policy for Electronics - Lessons Learned
    id: "NTRS 20080039268, TRISMAC 08 NASA/ESA/JAXA conference, 14 April 2008"
    url: https://ntrs.nasa.gov/citations/20080039268
    year: 2008
    kind: paper
    license: public domain (NASA)
  eurlex-rohs:
    title: Directive 2011/65/EU on the restriction of the use of certain hazardous substances in electrical and electronic equipment
    id: "CELEX 32011L0065"
    url: https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32011L0065
    year: 2011
    kind: standard
    license: EU law, reuse permitted
  reg-2015-628:
    title: Commission Regulation (EU) 2015/628 amending Annex XVII to REACH as regards lead and its compounds
    id: "Regulation (EU) 2015/628 of 22 April 2015"
    url: https://www.legislation.gov.uk/eur/2015/628/data.html
    year: 2015
    kind: standard
    license: Open Government Licence (legislation.gov.uk)
  ipc-svhc:
    title: Lead Added to EU REACH Candidate List of SVHCs (IPC)
    id: "IPC industry blog"
    url: https://www.electronics.org/blog/lead-added-eu-reach-candidate-list-svhcs
    year: 2018
    kind: web
    license: linked not reproduced
  who-lead:
    title: Lead poisoning (WHO fact sheet)
    id: "WHO fact sheet, updated 10 June 2026"
    url: https://www.who.int/news-room/fact-sheets/detail/lead-poisoning-and-health
    year: 2026
    kind: report
    license: linked not reproduced
  niosh-npg:
    title: "NIOSH Pocket Guide to Chemical Hazards: Lead"
    id: "npgd0368"
    url: https://www.cdc.gov/niosh/npg/npgd0368.html
    year: 2026
    kind: database
    license: public domain (CDC)
license: CC-BY-4.0

updated: "2026-10-17"
review:
  status: draft
  method: assistant
  checked_values: 22
  unreachable: 0
  caveats: 8
  note: "Written by an AI assistant on 2026-10-17. Values were read through web-page summaries and PDF text extraction (USGS, Kester, NASA slides) and were not independently re-read by a person. No values were taken from memory. Several property values are agency or website compilations without test conditions. See gaps."

story:
  risk_groups:
    - title: For people
      level: 4
      verdict: "Reproductive toxicant, no safe level"
      lead: "Lead is a toxic metal with an EU reproductive-toxicity classification, and the WHO says there is no known safe blood lead concentration."
      points:
        - label: Classification
          line: "ECHA's C&L Inventory, as shown in PubChem, carries signal word Danger and pictograms GHS07, GHS08 and GHS09, with H360 (may damage fertility or the unborn child) notified by 84.4% of companies and H372 or H373 organ damage by 50.5% and 34.4%."
        - label: Children and pregnancy
          line: "The WHO says young children absorb more lead than adults from the same dose and can suffer permanent brain-development harm, and that lead stored in bone can be released in pregnancy and reach the fetus."
        - label: Workplace
          line: "NIOSH gives an OSHA limit and a NIOSH limit of 0.050 mg/m3 over 8 hours, and an IDLH of 100 mg/m3, all as lead."
    - title: If it fails
      lead: "The failures recorded for lead are mostly about what happens when it is taken out of solder and finishes."
      points:
        - label: Tin whiskers
          line: "NASA reports at least three commercial satellites completely failed from tin-whisker short circuits in pure-tin plated relays, with more partial losses listed; the site says whiskers can reach several millimetres."
        - label: Recycling and mining
          line: "The WHO says contaminated dust and soil from battery recycling and mining has caused mass lead poisoning outbreaks in some countries."
    - title: Handling and storage
      points:
        - label: Rules on lead content
          line: "RoHS limits lead to 0.1% by weight in homogeneous materials of most new electronics, with exemptions in Annex III such as high-lead solder of 85% lead or more. Lead became a REACH Candidate List substance on 27 June 2018, and REACH Annex XVII limits lead to 0.05% in some mouthable consumer articles."
        - label: Space hardware
          line: "NASA's parts policy of 2008 asks for tin-lead solder and at least 3% Pb in tin finishes unless a mitigation is approved, so a spacecraft team has to manage lead rules and tin-whisker risk together."
  why: >-
    Lead (Pb, element 82) is a dense, soft, easily melted metal. The density is 11.34 g/cm3 and it melts at 327.5 °C, a
    temperature that soldering and casting can reach easily. Its high atomic number makes it absorb X-rays and gamma rays very
    strongly: NIST gives a mass attenuation coefficient of 0.07102 cm2/g at 1 MeV, and the coefficient jumps from 1.910 to 7.683
    cm2/g at the lead K edge at 88 keV. That is why lead is the classic shielding metal. It is also soft and toxic, and the EU
    restricts it in most new electronics (RoHS). For spacecraft the story has a twist: tin-lead alloy is the finish NASA trusts
    because lead holds back tin whiskers, so taking lead out creates a reliability problem of its own.
  uses:
    - where: Mobile-phone circuit boards
      line: >-
        A study of printed circuit boards from 30 mobile phones and 30 smartphones found 3747 ppm lead in the older mobile
        phones and 260 ppm in the smartphones, and says the lead content is lower in modern smartphones.
    - where: Space electronics
      line: >-
        NASA's parts policy of 2008 asks for traditional tin-lead solder and at least 3% lead in tin platings unless a
        whisker mitigation is approved.
    - where: Batteries
      line: >-
        The USGS estimates lead-acid batteries accounted for 67% of US apparent lead consumption in 2025, mainly starting
        batteries for vehicles, standby power for computer and telecom networks, and motive power.
  can_do:
    - label: Stopping photons
      benchmark: mass_atten_1_25MeV
      value: 0.05876 cm2/g at 1.25 MeV
      line: >-
        NIST tabulates the attenuation of lead from 1 keV to 20 MeV. It is 5.549 cm2/g at 100 keV, 0.1614 cm2/g at 500 keV
        and 0.05876 cm2/g at 1.25 MeV, the energy range of cobalt-60 gamma rays. These are narrow-beam values from tables, not
        a shield design.
    - label: Density
      benchmark: density
      line: >-
        Solid lead is 11.34 g/cm3 in the ILO-WHO safety card as quoted by PubChem.
    - label: Soldering
      benchmark: solder_melt_sn63pb37
      line: >-
        Eutectic tin-lead solder Sn63Pb37 melts at one temperature, 183 °C, while lead-free SAC305 melts over 217 to 220 °C in
        the same manufacturer chart, so tin-lead is processed about 34 to 37 °C cooler (difference calculated here).
    - label: Stiffness
      benchmark: youngs_modulus
      line: >-
        WebElements lists a Young's modulus of 16 GPa and a Brinell hardness of 38.3 MN/m2, which makes lead very soft. No
        tensile strength was found in an opened source.
  compare: >-
    Against lead-free solder, Sn63Pb37 melts at 183 °C and SAC305 at 217 to 220 °C (Kester chart). In tin-whisker evidence
    from NASA, Sn-Pb is rated 'greatly reduced whisker tendencies' and pure tin 'significant whisker tendencies'. No source
    in this record compares lead with tungsten, tantalum or polymer shielding, so no such comparison is made.
  compare_rows:
    - {label: "Density", benchmark: density}
    - {label: "Melting point", benchmark: melting_point}
    - {label: "Thermal conductivity", benchmark: thermal_conductivity}
    - {label: "Thermal expansion (CTE)", benchmark: cte}
  handling:
    - Lead is a reproductive toxicant (H360); keep dust and fume exposure under the 0.050 mg/m3 workplace limits quoted by NIOSH.
    - Check whether a part is covered by RoHS (0.1% in homogeneous materials) or the REACH Candidate List duty at 0.1% by weight per article.
    - For space hardware, follow the project's lead-free control plan and never accept unverified "no pure tin" claims; NASA found some were pure tin.
    - Treat lead-acid battery and solder waste as hazardous; the WHO links careless recycling to mass poisonings.
  good_for:
    - "Compact photon shielding. NIST gives 0.1614 cm2/g at 500 keV and 0.05876 cm2/g at 1.25 MeV, with a density of 11.34 g/cm3."
    - "Tin-whisker suppression. NASA's policy asks for at least 3% Pb in tin finishes, and its table rates Sn-Pb as greatly reduced whisker tendency."
    - "Easy low-temperature joining. Sn63Pb37 melts at 183 °C."
  watch_out:
    - "Toxicity. H360 reproductive toxicity was notified by 84.4% of companies, and the WHO says no safe blood level is known."
    - "Regulation. RoHS caps lead at 0.1% in most new electronics; lead has been a REACH Candidate List substance since 27 June 2018."
    - "Softness and mass. Young's modulus is 16 GPa and Brinell hardness 38.3 MN/m2; no tensile strength was sourced."
    - "Absorption edge. Shielding per gram is lower just below 88 keV than just above it (1.910 against 7.683 cm2/g in the NIST table), so energy matters."
  verdict: "Lead is an effective, cheap photon absorber and the solder and finish NASA still prefers for space electronics because it suppresses tin whiskers, but it is a reproductive toxicant that EU rules have removed from most consumer electronics. This profile has solid NIST, USGS, NASA and EU-law backing, but no tensile data and no space-environment data."
  recipe:
    line: >-
      Lead is the element Pb, atomic number 82, a single-element metal with cubic close-packed crystals (ccp, space group Fm-3m, WebElements). USGS says lead concentrate was mined in five Missouri mines and as a by-product at zinc and silver mines, and that nearly all of it is exported because the last primary lead refinery closed in 2013. Secondary lead from old scrap, mostly lead-acid batteries, gave about 1 million tons in 2025, equal to 70% of apparent domestic consumption (USGS).
    parts:
      - name: Lead
        symbol: Pb
        atoms: 1
        atomic_weight: 207.2
        role: "The whole material. WebElements prints the relative atomic mass on its main page."