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Superfund / NPL site · EPA Superfund SEMS through latest publishNPL FinalFEDERAL FACILITY

Hanford 100-Area (Usdoe)

This site is currently on the EPA Superfund National Priorities List and remains under federal cleanup oversight. Most-cited contaminant of concern: Cesium-137.

100 Area, Benton County, Washington · ZIP 99352 · EPA ID WA3890090076

See Benton ContaminantsEquity contextHow we read Superfund data
CLEANUP TIMELINE

Listing-date and cleanup-phase enrichment from EPA's per-site SEMS profile is queued for a follow-up ingest pass. Until then, this section will populate from EPA's published timeline data.

Anomaly engine

Notable Signals

No notable signals at this Superfund site for the current ingest. Cleanup-phase and SEMS-action flags are deferred to a follow-up engineering pass.

Contaminants of concern · per EPA SEMS

What's In This Site

Each row pairs a contaminant with the medium it was found in (the exposure pathway). Hover any named contaminant for an agency-cited health-risk summary. Cited count = number of SEMS decision records (RODs and related) that name the pair.

ContaminantPathwayCited
Cesium-137Health riskBeta/gamma emitter (half-life ~30 yr); whole-body irradiator; legacy of nuclear weapons fallout and reactor accidents. (EPA)Soil7
Cobalt-60Health riskGamma emitter (half-life ~5.3 yr); used in industrial radiography and cancer therapy; legacy contaminant at federal sites. (EPA)Soil7
Chromium(Vi)Health riskHexavalent chromium (Cr-VI) is an IARC Group 1 carcinogen via inhalation, causing lung cancer; trivalent chromium is far less toxic. (IARC, EPA)Soil6
Europium-152Soil6
Strontium-90Health riskBeta emitter (half-life ~29 yr); bone-seeking — chemically mimics calcium; legacy of nuclear weapons fallout. (EPA, ATSDR)Soil6
ArsenicHealth riskIARC Group 1 carcinogen via inhalation and ingestion. EPA MCL 10 µg/L; chronic exposure causes skin, lung, bladder cancer and cardiovascular disease. (IARC, EPA, ATSDR)Soil5
Chromium(Vi)Health riskHexavalent chromium (Cr-VI) is an IARC Group 1 carcinogen via inhalation, causing lung cancer; trivalent chromium is far less toxic. (IARC, EPA)Groundwater5
LeadHealth riskNeurotoxin. Even low childhood exposure impairs cognitive development; chronic adult exposure damages kidneys and the cardiovascular system. (EPA, ATSDR)Soil5
Strontium-90Health riskBeta emitter (half-life ~29 yr); bone-seeking — chemically mimics calcium; legacy of nuclear weapons fallout. (EPA, ATSDR)Groundwater5
ChromiumHealth riskHexavalent chromium (Cr-VI) is an IARC Group 1 carcinogen via inhalation, causing lung cancer; trivalent chromium is far less toxic. (IARC, EPA)Groundwater4
EuropiumSoil4
NitrateHealth riskDrinking-water nitrate causes methemoglobinemia ('blue-baby syndrome') in infants; EPA MCL is 10 mg/L as N. (EPA)Groundwater4
TritiumHealth riskHydrogen-3 (beta emitter, half-life ~12.3 yr); travels with water and is hard to remove from groundwater. EPA MCL 20,000 pCi/L. (EPA)Groundwater4
ArsenicHealth riskIARC Group 1 carcinogen via inhalation and ingestion. EPA MCL 10 µg/L; chronic exposure causes skin, lung, bladder cancer and cardiovascular disease. (IARC, EPA, ATSDR)Buildings/Structures3
CadmiumSoil3
Carbon-14Soil3
Cesium-137Health riskBeta/gamma emitter (half-life ~30 yr); whole-body irradiator; legacy of nuclear weapons fallout and reactor accidents. (EPA)Buildings/Structures3
Cobalt-60Health riskGamma emitter (half-life ~5.3 yr); used in industrial radiography and cancer therapy; legacy contaminant at federal sites. (EPA)Buildings/Structures3
Europium-152Buildings/Structures3
MercuryHealth riskNeurotoxin. Methylmercury bioaccumulates up the food chain and damages the developing nervous system. (EPA, ATSDR)Soil3
Nickel-63Soil3
Plutonium-239/240Buildings/Structures3
Plutonium-239/240Soil3
Strontium-90Health riskBeta emitter (half-life ~29 yr); bone-seeking — chemically mimics calcium; legacy of nuclear weapons fallout. (EPA, ATSDR)Buildings/Structures3
TrichloroetheneHealth riskTCE. IARC Group 1 carcinogen — kidney cancer; suspected liver cancer and non-Hodgkin lymphoma. EPA MCL 5 µg/L; common DNAPL groundwater plume contaminant. (IARC, EPA, ATSDR)Groundwater3
Aroclor 1254Health riskPCBs. IARC Group 1 carcinogen; immune, reproductive, and neurological effects; bioaccumulate in fish and breast milk. Banned in 1979; persist as legacy contamination. (IARC, EPA)Soil2
Aroclor 1260Health riskPCBs. IARC Group 1 carcinogen; immune, reproductive, and neurological effects; bioaccumulate in fish and breast milk. Banned in 1979; persist as legacy contamination. (IARC, EPA)Soil2
BariumHealth riskSoluble barium compounds are toxic if ingested, affecting the heart, kidneys, and nervous system. Insoluble forms (e.g. barium sulfate) are far less toxic. (EPA)Soil2
Benzo[A]PyreneHealth riskPAH; IARC Group 1 carcinogen; the prototypical PAH used to benchmark PAH-mixture cancer risk. EPA MCL 0.2 µg/L. (IARC, EPA)Soil2
CadmiumBuildings/Structures2

Showing the top 30 pairs by SEMS citation count. 74 additional (contaminant, pathway) pairs are recorded for this site.

Drinking-water linkage · SDWIS

No Groundwater PWSes Serving Communities Within 3 Miles

No SDWIS public water systems drawing groundwater (or mixed sources) serve a community whose centroid sits within 3 miles of this site. Empty results are not a guarantee of non-impact — distance is computed to served-place centroids, and SDWIS does not expose individual wellhead locations.

Methodology: served-city centroid (TIGER 2020) is used as the PWS coordinate. Source-water classification from SDWIS primary_source_code; only groundwater and mixed-source systems are queried. Click any system above for its full SDWIS profile.

Equity context · ACS 2018-2022 block-group demographics

Who Lives Near This Site

Benton County, Washington (no Census block groups within 1 mile and no host city — falling back to containing county): a population of 207,560. Why we surface this →

POPULATION SHARE
10.5%

Low-income

POPULATION SHARE
32.6%

People of color

POPULATION SHARE
8.0%

Under age 5

POPULATION SHARE
15.4%

Over age 64

Source: Census ACS 2018-2022 (5-year) + USEPA-clone EJ blockgroup stats (raw indicators + EJ disparity mirror). NPL site proximity contributes to the national EJ pattern; indicator-level percentile and disparity scores are surfaced on the county page and the state page.

Source. EPA Superfund Enterprise Management System (SEMS) · retrieved 2026-05-07. SEMS is a federal public-domain dataset under 17 USC §105.

What this is not. We report EPA's published Superfund record — site listing, status, and contaminants of concern as named in EPA's decision documents. We do not perform site visits, independent air or water sampling, or current-state health-risk assessment. NPL listing reflects EPA's Hazard Ranking Score at a point in time; it does not by itself describe present-day exposure.