Japan's Soil Contamination Countermeasures Act (土壌汚染対策法, abbreviated SCCA) has been in force since 2003 and substantially amended in 2010 and again in 2017. For anyone managing a site closure, redeveloping former factory land, or responding to a municipal investigation order, the law's scope is not always intuitive. It designates exactly 26 hazardous substances, assigns each substance to one of three categories depending on how it behaves in soil, and prescribes specific analytical methods for each. Getting those distinctions right determines how a site is classified, what remediation obligation follows, and what costs a landowner or tenant faces. This article walks through the statute's logic, names every designated substance, and explains the two primary test protocols — elution testing and content testing — so that the obligations are legible before you engage a certified investigator.
Why the SCCA was enacted and what it actually governs ¶
Before 2003, soil contamination in Japan was addressed patchwork-style through the Water Pollution Control Act and local ordinances. Incidents at former chromate-manufacturing sites in Tokyo and cadmium-contaminated agricultural land in Toyama made the gaps obvious. The SCCA created a unified national framework with three triggers for mandatory investigation: a prefectural governor's order when health risk is suspected, voluntary notification by a landowner, and notification upon cessation of use of a facility handling designated hazardous substances. The law applies to land, not groundwater per se, though groundwater standards are used as the elution benchmark. It does not apply to agricultural land under the Agricultural Land Soil Pollution Prevention Law, which handles cadmium in rice paddies under a separate regime.
The three substance categories and the logic behind them ¶
The 26 designated substances are split into three groups based on their primary migration pathway and the tests required. First Group substances are volatile organic compounds — they move through soil vapor and dissolve readily into groundwater, so only elution testing is required. Second Group substances are heavy metals and similar inorganic compounds whose soil content matters independently of leachate, so both elution testing and content testing are required. Third Group substances are organochlorine pesticides and related compounds that bind strongly to soil particles; again, both test types apply. The grouping determines analytical cost and investigation depth. A site contaminated only with trichloroethylene sits in a simpler analytical category than one contaminated with lead or arsenic.
All 26 designated hazardous substances by group ¶
First Group (volatile organics, elution test only): tetrachloroethylene, trichloroethylene, cis-1,2-dichloroethylene, 1,1-dichloroethylene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,2-dichloroethane, dichloromethane, chloroform, carbon tetrachloride, 1,3-dichloropropene, benzene. Twelve substances total, all solvents or chlorinated hydrocarbons widely used in dry cleaning, metalworking, and semiconductor fabrication. Second Group (heavy metals and inorganics, both tests): cadmium and its compounds, hexavalent chromium compounds, cyanide compounds, mercury and its compounds, selenium and its compounds, lead and its compounds, arsenic and its compounds, fluorine and its compounds, boron and its compounds. Nine substances covering the metals most associated with industrial process waste. Third Group (pesticides and specific organics, both tests): simazine, thiuram, thiobencarb, PCBs (polychlorinated biphenyls), and organic phosphorus compounds. Five substances, several now banned from production but persistent in legacy industrial and agricultural sites.
Elution testing: method, reference solution, and standards ¶
Elution testing simulates the leaching of contaminants into groundwater. The standard method, defined in Environment Ministry Notification No. 18 of 2003, requires a soil sample to be mixed with pure water at a ratio of 1:10 (soil weight to water volume) and agitated continuously for six hours at room temperature. The extract is then filtered through a 0.45-micrometer membrane filter before analysis. Results are compared against elution standard values, which mirror Japan's groundwater quality environmental standards. For example, the elution standard for lead is 0.01 mg/L; for arsenic, 0.01 mg/L; for tetrachloroethylene, 0.01 mg/L; for benzene, 0.01 mg/L. Exceeding the standard in the elution test places the site in a contamination designation category that triggers a remediation or risk management obligation.
Content testing: method, digestion, and standards ¶
Content testing measures the total concentration of a substance bound within the soil matrix itself, regardless of whether it would leach under natural conditions. It applies only to Second Group and Third Group substances. The standard digestion method for most heavy metals involves dissolving a dried and sieved soil sample in a mixture of hydrochloric acid and nitric acid at elevated temperature, then analyzing the solution by atomic absorption spectrometry or ICP-OES. Content standard values are set independently of elution standards and reflect long-term accumulation risk. The content standard for lead is 150 mg/kg; for arsenic, 150 mg/kg; for cadmium, 45 mg/kg; for fluorine, 4,000 mg/kg. A site can fail content standards while passing elution standards, particularly for metals in alkaline soils where leaching is suppressed but total load is high.
How sampling grids and investigation phases work in practice ¶
A SCCA investigation proceeds in two phases. Phase 1 (第一段階) covers the entire site area divided into 10m x 10m grid units. Surface soil is collected from a depth of zero to five centimeters for volatile First Group substances; for Second and Third Group substances, samples are taken from a depth of zero to 50 centimeters. If Phase 1 reveals exceedances, Phase 2 (第二段階) involves boring investigations to map vertical contamination extent, typically drilling to the depth of the lowest groundwater-bearing layer encountered. Results feed into a risk assessment distinguishing between areas with direct ingestion risk (人の健康被害が生ずるおそれ区域, designated contaminated areas) and areas where groundwater risk alone is present. The distinction affects what remediation method is considered acceptable — in situ containment is permitted in some groundwater-risk-only scenarios.
Certified investigators, reporting obligations, and the contamination register ¶
Only certified soil contamination site investigators (指定調査機関) licensed under Article 3 of the SCCA may conduct mandatory investigations. As of 2024, approximately 1,900 designated investigation organizations hold this license across Japan. Their reports are submitted to the prefectural governor, who determines whether the site is entered into the contamination register (汚染状況報告). Once registered, the site cannot be sold or subdivided without disclosure. Remediation plans must also be submitted and approved before work begins. Approved remediation methods include soil excavation and disposal, soil washing, in situ chemical treatment, capping, and pump-and-treat for dissolved plumes. The investigator's role ends at characterization; remediation contractors are a separate category, though some large environmental engineering firms hold both licenses.
The SCCA's framework is precise in structure but demands careful reading at each step — the substance group determines the test, the test determines the standard, and the standard determines the regulatory pathway. Silt Lab Zone holds a designated investigation organization license and conducts both elution and content testing across all 26 substances at its Osaka facility, with reporting turnaround typically within 15 business days of sample receipt.