Soil contamination statistics show both a large management challenge and very different risks across landscapes. European assessments count millions of potentially contaminated sites, while agricultural surveys find pesticide residues in most sampled topsoils. Urban garden studies also show why location, contaminant, sampling design, and screening benchmark matter when interpreting a result.
Contents
- How widespread is soil contamination in Europe?
- What do contaminated-site management statistics show?
- Which contaminants are most common?
- How prevalent are pesticide residues?
- What heavy-metal measurements are available?
- What do urban and community garden studies find?
- What concentrations and benchmarks are reported for gardens?
How widespread is soil contamination in Europe?
The European Environment Agency (EEA) estimated about 2.8 million potentially contaminated sites in the European Union in a 2016 projection. The same projection reported an average density of 15.7 potentially contaminated sites per square kilometre of artificial surface. An EEA update using extensive inventories from 16 countries found a higher average density of 23 sites per square kilometre of artificial surface in 2022. These are estimates of potentially contaminated locations, not a count of sites confirmed to pose the same level of risk. (EEA, “Progress in the management of contaminated sites in Europe”)
Coverage and registration remain uneven. In the EEA’s 2020 assessment, only 24% of potentially contaminated EU sites were inventoried. In the 2022 assessment, more than 50% were unregistered or had not been risk-assessed. In the comparison underlying the 2016 reporting, only 12 European countries had detailed contaminated-site registers, while 10 countries had no national register or covered only a very limited set of polluting activities. (EEA, “Soil”; EEA, “Progress in the management of contaminated sites in Europe”)
The reporting network expanded over time: the number of countries reporting statistics on registered potentially contaminated sites rose from 18 to 23 between 2006 and 2016. That increase improves the information base, but it does not make figures from different periods directly interchangeable. (EEA, “Progress in the management of contaminated sites in Europe”)
What do contaminated-site management statistics show?
EU countries reported 115,000 contaminated sites remediated in 2016, equivalent to 8.3% of currently registered potentially contaminated sites. The EEA projected that at least 166,000 additional EU sites might need risk-reduction measures or remediation. Assuming EUR100,000 per site, the projected cost for those remaining sites was EUR16.6 billion. The cost is an EEA projection based on that assumption, not a universal remediation price. (EEA, “Progress in the management of contaminated sites in Europe”)
Reported national progress in detecting, investigating, and remediating contaminated sites ranged from 20 to 3,000 sites per year in the 2016 assessment. The total number of sites under remediation changed over the reported years:
| Year | Sites under remediation |
|---|---|
| 2006 | 6,269 |
| 2011 | 12,073 |
| 2016 | 10,539 |
The EEA estimated that completing remediation could take 10 years at the average current rate of 614 sites per country per year, or 47 years at the median national rate of 129 sites per country per year. Those timeframes are estimates derived from reported rates and should not be read as a fixed schedule for every country or site. (EEA, “Progress in the management of contaminated sites in Europe”)
Which contaminants are most common?
The EEA’s 2011 assessment of contaminated-site solid-matrix observations identified heavy metals as the most common contaminant group, affecting 34.8% of observations. Mineral oil affected 23.8%, followed by polycyclic aromatic hydrocarbons at 10.9% and aromatic hydrocarbons at 10.2%. Chlorinated hydrocarbons accounted for 8.3%, while the “other” category accounted for 9.3%.
| Contaminant group | Share of solid-matrix observations |
|---|---|
| Heavy metals | 34.8% |
| Mineral oil | 23.8% |
| Polycyclic aromatic hydrocarbons | 10.9% |
| Aromatic hydrocarbons | 10.2% |
| Chlorinated hydrocarbons | 8.3% |
| Other | 9.3% |
The same EEA assessment estimated 2.5 million contaminated sites across the 39 EEA member and cooperating countries and identified manufacturing as responsible for around 60% of contaminated sites. The observation percentages describe the distribution of reported solid-matrix observations; they do not mean that every site contains every listed contaminant. (EEA, “SOER 2015: Soil — Soil contamination from industry”)
How prevalent are pesticide residues?
Pesticide sales in the EU remained around 350,000 tonnes per year from 2011 through 2020. Sales are not the same measure as soil concentration, but they provide context for the continued use of agricultural pesticides during that period. (EEA, “How pesticides impact human health and ecosystems in Europe”)
In a study based on the 2015 LUCAS survey, pesticide residues were found in 83% of EU agricultural topsoil samples. Mixtures containing two or more pesticide residues occurred in 58% of samples. Glyphosate plus its metabolite AMPA represented 25% of all pesticide combinations detected in the study. These findings describe the sampled agricultural topsoils and the study’s analytical coverage; they are not a direct estimate of contamination in every European soil type. (EEA, “How pesticides impact human health and ecosystems in Europe”)
What heavy-metal measurements are available?
The Joint Research Centre’s heavy-metal topsoil dataset, based on LUCAS 2009 data and published in 2018, provides concentration maps for 10 elements: arsenic, cadmium, chromium, copper, mercury, manganese, antimony, cobalt, nickel, and lead. The maps use a 1-kilometre spatial resolution and cover EU27, defined for this dataset as the EU28 excluding Croatia. (JRC, “Maps of heavy metals in the soils of the EU, based on LUCAS 2009 HM data”)
The dataset’s stated detection limits vary substantially by element. They were 2.84 mg/kg for arsenic, 0.07 mg/kg for cadmium, 0.32 mg/kg for chromium, 0.26 mg/kg for copper, 0.00005 mg/kg for mercury, and 1.16 mg/kg for lead. A detection limit indicates the analytical reporting threshold in the dataset; it is not a health-based screening benchmark. (JRC, “Maps of heavy metals in the soils of the EU, based on LUCAS 2009 HM data”)
What do urban and community garden studies find?
A 2015 New York City study measured trace metals in 1,652 garden-soil samples from 904 gardens. About 21% of community-garden samples exceeded the study’s combined lead-and-arsenic Soil Cleanup Objective limits, compared with about 71% of home-garden samples. Less than 3% of all home- and community-garden samples met unrestricted-use criteria for all measured trace metals. These percentages use the study’s criteria and should not be generalized to all urban gardens. (EPA, “Trace metal contamination in New York City garden soils”)
The median lead concentration across the 1,652 New York City urban-garden soil samples was 355 mg/kg. Three percent of community-garden samples exceeded 1,200 mg/kg lead, compared with 18% of home-garden samples. In a 2016 study, median lead was 96 mg/kg in 508 garden-bed samples and 181 mg/kg in 54 non-bed samples. Mean dust lead attributed to soil tracking was 72 mg/kg. (EPA, “Integrated Science Assessment for Lead Appendix 2: Exposure, Toxicokinetics, and Biomarkers January 2024”)
Results can vary even within the urban-garden context. A Terre Haute, Indiana study found surface-soil lead ranging from background levels to above 800 ppm. The range is a reminder that a city, garden type, or sample location alone cannot substitute for site-specific testing. (EPA, “Integrated Science Assessment for Lead Appendix 2: Exposure, Toxicokinetics, and Biomarkers January 2024”)
What concentrations and benchmarks are reported for gardens?
An EPA review of Puerto Rico urban garden soils and plants summarized reported total soil concentrations across the conterminous United States of 0.1–55 mg/kg for arsenic and 2–300 mg/kg for lead. The review also reported plant lead concentrations of 0.7–7.2 mg/kg in background soils and 2.5–82 mg/kg in soils containing 200 mg/kg total lead. These are literature ranges summarized in the 2015 review, not a single national survey. (EPA, “Puerto Rico Urban Garden Soils and Plants Study Summary”)
The same review identified EPA ecological soil screening levels for plants of 18 mg/kg for arsenic and 120 mg/kg for lead. It identified 40 mg/kg arsenic as a general unrestricted-residential soil screening level and 400 mg/kg lead as the OSWER human-health soil screening concentration for unrestricted residential contact. Screening levels serve specific assessment purposes; they should not be treated as universal definitions of safe gardening soil. (EPA, “Puerto Rico Urban Garden Soils and Plants Study Summary”)
At the El Pilar urban-garden location, two sampled soils exceeded 100 mg/kg lead, the urban-garden guideline cited in the EPA review. The Puerto Rico tables reported 55.4 mg/kg arsenic and 130.9 mg/kg lead in El Pilar sample EP1, and 14.1 mg/kg arsenic and 172.0 mg/kg lead in El Pilar composite EP6. Einstein School composite soil contained 8.11 mg/kg arsenic and 35.6 mg/kg lead, while Las Monjas composite soil contained 8.8 mg/kg arsenic and 34.7 mg/kg lead. (EPA, “Puerto Rico Urban Garden Soils and Plants Study Summary”)
Taken together, these measurements show why soil contamination statistics need their geography, sampling period, contaminant, and benchmark stated alongside the number. European inventories describe potential sites at a continental scale; LUCAS studies measure agricultural topsoil; and urban-garden studies report results from particular gardens and criteria. Those measures answer different questions and should not be combined into one generalized contamination rate.