Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
BS EN ISO 11268 — Effects of Pollutants on Earthworms (Soil Quality)
Soil quality — Effects of pollutants on earthworms — Parts 1, 2 and 3
📐 BS EN ISO 11268 is the British Standard series specifying test methods for the toxic effects of soil pollutants on earthworms, equivalent to the ISO 11268 series and implemented by BSI under the soil quality committee EH/4. Earthworms are key engineer organisms in soil ecosystems: their activity improves soil structure, nutrient cycling and organic-matter decomposition, and their sensitivity to pollutants makes them classic test organisms in soil ecotoxicology. The series covers the full gradient from laboratory acute toxicity, through reproduction toxicity, to field in-situ effect evaluation, providing standardized methods for chemical soil-ecological risk assessment, contaminated-site evaluation and soil protection.
💡 The test species used in this series are Eisenia fetida and Eisenia andrei, which are easy to culture and breed under laboratory conditions and are internationally recognized model species for earthworm ecotoxicology.
1. Series Overview and Scope 📌
The series applies to evaluating the ecotoxicological effects of chemicals, contaminated soils, sewage sludge and other test substances on earthworms. Part 1 specifies the acute toxicity test method (determination of acute toxicity to Eisenia fetida/Eisenia andrei); Part 2 specifies the reproduction-effect test method; Part 3 provides guidance on determining effects under field conditions. Together they form a tiered ecotoxicological evaluation system from laboratory screening to field confirmation.
From a drafting perspective, Parts 1 and 2 supersede and withdraw BS 7755-4.2.1:1994 and BS 7755-4.2.2:1998 respectively; Part 3 was renumbered by a 2015 corrigendum from BS ISO 11268-3:2014 to BS EN ISO 11268-3:2015.
⚠️ Earthworm toxicity results are highly relevant to soil-ecological risk assessment, but laboratory tests differ from real field conditions: the laboratory uses artificial soil, constant temperature and humidity, and a single species, whereas the field is affected by climate, indigenous communities and multiple contaminants in combination — extrapolation must acknowledge this uncertainty.
2. Series Structure and Key Content of Each Part 🔧
| Standard | Part Subject | Status | Core Content |
|---|---|---|---|
| BS EN ISO 11268-1:2015 | Part 1: Acute toxicity determination | 2015 edition; supersedes BS 7755-4.2.1:1994 | Determination of acute toxicity to Eisenia fetida/Eisenia andrei (e.g., LC50) |
| BS EN ISO 11268-2:2015 | Part 2: Reproduction-effect determination | 2015 edition; supersedes BS 7755-4.2.2:1998 | Determination of effects on reproduction (cocoons, hatching, juveniles) |
| BS EN ISO 11268-3:2015 | Part 3: Guidance on field determination | 2015 edition (renumbered from BS ISO 11268-3:2014) | Guidance on evaluating earthworm effects under field conditions |
3. Key Technical Requirements 🔬
3.1 Acute Toxicity Test (Part 1)
Part 1 specifies the method for determining acute toxicity in an artificial soil matrix: the test substance is added to standard artificial soil at several concentrations, healthy adult earthworms are inoculated, and the organisms are kept under specified temperature, humidity and light conditions for a set period (typically 14 days), recording mortality and computing toxicity endpoints such as the LC50. The standard specifies the composition of the test matrix, the age and health of the test organisms, the test vessels, light and temperature-humidity conditions, control and replicate design, statistical treatment of results, and validity criteria.
3.2 Reproduction-Effect Test (Part 2)
Part 2 specifies the reproduction test: over a longer period (typically 56 days) it measures the effect of the test substance on earthworm reproductive capacity, recording endpoints such as cocoon production, hatching rate and juvenile numbers, and computing parameters such as NOEC and ECx. Reproduction tests are more sensitive than acute tests to low-concentration long-term exposure and are an important line of evidence in soil-ecological risk assessment.
3.3 Guidance on Field Determination (Part 3)
Part 3 provides guidance on determining the effects of pollutants on earthworms under field conditions, covering site selection, plot design, survey of the indigenous earthworm community, sampling and statistical methods, and data interpretation, used to validate the extrapolation of laboratory results to real field ecosystems.
4. Engineering Practice 🛠️
- 🔍 Chemical registration assessment: earthworm acute/reproduction toxicity data commonly support the ecotoxicological evaluation in soil-exposure assessments of pesticides and industrial chemicals.
- 🔧 Contaminated-site assessment: combine soil physicochemical and biological-effect surveys to judge the impact of pollutants on soil ecological function.
- 📊 Sewage sludge and organic-fertilizer evaluation: assess the potential risk to soil organisms when sewage sludge, compost and similar are applied to soil.
- 📋 Ecological remediation and monitoring: use the recovery of the earthworm community as a bioindicator of soil-ecological remediation.
✅ Evaluation path: screen quickly with the Part 1 acute test, assess long-term low-dose effects with the Part 2 reproduction test, and where necessary confirm with the Part 3 field study — a tiered “laboratory-to-field” evidence chain that strengthens the reliability of the assessment conclusion.
5. Frequently Asked Questions ❓
❓ Q: Why are earthworms used as test organisms?
A: Earthworms are key soil species that directly contact soil contaminants and are easy to culture and breed in the laboratory; their toxic response reflects the potential impact of pollutants on the soil ecosystem.
A: Earthworms are key soil species that directly contact soil contaminants and are easy to culture and breed in the laboratory; their toxic response reflects the potential impact of pollutants on the soil ecosystem.
❓ Q: How long does the acute toxicity test normally run?
A: The acute test is usually 14 days, observing mortality and computing the LC50; the reproduction test normally runs about 56 days, observing cocoons, hatching and juvenile numbers.
A: The acute test is usually 14 days, observing mortality and computing the LC50; the reproduction test normally runs about 56 days, observing cocoons, hatching and juvenile numbers.
❓ Q: What is the difference between NOEC and LC50?
A: LC50 is the concentration causing 50% mortality (or effect), reflecting acute toxicity; NOEC is the no-observed-effect concentration, reflecting the safe level under long-term low-dose exposure. The two serve different assessment tiers.
A: LC50 is the concentration causing 50% mortality (or effect), reflecting acute toxicity; NOEC is the no-observed-effect concentration, reflecting the safe level under long-term low-dose exposure. The two serve different assessment tiers.
❓ Q: Why may field and laboratory results differ?
A: The field involves climate variation, indigenous communities, multiple contaminants in combination and soil heterogeneity, whereas laboratory conditions are controlled; such differences are normal, and extrapolation should follow Part 3 guidance with background data for interpretation.
A: The field involves climate variation, indigenous communities, multiple contaminants in combination and soil heterogeneity, whereas laboratory conditions are controlled; such differences are normal, and extrapolation should follow Part 3 guidance with background data for interpretation.
❓ Q: What test substances does this series apply to?
A: It applies to chemicals, contaminated soils, sewage sludge and solid wastes; for poorly water-soluble or volatile substances, appropriate addition and exposure methods should be used as specified.
A: It applies to chemicals, contaminated soils, sewage sludge and solid wastes; for poorly water-soluble or volatile substances, appropriate addition and exposure methods should be used as specified.