ISO 6341-2012 PDF

Full title and description

ISO 6341:2012 — Water quality — Determination of the inhibition of the mobility of Daphnia magna Straus (Cladocera, Crustacea) — Acute toxicity test. This International Standard specifies a laboratory method to assess acute toxic effects of substances, effluents and water samples on the freshwater crustacean Daphnia magna by measuring inhibition of mobility (immobilisation) under defined conditions.

Abstract

ISO 6341:2012 describes a standardized acute immobilisation test using Daphnia magna to determine toxicity (e.g., EC50 values) for chemical substances, industrial and sewage effluents, treated/untreated wastewater, aqueous extracts and leachates, surface and ground waters, and sediment eluates/pore waters. The test evaluates the percentage immobilisation of neonate D. magna after 24 h or 48 h exposure and includes procedures for preliminary and definitive tests, control and reference checks, measurement of test concentrations, and reporting requirements.

General information

• Status: Published (confirmed current)
• Publication date: 15 October 2012 (Edition 4)
• Publisher: International Organization for Standardization (ISO)
• ICS / categories: 13.060.70 (Water quality — Biological methods)
• Edition / version: 4 (ISO 6341:2012)
• Number of pages: 22

Scope

The standard specifies an acute toxicity test to determine the inhibition of mobility (immobilisation) of Daphnia magna Straus following 24 h or 48 h exposure to test media. It is applicable to soluble chemical substances and stable suspensions/ dispersions, industrial and sewage effluents, treated or untreated wastewaters, aqueous extracts and leachates, surface and ground waters, and eluates or pore waters from freshwater sediments. The method includes requirements for culturing/test organisms, test media (Elendt M4 medium option), test design (preliminary, definitive, limit tests), reference-check procedures and criteria for validity and reporting.

Key topics and requirements

• Test organism: Daphnia magna Straus (neonates), age and culturing guidance (including use of ephippia where applicable).
• Exposure period: immobilisation assessed at 24 h or 48 h (user/national authority choice).
• Endpoint definition: organisms unable to swim within 15 s after gentle agitation are considered immobilised.
• Test design: preliminary range-finding and definitive tests (recommended minimum 20 daphnia per concentration, typically in four replicates of five each).
• Reference check: sensitivity verification using potassium dichromate (24 h EC50 expected range 0.6–2.1 mg/L).
• Water quality and conditions: use of defined dilution/culture media (Elendt M4 option), temperature control (specified range), dissolved oxygen monitoring (e.g., check DO in control and highest concentration — avoid batches with DO < 2 mg/L), and pH monitoring/limits.
• Concentration analysis: measure test substance concentrations at least at the highest and lowest concentrations at test start and end; results preferably based on measured concentrations or justified nominal values within ±20 %.
• Acceptance/validity criteria: control immobilisation ≤ 10 % and successful reference test with potassium dichromate in specified range; additional operational criteria (DO, test conditions) apply.
• Data analysis and reporting: calculation/estimation of 24 h or 48 h EC50 by appropriate statistical methods (probit, moving average, binomial methods, or graphical estimation), reporting of 0 % and 100 % immobilisation concentrations, LID where applicable, and full test details in the test report.

Typical use and users

Used by environmental and ecotoxicology laboratories, regulatory agencies, chemical manufacturers, wastewater and effluent monitoring laboratories, environmental consultants and research institutions to assess acute aquatic toxicity and to generate toxicity endpoints (EC50, NOEC/LOEC where applicable) for regulatory submissions, environmental monitoring, product safety assessment and hazard classification.

Related standards

Closely aligned with OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) and EU test method C.2. Related ISO standards and references include ISO 5667 series (sampling guidance, e.g., ISO 5667-16), ISO 5814 (dissolved oxygen measurement), ISO 10523 (pH), and other water-quality biological-method standards prepared by ISO/TC 147.

Keywords

Daphnia magna, acute toxicity, immobilisation, EC50, water quality, aquatic toxicity test, potassium dichromate (reference chemical), Elendt M4 medium, immobilisation test, OECD 202, effluent testing, sediment eluate, test validity criteria.

FAQ

Q: What is this standard?

A: ISO 6341:2012 is an international standard that specifies a laboratory method to determine acute toxicity to the freshwater crustacean Daphnia magna by measuring inhibition of mobility (immobilisation) after 24 or 48 hours of exposure.

Q: What does it cover?

A: It covers test organism selection and culture, test media and conditions (including an Elendt M4 medium option), preliminary and definitive test procedures, limit tests, concentration measurement, reference checks (potassium dichromate), validity criteria, data analysis (EC50 estimation) and required test reporting for chemical substances, effluents, waters, and sediment eluates/pore waters.

Q: Who typically uses it?

A: Accredited ecotoxicology and environmental testing labs, regulators, chemical producers, wastewater monitoring organizations, environmental consultancies and researchers use the standard for acute aquatic hazard assessment and regulatory testing.

Q: Is it current or superseded?

A: ISO 6341:2012 (4th edition) was published 15 October 2012. It was systematically reviewed and confirmed current by ISO (confirmed on 12 January 2024). The 2012 edition replaces the 1996 edition and remains the current ISO edition unless superseded by a later revision after that confirmation.

Q: Is it part of a series?

A: The standard is part of ISO/TC 147 (Water quality) biological-methods work and is related to other ISO water-quality standards (e.g., ISO 5667 sampling guidance, ISO 5814 dissolved oxygen, ISO 10523 pH) and to internationally used methods such as OECD 202 and EU method C.2.

Q: What are the key keywords?

A: Daphnia magna; acute toxicity; immobilisation; EC50; water quality; aquatic ecotoxicology; potassium dichromate; Elendt M4; OECD 202; effluent testing; validity criteria.