ISO 10253-2024 PDF

Full title and description

ISO 10253:2024 — Water quality — Marine algal growth inhibition test with Skeletonema sp. and Phaeodactylum tricornutum. This international standard specifies a laboratory method to determine the inhibition of growth of the unicellular marine algae Skeletonema sp. and Phaeodactylum tricornutum caused by substances, mixtures or environmental water samples (effluents, elutriates, etc.).

Abstract

The standard describes a 72-hour exposure test during which algal cell density is measured at regular intervals (at least every 24 hours) to calculate specific growth rates and percentage inhibition relative to controls. It is intended primarily for substances that remain in the test medium (readily water‑soluble and not significantly degraded during the test), with references to procedures for poorly soluble, volatile or metal compounds and for complex matrices.

General information

• Status: Published.
• Publication date: 10 July 2024 (ISO publication stage: 2024-07-10).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 13.060.70 (Water quality — biological methods).
• Edition / version: 4 (fourth edition, 2024).
• Number of pages: 26 (ISO edition). Note: some national/adopted versions or combined national forewords/annexes may show different pagination.

Scope

ISO 10253:2024 specifies a standardised algal growth inhibition test using the marine diatoms Skeletonema sp. and the pennate diatom Phaeodactylum tricornutum to assess toxic effects of chemicals and environmental samples in seawater. The method covers preparation of test media (synthetic or filtered natural seawater), inoculum preparation, selection of concentrations and replicates, incubation and measurement procedures, calculation of endpoints (e.g., specific growth rate inhibition, ECx values, yield), and validity criteria. Modifications and referenced standards are provided for testing poorly soluble materials, volatile compounds, metal compounds and complex environmental matrices.

Key topics and requirements

• Test organisms: Skeletonema sp. or Phaeodactylum tricornutum as specified; guidance on accepted strains and culture maintenance.
• Exposure period and measurements: (72 ± 2) h exposure with cell-density measurements at least every (24 ± 2) h to determine specific growth rates and yield.
• Test design and replicates: at least five concentrations in a geometric series (ratio ≤ 3.2), with three replicates per concentration and six replicates for controls (limit test option described).
• Test conditions: controlled temperature (~20 °C ± 2 °C), continuous light at specified irradiance, salinity and pH control, and gentle mixing or shaking to keep cells in suspension.
• Endpoints and data analysis: calculation of percent inhibition, ECx (effect concentrations), NOEC/LOEC where applicable, and statistical/graphical validity checks.
• Special cases and annexes: procedures for poorly soluble substances, effluents, elutriates, use of microwell methods for Phaeodactylum, and performance data/examples.

Typical use and users

Used by environmental and ecotoxicology laboratories, chemical and product manufacturers, regulators, and consultants for hazard assessment, environmental monitoring, effluent testing and registration studies. Laboratories apply the method for routine toxicity testing of marine‑relevant chemicals, for pre‑screening during chemical registration, and for monitoring impacts of discharges on coastal waters.

Related standards

ISO 10253:2024 references and aligns with other ISO and national standards covering sampling and test modifications, including ISO 14442 and ISO 5667‑16 for sample handling and special test procedures. National bodies often publish identical or adopted versions (for example, EN/BSI adoptions) with national forewords.

Keywords

marine algal test, algal growth inhibition, Skeletonema, Phaeodactylum tricornutum, water quality, ecotoxicity, ECx, NOEC, effluent testing, seawater test method.

FAQ

Q: What is this standard?

A: ISO 10253:2024 is an international standard that defines a laboratory method to measure growth inhibition of specified marine algae (Skeletonema sp. and Phaeodactylum tricornutum) caused by chemicals or environmental water samples.

Q: What does it cover?

A: It covers test organism selection and culture, test media and conditions, concentration series and replicates, exposure and measurement schedule (72-hour test with 24-hour intervals), calculation of growth-rate and yield endpoints, validity criteria and data interpretation, plus guidance for special matrices.

Q: Who typically uses it?

A: Accredited ecotoxicology and environmental testing laboratories, regulators, manufacturers performing environmental hazard assessments, and consultants involved in marine environmental monitoring.

Q: Is it current or superseded?

A: Current. The 2024 fourth edition (published 10 July 2024) supersedes earlier editions (for example the 2016 edition).

Q: Is it part of a series?

A: It is part of ISO’s water quality and biological testing suite; related documents (e.g., ISO 14442, ISO 5667‑16) provide complementary procedures for sample handling and modified testing of special matrices.

Q: What are the key keywords?

A: Marine algal growth inhibition, Skeletonema, Phaeodactylum tricornutum, ECx, NOEC, seawater toxicity test, water quality.