12.1. Toxicity

This section provides information on the toxic effects of substances or mixtures on aquatic and terrestrial organisms. It is crucial for environmental hazard classification and risk assessment, helping to determine appropriate risk management measures to protect ecosystems.

Aquatic Toxicity Overview

Aquatic toxicity data is essential for classifying substances according to their environmental hazards under the CLP Regulation (EC) No 1272/2008. This data typically includes:

  • Acute toxicity: Effects observed after short-term exposure (typically 24-96 hours)
  • Chronic toxicity: Effects observed after longer exposure periods (7 days to months)
  • Bioaccumulation: Tendency to accumulate in organisms
  • Degradation: Breakdown of substances in the environment

Key Aquatic Toxicity Endpoints:

  • LC50: Lethal Concentration causing 50% mortality in test organisms
  • EC50: Effective Concentration causing 50% of maximal effect
  • ErC50: Concentration causing 50% reduction in growth rate
  • NOEC: No Observed Effect Concentration
  • LOEC: Lowest Observed Effect Concentration

Aquatic Toxicity Test Species

Standard test species are used to assess aquatic toxicity:

  • Fish:
    • Oncorhynchus mykiss (Rainbow trout)
    • Pimephales promelas (Fathead minnow)
    • Danio rerio (Zebrafish)
    • Lepomis macrochirus (Bluegill sunfish)
  • Invertebrates:
    • Daphnia magna (Water flea)
    • Ceriodaphnia dubia (Water flea)
    • Americamysis bahia (Mysid shrimp)
  • Algae/Aquatic Plants:
    • Pseudokirchneriella subcapitata (Green algae)
    • Desmodesmus subspicatus (Green algae)
    • Lemna minor (Duckweed)

Terrestrial Toxicity

Terrestrial toxicity assessment evaluates effects on soil-dwelling organisms and land-based wildlife:

  • Soil Organisms:
    • Earthworms (Eisenia fetida)
    • Springtails (Folsomia candida)
    • Soil microorganisms
  • Plants:
    • Crop plants (various species)
    • Non-target plants
  • Birds:
    • Mallard duck (Anas platyrhynchos)
    • Bobwhite quail (Colinus virginianus)
  • Bees and Other Pollinators:
    • Honeybee (Apis mellifera)
    • Bumblebees (Bombus spp.)

Standard Test Methods

OECD Test Guidelines:

  • Fish:
    • OECD 203: Fish, Acute Toxicity Test
    • OECD 210: Fish, Early-life Stage Toxicity Test
    • OECD 212: Fish, Short-term Toxicity Test on Embryo and Sac-Fry Stages
    • OECD 215: Fish, Juvenile Growth Test
  • Invertebrates:
    • OECD 202: Daphnia sp. Acute Immobilisation Test
    • OECD 211: Daphnia magna Reproduction Test
  • Algae/Aquatic Plants:
    • OECD 201: Freshwater Alga and Cyanobacteria, Growth Inhibition Test
    • OECD 221: Lemna sp. Growth Inhibition Test
  • Terrestrial:
    • OECD 207: Earthworm, Acute Toxicity Tests
    • OECD 222: Earthworm Reproduction Test
    • OECD 208: Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test
    • OECD 213/214: Honeybee, Acute Oral/Contact Toxicity Test

Aquatic Toxicity Classification

Under the CLP Regulation (EC) No 1272/2008, substances are classified for aquatic toxicity as follows:

Classification Acute Toxicity Criteria Chronic Toxicity Criteria Pictogram
Aquatic Acute 1 LC50/EC50/ErC50 ≤ 1 mg/L - GHS09
Aquatic Chronic 1 LC50/EC50/ErC50 ≤ 1 mg/L NOEC or ECx ≤ 0.1 mg/L GHS09
Aquatic Chronic 2 1 < LC50/EC50/ErC50 ≤ 10 mg/L 0.1 < NOEC or ECx ≤ 1 mg/L GHS09
Aquatic Chronic 3 10 < LC50/EC50/ErC50 ≤ 100 mg/L 1 < NOEC or ECx ≤ 10 mg/L No pictogram
Aquatic Chronic 4 Low water solubility, no acute toxicity, not rapidly degradable, log Kow ≥ 4 - No pictogram

Example Toxicity Data

Species Endpoint Value Test Duration
Oncorhynchus mykiss (Rainbow trout) LC50 10 mg/L 96 hours
Daphnia magna (Water flea) EC50 8.5 mg/L 48 hours
Pseudokirchneriella subcapitata (Green algae) ErC50 12 mg/L 72 hours
Pimephales promelas (Fathead minnow) NOEC 1.2 mg/L 28 days

Based on this data, the substance would be classified as Aquatic Chronic Category 2.

Terrestrial Toxicity Data

Species Endpoint Value Test Duration
Anas platyrhynchos (Mallard duck) LD50 >2000 mg/kg Acute
Eisenia fetida (Earthworm) LC50 >1000 mg/kg soil 14 days
Apis mellifera (Honeybee) LD50 contact >100 μg/bee 48 hours
Soil microorganisms EC50 No significant impact 28 days

Factors Affecting Toxicity

Mixture Classification

For mixtures, classification is based on:

  1. Test data for the mixture as a whole (preferred approach)
  2. Bridging principles (using data from similar tested mixtures)
  3. Calculation method based on the classification of individual components

Calculation Method:

For acute aquatic toxicity:

Σ (Ci × L(E)C50i) ≤ 1

Where:

  • Ci = concentration of component i (weight percentage)
  • L(E)C50i = LC50 or EC50 for component i (mg/L)

For chronic aquatic toxicity, similar summation methods apply, taking into account M-factors for highly toxic components.

Regulatory Requirements

Quality Assurance Checklist

  • Verify that toxicity data is reported for all relevant trophic levels (fish, invertebrates, algae)
  • Ensure test methods are cited and comply with recognized guidelines
  • Check that classification is consistent with the reported toxicity data
  • Confirm that M-factors are provided for highly toxic substances
  • Verify that both acute and chronic data are provided when available
  • Ensure that the most sensitive species data is used for classification

Environmental Impact