Calculator Inputs
Enter toxicity, persistence, exposure, and site adjustment values. The result appears above this form after submission.
Formula Used
Acute Score = min((Concentration / LC50) × 100, 300)
Higher values indicate stronger short-term aquatic toxicity pressure.
Chronic Score = min((Concentration / NOEC) × 100, 300)
This score emphasizes longer-term ecological effects and chronic exposure sensitivity.
Persistence Score = min((Half-Life / 180) × 100, 100)
Longer persistence raises the environmental residence contribution.
Bioaccumulation Score = min((log10(BAF + 1) / 5) × 100, 100)
This compresses very large BAF values into a usable comparison scale.
Base Index = (Acute × 0.35) + (Chronic × 0.35) + (Persistence × 0.15) + (Bioaccumulation × 0.15)
Weights emphasize toxicity while still considering fate and buildup behavior.
Final Ecotoxicity Index = Base Index × (1 + Exposure Days / 60) × Sensitive Species Factor × Regulatory Safety Factor ÷ Dilution Factor
Site exposure, ecological sensitivity, control conservatism, and dilution adjust the final index.
How to Use This Calculator
- Enter the chemical or mixture name and an optional sample identifier.
- Provide the measured concentration in the receiving medium, typically water.
- Enter a short-term effect threshold such as LC50 or EC50.
- Enter a chronic benchmark such as NOEC or PNEC.
- Supply half-life and bioaccumulation values for persistence and buildup pressure.
- Set exposure days, species sensitivity, safety factor, and dilution factor.
- Click the calculate button to show the result above the form.
- Review the breakdown table, plotly graph, and risk band.
- Use the export buttons to save CSV and PDF output.
Example Data Table
| Substance | Concentration (mg/L) | LC50 (mg/L) | NOEC (mg/L) | Half-Life (days) | BAF | Exposure Days | Sensitivity | Safety | Dilution | Index | Band |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Copper Sulfate | 0.08 | 0.50 | 0.02 | 45 | 120 | 12 | 1.6 | 1.2 | 1.5 | 185.24 | Very High |
| Atrazine | 0.012 | 11.00 | 0.10 | 60 | 35 | 20 | 1.3 | 1.1 | 1.0 | 26.52 | Moderate |
| Phenol | 0.30 | 8.90 | 0.75 | 15 | 17 | 5 | 1.1 | 1.0 | 2.5 | 9.63 | Low |
These examples illustrate how strong chronic toxicity, persistence, or limited dilution can shift the final index quickly.
FAQs
1. What does the ecotoxicity index represent?
It is a weighted screening score that combines toxicity thresholds, persistence, bioaccumulation, exposure frequency, sensitivity, and dilution into one comparison value.
2. Is this a regulatory compliance result?
No. It is a decision-support metric for prioritization and comparison. Final compliance decisions should still rely on approved methods, local guidance, and complete site data.
3. Why are LC50 and NOEC both included?
LC50 or EC50 captures acute effects, while NOEC or PNEC addresses chronic sensitivity. Using both helps reflect immediate and long-duration ecological pressure.
4. Why is log scaling used for bioaccumulation?
BAF values can vary across several orders of magnitude. Log scaling keeps the score useful and prevents extremely large values from dominating every result.
5. How should I choose the sensitive species factor?
Use higher values when rare, juvenile, or especially vulnerable organisms are present. Keep the factor lower when the receiving environment is less sensitive.
6. What does the dilution factor do?
It reduces the final score when mixing, dispersion, or dilution lowers effective exposure. Smaller dilution means the final ecological pressure remains higher.
7. Can I use mixture data in this calculator?
Yes, but use representative composite values carefully. For complex mixtures, a constituent-by-constituent review is usually more defensible than a single aggregate score.
8. What risk band should trigger action first?
High, Very High, and Severe bands usually deserve immediate review. Start by checking chronic thresholds, dilution assumptions, and whether exposure can be reduced.