Why it exists
It prevents very toxic low-concentration components from being underestimated.
Acute and chronic
Factors may differ between categories.
Source of the value
Verify the exact entry and regulatory status.
Summation method
Apply it only where the method requires it.
Updates
A changed factor requires reassessment.
Practical example
An Aquatic Acute 1 component with a verified M-factor is weighted using the value linked to the correct entry.
Checklist
Correct CAS
Correct category
Factor sourced
Version checked
Calculation retained
Common mistakes
×applying it to every component
×confusing acute and chronic
×ignoring the source
×omitting it from the sum
Frequently asked questions
Does every aquatic hazard have an M-factor?
No.
Is an M-factor a concentration limit?
No. It changes weighting in a summation method.
Does a general answer validate a specific product?
No. The actual composition, form, supplier data and intended use must be assessed.
Who should approve the result?
A competent person should review the data, method and internal consistency before supply.
Primary sources
Check the current consolidated version and the exact substance or product scope before use.