HP5: Specific target organ toxicity (STOT) / aspiration toxicity
Waste which can cause specific target organ toxicity either from a single or repeated exposure, or which causes acute toxic effects following aspiration.
What this usually means in practice
HP5 covers wastes that can damage specific organs after one exposure or repeated exposure, or that can be dangerous if aspirated into the lungs. It is often relevant for solvent-rich mixtures, hydrocarbons and wastes containing toxic organ-specific substances.
Definition
Exact definition wording taken from WM3 Appendix C / Annex III for this hazardous property.
waste which can cause specific target organ toxicity either from a single or repeated exposure, or which cause acute toxic effects following aspiration
What to check when assessing this property
Use the official definition, composition data and waste-process knowledge together. These points are meant to help frame the assessment, not replace WM3.
- Review H370, H371, H372, H373, H335 and H304 classifications and their concentration thresholds.
- For aspiration toxicity, check whether the viscosity criteria are met as well as the presence of H304 substances.
- Use process knowledge to identify likely inhalation or aspiration risk pathways, not just skin contact.
Supporting points
Additional points shown where the official definition or WM3 guidance breaks the hazard into categories or clarifications.
- H370 and H372 trigger HP5 at an individual substance concentration of 1% or more.
- H371 and H373 trigger HP5 at 10% or more; H335 triggers HP5 at 20% or more.
- H304 Asp. Tox. 1 triggers HP5 at a total concentration of 10% or more only where the overall kinematic viscosity at 40°C does not exceed 20.5 mm²/s.
How to use this page
Hazardous properties explain why a waste may be hazardous. They sit alongside EWC classification and they do not replace formal WM3 assessment or site acceptance checks.
1. Start with the waste
Identify the likely EWC entry, the process that produced the waste and whether it is part of a mirror-entry assessment.
2. Check the hazard evidence
Use composition data, SDSs, testing, pH, flash point and process knowledge as relevant to the property in question.
3. Confirm the final outcome
Confirm the conclusion against WM3 and any permit-specific or site-specific acceptance requirements before relying on it.
Wording is based on Annex III of the consolidated Waste Framework Directive opens in a new tab and should be used alongside Waste classification technical guidance (WM3, 3rd edition, 2021) — GOV.UK opens in a new tab.