Category Z Noxious Liquid Substances are defined as substances that, when discharged, present a minor hazard and justify less stringent restrictions.

• A. They present a minor hazard and justify less stringent restrictions on the discharge.
• B. They present a major hazard.
• C. They present no hazard.
• D. They are OS.

Answer: (A)

Understanding how Noxious Liquid Substances are classified to determine discharge restrictions under MARPOL Annex II. The system ranks substances by how hazardous they are to the marine environment, so the least hazardous categories justify fewer or less stringent restrictions on discharge. Substances in Category Z are recognized as presenting only a minor hazard if discharged, which is why they are allowed to be discharged under less stringent rules than the higher-hazard categories. This is exactly what the statement describes. In contrast, substances with greater hazards fall into stricter categories, and there is a separate OS category for substances that don’t fit X, Y, or Z but remain regulated under Annex II.