Which statement best describes Category X Noxious Liquid Substances under MARPOL Annex II?

• A. They pose no hazard and can be discharged freely.
• B. Category X Noxious Liquid Substances are considered to present a major hazard to marine resources or human health, and their discharge is prohibited.
• C. They present a hazard only to amenities and require no restrictions.
• D. They are outside Annex II and not regulated.

Answer: (B)

Noxious Liquid Substances are graded in MARPOL Annex II by how dangerous they are, with Category X representing the highest level of hazard. Substances in this category pose a major risk to marine resources or human health, so discharging them at sea is prohibited. Ships must retain residues or washings and dispose of them only at port reception facilities, ensuring the most dangerous cargoes don’t contaminate the ocean.

That stricter rule makes sense because the potential harm is greatest, unlike the other statements which either downplay the hazard, suggest only minimal restrictions, or imply the substance isn’t covered by Annex II.