Why is discharging tank washings at sea generally prohibited or restricted?

• A. To prevent oil pollution and chemical contamination; washings must be processed by an OWS and disposed at port reception facilities.
• B. Because washings are harmless and can be dumped anywhere.
• C. To stop pollution but only for oil; chemicals allowed.
• D. Because washings attract fish.

Answer: (A)

Discharging tank washings at sea is restricted to prevent pollution of the marine environment. Tank washings carry oil residues and, in many cases, noxious chemical substances from cargo. Releasing them directly would spread oil slicks and toxic residues, harming marine life, water quality, and coastal areas. Regulations require that washings be treated on board—typically with an oily water separator—to reduce the oil content to permitted levels, and then discharged only under the allowed conditions or held for disposal at port reception facilities. That combination of treating the washings and disposing of them properly is what stops ocean pollution. The other options miss the pollution risk or misstate the rules.