Each kilometre of beach is littered with an average 7,700 pieces of rubbish, a survey has found. The garbage ranges from fridges to condoms, but the most common item is polystyrene foam. The foam, often from lunch boxes, poses a threat to sea creatures when it breaks into tiny balls. The Hong Kong Marine Conservation Society found 54,679 items of rubbish on 56 beaches. Plastics made up nearly half the total items, some of which would take up to 400 years to decompose naturally, said Frazer McGilvray, co-author of the Marine Debris Report. He said fishing nets and lines, plastic yokes from drink cans and plastic bands provided the biggest threat to marine animals and birds which could easily be suffocated if they became entangled. Last year, an endangered Chinese White dolphin was spotted struggling to escape from a fishing net. The five-month survey found 348 such nets. The origin of most debris was impossible to locate. The study found more than 13 per cent came from recreational sources, 7.5 per cent from fishing, 3.4 per cent from shipping, 2.8 per cent from fly tipping and one per cent from sewage. Researchers found condoms, sanitary towels and cotton buds on beaches. They saw this as a legacy of the inadequate sewage system. Report co-author Brenda Shaw said fly tipping was to blame for the larger items found, such as fridges and televisions. Twenty fridges had been dumped on one remote beach. Mrs Shaw said: 'It is dangerous. Children can get caught in a refrigerator. It is really disgusting.' The maximum fine for dumping at sea is $180,000, but Mrs Shaw said judges were handing down penalties of just $350.