it is similar to 小龍蝦, cray fish, some place in China, when people who ate them had cramps, and other serious symptoms, and rumor has it that they were washed by industrial chemicals to make them shiny! but what can you do? how can you prevent?
Well....how do you know that HK restaurant are not using the same thing ? Those guys can easily import from China as it is very cheap to get. Not much you can do unless you don't go out & eat......