Asian skin lighteners, could I get mercury poisoning?

Yes. Lighteners containing mercury are banned in the US, but some lighteners manufactured in Asia and other foreign countries do contain mercury. If the concentration is high enough and it is applied often, mercury poisoning is a real possibility. Avoid any topical product that contains mercury.
Yes. Some of these creams have mercury at concentrations thousands of times higher than that allowed by the fda. Some people using these creams have been treated for mercury poisoning. See http://www.Medpagetoday.Com/dermatology/generaldermatology/31690 for more info.