I can speak for my own field which is dentistry. There is evidence that researchers have gone to poorer countries where they can get away with doing unethical research on the people there, children included.

Some people may say….well intentionally inflicting a cavity….oh that’s no big deal! Let me say that if you intentionally inflict a cavity on someone who may not have access to a doctor, dentist or some antibiotics, it can be fatal. This is esp true in kids where cavities travel faster within the tooth and so do the subsequent dental infections that can eventually lead to asphyxiation, brain infection and death.

There is a looong history of using people in the Third World as guinea pigs and other medical abuses.

Also, (from: http://www.geocities.com/sassme.geo/sass-unicef.html) During the summer of 1995, the Catholic Women’s League of the Philippines won a restraining order against a two year old WHO and UNICEF anti-tetanus program. Two labs had found “B-hCG” sterilizing agent in the vaccine. The Filipino program had already “vaccinated” 3.4 million people (all women, mainly between the ages of 12-45). The hormone-laced vaccine was also discovered in Mexico, Nicaragua, Tanzania, India and possibly Nigeria. The anti-hCG hormone causes not only surreptitious sterilizations, but also incurable auto-immune disorders, miscarriages and birth defects.