Appetite for danger

the "healthy worker' effect has been a mystery to scientists. This effect is a paradoxical situation in which people working with hazardous chemicals, or those exposed to radiation at their job, often appear more healthy that the general population. Epidemiologists have suspected that among people employed in jobs involving hazardous chemicals, those who are more adversely affected by exposure to toxic chemicals tend to leave their jobs, while those who are more resilient remain in the workforce. But this could not be proved at the genetic level. Until now, that is.

A recent study involving a small group of Costa Rican banana farmers has thrown some extraordinary clues about jobs that