A. industrially polluted soils
B. rock and soil chemistry
C. naturally polluted soils
D. the pathways of metals into the food chain
E. the element of iodine
F. the persistence of heavy metals
It is extremely necessary to study the long -term effects caused by living on ______.

Also, several legal requirements (56) be met before the procedure.
The candidate must provide proof from police that he or she has does not have any criminal offenses in the past.
Police must also agree to change the sex status on the identity card of the (57) receiver before the operation can, take (58) .
The advent of such a guideline (59) to show that the government is concerned (60) the needs of a relatively small (61) of people who want to change sex.
But doctors also warn that all stakeholders, including the hospital and prospective receivers, should be highly cautious about this surgery.
The operation is more than a medical procedure due (62) its huge social and legal consequences. Doctors should make it clear to those (63) sex-change surgeries that the option always remains to continue to live in the original role. The guideline requires surgeons to tell patients about other options (64) hormone therapy. They are also required to explain the risks involved, and underlying social barriers including discrimination, and administrative recognition and approval.
For the candidates, the surgery itself is not the big issue (65) the long run. The real issue is the kind of life he or she will have to lead afterward.