To perform efficient activities aimed at managing population health risks, it is necessary to examine regularities related to distribution of chemical elements in the biosphere; especially in so called biogeochemical provinces of natural or technogenic origin. We used semimetals of arsenic and antimony as an example to show that similarity of their physical and chemical properties is accompanied with similar effects they produce on living organisms. However, amphoteric character of arsenic and antimony determines wide range of possible interactions between these elements and biological molecules in a body. As a result, combined influence exerted by these substances on living organisms leads to both antagonistic relations and competition between them and to synergy as well. Basing on reviewed literature data, we showed that animals selectively limited accumulation of arsenic in their bodies and consumed less toxic antimony in greater quantities in case of biochemical anomalies while plants were much less selective and accumulated toxic arsenic easily. Accordingly, any activities aimed at population health risk reduction that are to be performed on territories of biogeochemical provinces should take into account peculiarities related to accumulation of these elements in bodies of warm-blooded animals and people. These peculiarities should also be taken into account when hygienic research programs and hygienic inspections are drawn up. When such research is performed experts should do the following: to analyze ways and chemical forms of elements migration in the environment; to determine molecular mechanisms of elements penetration into a cell and conditions of various scenarios of their metabolism and biological efficiency.