The Chernobyl accident is recognised as the global disaster. The wide amount of civil population was involved, including children from 0 to 14 years old at the Chernobyl accident time (CAT). According to results of direct measurements the 40% of examined paediatric population received irradiation doses from 0.3 to 2.0 Gy on thyroid gland and the 10% - more than 2.0 Gy respectively. The intracorporal Cs-137 content via calculation for irradiation dose didn't exceed 0.5 rem for 97% of children. Simultaneously different quickly passing off reactions of nervous system, skin, mucosas, blood formula were revealed.

In 12 years after the accident as a result of large-scale epidemiologic study it was ascertained that children's population was exposed to both acute dose of radiation (evacuated children) and long-term chronic influence of the radioactive isotopes (children residing on the polluted territories).

This study is to define health effects of the low level chronic exposure. Children who was 15 year old and younger at CAT were object of the study. The cohort was divided into four subcohorts in conformity with types of the taken exposure and with doses accumulated for 10 years. Methods of computing of a cumulative morbidity (accumulated for 100000 person-years), relative and attributive risks, trends and other were used in order to estimate the morbidity indexes.

It has been revealed that there are negative health effects for population of the affected children residing on the polluted territories. Those health detriments are expressed in additional cases of endocrine system diseases - 24%, blood and hemopoietic organs diseases - 33%, digestive system diseases - 24%, mental disorders - 52% respectively and thyroid cancer with exceeding of an attributive fraction for persons having higher collective dose.