T.V. Feofanova - Ph.D. (Phys.-Math.), Leading Research Scientist, FSBO SSC Institute of immunology of Federal medical-biological Agency of Russia, Moscow. E-mail: tatianafeofanova@yandex.ru
N.I. Khorseva - Ph.D. (Boil.), Senior Research Scientist, Federal State Budgetary Institution of the Science of the Russian Academy of Sciences Institute of Biochemical Physics named after N. M. Emanuel RAS, Moscow. E-mail: sheridan1957@mail.ru

We propose a new method for the estimation of the association between the two factors - the harmful effects (HE) and the negative outcome (NO). Each factor can have two values, can be either yes or no (yes - HE +, NO+, no - HE -, NO-). Outcomes are quantitative data. We offer the method of the selection of the negative outcome for them. A quantitative indicator of the living object has a range of average values, the low and high values. If the value of the indicator is low (high), we have NO+. If the value of indicator is the average value, we have NO-. Then, all objects are divided into 4 groups: group 1 (HE+, NO+, a - number of objects), group 2 (HE+, NO-, b - number of objects), group 3 (HE-, NO+, c - number of objects), group 4 (HE-, NO-, d - number of objects). These groups are a 2x2 contingency table [1]. We take the values of the groups (a, b, c, d) and estimate the association between HE + and NO+ with the help of Fisher-s exact test [2]. We used this method to evaluate the association between radiation and antioxidant system in the human body. We had these data for 104 people, who worked in the zone of the Chernobyl accident in 1986-1987 and for 34 people (control). Our results: the effect of radiation in 2 times increases the risk of negative changes in the system of antioxidant protection of the organism compared with the control.