# The Impact of Tritium in the Environment
## 4 Biological Effects
Therefore, the uniform distribution characteristic of tritium water is not typical for organically bound tritium and can lead to uneven exposure of certain cells and organs (cells) of the body [52]. \begin{table}
\begin{tabular}{c c c c c} \hline
**County** & **Source** & **TRL** & **CRC** & **Equivalent Dose/IDC [\(\mu\)Sv.y\({}^{-1}\)]** \\ \hline Recommended for EU & & & & \\ countries & [57] & 100 & 5/7 & 1.31/100 \\ \hline Switzerland & [73] & 100 & 5/7 & 1.31/100 \\ \hline Norway & [74] & 100 & 5/7 & 1.31/100 \\ \hline USA & [75] & 740 & 36/52 & 9.72/40 \\ \hline Canada & [76; 77] & 700 & 338/490 & 92/50 \\ \hline Russia & [78] & 7600 & 367/523 & 100/1000 \\ \hline Recommended by the WHO & [78] & 10,000 & 482/700 & 131/100 \\ \hline Finland & [79; 80] & 30,000 & 1447/2100 & 394/100 \\ \hline Ukraine & [81] & 30,000 & 1447/2100 & 394/1000 \\ \hline Japan & [82; 83] & 60,000 1  & 2894/4200 & 788.4/1000 \\ \hline Australia & [72] & 76,103 & 3671/5228 & 100/1000 \\ \hline \end{tabular}
\end{table} 
Table 4: Tritium water regulatory limits (TRLs) around the world. The RBE is calculated (with a linear dependence of the effect under study on the dose of both compared types of ionizing radiation) as the ratio of the angle of the slope of the dose line of the test radiation to the angle of the slope of the similar line of the standard radiation, with the different dose dependence being the ratio of isoeffective (causing the same effect) doses of the standard and test radiation. The dependence of the RBE on the dose may be different. The RBE of radiation depends mainly on differences in the spatial distribution of the absorbed energy in the irradiated biosynthetic, as measured by linear energy losses per unit length of the ionizing particle's travel. The dependence of the RBE on the linear energy transfer factor (LET) varies for different objects and in different biological responses to irradiation. The efficiency of radiation with a low LET is usually similar. As the LET increases, the RBE usually increases as well. The RBE coefficient for electron, positron, X-ray, and gamma radiation, as well as for fast protons, is usually close to 1; for alpha particles and fast neutrons, it increases to 10; and for heavy multi-charge ions and recoil nuclei, it increases to 20 [91; 92]. Compared to other \(\beta\)-emitters, such as \({}^{137}\)Cs, the energy of the \(\beta\) particle produced by tritium decay is low, which leads to the comparative safety of direct tritium exposure. However, the LET factor for the passage of a \(\beta\) particle produced by tritium decay through living tissues is 23 times higher than for a \(\beta\) particle produced by \({}^{137}\)Cs decay. Accordingly, the number of ionic pairs formed during its passage through living tissue is almost 25 times higher, which leads to a much greater destructive effect of tritium exposure on living tissues. For comparison, the energy of \(\alpha\) radiation from \({}^{239}\)Pu is almost 1000 times higher, and the energy-to-length ratio and, accordingly, the ionization density are only 10 times higher than for a \(\beta\) tritium particle [52]. Studies in cellular radiobiology have shown that the RBE of high-energy radiation with a low LET (gamma radiation 2-5 MeV, electrons, \({}^{60}\)Co) is 3-4 times lower than that of low-energy radiation with a low LET (X-rays, tritium beta rays) [93]. The RBE of \({}^{137}\)Cs relative to that of 6 MV X-rays was experimentally determined to be \(\sim\)1.00 [94]. Given the significant dependence of tritium's RBE on the radiation dose, the ICRP recommends using a value of at least 1 (Table 5). For different age groups, when incorporated into different body tissues, experimentally obtained average values of tritium's RBE exceed those of X-rays by 2.3-9.8 times.