Int. J. Environ. Res. Public Health 2009, 6 193 In addition to various types of cancer, chronic radiation sickness (CRS) has also been suggested as having detrimental health effects on local residents around the Mayak PA. Dr. A.K. Guskova and Dr. G.D. Baysogolov first described CRS in several hundred workers at the Mayak PA: it was later diagnosed in riverside residents during the early 1950s [47]. Little agreement on what specific symptoms arise from chronic exposure to doses approaching 0.5 to 1.0 Gy yr-1 was found in the wider scientific community, though a key symptom was impairment of the hemopoietic system (formation of blood cells) often accompanied with neurological and immune disorders and hypotension. According to Kossenko et al., [45] no new cases of CRS have been diagnosed in recent years and symptoms declined when patients were removed from chronic exposure environments, usually resulting in recovery. 3.2. Observed Health Effects in the Techa River Area Kossenko and Degteva [28] reported an increase in total cancer mortality for riverside residents during the period 1950-1982 compared to unexposed residents in the same region with significant differences between the two ethnic groups, Russians and Tartar-Bashkir, in both exposed and unexposed groups. Buldakov [48] has also reported the existence of CRS and increased frequencies (up to 2 to 5 times as many cases) of leukopenia, neutropenia, thrombopenia, immuno-suppression and still-births in upper Techa residents. A study in the early 1990’s performed by Kossenko et al., [49] showed a significant increase of the incidence of leukemia in the exposed population (OTRC) compared to control groups, with dose estimates based on the reconstruction of external (gamma dose rates) and internal dose (89Sr, 90Sr and 137Cs). The excess cases of leukemia in the study group compared to the controls were primarily acute and chronic granulocytic leukemia with a significant correlation of leukemia, morbidity and mortality with dose being observed. Most of the excess leukemia cases were observed 5-20 years after the contamination started. Further analyses [26] suggested that 40 % of the 50 recorded deaths from leukemia were related to radiation exposures and that the excess rate for leukemia was 0.85 excess cases per 10,000 person-year Gy (95 %, CI: 0.2-1.5) [estimated excess cases were computed as the difference between the observed number of cases and an estimate of the number expected in the absence of exposure]. For doses over 0.5 Gy on RBM (22 % of person-years recorded: person-years were computed through to date of death/loss to follow-up or 31 December 1989), 50 % of leukemia cases were related to exposure. The absolute risk value of leukemia genesis calculated by Kossenko et al., [50] of 2.94 per 10,000 person-year Gy was lower than atomic bomb survivors, hypothesized as a possible result of the chronic nature of exposures. A statistically significant increase in leukemia incidence had also been observed in patients diagnosed with CRS, though this increase was not reported to cause a decrease in lifespan [47]. Kossenko et al., [27] have also reported a statistically significant dose-response relationship for solid cancers. Results suggested that about 3% of the 969 recorded deaths from solid cancers were associated with radiation exposure with an excess relative risk per Sv of 0.65 (95%, CI: 0.3-1.0). Absolute risk values for solid cancers in OTRC members were comparable to atomic bomb survivors. A more recent study [51] where individual dose estimates were calculated using TRDS-2000 for members of the ETRC who had died from either solid cancers (excluding bone cancer) or leukemia concluded that low-dose rate exposures over longer time periods were associated to increased long-term cancer risks. They report