In the indigenous dwellers of coastal Chukotka, blood DDT levels are 1.5-2 times higher than those of continental areas, which is due to the higher global DDT pollution of a sea food chain. The blood levels of 4,4-DDE in the reproductive-age women of coastal Chukotka are comparable to those in other Russian Arctic regions, slightly lower than in Greenland, but essentially higher than in Canada, Alaska and Scandinavian countries. Blood DDE/DDT ratio in the coastal indigenous dwellers is almost twice higher than that in the inland inhabitants, which is indicative of the "older" exposure of coastal people to DDT. There was an about equal (70-75%) decrease in 4,4-DDE and 4,4-DDT levels with a practically invariable ratio (12-15) and a nearly equal elimination half-life period (about 3.5 years) in the mothers of coastal Chukotka 5 years after the first examination. The elevated 4,4-DDE/4,4-DDT ratios in the tissues of sea mammals generally correspond to higher isomer ratios in the blood of coastal natives and relatively low 4,4-DDE/4,4-DDT ratios in the venison, fowl, and fish predetermine lower ratios in the blood of inland inhabitants. The extremely low of DDE/DDT ratio (0.4) in the washouts and scrapes from the kitchen walls of dwellings are conclusively associated with the recent application of DDT as a household insecticide.
A considerable reduction in the blood levels of stable organic pollutants (SOP) has been noted in the mothers of native ethnicities of costal Chukotka during a 5-year period, which may be accounted for by certain purification of food chains, altered diet with emphasis on delivered products, and long-term breastfeeding. The elevated level of SOP in children from birth to age 5 years is explained by long-term breastfeeding and the early consumption of local foods. The content of heavy metals (mercury and lead) in both maternal and children's blood has unchanged for 5 years. The children's infection morbidity has been quite high; at the same time no associations of the children's blood levels of toxic substances with the incidence of infectious diseases have been found. However, two children maximally exposed to SOP and metals have been observed to be rarely susceptible to diseases.