Cancer Risks near Nuclear Facilities: The Importance of Research Design and Explicit Study Hypotheses

BackgroundIn April 2010, the U.S. Nuclear Regulatory Commission asked the National Academy of Sciences to update a 1990 study of cancer risks near nuclear facilities. Prior research on this topic has suffered from problems in hypothesis formulation and research design.ObjectivesWe review epidemiologic principles used in studies of generic exposure–response associations and in studies of specific sources of exposure. We then describe logical problems with assumptions, formation of testable hypotheses, and interpretation of evidence in previous research on cancer risks near nuclear facilities.DiscussionAdvancement of knowledge about cancer risks near nuclear facilities depends on testing specific hypotheses grounded in physical and biological mechanisms of exposure and susceptibility while considering sample size and ability to adequately quantify exposure, ascertain cancer cases, and evaluate plausible confounders.ConclusionsNext steps in advancing knowledge about cancer risks near nuclear facilities require studies of childhood cancer incidence, focus on in utero and early childhood exposures, use of specific geographic information, and consideration of pathways for transport and uptake of radionuclides. Studies of cancer mortality among adults, cancers with long latencies, large geographic zones, and populations that reside at large distances from nuclear facilities are better suited for public relations than for scientific purposes

Izloženost genotoksičnim agensima iz životnog okoliša tijekom prenatalnog razvoja i djetinjstva

Health disorders and diseases related to environmental exposure in children such as cancer and immunologic disturbances (asthma, allergies) are on the rise. However, complex transplacental and prepubertal genotoxicology is given very limited consideration, even though intrauterine development and early childhood may be critical for elucidating the cancer aetiology. The foetus is transplacentally exposed to contaminants in food and environment such as various chemicals, drugs, radiochemically contaminated water and air. Target organs of xenobiotic action may differ between the mother and the foetus due to specific stage of developmental physiology and enzyme distribution. This in turn may lead to different levels of clastogenic and aneugenic metabolites of the same xenobiotic in the mother and the foetus. Adult’s protective behaviour is not sufficient to isolate children from radioisotopes, pesticides, toxic metals and metalloids, environmental tobacco smoke, endocrine disrupting chemicals, and various food contaminants, which are just a part of the stressors present in a polluted environment. In order to improve legislation related to foetus and child exposure to genotoxic and possibly carcinogenic agents, oncologists, paediatricians, environmental health specialists, and genotoxicologists should work together much more closely to make a more effective use of accumulated scientific data, with the final aim to lower cancer incidence and mortality.Unatoč velikim naporima da se smanji okolišna izloženost u djece se dalje bilježi trend porasta pojavnosti karcinoma i imunosnih poremećaja (astma, alergije). Premda su intrauterini razvoj i rano djetinjstvo kritično razdoblje za tumačenje etiologije nastanka karcinoma, transplacentalna i prepubertetna genotoksikologija do danas su slabo istražene. Fetus je transplacentalno izložen brojnim fizikalnim i kemijskim čimbenicima: kontaminantima iz hrane i okoliša, radiokemijski kontaminiranoj vodi, zraku te lijekovima. Ciljna tkiva za djelovanje ksenobiotika mogu biti različita u majke i fetusa zbog različitosti u razvojnoj fiziologiji i distribuciji enzima. Zbog toga u organizmu majke i fetusa mogu nastati različite razine klastogenih i aneugenih metabolita istog ksenobiotika. Zaštitna uloga odraslih u namjeri da spriječe negativne utjecaje onečišćenog okoliša na djetetovo zdravlje često je ograničena jer su radioizotopi, olovo, PCB, pasivno pušenje, živa, endokrino aktivne tvari, pesticidi i kontaminanti prisutni u svim životnim područjima tijekom razvoja i rasta djeteta. Kako bi se poboljšalo zakonodavstvo vezano uz izloženost djece genotoksičnim i vjerojatno kancerogenim tvarima, tijekom razvoja potrebna je bolja suradnja onkologa, pedijatara, stručnjaka zdravstvene ekologije i genotoksikologa. Na taj način ostvarilo bi se uspješnije iskorištavanje postojećih znanstvenih podataka u cilju smanjenja incidencije karcinoma i mortaliteta

NUCLEAR SPIN-LATTICE RELAXATION IN LIQUID Li-Na, Li-Mg AND Li-Pb ALLOYS

The nuclear spin-lattice relaxation rate T-11 of 8Li in liquid Li-Na, Li-Mg and Li-Pb alloys has been measured by means of the asymmetric β-decay radiation of polarized 8Li (T1/2 = 0.8s) nuclei as a function of temperature T and solute concentration c. T-11 is dominated by magnetic hyperfine interaction with conduction electrons. The reduced rate (T1T)-1 depends slightly on T in a way which, for Li-Na and Li-Mg, is similar to that reported for the electrical resistivity. The T dependence of the liquid structure is assumed to be the main reason for both these findings. (T1T)-1/2 varies about linearly with c in Li-Na and Li-Mg and obeys the Korringa relation (T1T)-1/2 = const.K in Li-Na, where the Knight shift K is known, over the entire c-range. In Li-Pb, however, (T1T)-1/2 has a marked minimum near c= 20 at% Pb which can be ascribed to the compound forming tendency of Li and Pb in the melt. Comparison with recent Knight shift measurements shows that the measured rate is significantly enhanced over the Korringa rate around c =20 at%. The result fits into the scheme proposed by Warren which relates the enhancement to the electrical conductivity in the strong scattering regime

Leukaemia in young children in the vicinity of British nuclear power plants: a case–control study

BACKGROUND: Concern about the risk of leukaemia in children living near nuclear power plants (NPPs) persists. Previous British analyses have been area based and consequently thought to be less effective than case–control studies. METHODS: Cases of childhood leukaemia and non-Hodgkin lymphoma (LNHL) born and diagnosed in Great Britain between 1962 and 2007, with matched cancer-free controls, were analysed by logistic regression to estimate the risk of residential proximity at birth and diagnosis to the nearest NPP, adjusting for relevant variables. RESULTS: For 9821 children with LNHL under the age of 5 years, the estimated extra risk associated with residential proximity to an NPP at birth was negative—interpolated Odds Ratio (OR) at 5 km was 0.86 (0.49–1.52). The comparison of 10 618 children with LNHL under five with 16 760 similarly aged children with other cancers also gave a negative estimate of the extra risk of residential proximity at diagnosis—interpolated OR at 5 km was 0.86 (0.62–1.18). CONCLUSION: Our results show little evidence of an increase in risk of LNHL to children aged under 5 years from living in the vicinity of an NPP. Risk estimates are incompatible with comparable ones published in a recent German case–control study