Richard J. Hickey

Radiation hormesis, public health, and public policy: a commentary

Public policy affecting public health regarding effects of low-level ionizing radiations has been, and is being, determined by effects estimates based on linear or other monotonic extrapolation from high-level radiation dose-response data to presumed ecologically realistic low-level exposure effects. Such predictive, unmeasured estimates are very possibly in serious error; they are incompatible with observed low-level dose-response data that indicate a negative correlation between low-level radiation data and health effects, such as cancer mortality rates. Observed negative correlations with low-level radiation data are to be expected on the basis of evidence supporting the validity of the hormesis phenomenon. Hormesis theory, derived in part from evolutionary biology, asserts that while high levels of exposure to an agent such as ionizing radiation are indeed hazardous, ecologically realistic low levels can be stimulatory and largely beneficial. Stimulation of activities of DNA and other repair mechanisms may be involved. Although evidence of the reality of radiation hormesis has been reported in about 1000 scientific publications over the last century, this effect has been largely unrecognized. Moreover, this widespread non-acceptance of hormesis as a real-world phenomenon is usually but not always present in the case of chemical hormesis; the oversight appears systematic. The ignoring of the hormesis phenomenon seems to constitute a very serious error in modern biomedical science and in preventive medicine. A mathematical model is offered that describes the general shape of certain dose-response functions when radiation hormesis at low-level exposure is taken into consideration along with the well-known detrimental effects of high-level radiation.

Low level ionizing radiation and human mortality: multi-regional epidemiological studies. A preliminary report.

AbstractAnalyses of relationships involving environmental chemicals, background radiation, and mortality rates for diseases of the heart and several cancer categories are presented. Bivariate correlation coefficients between radiation and mortality rate were significantly negative for cancer of the

Maternal smoking birth weight infant death and the self-selection problem.

Several aspects of the relationship between maternal smoking and birth weights of infants are discussed. No satisfactory explanation for Yerushalmys results has been given other than that low birth weight appears to relate more to the smoker than to the smoking. Recent studies by Silverman support this position. The possibility that nicotine may induce a physiologic response that serves to alleviate bioenergetic deficiency in some individuals should not be overlooked. In this view, both smoking and low birth weight are symptoms of deficient maternal bioenergetic systems.

Ecological Statistical Studies concerning Environmental Pollution and Chronic Disease

Ecological statistical studies employing methods of multivariate analysis, based on a radiomimetic or mutagenic hypothesis, have yielded a number of statistically significant multiple regression equations in which concentrations of environmental chemicals, largely air pollutants, predict annual mortality rates for major categories of cancer and heart disease, as well as for congenital malformations, for populations of 38 metropolitan areas of the United States. Median age of these populations was also predicted statistically. Squares of multiple correlation coefficients R2 in excess of 0.5 were frequently obtained for these equations along with related t and F statistics of suitable magnitude. A new computer program for optimal regression analysis was employed in the studies. Among the chemical predictors whose atmospheric concentrations are frequently found positively correlated with mortality rates are SO2, NO2, and particulate sulfate. Among frequently recurring negatively correlated predictors are Cu, Cd, and Ti. Evidence regarding whether SO2 and NO2 may be considered as mutagenic hazards to life is discussed, as are some potentially relevant biochemical functions of the metals.

Epidemiological studies of chronic disease: maladjustment of observed mortality rates.

Age adjustment of observed mortality and morbidity rates is not a substitute for age-specific analysis. Measures of association between potential causal factors and adjusted mortality rates are functions of the particular adjustment procedure and the choice of reference population. We exhibit here the wide variation in simple correlation statistics that occurs with eight adjustment methods and three reference populations. We then generalize these results to the multivariate situation showing an example in which there is coherent structure for the associations between predictors and mortality. This is contrasted with another example in which no such meaningful pattern exists. Studies are cited that could have been improved by greater attention to the underlying structure of age-adjusted rates. Age adjustment of total observed rates yields meaningless numbers that are useful for comparative purposes only. Total observed rates have substantive meaning but provide useful etiological clues primarily when supported by analyses of appropriate age-specific data.

Health Effects of Atmospheric Sulfur Dioxide and Dietary Sulfites: The Fallacy of Typology

Some animal studies have shown that exposure to low levels of sulfur dioxide and dietary bisulfite is relatively harmless. To the contrary, sulfite oxidase deficiency is known in man, bisulfite is mutagenic for several test organisms, and the atmospheric SO2 level is positively correlated with death rates for several chronic diseases among some human populations. The studies reporting harmlessness for animals may be misleading because of the fallacy of typology.

Health Effects of Atmospheric Sulfur Dioxide and Dietary Sulfites

Some animal studies have shown that exposure to low levels of sulfur dioxide and dietary bisulfite is relatively harmless. To the contrary, sulfite oxidase deficiency is known in man, bisulfite is mutagenic for several test organisms, and the atmospheric SO2 level is positively correlated with death rates for several chronic diseases among some human populations. The studies reporting harmlessness for animals may be misleading because of the fallacy of typology.