Cyclic polyamine ionophore for use in a dibasic phosphate-selective electrode.

A cyclic polyamine, 3-decyl-1,5,8-triazacyclodecane-2,4-dione (N3-cyclic amine), was used as the ionophore for a dibasic phosphate-selective electrode. This electrode exhibited a linear response between 1.0 mumol/L and 0.1 mol/L dibasic phosphate activity with a near-Nernstian slope of approximately -29 mV per activity decade. The electrode selectivity for dibasic phosphate over other commonly occurring anions was evaluated. A mechanism for the selectivity of the electrode toward HOP4(2-) ions is postulated to be a function of the size and charge of the N3-cyclic amine ionophore relative to the size and charge of HPO4(2-) ions. The electrode's superior selectivity and sensitivity make possible the direct measurement of phosphate activity in a wide variety of applications.

Assessment of spatial variation of risks in small populations.

Often environmental hazards are assessed by examining the spatial variation of disease-specific mortality or morbidity rates. These rates, when estimated for small local populations, can have a high degree of random variation or uncertainty associated with them. If those rate estimates are used to prioritize environmental clean-up actions or to allocate resources, then those decisions may be influenced by this high degree of uncertainty. Unfortunately, the effect of this uncertainty is not to add "random noise" into the decision-making process, but to systematically bias action toward the smallest populations where uncertainty is greatest and where extreme high and low rate deviations are most likely to be manifest by chance. We present a statistical procedure for adjusting rate estimates for differences in variability due to differentials in local area population sizes. Such adjustments produce rate estimates for areas that have better properties than the unadjusted rates for use in making statistically based decisions about the entire set of areas. Examples are provided for county variation in bladder, stomach, and lung cancer mortality rates for U.S. white males for the period 1970 to 1979.

Empirical Bayes procedures for stabilizing maps of U.S. cancer mortality rates.

"The geographic mapping of age-standardized, cause-specific death rates is a powerful tool for identifying possible etiologic factors, because the spatial distribution of mortality risks can be examined for correlations with the spatial distribution of disease-specific risk factors. This article presents a two-stage empirical Bayes procedure for calculating age-standardized cancer death rates, for use in mapping, which are adjusted for the stochasticity of rates in small area populations. Using the adjusted rates helps isolate and identify spatial patterns in the rates. The model is applied to sex-specific data on U.S. county cancer mortality in the white population for 15 cancer sites for three decades: 1950-1959, 1960-1969, and 1970-1979. Selected results are presented as maps of county death rates for white males."

Cancer mortality in U.S. counties with hazardous waste sites and ground water pollution.

Since the late 1950s, more than 750 million tons of toxic chemical wastes have been discarded in an estimated 30,000 to 50,000 hazardous waste sites (HWSs). Uncontrolled discarding of chemical wastes creates the potential for risks to human health. Utilizing the National Priorities Listing (NPL) of hazardous waste sites developed by the United States Environmental Protection Agency (EPA), this study identified 593 waste sites in 339 U.S. counties in 49 states with analytical evidence of contaminated ground drinking water providing a sole source water supply. For each identified county, age-adjusted, site-specific cancer mortality rates for 13 major sites for the decade 1970-1979, for white males and females, were extracted from U.S. Cancer Mortality and Trends 1950-1979. Also, HWS and non-HWS counties that showed excess numbers of deaths were enumerated for each cancer selected. Significant associations (p less than .002) between excess deaths and all HWS counties were shown for cancers of the lung, bladder, esophagus, stomach, large intestine, and rectum for white males; and for cancers of the lung, breast, bladder, stomach, large intestine, and rectum for white females when compared to all non-HWS counties. There were no consistent geographical patterns that suggested a broad distribution of gastrointestinal cancers associated with HWSs throughout the United States, although we did identify a cluster of excess gastrointestinal cancers in counties within states located in EPA Region 3 (Delaware, Maryland, Pennsylvania, Virginia, West Virginia).(ABSTRACT TRUNCATED AT 250 WORDS)

Statistically adjusted estimates of geographic mortality profiles.

The spatial variation of site-specific cancer mortality rates at the county or state economic area level can provide a) insights into possible etiologic factors and b) the basis for more detailed epidemiologic studies. One difficulty with such studies, especially for rare cancer types, is that unstable local area rate estimates, resulting from small population sizes, can obscure the underlying spatial pattern of disease risk. This paper presents a methodology for producing more stable rate estimates by statistically weighting the local area rate estimate toward the experience at the national level. The methodology is illustrated by the analysis of the spatial variation of two cancer types, bladder and lung, for U.S. white males over the three decades 1950-79.

Compartment model approaches for estimating the parameters of a chronic disease process under changing risk factor exposures.

Compartment model approaches have been proposed for the analysis of the age incidence of specific types of cancer. These models represented the age increases in incidence as the result of a compound hazard function where individual level risks were described by the Weibull hazard function and where the population level hazard rate is a continuous mixture of the Weibull hazards. These formulations assumed that the mixing function, which described differences in risk due to different exposure histories, was constant after the age at which the model was first applied. In this paper we show how the mixing distribution can be allowed to change with time reflecting changing exposures. The model is fitted to U.S. lung cancer mortality data where for recent male cohorts there appear to be changing patterns of exposure possibly related to recent declines in male smoking. The implications for future lung cancer mortality trends in the United States are discussed.

Geographic variation in declining ischemic heart disease mortality in the United States, 1968-1978. I. Rates and change, whites aged 35-74 years.

Despite the well known geographic pattern for heart disease mortality, studies of the decline in ischemic heart disease have not provided a comprehensive examination of its spatial component. In this study, the authors computed and mapped mean rates and per cent change in ischemic heart disease mortality for whites aged 35-74 years, for the period of the Eighth Revision (1968-1978) of the International Classification of Diseases. Visual evidence of clustering and markedly different spatial patterns were found for mean rate and per cent change among the state economic areas of the United States.

U.S. cancer mortality 1950-1978: a strategy for analyzing spatial and temporal patterns.

There are a number of technical and statistical problems in monitoring the temporal and spatial variation of local area death rates in the United States for evidence of systematically elevated risks. An analytic strategy is proposed to reduce one of the major statistical concerns, i.e., that of identifying areas with truly elevated mortality risks from a large number of local area comparisons. This analytic strategy involves two stages. The first is a procedure for examining the entire distribution of local area death rates instead of simply selecting high risk "outliers." The second is the development of an analytic procedure to relate the temporal changes in the cross-sectional distribution of local area death rates to models of the disease process operating within the populations in those areas. The procedures are applied to data on cancer mortality for the 3050 counties (or county equivalents) of the United States over the period 1950 to 1978. A number of striking mortality patterns, both within the entire United States and within various regions and states, are identified. For example, perhaps the most persistent finding was that the risk increases in the death rates for respiratory cancer mortality were due to a "catching up" of nonmetropolitan county mortality rates with metropolitan area mortality rates.

Acute respiratory illness in families exposed to nitrogen dioxide ambient air pollution in Chattanooga, Tennessee.

The incidence of acute respiratory illness in families in Chattanooga, Tennessee was studied in 1972 and 1973 to determine if residents of a formerly high nitrogen dioxide exposure community continued to experience a high incidence of illness after ambient air concentrations of the pollutant had been reduced substantially. Illness data were collected by telephone at 2-wk intervals and illness rates per 100 person weeks of observation were contrasted with air pollution concentrations measured no more than 3.2 km from the home. Data were contrasted by communities designated as high, intermediate, or low pollution exposure. In 1972, higher rates of respiratory illness continued to occur in the designated high pollution area. These were associated with current higher short-term concentrations of nitrogen dioxide even though the long-term mean concentrations of the pollutant were little higher than those in the low pollution area. It was not possible to attribute the excesses in illness to specific pollutants or to specific exposure periods. However, reduction of the illness rate in 1973 associated with a strike at the primary source industry that curtailed nitrogen dioxide pollution in the high exposure community suggested that the short-term exposure may be more important than long-term exposure.