Hari H. Dayal

Age at smoking onset and its effect on smoking cessation.

The aim of this study was to examine the relationship between cessation and age at which person starts smoking. Data from a survey of nine neighborhoods in Philadelphia (1985-1987) were analyzed. Interviews were conducted in the home using a structured questionnaire. Participants were from a probability sample (n = 1,700) of males aged 35 years or older. Sixty-six percent of the smokers in this series started smoking before 18 years of age. Smoking cessation rate was 58.1% in Whites and 38.8% in Blacks. Age, race, marital status, education, health condition, amount smoked, and duration of smoking were significant predictors of smoking cessation. Age at initiation of smoking was a significant factor for continuation of smoking. Men who started smoking before 16 years of age had an odds ratio of 2.1 (95% confidence interval: 1.4-3.0) for not quitting smoking compared to those who started at a later age. These findings emphasize the need for prevention program targeted to children below 16 years of age.

Effects of repletion with zinc and other micronutrients on neuropsychologic performance and growth of Chinese children.

The knowledge that zinc is essential for growth and neuropsychologic performance and a report of zinc-responsive stunting in Chinese children prompted this project. This article summarizes findings from a 10-wk, double-blind, controlled trial of zinc repletion in 740 urban, 6-9-y-old first graders from low-income families in Chongqing, Qingdao, and Shanghai, Peoples Republic of China. Treatments were 20 mg Zn alone (Z), 20 mg Zn with micronutrients (ZM), and micronutrients alone (M). The M mixture was based on National Research Council guidelines. Nutrients that might interfere with zinc retention were excluded or given in lower amounts. Main outcomes were changes in neuropsychologic performance and knee height. Hemoglobin, serum ferritin, plasma and hair zinc, and whole blood and hair lead were also measured. Anemia was not common, and serum ferritin concentrations were usually within the range of normal. Mean baseline plasma zinc concentrations were marginal in children from Chongqing and Qingdao and normal in children from Shanghai. After treatment with ZM or M plasma zinc increased. Hair zinc tended to decrease after all treatments. Mean baseline whole blood lead concentrations were slightly below the limit considered excessive for children by the US Centers for Disease Control and Prevention. Neuropsychologic performance and growth were most improved after treatment with ZM. These findings were consistent with the presence of zinc and other micronutrient deficiencies.

Chronic Liver Disease and Consumption of Raw Oysters: A Potentially Lethal Combination—A Review of Vibrio vulnificus Septicemia

Vibrio vulnificus septicemia is the most common cause of fatality related to seafood consumption in the United States. It occurs predominantly in patients with chronic liver disease following consumption of raw oysters. V. vulnificus is a highly virulent human pathogen, normally found in warm estuarine and marine environment. It lodges in filter feeders like oysters. The onset of this illness is abrupt, rapidly progressing to septic shock with a high mortality. Clinicians managing patients with chronic liver disease need to educate their patients of the risk associated with the consumption of raw seafood, especially oysters. A high index of suspicion is necessary for appropriate treatments, as doxycycline, the antibiotic of choice, is not usually a part of the empiric therapy for septicemia. The high mortality associated with this septicemia demands aggressive preventive measures: susceptible individuals must be forewarned by signs displayed in restaurants; physicians must educate patients with chronic liver disease about the risk of raw oyster consumption; and harvesting methods which reduce contamination by V. vulnificus must be utilized.

Effect of cigarette smoking on major histological types of lung cancer in men

This study examined the effect of cigarette smoking parameters such as intensity, duration, age at initiation, and quitting on the development of different histological types of lung cancer in men. We used data from a case-control study conducted in Philadelphia between 1985 and 1987. Cases included 482 men with histologically confirmed lung cancer diagnosed in 15 selected hospitals in Philadelphia. Controls were selected from a neighborhood survey of men in Philadelphia conducted concurrently to the case recruitment. Most aspects of smoking were associated with all the major histological types of lung cancer. Number of cigarettes smoked per day was the strongest predictor of risk of developing lung cancer. Early age at initiation of smoking significantly increased the risk of small cell carcinoma (odds ratio = 3.0; 95% CI, 1.1-8.4). Quitting smoking reduced the risk of squamous cell and adenocarcinoma; however, it did not affect the risk of small cell lung cancer. The findings of this study suggest the need for greater emphasis on smoking prevention programs, especially in adolescents.

Hazardous chemicals: psychological dimensions of the health sequelae of a community exposure in Texas

STUDY OBJECTIVE--A chemical spill from an oil refinery exposed the local community to more than 40,000 lb of highly toxic and corrosive hydrofluoric acid. A community based symptom prevalence study found an association between exposure and physical symptoms: the psychological impact of the disaster and its potential effect on the reporting of physical symptoms is examined here. DESIGN--The study used a population based survey design consisting of two phases: phase I, the exposure phase, and, phase II, the symptom prevalence phase. SUBJECTS--In phase I, information indicative of exposure was collected on 10,811 individuals in a door to door survey of a geographically defined area. In phase II, symptom prevalence information was gathered through in-person interviews with 2509 subjects selected from the phase I census in a sampling scheme that balanced across the exposure categories with regard to age, gender, and predisposition. The refusal rate in both phases was < 5%. MEASUREMENT AND MAIN RESULTS--Stepwise logistic regression analyses were used to assess the relative predictive importance of psychological variables and hydrofluoric acid exposure in explaining the reported physical symptoms two years after the disaster. The findings show a linear relationship between the level of hydrofluoric acid exposure and the degree of psychological stress two years after the accident. High exposure had a long term (more than two years) impact on physical health for some self reported symptoms, even after controlling for the psychological impact. Some physical symptom reports, however, were better explained by psychological status than by exposure to hydrofluoric acid. The physical symptoms for which exposure was the major predictor were those for which the biological plausibility of a relationship with hydrofluoric acid exposure was direct. CONCLUSIONS--Measures of psychological status should be included in symptom studies of health sequelae to man-made disasters so that the physical effects of exposure can be more accurately assessed.

Symptom Clusters in a Community with Chronic Exposure to Chemicals in Two Superfund Sites

Sikes and French, Ltd., two National Priority List sites that are proximal to one another, are located approximately 20 mi (32 km) east of Houston, Texas. Dumping at Sikes occurred during the early 1960s and continued until 1967. Benzene, 1,2-dichloroethane, toluene, 1,1,2-trichloroethane, naphthalene, lead, fluorene, and pyrene are chemicals that pose a particular public health concern. French, Ltd., commenced operations in 1966, and dumping ceased in 1973. Chemicals of potential public health impact at the French, Ltd., site are benzene, benzo(a)anthracene, benzo(a)pyrene, copper, chrysene, chromium, dichlorodiphenyltrichloroethane, heptachlor, lead, nickel, polychlorinated biphenyls, tetrachloroethylene, trichloroethylene, and zinc. During the 1980s, both sites were placed on the National Priority List. Barrett Station is a stable black community located near the two sites. The question of whether levels of exposure to dumpsite chemicals were related to health complaints in the Barrett Station population was examined. The prevalence of 29 symptoms reported by 321 individuals who had been highly exposed was compared with symptoms reported by a group of 351 persons from the same community who had limited exposure. A meaningful difference between the two groups emerged for some of the symptoms, the most notable of which symptoms were neurologic. Almost twice as many subjects in the high-exposure group reported five or more neurologic symptoms, compared with the low-exposure group. This excess of neurological symptoms is consistent with the known toxic properties of the chemicals at the sites.

A community-based epidemiologic study of health sequelae of exposure to hydrofluoric acid

An accident at an oil refinery in Texas City, Texas, released around 40,000 lb of hydrogen fluoride, exposing the community to the highly toxic and corrosive substance. A population-based epidemiologic study was conducted to evaluate the impact of the accident on the health of the community. Exposure assessment was done using a multipronged approach through a door-to-door survey of 10,811 individuals. A symptom survey resulting in 1994 completed interviews was conducted with a stratified random sample selected from the exposure study database. The sampling was balanced with respect to age, gender, and predisposition across the three ordinal exposure categories. The results show a strong dose relationship (P < 10(-4)) between the exposure and symptoms reported following the accident and 2 years later, most notably breathing and eye symptoms. However, substantial improvement in health was reported over the 2-year period regardless of the level of exposure. Problems of recall bias and behavioral sensitization are considered and it is recognized that the study may have overestimated the effect. It is also recognized that the study may not have completely unraveled the relative importance of exposure and host response in health outcome, since the two were probably conflated in the exposure measure. Nevertheless, the independence of predisposition and reported level of exposure, the magnitude of effect and its consistency, the unmistakable dose response, the large sample size, and the mutual corroboration of various findings make it difficult to dismiss the interpretation that the hydrofluoric acid exposure indeed caused health problems in the community that continued for at least 2 years after the accident.

Association between zinc pool sizes and iron stores in premenopausal women without anaemia

The simultaneous occurrence of Zn and Fe deficiencies in man has been known since the discovery of human Zn deficiency. However, it is not established that low Fe stores per se or Fe-deficiency anaemia infer low Zn status. Therefore our objective was to identify relationships between Zn and Fe status in premenopausal women without anaemia. We also examined the contribution of food frequencies and blood loss to Zn and Fe status. The subjects were thirty-three apparently healthy premenopausal women without anaemia, who were not taking dietary supplements containing Zn or Fe or oral contraceptives. Main outcomes were Zn kinetic parameters based on the three-compartment mammillary model and serum ferritin (SF) concentration; contributing factors were the frequency of consumption of specific foods and menorrhagia. Lower SF was significantly associated with smaller sizes of Zn pools. The breakpoint in the relationship between SF and the lesser peripheral Zn pool was found to be 21.0 microg SF/l. SF also correlated positively with frequency of beef consumption and negatively with bleeding through menstrual pads (BTMP). Similar to SF, the Zn pool sizes correlated positively with frequency of beef consumption, and negatively with BTMP. In summary, Zn pool sizes and Fe stores were highly correlated in premenopausal women. SF concentrations < 20 microg/l suggest an increased likelihood of low Zn status.

Polyatomics in zinc isotope ratio analysis of plasma samples by inductively coupled plasma-mass spectrometry and applicability of nonextracted samples for zinc kinetics

Inductively coupled plasma-mass spectrometry (ICP-MS) is a powerful tool for both quantitative multielement analyses of inorganic elements and measurement of isotope ratios (IRs). The main disadvantage of this technique is the existence of polyatomic isobaric interferences at some key masses. Zinc has been investigated for such potential interferences in serum or plasma. The Zn isotopes,66Zn and68Zn, have no apparent interferences, but32S16O2 and32S2 are isobaric with64Zn. The possible effects of S and other major components of blood plasma—Na, K, Cl, P, Ca—on Zn IRs were investigated using a series of mineral solutions which simulated human plasma with respect to these elements. The mixture of all mineral elements interfered only with64Zn (6.66 ng/mL) and70Zn (8.51 ng/mL). Interferences to66Zn,67Zn, and68Zn were minimal containing 0.90, 0.94, and 0.39 ng/mL, respectively. The copresence of Na or S shifted35Cl16O2 (atomic mass 67 coming from Cl solution) to35Cl2 which reduced the contribution to67Zn. The hypothesis that Zn IRs obtained from plasma at various intervals after the intravenous administration of enriched67Zn to humans would reflect those obtained after extraction of Zn was therefore tested. To compare the two pretreatment methods, “extraction” versus “nonextraction,” specimens were collected from 10 human subjects at intervals of 5 min to 24 h postinjection, and in 4 subjects from 5 min to 9 d postinjection. Two separate aliquots of plasma from each time-point were dried and digested with hydrogen peroxide, and the residue dissolved in nitric acid. One specimen was subjected to zinc extraction using ammonium diethyldithiocarbamate chelate followed by back extraction into nitric acid. The matching aliquot received no further pretreatment. The normalized IRs obtained from67Zn/66Zn and67Zn/68Zn in both the “extracted” and “nonextracted” samples agreed well(r2 = 0.976 andr2 = 0.985, respectively) compared to those from other ratios (r2 = 0.838 for67Zn/64Zn andr2 = 0.747 for67Zn/70Zn). Considering the minimum possibility of isobaric interferences in plasma samples,67Zn/68Zn obtained from “nonextracted” samples is sufficient for routine Zn kinetic analysis by ICP-MS.

Survival Analysis in Genetics: Danish Twin Data Applied To a Gerontological Question

Genetic variation among individuals is known to account for some of the observed variation in lifespans, waiting times to conceptions, and other durations. Geneticists typically study such variation by using methods based on the analysis of variance. Survival analysis provides an alternative means of approaching such duration data. Recent advances in multivariate survival analysis provide some new ways to analyze data on genetically related individuals. In this paper we develop some approaches of this kind and present some illustrative applications. In particular, we examine Fries’ hypothesis that individuals are born with genetically-determined maximum lifespans.