Lung cancer risk and red meat consumption among Iowa women.

OBJECTIVE: Some epidemiologic studies suggest that diets high in total fat, saturated fat, or cholesterol are associated with increased risk of lung cancer. Others suggest that diets high in red meat consumption, particularly well-done red meat, are a lung cancer risk factor. In Iowa, we had the opportunity to investigate concurrently the role of meat intake and macronutrients in lung cancer etiology. METHODS: A population-based case-control study of both non-smoking and smoking women was conducted in Iowa. A 70-item food frequency questionnaire (FFQ) was completed by 360 cases and 574 frequency-matched controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression. Multivariate models included age, education, pack-years of smoking, yellow-green vegetable intake, fruit/fruit juice intake, nutrient density calories, previous non-malignant lung disease, alcohol consumption and body mass index (BMI). RESULTS: When comparing the fifth (highest) to the first (lowest) quintile of consumption of total fat, saturated fat and cholesterol, we obtained odds ratios of 2.0 (1.3-3.1), 3.0 (1.9-4.7), and 2.0 (1.3-3.0) respectively. However, when red meat was entered into the model along with total fat, saturated fat or cholesterol, the excess risk for the macronutrients disappeared while an odds ratio of 3.3 (1.7-7.6) was obtained for red meat. The odds ratios for red meat consumption were similar among adenocarcinoma cases, OR=3.0 (1.1-7.9) and non-adenocarcinoma cases, OR=3.2 (1.3-8.3) and among life-time nonsmokers and ex-smokers OR=2.8 (1.4-5.4), and current smokers, OR=4.9 (1.1-22.3). Yellow-green vegetables were protective with an odds ratio of 0.4 (0.2-0.7). CONCLUSIONS: Consumption of red meat, was associated with an increased risk of lung cancer even after controlling for total fat, saturated fat, cholesterol, fruit, yellow-green vegetable consumption and smoking history, while yellow-green vegetables are associated with a decreased risk of lung cancer.

Reduced lung endothelial angiotensin-converting enzyme activity in Watanabe hyperlipidemic rabbits in vivo.

We investigated pulmonary endothelial function in vivo in 12- to 18-mo-old male Watanabe heritable hyperlipidemic (WHHL; n = 7) and age- and sex-matched New Zealand White (n = 8) rabbits. The animals were anesthetized and artificially ventilated, and the chest was opened and put in total heart bypass. The single-pass transpulmonary utilizations of the angiotensin-converting enzyme (ACE) substrate [(3)H]benzoyl-Phe-Ala-Pro (BPAP) and the 5'-nucleotidase (NCT) substrate [(14)C]AMP were estimated, and the first-order reaction parameter A(max)/K(m), where A(max) is the product of enzyme mass and the catalytic rate constant and K(m) is the Michaelis-Menten constant, was calculated. BPAP transpulmonary utilization and A(max)/K(m) were reduced in WHHL (1.69 +/- 0.16 vs. 2.9 +/- 0.44 and 599 +/- 69 vs. 987 +/- 153 ml/min in WHHL and control rabbits, respectively; P < 0.05 for both). No differences were observed in the AMP parameters. BPAP K(m) and A(max) values were estimated separately under mixed-order reaction conditions. No differences in K(m) values were found (9.79 +/- 1 vs. 9.9 +/- 1.31microM), whereas WHHL rabbit A(max) was significantly decreased (5.29 +/- 0.88 vs. 7. 93 +/- 0.8 micromol/min in WHHL and control rabbits, respectively; P < 0.05). We conclude that the observed pulmonary endothelial ACE activity reduction in WHHL rabbits appears related to a decrease in enzyme mass rather than to alterations in enzyme affinity.

Residential radon gas exposure and lung cancer: the Iowa Radon Lung Cancer Study.

Exposure to high concentrations of radon progeny (radon) produces lung cancer in both underground miners and experimentally exposed laboratory animals. To determine the risk posed by residential radon exposure, the authors performed a population-based, case-control epidemiologic study in Iowa from 1993 to 1997. Subjects were female Iowa residents who had occupied their current home for at least 20 years. A total of 413 lung cancer cases and 614 age-frequency-matched controls were included in the final analysis. Excess odds were calculated per 11 working-level months for exposures that occurred 5-19 years (WLM(5-19)) prior to diagnosis for cases or prior to time of interview for controls. Eleven WLM(5-19) is approximately equal to an average residential radon exposure of 4 pCl/liter (148 Bq/m3) during this period. After adjustment for age, smoking, and education, the authors found excess odds of 0.50 (95% confidence interval: 0.004, 1.81) and 0.83 (95% percent confidence interval: 0.11, 3.34) using categorical radon exposure estimates for all cases and for live cases, respectively. Slightly lower excess odds of 0.24 (95 percent confidence interval: -0.05, 0.92) and 0.49 (95 percent confidence interval: 0.03, 1.84) per 11 WLM(5-19) were noted for continuous radon exposure estimates for all subjects and live subjects only. The observed risk estimates suggest that cumulative ambient radon exposure presents an important environmental health hazard.

Dissolution of 226Radium from pipe-scale deposits in a public water supply.

This study was undertaken to determine if dissolution of 226Radium from pipe-scale deposits contributes to enhanced waterborne 226Radium concentrations at the point of use. Water samples were collected from residential water customers of a small rural Iowa town. Sites were evenly divided between new and old water main connections. Daily samples were collected from the point-of-entry water. Point-of-use 226Radium concentrations ranged from 0.4 to 12.9 pCi L-1 (0.01 to 0.5 Bq L-1). The mean 226 Radium concentration for homes connected to old water mains was significantly higher than the mean 226Radium concentration of homes connected to new water mains, mean(standard deviation) equal 8.3(1.1) and 5.3(0.8) pCi L-1 [0.3(1.1) and 0.2(0.8) Bq L-1], respectively. 226Radium concentrations of the point-of-entry water ranged from 5.0 pCi L-1 to 10.3 pCi L-1 (0.2 Bq L-1 to 0.4 Bq L-1). This study indicates considerable variability of 226Radium exposure from drinking water among residents of the same water supply and has implications for regulatory compliance and exposure assessment in epidemiologic studies.

Spatial variation of residential radon concentrations: the Iowa Radon Lung Cancer Study.

Homeowners and researchers frequently estimate the radon concentrations in various areas of the home from a single radon measurement often performed in the home's basement. This study describes the spatial variation of radon concentrations both between floors and between rooms on the same floor. The geometric mean basement and first floor radon concentrations for one-story homes were 13.8% and 9.0% higher, respectively, as compared to their counterparts in two-story homes. The median first floor/basement ratio of radon concentrations for one-story homes was 0.60. The median ratios between first floor/basement and second floor/basement for two-story homes were 0.51 and 0.62, respectively. The mean coefficient of variation for detectors placed on the same floor was 9.5%, which was only 2.6% higher than the mean coefficient of variation found for collocated (duplicate) quality control detectors. The wide individual variations noted in radon concentrations serve as a reminder of the importance of performing multiple radon measurements in various parts of the home when estimating home radon concentrations.

Temporal and spatial variation of waterborne point-of-use 222Rn in three water distribution systems.

Three water supply systems in Iowa were studied to examine temporal variation of 222Rn at the point of entry and the point of use. For the three towns, 71, 9, and 0% of the maximum point-of-use 222Rn concentrations were significantly higher than the point-of-entry 222Rn concentrations. Homes connected to older water mains in two of the towns had higher 222Rn concentrations than those connected to newer water mains. In one town, the waterborne 222Rn concentrations in the home were related to the home's location along an old water main. The increase in 222Rn concentrations, after the water leaves the water plant, were attributed to radium deposits in the water distribution system. In addition, the water plant's radium laden iron filters contributed 7 Bq L-1 and 60 Bq L-1 of 222Rn to the finished water in What Cheer, Iowa, and Wellman, Iowa, respectively. Backwashing schedules in the water treatment systems greatly affected point-of-entry 222Rn concentrations. The results of this study have important implications for 222Rn sampling, required for regulatory compliance.

Occupational exposure of water-plant operators to high concentrations of radon-222 gas.

Water-plant operators may be exposed to high airborne radon-222 (222Rn) concentrations created when 222Rn gas transfers from water to air during the water treatment processes. To evaluate this hazard, we placed yearlong alpha-track radon detectors in 31 water plants. The geometric mean of the annual average airborne 222Rn concentrations was 3.4 pCi L-1 (126 Bq m-3), with a maximum of 133 pCi L-1 (4921 Bq m-3). We assessed the short-term temporal variability of 222Rn by monitoring four water plants continuously for a 3- to 6-day period. Cumulative working level months were estimated for the time workers were in the water plants. Because airborne 222Rn concentrations in water plants can reach levels considered unsafe for underground miners, it would be prudent to monitor airborne 222Rn concentrations in water plants which aerate water as part of their treatment process.

Radium-bearing pipe scale deposits: implications for national waterborne radon sampling methods.

A point-of-use waterborne radon-222 (222Rn) survey of a small Iowa town was performed to determine the cause of unnaturally high waterborne 222Rn concentrations in the municipality. The source of the elevated 222Rn concentrations was a newly discovered reservoir of waterborne 222Rn originating from distribution-system radium-226 (226Ra) adsorbed internal pipe scale deposits. Because the proposed national drinking water regulations for 222Rn require sampling at the origin of the distribution system rather than at the point of use, the proposed scheme for collection of water samples may not represent actual consumer waterborne 222Rn exposure in all cases.

Epidemiological considerations of the present status and future growth of the acquired immunodeficiency syndrome epidemic in South Africa.

Limited epidemiological data on acquired immunodeficiency syndrome (AIDS) and human immunodeficiency virus (HIV) infection have been assembled by voluntarily reported AIDS figures, blood donor serum prevalence and high-risk sentinel population and random background population sero-prevalence studies. The HIV epidemic in South Africa can thus be shown to consist of four separate epidemics of which the heterosexual epidemic will undoubtedly constitute the major growth in this country. Intervention must be directed to shrinking the promiscuous core which sustains this epidemic by directing attention at female prostitution and limiting the reproductive rate of the epidemic by energetic and professionally directed education at an early stage of a child's school career. Sexually transmitted diseases will play a major role in the determination of the extent of the heterosexual epidemic.

Alteichin: an unusual phytotoxin from Alternaria eichorniae, a fungal pathogen of water hyacinth.

The phytopathogenic fungus Alternaria eichorniae attacks water hyacinth, an economically significant aquatic weed. The novel phytotoxin alteichin was isolated from liquid cultures of this fungus and its structure was deduced by X-ray crystallographic analysis. Altheichin is a doubly hydrated form of 4,9-dihydroxy perylene-3, 10-quinone. A single step dehydration of alteichin to anhydroalteichin is catalyzed both by acid and by a crude enzyme preparation from water hyacinth.