Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies

OBJECTIVE

To determine the risk of lung cancer associated with exposure at home to the radioactive disintegration products of naturally occurring radon gas.

DESIGN

Collaborative analysis of individual data from 13 case-control studies of residential radon and lung cancer.

SETTING

Nine European countries.

SUBJECTS

7148 cases of lung cancer and 14,208 controls.

MAIN OUTCOME MEASURES

Relative risks of lung cancer and radon gas concentrations in homes inhabited during the previous 5-34 years measured in becquerels (radon disintegrations per second) per cubic metre (Bq/m3) of household air.

RESULTS

The mean measured radon concentration in homes of people in the control group was 97 Bq/m3, with 11% measuring > 200 and 4% measuring > 400 Bq/m3. For cases of lung cancer the mean concentration was 104 Bq/m3. The risk of lung cancer increased by 8.4% (95% confidence interval 3.0% to 15.8%) per 100 Bq/m3 increase in measured radon (P = 0.0007). This corresponds to an increase of 16% (5% to 31%) per 100 Bq/m3 increase in usual radon--that is, after correction for the dilution caused by random uncertainties in measuring radon concentrations. The dose-response relation seemed to be linear with no threshold and remained significant (P = 0.04) in analyses limited to individuals from homes with measured radon < 200 Bq/m3. The proportionate excess risk did not differ significantly with study, age, sex, or smoking. In the absence of other causes of death, the absolute risks of lung cancer by age 75 years at usual radon concentrations of 0, 100, and 400 Bq/m3 would be about 0.4%, 0.5%, and 0.7%, respectively, for lifelong non-smokers, and about 25 times greater (10%, 12%, and 16%) for cigarette smokers.

CONCLUSIONS

Collectively, though not separately, these studies show appreciable hazards from residential radon, particularly for smokers and recent ex-smokers, and indicate that it is responsible for about 2% of all deaths from cancer in Europe.

Nutritional management for enteric methane abatement: a review

A variety of nutritional management strategies that reduce enteric methane (CH4) production are discussed. Strategies such as increasing the level of grain in the diet, inclusion of lipids and supplementation with ionophores (>24 ppm) are most likely to be implemented by farmers because there is a high probability that they reduce CH4 emissions in addition to improving production efficiency. Improved pasture management, replacing grass silage with maize silage and using legumes hold some promise for CH4 mitigation but as yet their impact is not sufficiently documented. Several new strategies including dietary supplementation with saponins and tannins, selection of yeast cultures and use of fibre-digesting enzymes may mitigate CH4, but these still require extensive research. Most of the studies on reductions in CH4 from ruminants due to diet management are short-term and focussed only on changes in enteric emissions. Future research must examine long-term sustainability of reductions in CH4 production and impacts on the entire farm greenhouse gas budget.

Supplementation of Acacia mearnsii tannins decreases methanogenesis and urinary nitrogen in forage-fed sheep

The objective of this experiment was to assess the effects of a partial replacement of ryegrass (Lolium perenne) by red clover (Trifolium pratense) or alfalfa (Medicago sativa) supplemented with 0 or 41 g Acacia mearnsii extract (containing 0.615 g/g condensed tannins)/kg dietary dry matter on nitrogen turnover and methane release by sheep, using the respiration chamber technique. Across all variables, there was no significant interaction between basal diet and tannin supplementation. The partial replacement of the grass by the legumes remained without effect on the amounts of nitrogen excreted through faeces or urine. Nitrogen and energy utilisation was lower (P < 0.05) with ryegrass–alfalfa than with ryegrass alone, and methane release (kJ/MJ gross energy intake) was higher (P < 0.05) with ryegrass–red clover than with ryegrass alone. Tannin supplementation decreased (P < 0.05) ruminal ammonia concentration and urinary nitrogen excretion without affecting body nitrogen and energy retention, and reduced (P < 0.001) methane release by 13% on average. The results suggest that supplemented Acacia mearnsii tannins can be useful in mitigating methane and potential gaseous nitrogen emissions, whereas a replacement of grass by legumes obviously shows no advantage in this respect.

Differences in carcass and meat characteristics between chicken indigenous to northern Thailand (Black-boned and Thai native) and imported extensive breeds (Bresse and Rhode Island red)

This study examined the effects of 4 genotypes of chicken, all suitable for extensive fattening, on carcass and meat quality using 320 chickens divided into 4 equally sized groups. The comparison included 2 indigenous chicken strains from Thailand, Black-boned and Thai native (Thai), and 2 imported chicken breeds, Bresse and Rhode Island Red (Rhode, a layer breed). The animals were fed until 16 wk of age. Breast (pectoralis major) and thigh (biceps femoris) muscles were studied in detail. Chickens of the imported breeds were heavier at slaughter than indigenous strains, especially Black-boned chickens. Proportions of retail cuts with bones were similar among genotypes, whereas deboned breast meat and lean:bone ratio were lowest in the layer breed (Rhode). The meat of the Black-boned chickens was darker than that of the other genotypes. Thai and Rhode chickens had a particularly yellow skin. The ratio of red and intermediate to white fibers was higher in the thigh muscle, and the diameter of all muscle fiber types in both muscles was smaller in the indigenous compared with the imported breeds. The meat of the 2 indigenous Thai strains had lower contents of fat and cholesterol compared with that of the imported breeds, especially relative to the Rhode chickens (thigh meat). The meat of the indigenous origins, especially of the Thai chickens, was higher in shear force and collagen content (thigh only) than meat of the imported breeds. The meat lipids of the Thai chickens had particularly high proportions of n-3 fatty acids and a favorably low n-6/n-3 fatty acid ratio compared with the other genotypes. In conclusion, meat of indigenous chickens has some unique features and seems to have more advantages over imported breeds than disadvantages, especially when determined for a niche market serving consumers who prefer chewy, low-fat chicken meat.

A study on the causes for the elevated n-3 fatty acids in cows' milk of alpine origin

The influence of grass-only diets either from rye-grass-dominated lowland pastures (400 m above sea level) or botanically diverse alpine pastures (2000 m) on the FA profile of milk was investigated using three groups of six Brown Swiss cows each. Two groups were fed grass-only on pasture (P) or freshly harvested in barn (B), both for two experimental periods in the lowlands and, consecutively, two periods on the alp. Group C served as the control, receiving a silage-concentrate diet and permanently staying in the lowlands. Effects of vegetation stage or pasture vs. barn feeding on milk fat composition were negligible. Compared with the control, alpha-linolenic acid (18:3n-3) consumption was elevated in groups P and B (79%; P< 0.001) during the lowland periods but decreased on the alp to the level of C owing to feed intake depression and lower 18:3n-3 concentration in the alpine forage. Average 18:3n-3 contents of milk fat were higher in groups P and B than in C by 33% (P< 0.01) at low and by 96% (P < 0.001) at high altitude, indicating that 18:3n-3 levels in milk were to some extent independent of 18:3n-3 consumption. The cis-9, trans-11 CLA content in milk of grass-fed cows was higher compared with C but lower for the alpine vs. lowland periods whereas the trans-11, cis-13 isomer further increased with altitude. Long-chain n-3 FA and phytanic acid increased while arachidonic acid decreased with grass-only feeding, but none of them responded to altitude. Grass-only feeding increased milk alpha-tocopherol concentration by 86 and 134% at low and high altitude (P < 0.001), respectively. Changes in the ruminal ecosystem due to energy shortage or specific secondary plant metabolites are discussed as possible causes for the high 18:3n-3 concentrations in alpine milk.

Multicenter case-control study of exposure to environmental tobacco smoke and lung cancer in Europe

BACKGROUND

An association between exposure to environmental tobacco smoke (ETS) and lung cancer risk has been suggested. To evaluate this possible association better, researchers need more precise estimates of risk, the relative contribution of different sources of ETS, and the effect of ETS exposure on different histologic types of lung cancer. To address these issues, we have conducted a case-control study of lung cancer and exposure to ETS in 12 centers from seven European countries.

METHODS

A total of 650 patients with lung cancer and 1542 control subjects up to 74 years of age were interviewed about exposure to ETS. Neither case subjects nor control subjects had smoked more than 400 cigarettes in their lifetime.

RESULTS

ETS exposure during childhood was not associated with an increased risk of lung cancer (odds ratio [OR] for ever exposure = 0.78; 95% confidence interval [CI] = 0.64-0.96). The OR for ever exposure to spousal ETS was 1.16 (95% CI = 0.93-1.44). No clear dose-response relationship could be demonstrated for cumulative spousal ETS exposure. The OR for ever exposure to workplace ETS was 1.17 (95% CI = 0.94-1.45), with possible evidence of increasing risk for increasing duration of exposure. No increase in risk was detected in subjects whose exposure to spousal or workplace ETS ended more than 15 years earlier. Ever exposure to ETS from other sources was not associated with lung cancer risk. Risks from combined exposure to spousal and workplace ETS were higher for squamous cell carcinoma and small-cell carcinoma than for adenocarcinoma, but the differences were not statistically significant.

CONCLUSIONS

Our results indicate no association between childhood exposure to ETS and lung cancer risk. We did find weak evidence of a dose-response relationship between risk of lung cancer and exposure to spousal and workplace ETS. There was no detectable risk after cessation of exposure.

Prediction of enteric methane production, yield, and intensity in dairy cattle using an intercontinental database

Enteric methane (CH₄ ) production from cattle contributes to global greenhouse gas emissions. Measurement of enteric CH₄ is complex, expensive, and impractical at large scales; therefore, models are commonly used to predict CH₄ production. However, building robust prediction models requires extensive data from animals under different management systems worldwide. The objectives of this study were to (1) collate a global database of enteric CH₄ production from individual lactating dairy cattle; (2) determine the availability of key variables for predicting enteric CH₄ production (g/day per cow), yield [g/kg dry matter intake (DMI)], and intensity (g/kg energy corrected milk) and their respective relationships; (3) develop intercontinental and regional models and cross-validate their performance; and (4) assess the trade-off between availability of on-farm inputs and CH₄ prediction accuracy. The intercontinental database covered Europe (EU), the United States (US), and Australia (AU). A sequential approach was taken by incrementally adding key variables to develop models with increasing complexity. Methane emissions were predicted by fitting linear mixed models. Within model categories, an intercontinental model with the most available independent variables performed best with root mean square prediction error (RMSPE) as a percentage of mean observed value of 16.6%, 14.7%, and 19.8% for intercontinental, EU, and United States regions, respectively. Less complex models requiring only DMI had predictive ability comparable to complex models. Enteric CH₄ production, yield, and intensity prediction models developed on an intercontinental basis had similar performance across regions, however, intercepts and slopes were different with implications for prediction. Revised CH₄ emission conversion factors for specific regions are required to improve CH₄ production estimates in national inventories. In conclusion, information on DMI is required for good prediction, and other factors such as dietary neutral detergent fiber (NDF) concentration, improve the prediction. For enteric CH₄ yield and intensity prediction, information on milk yield and composition is required for better estimation.

Methane suppression by coconut oil and associated effects on nutrient and energy balance in sheep

Three different diets with increasing proportions of coconut oil (0, 3.5 and 7%) were fed to six sheep in an incomplete Latin square experiment with four replicates per diet. The diets were composed of hay and concentrates either without or with coconut oil. Concentrate comprised 28.8 and 54.6% of the diet DM in the treatments containing 3.5 and 7% coconut oil, respectively. Wethers on all treatments were fed at 1.2 × maintenance. Gaseous exchange was measured in respiratory chambers. Protozoa counts were reduced (P < 0.05) by 88 and 97% when diets contained 3.5 and 7% coconut oil, respectively, whereas bacteria counts increased (P < 0.05). Supplementation of coconut oil at proportions of 3.5 and 7% suppressed (P < 0.001) methane production by 28 and 73%, respectively, as related to the unsupplemented diet. This proportionately reduced (P < 0.001) the amount of gross energy lost through methane from 7.5 to 5.7 and 2.5%, in diets containing 0, 3.5 and 7% coconut oil, respectively. Assuming a linear suppressive effect of coconut oil, about half of the additional methane reduction with the 7% coconut oil diet as compared with the 3.5% diet was attributed to the substitution of concentrate for hay. Digestibility of cell wall constituents was numerically decreased by coconut oil. Apart from this and its effect on methane emissions coconut oil had no major influence on digestion or on energy and nitrogen balance. Key words: Coconut oil, methane, energy balance, sheep, ruminants

Lung cancer and cigarette smoking in Europe: an update of risk estimates and an assessment of inter-country heterogeneity

Ten case-control studies have been carried out in 6 European countries to investigate the major risk factors for lung cancer. Carcinogenic effect from cigarette smoke was the most relevant interest in our study, which has included 7,609 cases of lung cancer and 10,431 controls, mainly population based. The results indicate elevated odds ratios (ORs; 23.9 among men and 8.7 among women) with attributable risks exceeding 90% for men and close to 60% for women. A large, and statistically significant, variability of the results across countries was detected after adjusting for the most common confounding variables, and after controlling, at least in part, for the instability of the ORs due to the small number of non-smokers in some of the study subsets. This pattern of lung cancer risk associated with cigarettes smoke, across different European regions, reflects inherent characteristics of the studies as well as differences in smoking habits, particularly calendar periods of starting, and it is likely to have been influenced by effect modifiers like indoor radon exposure, occupation, air pollution and dietary habits.

Ruminal methanogenesis as influenced by individual fatty acids supplemented to complete ruminant diets

The objective of the present study was to investigate the effects of seven different pure fatty acids on rumen fermentation using the rumen simulation technique (RUSITEC). The fatty acids were supplied to a complete ruminant diet at a proportion of 50 g x kg(-1) dietary dry matter and compared with an unsupplemented control. Methane release and methanogenic counts were suppressed by the fatty acids C12 : 0, C14 : 0 and C18 : 2 whereas C8 : 0, C10 : 0, C16 : 0 and C18 : 0 showed no corresponding effects. Apart from C12 : 0 and C18 : 2, C8 : 0 and C10 : 0 also adversely affected ciliate protozoa suggesting independence from the methane-suppressing effect of medium-chain fatty acids (MCFA). Although MCFA but not C18 : 2 reduced ruminal fibre degradation, the influence on other fermentation traits remained low. In conclusion, the supply of certain fatty acids to ruminant diets seems to have the potential to reduce methane release.

Full adoption of the most effective strategies to mitigate methane emissions by ruminants can help meet the 1.5 °C target by 2030 but not 2050

To meet the 1.5 °C target, methane (CH4) from ruminants must be reduced by 11 to 30% by 2030 and 24 to 47% by 2050 compared to 2010 levels. A meta-analysis identified strategies to decrease product-based (PB; CH4 per unit meat or milk) and absolute (ABS) enteric CH4 emissions while maintaining or increasing animal productivity (AP; weight gain or milk yield). Next, the potential of different adoption rates of one PB or one ABS strategy to contribute to the 1.5 °C target was estimated. The database included findings from 430 peer-reviewed studies, which reported 98 mitigation strategies that can be classified into three categories: animal and feed management, diet formulation, and rumen manipulation. A random-effects meta-analysis weighted by inverse variance was carried out. Three PB strategies—namely, increasing feeding level, decreasing grass maturity, and decreasing dietary forage-to-concentrate ratio—decreased CH4 per unit meat or milk by on average 12% and increased AP by a median of 17%. Five ABS strategies—namely CH4 inhibitors, tanniferous forages, electron sinks, oils and fats, and oilseeds—decreased daily methane by on average 21%. Globally, only 100% adoption of the most effective PB and ABS strategies can meet the 1.5 °C target by 2030 but not 2050, because mitigation effects are offset by projected increases in CH4 due to increasing milk and meat demand. Notably, by 2030 and 2050, low- and middle-income countries may not meet their contribution to the 1.5 °C target for this same reason, whereas high-income countries could meet their contributions due to only a minor projected increase in enteric CH4 emissions.

Invited review: Nitrogen in ruminant nutrition: A review of measurement techniques

Nitrogen is a component of essential nutrients critical for the productivity of ruminants. If excreted in excess, N is also an important environmental pollutant contributing to acid deposition, eutrophication, human respiratory problems, and climate change. The complex microbial metabolic activity in the rumen and the effect on subsequent processes in the intestines and body tissues make the study of N metabolism in ruminants challenging compared with nonruminants. Therefore, using accurate and precise measurement techniques is imperative for obtaining reliable experimental results on N utilization by ruminants and evaluating the environmental impacts of N emission mitigation techniques. Changeover design experiments are as suitable as continuous ones for studying protein metabolism in ruminant animals, except when changes in body weight or carryover effects due to treatment are expected. Adaptation following a dietary change should be allowed for at least 2 (preferably 3) wk, and extended adaptation periods may be required if body pools can temporarily supply the nutrients studied. Dietary protein degradability in the rumen and intestines are feed characteristics determining the primary AA available to the host animal. They can be estimated using in situ, in vitro, or in vivo techniques with each having inherent advantages and disadvantages. Accurate, precise, and inexpensive laboratory assays for feed protein availability are still needed. Techniques used for direct determination of rumen microbial protein synthesis are laborious and expensive, and data variability can be unacceptably large; indirect approaches have not shown the level of accuracy required for widespread adoption. Techniques for studying postruminal digestion and absorption of nitrogenous compounds, urea recycling, and mammary AA metabolism are also laborious, expensive (especially the methods that use isotopes), and results can be variable, especially the methods based on measurements of digesta or blood flow. Volatile loss of N from feces and particularly urine can be substantial during collection, processing, and analysis of excreta, compromising the accuracy of measurements of total-tract N digestion and body N balance. In studying ruminant N metabolism, nutritionists should consider the longer term fate of manure N as well. Various techniques used to determine the effects of animal nutrition on total N, ammonia- or nitrous oxide-emitting potentials, as well as plant fertilizer value, of manure are available. Overall, methods to study ruminant N metabolism have been developed over 150 yr of animal nutrition research, but many of them are laborious and impractical for application on a large number of animals. The increasing environmental concerns associated with livestock production systems necessitate more accurate and reliable methods to determine manure N emissions in the context of feed composition and ruminant N metabolism.

A multicenter case-control study of diet and lung cancer among non-smokers

OBJECTIVE

We have examined the role of dietary patterns and specific dietary nutrients in the etiology of lung cancer among non-smokers using a multicenter case-control study.

METHODS

506 non-smoking incident lung cancer cases were identified in the eight centers along with 1045 non-smoking controls. Dietary habits were assessed using a quantitative food-frequency questionnaire administered by personal interview. Based on this information, measures of total carotenoids, beta-carotene and retinol nutrient intake were estimated.

RESULTS

Protective effects against lung cancer were observed for high consumption of tomatoes, (odds ratio (OR) = 0.5; 95% confidence interval (CI) 0.4-0.6), lettuce (OR = 0.6; 95% CI 0.3-1.2), carrots (OR = 0.8; 95% CI 0.5-1.1), margarine (OR = 0.7; 95% CI 0.5-0.8) and cheese (OR = 0.7; 95% CI 0.5-1.0). Only weak protective effects were observed for high consumption of all carotenoids (OR = 0.8; 95% CI 0.6-1.0), beta-carotene (OR = 0.8; 95% CI 0.6-1.1) and retinol (OR = 0.9; 95% CI 0.7-1.1). Protective effects for high levels of fruit consumption were restricted to squamous cell carcinoma (OR = 0.7; 95% CI 0.4-1.2) and small cell carcinoma (OR = 0.7; 95% CI 0.4-1.2), and were not apparent for adenocarcinoma (OR = 0.9; 95% CI 0.6-1.3). Similarly, any excess risk associated with meat, butter and egg consumption was restricted to squamous and small cell carcinomas, but was not detected for adenocarcinomas.

CONCLUSIONS

This evidence suggests that the public health significance of increasing vegetable consumption among the bottom third of the population would include a reduction in the incidence of lung cancer among lifetime non-smokers by at least 25%, and possibly more. A similar protective effect for increased fruit consumption may be present for squamous cell and small cell lung carcinomas.

Gender differences in lung cancer risk by smoking: a multicentre case-control study in Germany and Italy

Several studies in the past have shown appreciably higher lung cancer risk estimates associated with smoking exposure among men than among women, while more recent studies in the USA report just the opposite. To evaluate this topic in a European population we conducted a case-control study of lung cancer in three German and three Italian centres. Personal interviews and standardized questionnaires were used to obtain detailed life-long smoking and occupational histories from 3723 male and 900 female cases and 4075 male and 1094 female controls. Lung cancer risk comparing ever-smokers with never-smokers was higher among men (odds ratios (OR) adjusted for age and centre = 16.1, 95% confidence interval (CI) 12.8-20.3) than among women (OR = 4.2, CI 3.5-5.1). Because the smoking habits of women were different from men, we conducted more detailed analyses using comparable levels of smoking exposure. After restriction to smokers and adjustment for other smoking variables, risk estimates did not differ appreciably between genders. The analysis of duration of smoking (0-19, 20-39, 40+ years) adjusted for cigarette consumption and time since quitting smoking revealed similar risk estimates in men (OR = 1.0, 3.3 [CI 2.6-4.2], 4.1 [CI 3.1-5.6]) and women (OR = 1.0, 2.7 [CI 1.7-4.1], 3.3 [CI 1.9-5.8]). The same was true of the analysis of average or cumulative smoking consumption, and also of analyses stratified by different histological types. We conclude that for comparable exposure to tobacco smoke, the risk of lung cancer is comparable in women and men.

Occupational lung cancer risk for men in Germany: results from a pooled case-control study

Occupational exposures such as crystalline silica, diesel engine exhaust, polycyclic aromatic hydrocarbons, and man-made mineral fibers are strongly suspected to increase lung cancer risk. Two case-control studies in Germany conducted between 1988 and 1996 were pooled for a joint analysis. A total of 3,498 male cases and 3,541 male population controls, frequency matched for age and region, were included in the study. The lifelong history of all jobs and industries was coded and occupational exposures were evaluated by expert rating. Odds ratios, crude and adjusted for smoking and asbestos exposure, were calculated by conditional logistic regression. Job-related evaluation showed a statistically significant increased odds ratio adjusted for smoking among farmers; forestry workers, fishermen, and livestock workers; miners and quarrymen; chemical processors; cabinet makers and related wood workers; metal producers and processors; bricklayers and carpenters; road construction workers, pipelayers and well diggers; plasterers, insulators, and upholsterers; painters and lacquerers; stationary engine and heavy equipment operators; transport workers and freight handlers; and service workers. With regard to specific occupational exposures, elevated odds ratios (OR) (95% confidence intervals (CI)) for lung cancer risk adjusted for smoking and asbestos exposure were observed for man-made mineral fibers (OR = 1.48, 95% CI 1.17, 1.88); crystalline silica (OR = 1.41, 95% CI 1.22, 1.62); diesel engine exhaust (OR = 1.43, 95% CI 1.23, 1.67); and polycyclic aromatic hydrocarbons (OR = 1.53, 95% CI 1.14, 2.04). The risk of asbestos exposure, adjusted for smoking was also increased (OR = 1.41, 95% CI 1.24, 1.60).

Cigar and pipe smoking and lung cancer risk: a multicenter study from Europe

BACKGROUND

Because limited information is available on the quantitative association between consumption of tobacco products other than cigarettes and lung cancer risk, we undertook a case-control study of this relationship.

METHODS

We investigated lung cancer risk among smokers of cigars and/or cigarillos only and of pipes only and compared these risks with the risk of smokers of cigarettes only in a case-control study conducted in seven European areas. Our study population consisted of 5621 male case patients with lung cancer and 7255 male control subjects. Each subject or his proxy was interviewed with respect to the subject's smoking history and other risk factors for lung cancer.

RESULTS

The odds ratio (OR) for smoking cigars and cigarillos only was 9.0 (95% confidence interval [CI] = 5.8-14.1), based on 43 exposed case patients and 77 exposed control subjects, and the OR for smoking a pipe only was 7.9 (95% CI = 5.3-11.8), representing 61 case patients and 129 control subjects. The OR for smoking cigarettes only was 14.9 (95% CI = 12.3-18.1), based on 4204 case patients and 3930 control subjects. A dose-response relationship was present for duration of use and cumulative consumption both for cigars and cigarillos and for pipe tobacco. An effect was also suggested for inhalation of cigar and cigarillo smoke. The dose-response relationships between lung cancer risk and either duration of smoking or average and cumulative consumption were similar for cigar and cigarillo smoking, pipe smoking, and cigarette smoking.

CONCLUSION

Our results suggest that smoking of European cigars, cigarillos, and pipe tobacco might exert a carcinogenic effect on the lung comparable to that of cigarettes.

Biowaste treatment with black soldier fly larvae: Increasing performance through the formulation of biowastes based on protein and carbohydrates

A key challenge for black soldier fly larvae (BSFL) treatment is its variable reliability and efficiency when applied to different biowastes. Similar to other biowaste treatment technologies, co-conversion could compensate for variability in the composition of biowastes. Using detailed nutrient analyses, this study assessed whether mixing biowastes to similar protein and non-fibre carbohydrate (NFC) contents increased the performance and reduced the variability of BSFL treatment in comparison to the treatment of individual wastes. The biowastes examined were mill by-products, human faeces, poultry slaughterhouse waste, cow manure, and canteen waste. Biowaste formulations had a protein-to-NFC ratio of 1:1, a protein content of 14-19%, and a NFC content of 13-15% (dry mass). Performance parameters that were assessed included survival and bioconversion rate, waste reduction, and waste conversion and protein conversion efficiency. In comparison to poultry feed (benchmark), vegetable canteen waste showed the best performance and cow manure performed worst. Formulations showed significantly improved performance and lower variability in comparison to the individual wastes. However, variability in performance was higher than expected for the formulations. One reason for this variability could be different fibre and lipid contents, which correlated with the performance results of the formulations. Overall, this research provides baseline knowledge and guidance on how BSFL treatment facilities may systematically operate using biowastes of varying types and compositions.

Supplementation of a tropical grass diet with forage legumes and Sapindus saponaria fruits: effects on in vitro ruminal nitrogen turnover and methanogenesis

In two in vitro experiments with the RUSITEC-apparatus, Brachiaria dictyoneura was tested alone and with legumes at dietary proportions of 1/3, 2/3, or 3/3 of Arachis pintoi (Expt 1) and 1/3 of Arachis pintoi, Cratylia argentea, or Calliandra calothyrsus (Expt 2). In Expt 2, all diets were evaluated with and without 80 mg/g diet of Sapindus saponaria fruits. In Expt 1, the stepwise replacement of the grass by A. pintoi curvi-linearly increased rumen fluid concentrations of ammonia, volatile fatty acids, bacteria, and protozoa. Methane release rates were 1.7, 7.3, 8.8, and 9.0�mmol/day. With increasing legume proportion, more organic matter and protein were degraded, the latter being only partially recovered as ammonia. In Expt 2, 1/3 of A. pintoi basically had the same effects as in Expt 1. Cratylia argentea was less effective in modifying the fermentation pattern. In association with a higher nutrient degradation and rumen ammonia concentration, C. argentea and A. pintoi increased methane release to about 3- and 4-fold levels. Calliandra calothyrsus reduced nutrient degradation and methane release per gram of organic matter degraded. Tannins, predominant in C. calothyrsus, might have affected methanogenesis. Sapindus saponaria reduced methanogenesis by 11% on average in grass-alone and legume-supplemented diets.

Case-control study on lung cancer and residential radon in western Germany

In a 1990-1996 case-control study in western Germany, the authors investigated lung cancer risk due to exposure to residential radon. Confirmed lung cancer cases from hospitals and a random sample of community controls were interviewed by trained interviewers regarding different risk factors. For 1 year, alpha track detectors were placed in dwellings to measure radon gas concentrations. The evaluation included 1,449 cases and 2,297 controls recruited from the entire study area and a subsample of 365 cases and 595 controls from radon-prone areas of the basic study region. Rate ratios were estimated by using conditional logistic regression adjusted for smoking and for asbestos exposure. In the entire study area, no rate ratios different from 1.0 were found; in the radon-prone areas, the adjusted rate ratios for exposure in the present dwelling were 1.59 (95% confidence interval (CI): 1.08, 2.27), 1.93 (95% CI: 1.19, 3.13), and 1.93 (95% CI: 0.99, 3.77) for 50-80, 80-140, and >140 Bq/m3, respectively, compared with 0-50 Bq/m3. The excess rate ratio for an increase of 100 Bq/m3 was 0.13 (-0.12 to 0.46). An analysis based on cumulative exposure produced similar results. The results provide additional evidence that residential radon is a risk factor for lung cancer, although a risk was detected in radon-prone areas only, not in the entire study area.