A method for estimating dietary intake of environmental trace contaminants: Cadmium — a case study

Variations in either food content or dietary habit affect dietary intake of trace contaminants. Trace contaminants enter the human food chain through many environmental pathways, including contamination of water used for drinking or irrigation, sludge used on cropland, fertilizers and other agricultural chemicals, chemicals leached from disposal sites to water, or airborne deposition on soil, water, or crops. A flow chart (Fig. 1) summarizes these pathways.Dietary exposure to environmental trace contaminants places some segments of the U.S. population at substantially higher risk than others. A methodology to calculate population distribution curves for dietary intake of trace contaminants is presented in this report, using cadmium (Cd) as the specific example. This methodology can be applied both to calculate the distribution of daily individual intake of trace contaminants, as well as to estimate the size of the potentially at-risk population. The methodology is developed with both a stochastic approach and a matrix approach. The matrix approach is coded as program SCOPE, and the stochastic as program MONTE.The dietary habits of the U.S. population were determined by using computer codes to analyse and synthesize an array of dietary data. The 15- to 20-yr-old male population was selected for analysis because this group has the largest gram-caloric intake of any age-sex classification. Data from the U.S. Department of Agriculture and the Food and Drug Administration were analyzed to define Cd concentration distribution for 34 food categories, into which 1880 food items were classified. Food consumption frequency histograms were generated with this information, using data synthesis routines and SCOPE.A 1974 FDA survey of metal concentrations in selected foods at 71 U.S. sampling sites yielded tabular, truncated frequency histograms for Cd concentrations in 32 of the food categories studied. Histograms were then constructed by integrating consumption and Cd concentration for each food category for the total diet.The World Health Organization (WHO) recommended in 1972 a tolerable limit of Cd intake of approximately 70 μg per day. A comparison of SCOPE and MONTE total diet Cd intake frequency histograms indicates the likelihood of high Cd intake, at-rick populations. SCOPE results predict that approximately 13% of the 15- to 20-yr-old males studied ingest Cd at a rate greater than 70 μg per day. MONTE predicts that 14%, with a 12–17% range, ingest amounts greater than the WHO-recommended limit on a daily basis. This percentage represents a potential at-risk population. The actual at-risk population would be those persons who consistently ingest more than 70 μg/day.The percentage of the population projected to ingest more than 70 μg of Cd per day needs to be defined by geography, ethnicity, race, and dietary preference in order to fully evaluate Cd intake risks and to set parameters for epidemiological surveys needed for confirmation. Assuming validity for this methodology, there is justification for preventing significant increases in Cd dietary intake by way of man's activities.     

The development of self‐efficacy during aviation training

Given that self‐efficacy has been shown to be positively related to training outcomes, a better understanding of factors that affect self‐efficacy in complex training contexts is needed. This study examined the development of self‐efficacy in a flight‐training programme. Results indicate that training performance and self‐esteem predicted self‐efficacy for post‐training flight performance. Furthermore, prior flight experience moderated the relationships between training performance and self‐efficacy, and between self‐esteem and self‐efficacy. Implications regarding the development of self‐efficacy and the design of training programmes are discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

离子色谱/质谱联用分析水和食品中的高氯酸盐

摘要用离子色谱／质谱联用(IC／MS)测定低ppb水平高氯酸根离子的方法．IC／MS是根据EPA方法314开发出来的,原方法用Ic分离电导检测,检测范围为1ppb．IC／MS在整个测定范围内,高氯酸盐回收率不受干扰基质的影响．在饮料和废水中0．5和1ppb添加水平的测定回收率为90％-105％,方法检测限(DML)低于100ppt．     

Does the canopy mixing layer model apply to highly flexible aquatic vegetation? Insights from numerical modelling

Vegetation is a characteristic feature of shallow aquatic flows such as rivers, lakes and coastal waters. Flow through and above aquatic vegetation canopies is commonly described using a canopy mixing layer analogy which provides a canonical framework for assessing key hydraulic characteristics such as velocity profiles, large-scale coherent turbulent structures and mixing and transport processes for solutes and sediments. This theory is well developed for the case of semi-rigid terrestrial vegetation and has more recently been applied to the case of aquatic vegetation. However, aquatic vegetation often displays key differences in morphology and biomechanics to terrestrial vegetation due to the different environment it inhabits. Here we investigate the effect of plant morphology and biomechanical properties on flow–vegetation interactions through the application of a coupled LES-biomechanical model. We present results from two simulations of aquatic vegetated flows: one assuming a semi-rigid canopy and the other a highly flexible canopy and provide a comparison of the associated flow regimes. Our results show that while both cases display canopy mixing layers, there are also clear differences in the shear layer characteristics and turbulent processes between the two, suggesting that the semi-rigid approximation may not provide a complete representation of flow–vegetation interactions.     

Assessment of prenatal mercury exposure in a predominately Caribbean immigrant community in Brooklyn, NY

Prenatal mercury exposure and its fetotoxic effects may be of particular concern in urban immigrant communities as a result of possible contributing cultural factors. The most common source of exposure in these communities is ingestion of fish and shellfish contaminated with methylmercury. Other sources of exposure may occur in ritualistic practices associated with Hispanic and Caribbean-based religions. This study 1) assessed total mercury levels in both random urine specimens from pregnant women, and in cord blood; and 2) examined environmental sources of exposure from a convenience sample in a predominantly Caribbean immigrant population in Brooklyn, New York. A questionnaire designed in collaboration with health professionals from the Caribbean community assessed the frequency of fish consumption, ritualistic practices, occupational exposures, and use of dental amalgams and mercury-containing skin and household products. The geometric mean for total mercury in cord blood was 2.14 μg L(-1) (95%CI: 1.76-2.60) (n = 78), and 0.45 μg L(-1) (95%CI: 0.37-0.55) (n = 183) in maternal urine corrected for creatinine (μg g(-1)). Sixteen percent of cord blood mercury levels exceeded the estimated equivalent of U.S. Environmental Protection Agency's Reference Dose (5.8 μg L(-1) blood). Predictors of cord blood mercury included maternal fish consumption and foreign birth of the mother. Predictors of urine mercury included foreign birth of the mother, number of dental amalgams, and special product use. There were no reports of mercury use in ritualistic practices or in cosmetics; however some women reported use of religious medals and charms. This study characterized risk factors for mercury exposure in a sample of urban, predominantly Caribbean-born blacks. Findings may help target interventions in this population, which might include appropriate fish selection and consumption frequency during pregnancy, and safe handling of mercury-containing products in the home.     

A comparison of disposal methods for on-site sewage facilities within the state of Texas,USA

Currently, 1.5 million homes in Texas, USA utilize an on-site sewage facility to manage their household waste. This study compares the conventional septic dispersal technology of perforated pipe drain field with two of the new technologies recently implemented in Texas, multi-pipe and chamber systems, determining if soil classification and climate are influencing factors in functional ability for each of the technologies. There is no statistical significance for failure of a system with respect to system type or climate zone. The textural classification of soil is a statistically significant variable in septic system failures. Soil type III, which includes the clay groups except pure clays and silty clay, appears to significantly influence system failures. Additionally, occupant misuse and lack of maintenance are contributing factors to system failure.     

MM5 simulations for air quality modeling: An application to a coastal area with complex terrain

A series of modifications were implemented in MM5 simulation in order to account for wind along the Santa Clarita valley, a north–south running valley located in the north of Los Angeles. Due to high range mountains in the north and the east of the Los Angeles Air Basin, sea breeze entering Los Angeles exits into two directions. One branch moves toward the eastern part of the basin and the other to the north toward the Santa Clarita valley. However, the northward flow has not been examined thoroughly nor simulated successfully in the previous studies. In the present study, we proposed four modifications to trigger the flow separation. They were (1) increasing drag over the ocean, (2) increasing soil moisture content, (3) selective observational nudging, and (4) one-way nesting for the innermost domain. The Control run overpredicted near-surface wind speed over the ocean and sensible heat flux, in an urbanized area, which justifies the above 1st and 2nd modification. The Modified run provided an improvement in near-surface temperature, sensible heat flux and wind fields including southeasterly flow along the Santa Clarita valley. The improved MM5 wind field triggered a transport to the Santa Clarita valley generating a plume elongated from an urban center to the north, which did not exist in MM5 Control run. In all, the modified MM5 fields yielded better agreement in both CO and O₃ simulations especially in the Santa Clarita area.     

Valuation of open space and conservation features in residential subdivisions

Conservation subdivision design has been promoted as a way to protect ecologically sensitive areas while maintaining housing densities comparable to standard subdivisions, but many developers and planners question the appeal of conservation design to consumers. This study was conducted to compare economic aspects of conservation subdivision design to standard subdivision design in the midwestern United States. Three methods were used to determine the value homebuyers have for embedded conservation features in residential areas: transactional analyses (to indicate the value homebuyers have expressed for such features in the past); hedonic analyses (to determine the proportion of present value of homes attributable to such features); and contingent valuation (to examine willingness to pay according to homebuyers' preferred features, an indicator of potential future investment). Transactional analyses were based on assessment and transaction data for homes in three conservation-oriented subdivisions and three standard subdivisions in Cedar Rapids, Iowa, United States. Hedonic price models were also derived from assessment and transaction data. Contingent valuation analyses were based on a survey of residents in the same six subdivisions. Transactional data indicated higher 5-year appreciation rates for conservation versus standard subdivision design. Hedonic price models revealed that well-integrated conservation features (e.g. protected stream corridors) within subdivisions have a positive effect on home prices. Sixty-six percent of all respondents indicated willingness to pay for more embedded open space. Maximum willingness to pay was related to several factors including income, gender, desired level of open space, and concern about urban development. Overall, these results indicate that consumer demand and willingness to pay for conservation subdivision design are positive and should not be considered a barrier to implementation.     

Personalized Nutrition and Social Justice: Ethical Considerations Within Four Future Scenarios Applying the Perspective of Nussbaum’s Capabilities Approach

The idea of personalized nutrition (PN) is to give tailored dietary advice based on personal health-related data, i.e. phenotoype, genotype, or lifestyle. PN may be seen as part of a general trend towards personalised health care and currently various types of business models are already offering such services in the market. This paper explores ethical issues of PN by examining how PN services within the contextual environment of four future scenarios about health and nutrition in Europe might affect aspects of social justice according to Martha Nussbaum’s capability approach. The scenarios have been created by a mixed group of stakeholders and experts in three consecutive workshops. This resulted in the definition of four future scenarios within a scenario space consisting of two variables: the ‘logic of health care systems’ and ‘conception of health’. Within each scenario, PN is likely to play a more or less important role in improving health by influencing food consumption patterns in society. Nussbaum’s capability approach implies a concept of social justice as a function of a minimum standard of human dignity. This denotes an account for equality in terms of a minimum of entitlements. However, also the ability of achieving individual objectives is essential for social justice. Personalisation advice in health and food consumption patterns, as aimed for by PN, is therefore acceptable provided a minimum of entitlements is guaranteed to all members of a society, and at the same time freedom concerning personal preferences is respected. Potential variation of how different people might benefit from PN should therefore be consistent with the minimum required as defined by the list of capabilities.     

Analysis of organic nitrogen removal in municipal wastewater by reverse osmosis

The results of a pilot study that was conducted to determine the total nitrogen removal by the reverse osmosis process are presented. The organic nitrogen removal rates are compared with removals observed from three full-scale reverse osmosis facilities and four pilot studies. The results of this analysis suggest that organic nitrogen removal is variable and that reverse osmosis may not consistently produce total nitrogen levels less than 1.0 mg/L without additional treatment. Three hypotheses to explain the variability in organic nitrogen removal in the different data sets are presented.