Effect of cooking on levels of ethylene dibromide residues in rice

Two studies were conducted to determine the effect that cooking has on the level of residues of ethylene dibromide (EDB) in rice. In the first study, 4 samples of long and medium grain polished white rice containing 113, 295, 956, and 1568 ppb EDB were cooked according to typical label directions. Three batches of cooked rice were prepared from each sample of polished rice and frozen until analysis; each batch was analyzed in duplicate. EDB levels in all cooked rice samples were less than 10 ppb. In the second study, conducted jointly by the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA), a sample of medium grain polished white rice containing about 1600 ppb EDB was cooked by each laboratory. Overall average EDB levels in rice analyzed immediately after cooking were 16 and 37 ppb for FDA and EPA, respectively. The corresponding frozen samples contained 8 and 39 ppb EDB. The 2 laboratories exchanged these frozen samples and reanalyzed them to check variability in the analytical procedure. FDA found 49 ppb EDB in the sample cooked by EPA and EPA found 8 ppb EDB in the sample cooked by FDA, thus indicating that analytical methodology was not a major source of variability. The range of EDB levels was therefore attributed to minor differences in the way the rice was cooked or handled immediately after cooking.     

Optimized Monier-Williams method for determination of sulfites in foods: collaborative study

A collaborative study was conducted of the Food and Drug Administration (FDA)-optimized Monier-Williams method for determining sulfites in foods. Twenty-one industry and government laboratories participated in the study, which was jointly sponsored by the National Food Processors Association and FDA. Familiarization samples were shipped to each collaborator. Collaborators were permitted to proceed to the main study only after they demonstrated ability to perform the method to ensure that the study tested the performance of the method itself and not that of the individual laboratories. The study design involved 3 food matrixes (hominy, fruit juice, and protein [seafood]). Each matrix was prepared at 3 sulfite levels--the regulatory level, half the regulatory level, twice the regulatory level--and as a blank. All test samples were analyzed as blind duplicates, which gave each collaborator a total of 24 test portions. Collaborative recoveries gave a reproducibility (among-laboratories) coefficient of variation that ranged from 15.5 to 26.6% for sulfite determined as SO2 by weight in the 3 foods at the 10 ppm level. The optimized Monier-Williams method has been approved interim official first action to replace the AOAC modified Monier-Williams method, 20.123-20.125.     

Peer-led approaches to dietary change: report of the Food Standards Agency seminar held on 19 July 2006

OBJECTIVE: To summarise the discussions of a seminar on peer-led approaches to dietary change held at the Food Standards Agency (FSA) on 19 July 2006. DESIGN: Following presentations on three FSA-commissioned research projects involving peer-led dietary interventions, discussions in small workshop groups identified learning points for researchers, policy-makers and practitioners and considered how the findings of such studies can be effectively communicated to each of these groups. The target groups in the three separate projects were: older people living in sheltered accommodation; mothers and babies during the weaning period; and people with diabetes. RESULTS: The projects discussed here were quite different from one another, involving three separate populations, having different aims and approaches and different styles of peer leading. Their effectiveness in achieving quantitative dietary change was disappointing. However, results for some of the qualitative outcomes (social, psychological, behavioural) were more positive. Process evaluation, whether built in or post hoc, provided useful learning to inform future projects and potentially improve their effectiveness and usefulness for researchers, policy-makers and health promotion practitioners. CONCLUSIONS: The projects discussed here showed that peer-led interventions can achieve positive changes in outcomes such as knowledge, confidence and attitudes, as well as small improvements in diet. They also demonstrated that there is a need for a more sophisticated analysis of peer-led interventions that recognises the diversity of approaches and their suitability in different situations.     

Intercomparison study on the determination of single administration toxicity in rats.

In 1977, the Commission of the European Communities initiated an intercomparison study to determine the single administration oral LD50 value in rats of each of 5 chemicals with the aims of comparing experimentation technologies, determining the degree of variation in the results and the various parameters used to establish the LD50 value, and establishing a common protocol for the determination of the LD50 value. Sixty-five laboratories in 8 countries took part in the first study. The significant variation in protocol may have led to the large interlaboratory variation observed in the results. Therefore, participating laboratories carried out a second study using a common protocol, preceded by a pilot study. A total of 100 laboratories in 13 countries participated. A majority of results of the second study are currently being analyzed, and the indications are that the interlaboratory variation has been significantly reduced.     

Learning opportunities: Understanding farmers’ soil testing practice through workshop activities to improve extension support for soil health management

This paper examines the potential for extension providers to identify learning opportunities by intentionally surveying farmers attending soil testing workshops designed to improve soil health and its management. In south‐eastern Australia, regional government agencies have been running soil health workshops since 2014, yet they have rarely surveyed the participants to understand their previous experience or learning needs, and how that may inform their design. The workshop consisted of two sessions, separated by 6 weeks. Farmers at the first Session were told how to undertake soil measurements. At the second Session, they then discussed their soil test results. The workshop participants (n = 87) at four different localities in the Northern Tablelands of New South Wales were surveyed (68% response rate) at each session. Firstly, to examine their prior knowledge and experience of soil testing, and secondly on how they applied what they had learnt, examine if the soil test results matched their expectations, and their influence in land management decisions. The survey revealed to regional government agencies that the majority of survey respondents (62%) would soil test again. Despite more than half of the respondents infrequently or never having their soil tested, prior to the workshop, 50% indicated that the test results were unexpected. The motivation for those farmers who would soil test again was the specific desire to identify their soil's potential for improved production. The survey provided a way of profiling the workshop audience and obtaining important feedback on how to improve the impact of the workshops for participants.     

View of the International Dairy Federation on interlaboratory analytical studies

The International Dairy Federation develops and studies methods for the analysis of milk and milk products. A first draft of an IDF protocol for conducting interlaboratory studies is presented. Major features of the protocol are type and number of participating laboratories; nature, duplication, and number of sample materials; final design (numbers of samples and laboratories); statistical analysis of the data; report of the final results.     

Acute and prolonged toxicity tests.

An answer to the question of whether acute and prolonged toxicity tests are good candidates for standardization is developed by reviewing (1) the factors that are presumed to influence the results of these tests and (2) the collaborative studies that have been reported in the literature. In regard to acute toxicity tests it is clear that competent laboratories give due consideration for the control of factors that are known to influence these tests. Also competent laboratories using their own procedures provide reliable results, even though the procedures vary from laboratory to laboratory. In regard to prolonged toxicity tests there are no examples of controlled collaborative investigations which could be used to evaluate interlaboratory variation and its relation to the protocols involved. It is recommended that guidelines rather than rigid protocols would be an appropriate approach for improving the quality and accuracy of these toxicologic tests. Examples of such guidelines are given.     

Soil extension needs to be a continuum of learning; soil workshop reflections 10 years on

Effective extension of soil research builds landholder capacity to manage soils productively and sustainably. Government‐funded extension programmes also aim to improve the state of the environment through efficient use of resources and mitigating or preventing further land degradation. To these ends, a soil extension programme aimed at farmers in south‐eastern Australia was conducted during 2005–2008. The programme was designed to equip landholders with the knowledge, skills and confidence to diagnose and address soil constraints, as well as compile spatial information on soil properties. The programme involved four workshops that covered agricultural productivity, soil management and potential off‐site impacts. Workshops were held on‐farm and involved discussion, theory supported with practical exercises, and field visits. More than 1,400 participants were provided with subsidized soil tests to encourage soil monitoring and underpin the workshop theory on land capability and soil constraints (e.g., soil acidity, sodicity, salinity, nutrient decline and toxicities). Prior to the course, most participants did not regularly soil test so training on monitoring protocols was provided. The soil data indicated considerable phosphorus deficiencies, low organic carbon levels, and acidity across both cropping and pasture systems. Participant knowledge and land management intentions were tracked throughout the workshop series using surveys. The surveys identified a positive shift in the knowledge, understanding and confidence of most participants. However, a follow‐up survey 10 years later indicated that these changes may not have been broadly sustained. Based on our study, we recommend continued engagement of landholders along a learning pathway to maximize investment in soil extension.     

Meeting the Information Needs of the Extension Agent

ABSTRACT

The University of Kentucky Library is actively working with the County Agents to make them aware of electronic services available from their offices. An in-service training program was held in August 1992. Fifteen agents from around the stale participated. The organization and structure of the workshop is presented along with plans for future training.     

Assay for fluorescein diacetate hydrolytic activity: Optimization for soil samples

With the increased interest in integrated soil bioecosystem studies, there is a need to have a method of measuring overall microbial activity potential. Hydrolysis of fluorescein diacetate [3′,6′-diacetylfluorescein (FDA)] has been suggested as a possible method because the ubiquitous lipase, protease, and esterase enzymes are involved in the hydrolysis of FDA. Following hydrolysis of FDA, fluorescein is released and can be measured spectrophotometrically. Our objective was to optimize the assay for FDA hydrolytic activity in soil samples and determine the kinetic parameters involved in this reaction. The optimized method involves extraction and quantitative measurement of the fluorescein released when 1.0 g of soil is incubated with 50 ml of 60 mM Na-phosphate solution (buffered at pH 7.6) at 37 °C for 3 h. Results showed that FDA hydrolysis was optimum at buffer pH 7.6 and the soil enzymes were denatured at temperatures above 60 °C. Three soils were used to optimize this method: Heiden clay, Raub silt loam, and Cecil sandy loam. This procedure is simple, precise, and can be used in commercial soil testing laboratories to determine general microbial activity and as a soil quality indicator.     

Liquid chromatographic determination of lasalocid sodium in chicken skin: interlaboratory study

The U.S. Food and Drug Administration (FDA) sponsored an interlaboratory study of a liquid chromatographic determinative procedure for lasalocid sodium in chicken skin with adhering fat. Four laboratories analyzed 35 dosed tissue samples and 82 fortified tissue samples containing lasalocid at levels ranging from 0.1 to 0.6 ppm. Samples were homogenized with acetonitrile, washed with hexane, and partitioned into the mobile phase prior to analysis liquid chromatography with fluorescence detection. The results of the interlaboratory study showed good reproducibility for fortified samples. Fortification levels, average recoveries, and interlaboratory percent coefficients of variation were as follows: 0.6 ppm, 0.57 ppm, and 9.7; 0.3 ppm, 0.25 ppm, and 9.1; and 0.15 ppm, 0.14 ppm, and 7.0, respectively. Data for analysis of the dosed tissue also showed good agreement among the laboratories.     

Soil erosion and participatory remediation strategy for bench terraces in northern Thailand

This study was carried out in Pang Prarachatan village, which is located in Chiang Rai province of northern Thailand. The farmers in this village construct bench terraces to reduce soil erosion and increase plant productivity. However, severe soil erosion occurs frequently on the bare bench terraces. This study investigates the impact of bench terracing on soil erosion. The use of weeds and plant residues to control soil and nutrient losses were also investigated using model slope plots and an artificial rainfall system. Finally, the knowledge gained from this study was transferred to the farmers through a workshop in the village, and their acceptance of the results was evaluated by means of a questionnaire. The severity of soil erosion is thought to vary according to the structure of the bench terrace and the ground cover conditions. Rills are the primary form of erosion on bare bench terraces. In addition, some rills develop into gullies that can run from the upper terrace down to the lower terrace. Nevertheless, rills and gullies are rarely found on weed-covered terraces. Moreover, the results of an erosion experiment using model slope plots and artificial rainfall systems showed that plots covered with weeds and plant residues had much less surface runoff and soil and nutrient losses than bare soil. The amounts of nitrogen and phosphorus absorbed by weeds were 4.7 and 2.3 times smaller than the nitrogen and phosphorus losses due to soil erosion, respectively. The results of the field surveys and model slope experiment were announced to the farmers through participatory workshop in August 2003. The first questionnaire, conducted just after the workshop, clearly showed that around 90% of the farmers agreed to cover their slopes with weeds and plant residues so long as it did not affect soil fertility and plant growth. However, the second questionnaire, conducted in January 2004, showed that only 29% of farmers were covering the bench terraces or non-terraced slopes in their farmlands with weeds and plant residues. Therefore, participatory activities should continue to be held regularly in order to ensure greater acceptance and practice of soil conservation on the part of the farmers.     

Development and intercalibration of methods in nordic freshwater fish monitoring

The awareness of the effects of transboundary pollution has increased the necessity to use comparable methods and to initiate joint studies between countries in environmental monitoring. In freshwater fish monitoring a number of different methods have been used, strongly reducing the possibilities to comparative assessments between countries. In 1990, a workshop on freshwater fish sampling was initiated in order to develop and intercalibrate methods used in freshwater fish studies in the Nordic countries. During a three year period, a new type of multi-mesh gillnet to be used for fish monitoring in Norway, Finland and Sweden have been developed. Comparative studies and gillnet-selectivity assessments show that these new multi-mesh gillnets better describe the actual population structure of European perch (Perca fluviatilis), roach (Rutilus rutilus) and Arctic char (Salvelinus alpinus) than do the traditional gillnet series used in the Nordic countries. Ageing of fish is central in most environmental studies, however, the comparability of analyses performed at different laboratories may be low. Comparative age analyses between the three countries have been performed for a number of fish species. The results of ageing E. perch, whitefish (Coregonus sp.) and roach indicate that differences between laboratories can be reduced by intercalibration. In the future, the workgroup will be focused on a further development of joint methods within studies of freshwater fish and on joint intemordic assessments on species distribution, abundance and life history characteristics in relation to airborne pollutants and liming.     

Harmonisation, standardisation for soil and sediment fractionation studies, and usefulness in assessment and risk management

Single and sequential extraction procedures are often used to study the environmental fate of trace elements from soils and sediments. Although these schemes are quite popular, they are prone to various sources of errors, which require them to be thoroughly controlled. Owing to their operationally-defined character, the only way to compare analytical data is to stick closely to procedures that have been collaboratively studied and written in the form of an operating protocol. Groups of scientists have hence developed ‘harmonised’ procedures that are used as a reference for fractionation studies. A higher level is the formal standardisation of the procedures by official standardisation bodies, which also fulfils the need for achieving the comparability of data obtained by different laboratories from different countries. This paper discusses aspects of harmonisation (consensus obtained by groups of scientists) and standardisation (adoption of standards as mandated by an international organisation) as applied to single and extraction schemes for trace element fractionation studies, including quality control aspects.     

Interlaboratory comparison of behavioral testing.

New requirements by several regulatory agencies for testing the psychotoxic potential of new drugs, chemicals, and environmental contaminants raise unique problems. In order to assess intra- and interlaboratory reliability of behavioral tests a model animal maze learning procedure was designed and run in 3 cooperating laboratories. Uniform procedures were written and identical mazes were constructed. Normal control animals of identical age and sex, but of different strains, were used by the participants. A positive control group of neurologically impaired rats was run by one laboratory. Significant differences in test results among the laboratories were found. Data obtained from the positive control animals (mean errors=28.3) indicated a learning impairment statistically significant compared to the negative control data (mean errors=12.7) from any of the participating laboratories. Based on the results of this study, a reasonable standard of interlaboratory reliability in behavioral testing appears an attainable goal.     

Using a Numerical Model to Track the Discharge of a Wastewater Treatment Plant in a Tidal Estuary

Along the coast of Maine, USA, there are numerous wastewater treatment plants that discharge their treated effluents into a river estuary which is shared by commercial fishing and shellfish harvesting. Occasionally, there can be failures or bypasses of treatment plants that lead to untreated or partially treated sewage flowing into shellfish harvesting waters. To prevent any toxic contamination of harvested shellfish, a prohibitive zone is established around the treatment plant where shellfish harvesting is prohibited. The U.S. Food and Drug Administration has conducted numerous dye studies on both coasts of the USA to determine these prohibitive zones, based on the guidelines of the National Shellfish Sanitation Program. In May 2010, the FDA conducted such a dye study at the Yarmouth, Maine wastewater treatment plant. The results are compared with a numerical coastal model that provides the velocity field for the currents around the treatment plant. This model includes a diffusion equation to simulate dye dispersion from a point source which is used to determine the prohibitive zone. The numerical model shows good correlation with the FDA dye study report and establishes a prohibitive zone for commercial harvesting in keeping with that of the FDA study. The benefits of the numerical model include sampling at thousands of locations simultaneously, seasonal changes in river volumes, and changes in plant discharge volumes.     

Liquid chromatographic determination of N-methylcarbamate insecticides and metabolites in crops. II. Analytical characteristics and residue findings

Four laboratories obtained 177 carbamate recovery values using a liquid chromatographic method. The average recovery of 11 carbamates (aldicarb, aldicarb sulfone, bufencarb, carbaryl, carbofuran, 3-hydroxy carbofuran, 3-keto carbofuran, methiocarb, methiocarb sulfoxide, methomyl, and oxamyl) from 14 crops was 99% with a coefficient of variation of 8% (0.03-1.8 ppm fortification levels). No statistical difference in recovery was found between oxime and phenyl carbamates, or between parent and metabolite carbamates. Average recovery of aldicarb sulfoxide was 59% due to loss in the liquid-liquid partitioning because of the polarity of this compound. A fifth laboratory contributed 34 carbamate recoveries (average 99%) on table-ready food products for 4 carbamates. Bendiocarb, dioxacarb, isoprocarb, and propoxur are also quantitatively recovered through the method. Previously reported carbamate and noncarbamate recovery data are also discussed. In the Food and Drug Administration's (FDA) analysis of 319 samples (mainly crops), 86 (27%) were found to contain residues of carbamate insecticides and/or toxic carbamate metabolites. Carbaryl and methomyl were the most common carbamate residues found on the food products excluding the aldicarb sulfone and sulfoxide residues found on potatoes. In one FDA Total Diet Program "market basket", 11 of 69 table-ready food commodities contained from 0.005 to 0.094 ppm carbamate residues. Carbaryl was the most prevalent residue. Several laboratories reported adverse effects on the determinative system when inadequately purified reagents were used.     

Validation of a pre-coded food diary used among 13-year-olds: comparison of energy intake with energy expenditure

OBJECTIVE: To validate energy intake (EI) estimated from pre-coded food diaries against energy expenditure (EE) measured with a validated position-and-movement monitor (ActiReg) in groups of 13-year-old Norwegian schoolchildren. DESIGN: Two studies were conducted. In study 1 the monitoring period was 4 days; participants recorded their food intake for four consecutive weekdays using food diaries and wore the ActiReg during the same period. In study 2 the monitoring period was 7 days; participants recorded their food intake for four consecutive days but wore the ActiReg for a whole week.Settings: Participants were recruited from grade 8 in a school in and one outside Oslo (Norway).Subjects: Forty-one and 31 participants from study 1 and 2, respectively, completed the study. RESULTS: The group average EI was 34% lower than the measured EE in study 1 and 24% lower in study 2. The width of the 95% confidence limits of agreement in a Bland-Altman plot for EI and EE varied from -0.2 MJ to 8.2 MJ in study 1 and from -2.3 MJ to 6.9 MJ in study 2. The Pearson correlation coefficients between reported energy intake and expenditure were 0.47 (P=0.002) in study 1 and 0.74 (P<0.001) in study 2. CONCLUSION: The data showed that there was substantial variability in the accuracy of the food diary at the individual level. Furthermore, the diary underestimated the average energy intake. The ability of the food diary to rank individuals according to energy intake was found to be good in one of the studies and moderate in the other.     

Drying-rewetting cycles and γ-irradiation effects on enzyme activities of distinct layers from a Quercus ilex L. litter

In a Mediterranean climate, water stress is one of the principal constraints on proper forest ecosystem functioning. Drought influences rates of organic matter degradation by affecting microbial growth and enzyme activities. The objectives of this study were: (i) to evaluate the effect of repeated drying-rewetting cycles on cellulase, alkaline phosphatase and fluorescein diacetate (FDA) hydrolase activities of three distinct Quercus ilex L. litter layers, and (ii) to investigate the effect of these cycles on γ-irradiated litters in order to distinguish the abiotic influence on the fluctuations observed. Results, for all three layers, showed high correlations between litter water content and enzyme activities. Under mesocosm conditions, and using non-sterilized litter samples, cellulase, alkaline phosphatase, and FDA activities significantly decreased or increased during drying or rewetting cycles respectively. Significant differences were also found when evaluating the effect of litter depth on enzyme activities, the intermediate depth (OLv layer) generally being the most active. For γ-sterilized samples, FDA activity still fluctuated with drying-rewetting cycles. Assays showed that pre-humidification of γ-irradiated litter increased FDA activity two-fold in the first 30 min. All these results have shown that, following drying-rewetting cycles, some of the fluctuations occur independently of microbial growth, suggesting abiotic interactions, such as desorption, in combination with both solvatation status and conformational changes of enzymes.     

Gas chromatographic-thermal energy analysis method for determination of volatile N-nitrosamines in baby bottle rubber nipples: collaborative study

A collaborative study was conducted on the U.S. Food and Drug Administration (FDA) dichloromethane extraction method for determining volatile N-nitrosamines in baby bottle rubber nipples. Following dichloromethane extraction, N-nitrosamines were determined by gas chromatography-thermal energy analysis. Six pairs of blind duplicate rubber nipple samples representing 6 lots were analyzed by 11 collaborating laboratories. All samples were portions taken from equilibrated composites of cut-up rubber nipples obtained from manufacturers in the United States. Recoveries of the internal standard (N-nitrosodipropylamine) at approximately 20 ppb ranged from 10 to 120%. Reproducibility relative standard deviations (RSDx) were between 35 and 45% for N-nitrosamine levels from 10 to 20 ppb. However, when data from laboratories with recoveries less than 75% were excluded (this is now specified in the method), RSDx values were between 11 and 32% for N-nitrosamine levels from 6 to 26 ppb. Values were consistent with or better than those reported for other analytical techniques designed to quantitate trace contaminants at the low ppb level, e.g., aflatoxin in foods. The method has been adopted official first action for the quantitation of volatile N-nitrosamines in baby bottle rubber nipples.