Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Food Chain”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53Linked to original sources
PubMed2005

Introduction: food crops in a changing climate.

Changes in both the mean and the variability of climate, whether naturally forced, or due to human activities, pose a threat to crop production globally. This paper summarizes discussions of this issue at a meeting of the Royal Society in April 2005. Recent advances in understanding the sensitivity of crops to weather, climate and the levels of particular gases in the atmosphere indicate that the impact of these factors on crop yields and quality may be more severe than previously thought. There is increasing information on the importance to crop yields of extremes of temperature and rainfall at key stages of crop development. Agriculture will itself impact on the climate system and a greater understanding of these feedbacks is needed. Complex models are required to perform simulations of climate variability and change, together with predictions of how crops will respond to different climate variables. Variability of climate, such as that associated with El Niño events, has large impacts on crop production. If skilful predictions of the probability of such events occurring can be made a season or more in advance, then agricultural and other societal responses can be made. The development of strategies to adapt to variations in the current climate may also build resilience to changes in future climate. Africa will be the part of the world that is most vulnerable to climate variability and change, but knowledge of how to use climate information and the regional impacts of climate variability and change in Africa is rudimentary. In order to develop appropriate adaptation strategies globally, predictions about changes in the quantity and quality of food crops need to be considered in the context of the entire food chain from production to distribution, access and utilization. Recommendations for future research priorities are given.

Climate↗
PubMed2001

Safety considerations of DNA in food.

Recombinant DNA techniques are capable of introducing genetic changes into food organisms that are more predictable than those introduced through conventional breeding techniques. This review discusses whether the consumption of DNA in approved novel foods and novel food ingredients derived from genetically modified organisms (GMOs) can be regarded as being as safe as the consumption of DNA in existing foods. It concludes that DNA from GMOs is equivalent to DNA from existing food organisms that has always been consumed with human diets. Any risks associated with the consumption of DNA will remain, irrespective of its origin, because the body handles all DNA in the same way. The breakdown of DNA during food processing and passage through the gastrointestinal tract reduces the likelihood that intact genes capable of encoding foreign proteins will be transferred to gut microflora. The review does not specifically address food safety issues arising from the consumption of viable genetically modified microorganisms but it shows that the likelihood of transfer and functional integration of DNA from ingested food by gut microflora and/or human cells is minimal. Information reviewed does not indicate any safety concerns associated with the ingestion of DNA per se from GMOs resulting from the use of currently available recombinant DNA techniques in the food chain.

Consumer Product Safety↗
PubMed2001

Sublethal effects of silver in zooplankton: importance of exposure pathways and implications for toxicity testing.

In aquatic environments, organisms are exposed to contaminants via direct uptake from water and by trophic transfer. However, most toxicity tests only examine uptake via the dissolved phase. We compared the response of marine and freshwater crustacean zooplankton to silver following dissolved and food exposure. Silver, like other metals, concentrates in aquatic food chains and may exert toxicity. In standard solute exposure toxicity tests, Ag is toxic to zooplankton at concentrations of 400 nM for marine copepods and 100 nM for freshwater cladocerans, concentrations far greater than those in most waters. However, if Ag is accumulated from algal food, reproductive success decreases by >50% when algae are exposed to only 1 nM Ag in copepods and 0.5 nM Ag in cladocerans. These concentrations are within an order of magnitude of those found in contaminated estuaries. Following dietary exposure, decreased egg production and viability occur when tissue Ag concentrations increase three- to fourfold to 0.3 ppm in cladocerans and 0.5 ppm in copepods. Assimilated Ag depresses egg production by reducing yolk protein deposition and ovarian development. Our results indicate that ecologically relevant toxicity tests should consider sublethal effects of contaminants obtained from food since these effects cannot be predicted from exposures to only dissolved contaminants.

Animals↗
PubMed1990

Benzene: environmental partitioning and human exposure.

A multimedia transport model was used to evaluate the environmental partitioning of benzene. Measured and predicted environmental concentrations were used to estimate the accumulation of benzene in the food chain and the subsequent extent of human exposure from inhalation and ingestion. Results show that benzene partitions mainly into air (99.9%) and that inhalation is the dominant pathway of human exposure, accounting for more than 99% of the total daily intake of benzene. Ingestion of contaminated food items represents only a minor pathway of human exposure. The long-term average daily intake of benzene by the general population of the U.S. was estimated using three independent methods. Intake estimates based on measured personal air exposures, measured exhaled air concentrations, and a pharmacokinetically derived adipose tissue concentration (73, 63, and 72 micrograms/day, respectively) are in good agreement. Although inhalation is the primary route of human exposure to background levels of benzene in the environment, smoking was found to be the largest anthropogenic source of background human exposure to benzene.

Air↗
PubMed2002

Organochlorine pesticide residues in breastmilk: difficulties in sample collection and in assessing intakes.

Organochlorine pesticides are highly lipophilic and stable resulting both in their persistence in the environment and their tendency to pass up the food chain. Residues of these compounds are detectable in breastmilk and have been monitored since the 1950s. Samples can be collected using non-invasive techniques and the results are frequently used to assess degradation in the environment as well as risks to recipient infants. As a food, breastmilk is unique. It is manufactured entirely for an individual consumer with some of its constituents driven by its recipient. It can form the sole source of nutrition for a considerable period of an infant's life. Standard calculations of exposure to residues rely on consumption of 750-850 ml breastmilk day(-1) containing 3.5% fat for a 5-kg infant. The fat content of breastmilk, however, is highly variable, which means that that using fixed breastmilk volumes and fat can lead to an imprecise calculation of individual risk. The fat concentration of breastmilk changes throughout a single feed, between feeds and as lactation progresses. This variation therefore raises the methodological problem of how to secure a representative sample of breastmilk. Furthermore, maternal factors such as age and parity also affect concentrations because of the persistence of organochlorine pesticide residues in maternal fat stores. It is therefore critical that samples are collected in a systematic manner taking account of these variables, particularly if the results not only are to be used for risk assessment, but also in comparing changes in environmental concentrations. Reviews of the literature have shown that these variables have often been disregarded in drawing up sampling strategies and methodologies are poorly reported in publications. The paper discusses the literature currently available on monitoring organochlorine pesticide residues in breastmilk and presents an overview of some of the factors that need to be taken into account when collecting samples and assessing infant exposure.

Female↗
PubMed1984

Dietary intake and bioavailability of fluoride.

After almost 40 years of water fluoridation in the United States, its effect in the food chain is now being appreciated. Current surveys indicate significant increases in the F content of infant formulas, toddler cereals, fruit juices, and popular beverages, largely because fluoridated water is used in their processing. According to the best estimates, the daily total F intake of children from foods, beverages including water, and other sources such as unintentional ingestion of dentifrices containing F is on the rise, although it is generally within the currently accepted range for this age group. It is encouraging to note that appropriate steps are now being taken by some manufacturers of infant formulas to monitor F levels and keep them within an acceptable range. Because of the increasing contribution of dietary F to total F intake, dietary F should be included in any estimate of daily total F intake in children before F supplements are prescribed, whether the children live in communities with fluoridated or nonfluoridated water. To achieve this goal, it is essential to develop a generally accepted, sensitive method for the analysis of F in foods and beverages. This should help develop the bioavailability profiles for individual foods and beverages essential for accurate assessment of dietary F intake. Fluoridated salt, used in some European countries, appears to be the only food ingredient currently in use as an alternative to water fluoridation. Attempts to utilize staple foods and beverages as vehicles for systemic F delivery have generally failed because of the decreased bioavailability of F in such products, and because it is difficult to make them available to the general population and especially to the lower socioeconomic segments of the population.

Adolescent↗
PubMed1998

Assessment of dioxins in foods from animal origins.

Dioxin is the common name for 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD) but is also used for the structurally and chemically related polychlorinated dibenzo-para-dioxins (PCDD), dibenzofurans (PCDF), and the coplanar polychlorinated biphenyls (PCB). There are 75 PCDD congeners, 135 PCDF, and 209 PCB. Seven PCDD and 10 PCDF with substitutions at the 2,3,7, and 8 positions are considered toxic, and 11 PCB have dioxin-like toxicity. The majority of toxic dioxin is and(or) has been derived from industrial chlorination processes, incineration of municipal waste, and production of certain herbicides. The potential for health risks due to the cancer-promoting, immunomodulating, and teratogenic activities of dioxins in rodents has raised concerns over their presence in the human food chain. The lipophilic nature of dioxins results in higher concentrations in the fat of animal and fish products, and their excretion via milk secretion in dairy cattle may result in relatively high concentrations of dioxin contamination in high-fat dairy products. Surface contamination of plant foods and soil due to deposition of atmospheric emissions may also be a significant direct source of dioxin ingestion for livestock and thereby an indirect source of dioxin for humans. Despite numerous epidemiological studies, dioxin has not been conclusively determined to be problematic for humans. Certain management practices such as trimming fat from meat, consuming low-fat dairy products, and simply cooking food can substantially decrease exposure to dioxin compounds.

Animals↗
PubMed2003

Fungal toxicity with special reference to mycotoxins.

Mycotoxins are fungal secondary metabolites formed by consecutive series of enzyme-catalysed reactions from a few biochemically simple intermediates of primary metabolism. These mycotoxins can enter the human and animal food chain by direct or indirect contamination. Mycotoxins are equally harmful to animal and human beings. Realizing the importance of mycotoxins to the health of man and animals there have been concentrated efforts to develop highly sensitive analytical methods for detection and proper determination of mycotoxins in food, mixed feeds and feed ingredients, animal tissue, blood, urine and milk. Most of the mycotoxins are identified and most current research on it is concentrated on increasing sensitivity accuracy and reproducibility and above all to decrease the time of determination. A detailed review of mycotoxin and their detection is summarised in the paper.

Animals↗
PubMed2001

Traceability in the pig production chain.

Traceability is becoming a subject of significant interest to all those involved in pig production and marketing. Until the 1990s, the purposes of farm and animal identification were primarily related to implementation of breeding schemes and health programmes. More recently, other aspects have been emphasised, especially in certain countries where consumer demand has led to the need to trace animals and animal products along the food chain. Pigs are identified principally through ear tags and/or tattoos which are the common 'traditional' systems. However, an important research effort has been directed towards electronic identification. Electronic identification will allow telemetric data collection for quality care in pig production. The carcasses are identified after slaughter, and the meat can also be traced back later in the process. Examples of traceability systems for pigs in various countries are described by the authors.

Animal Husbandry↗
PubMed2001

Science, policy, stakeholders, and fish consumption advisories: developing a fish fact sheet for the Savannah River.

In recent years there has been a startling rise in the issuance of fish consumption advisories. Unfortunately, compliance by the public is often low. Low compliance can be due to a number of factors, including confusion over the meaning of advisories, conflicting advisories issued by different agencies, controversies involving health benefits versus the risks from consuming fish, and an unwillingness to act on the advisories because of personal beliefs. In some places, such as along the Savannah River, one state (South Carolina) had issued a consumption advisory while the other (Georgia) had not, although at present, both states now issue consumption advisories for the Savannah River. Herein we report on the development of a fish fact sheet to address the confusing and conflicting information available to the public about consuming fish from the Savannah River. The process involved interviewing fishers to ascertain fishing and consumption patterns, evaluating contaminant levels and exposure pathways, discussing common grounds for the provision of information, and consensus-building among different regulatory agencies (US Environmental Protection Agency, South Carolina Department of Health and Environmental Control, Georgia Department of Natural Resources) and the Department of Energy. Consensus, a key ingredient in solving many different types of "commons" problems, was aided by an outside organization, the Consortium for Risk Evaluation with Stakeholder Participation (CRESP). The initial role for CRESP was to offer scientific data as a basis for groups with different assumptions about risks to reach agreement on a regulatory response action. The process was an example of how credible science can be used to implement management and policies and provide a basis for consensus-building on difficult risk communication issues. The paper provides several lessons for improving the risk process from stakeholder conflicts, through risk assessment, to risk management. It also suggests that consensus-building and risk communication are continuing processes that involve assimilation of new information on contaminants and food-chain processes, state and federal law, public policy, and public response.

Animals↗
PubMed1997

Evaluation of dietary influences on Escherichia coli O157:H7 shedding by sheep.

The effect of diet, an abrupt diet change, and fasting on the shedding of Escherichia coli O157:H7 was investigated with experimentally inoculated sheep as a ruminant model. Sheep were fed a grass hay diet (G), which was low in protein and digestible energy and high in fiber, or a mixture of corn and pelleted alfalfa (C), which was high in protein and digestible energy and low in fiber. After a single oral inoculation of E. coli O157:H7, all the animals shed fecal E. coli O157:H7. However, sheep that were fed G shed the bacterium almost twice as long as, and in larger numbers than, did sheep that were fed C. The number of culture-positive animals increased after the diet was abruptly changed from C to G and decreased with the opposite change (G to C). A 24-h fast did not influence E. coli O157:H7 shedding. Horizontal transmission of infection between animals occurred. Recent shedding of E. coli O157:H7 did not affect recolonization with E. coli O157:H7. The findings presented in this study indicate that preharvest control of diet may reduce the risk of E. coli O157:H7-positive animals entering the food chain.

Animal Feed↗
PubMed1991

An overview of bovine spongiform encephalopathy.

None of the diseases caused by the "unconventional slow viruses" is highly infectious in its natural host. Transmission of infection to other species only occurs if the effective dose is high enough to overcome the species barrier. The current epidemic of bovine spongiform encephalopathy (BSE) in the U.K. is believed to have been initiated by scrapie infection of cattle via contaminated meat and bone meal in concentrated feedstuffs. But the effective exposure was extremely low. Subsequently the epidemic was driven by the re-cycling of infected cattle material which by-passed the species barrier and effectively "passaged" the infection within the cattle population. It is important that re-cycling would not apply to any public health risks arising from BSE. The safety of food can be ensured by excluding all potentially high titre tissues from the food chain. With medicines, risks can most simply be avoided by not using bovine materials from U.K. sources.

Animals↗
PubMed2000

Health risks to infants from exposure to PCBs, PCDDs and PCDFs.

Global contamination by a variety of anthropogenic persistent organic chemicals, such as dioxins and PCBs, has resulted in human exposure throughout all phases of development. Detectable concentrations of PCBs and dioxins have been found in amniotic fluid, placenta and foetal tissue samples while infants who are breast-fed can obtain blood levels greater than those of their mother's. In two separate food poisoning episodes where infants were exposed in utero to elevated levels of heat-degraded PCBs (PCBs, PCQs, PCDFs), a variety of adverse mental and physical developmental abnormalities have been observed. In additional human cohorts where exposure could be considered as environmental or background, more subtle effects, including lower birth weights, alterations in thyroid hormones and lymphocyte subpopulations and detriments in neurological development, have been consistently seen. In most instances, negative associations were made between in utero exposure to contaminants compared with lactational. Although the observed neurodevelopmental deficits have been described as subtle, there could be unknown consequences related to future intellectual functionality. Current regulatory efforts should focus on identification and control of environment and food chain contamination as in utero exposure is a direct consequence of the accumulated maternal body burdens.

Accidents↗
PubMed1977

Relative cumulation of beta-BHC in ecological and biological system.

During 1971-1974 a study was undertaken to analyze 1234 samples of different elements of food chain from three regions of Slovakia in order to obtain information on ecological relations of the dynamics of residues of four isomers of BHC compared with p,p-DDT and DDE. In contrast to most literature data, a higher relative cumulation of beta-BHC in animal food products compared to the other isomers was noted. The observed relations between the individual BHC isomers were verified in a model feeding experiment on poultry. Dynamics of the transfer of the BHC isomers between fodder, meat, liver, and eggs were studied in broilers and laying hens. All results of the model feeding experiment confirmed the conclusions of the ecological studies concerning beta-, gamma-, and -delta -BHC. The persistence of the alpha-BHC was not confirmed in this manner.

Animal Feed↗
PubMed2005

Persistence of Campylobacter jejuni on surfaces in a processing environment and on cutting boards.

AIMS: The objectives of the study were to determine the spread and persistence of Campylobacter in a poultry processing plant and to provide a quantitative estimate of the survival of Campylobacter jejuni on the surface of a cutting board. METHODS AND RESULTS: Several contact surfaces in a poultry processing plant were sampled before the start of processing, after 30 min and after 120 min. Next, the survival of four C. jejuni strains was studied on a beech and polypropylene cutting board during 120 min. CONCLUSIONS: A rapid introduction and spread of Campylobacter in a well cleaned processing plant as well as a significant survival in time on the example of a cutting board is shown. SIGNIFICANCE AND IMPACT OF THE STUDY: The need to prevent cross-contamination in the food processing and preparation area and the importance of an integrated approach throughout the whole food chain to control transmission of Campylobacter is highlighted.

Animals↗
PubMed2001

Pork producers' attitudes, knowledge, and production practices that relate to on-farm food safety.

A survey was distributed by mail to a random selection of Illinois pig farmers marketing 1,000 or more pigs in 1998 to assess their knowledge, attitude and behavior regarding on-farm food safety. Valid responses were received from 353 of the 946 surveys mailed (37.3%). Pork production accounted for more than 50% of gross agricultural revenues among 65.0% of respondents, and 91.2% were classified as "owner-operators." Knowledge of food-borne pathogens was mixed, with correct responses to questions as follows: Trichina, 80.4%; Salmonella, 58.5%; Toxoplasma, 19.9%; and Campylobacter, 12.8%. Producers strongly agreed that food safety was a shared responsibility at every level of the food chain, including the farm level, with an average score for all steps in the pork chain of 4.5 on a scale from 1 (not important) to 5 (very important). When asked whether third party verification of on-farm practices was important, 51.2% agreed and 48.8% either disagreed or neither agreed nor disagreed. Associations between demographic categories and knowledge of and attitudes toward food safety were detected for herd size, proportion of agricultural receipts from pig production, grower versus birth-to-market production, age categories, and whether the respondent owned the pigs or facilities. Many (53.4%) were willing to apply a suggested food safety practice, even if there was no net profit for the practice. Findings suggest that Illinois pork producers accept an important role in pork food safety and express a willingness to participate but have knowledge gaps that should be filled.

Animals↗
PubMed1980

Review of the dioxin problem. Mass spectrometric analyses of tetrachlorodioxins in environmental samples.

Major concern over the chemical group of chlorodioxins has arisen since 2,3,7,8-tetrachlorodibenzo-p-dioxin with its extremely toxic and teratogenic properties has been found in widely distributed pesticides such as the herbicide 2,4,5-trichlorophenoxy acetic acid. Because of its chemical stability and lipophilic nature, 2,3,7,8-tetrachlorodibenzo-p-dioxin released into the environment has the potential of accumulation in the food chain. Mass spectrometry in its various forms has been the method of choice to detect and confirm low parts per billion of 2,3,7,8-tetrachlorodibenzo-p-dioxin. Recently, a Consensus Forum held at the National Center for Toxicological Research amongst the various United States Government agencies (Food and Drug Administration, Environmental Protection Agency, US Department of Agriculture and National Institute of Environmental Health Sciences), eloquently demonstrated the potential, as well as the shortcomings, of the various techniques applied. In particular, the availability of a stable 13C labeled 2,3,7,8-tetrachlorodibenzo-p-dioxin has proved to be an essential component to achieve low level quantitation. A brief review of the findings of the Consensus Forum is presented together with a detailed survey of the application of atmospheric pressure ionization mass spectrometry to TCDD analysis at the National Center for Toxicological Research/Food and Drug Administration.

Animals↗
PubMed2003

Verocytoxigenic Escherichia coli in animal faeces, manures and slurries.

Animal wastes and effluents from farming operations, including manures and slurries, are frequently applied as fertilizer to land used for crop or silage production and cattle grazing. It is well documented that potentially harmful pathogens including verocytoxigenic Escherichia coli (VTEC) are shed in animal faeces and there is growing concern in many countries about the number of sporadic and outbreak cases of VTEC attributable to direct contact with faecal material either as a result of handling contaminated mud in fields or ingestion of produce grown in contaminated manures or slurries. VTEC has been detected in the faeces of ruminant and non-ruminant farmed animals, wild animals, domestic pets and birds and the pathogen appears to be well adapted to survive in animal faeces and can persist for extended periods ranging from several weeks to many months. Because of this persistence these materials are important as potential vehicles for transmission within herds, farms, the fresh food chain and the wider environment. Appropriate handling of bovine faeces is necessary to control spread of this pathogen and to limit the significant risks of human infection. It may be necessary to hold manure/slurry for extended periods prior to spreading on farmland, or for use in the production of food crops, particularly foods that are to be consumed in the raw or minimally processed state. Alternatively, it may be necessary to apply processes such as composting, heat drying or digestion which can expedite the decline of pathogens including VTEC in manures. However, there is a need for research work to develop economical and practical systems for treatment of manures and slurries. The risk from direct contact with faecal material at farms and petting zoos is also recognized and many public health authorities have put forward measures for strict practices to limit the risk of infection, particularly for young children visiting these environments.

Animals↗