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PubMed1983

Cadmium and lead through an agricultural food chain.

Two experiments measured quantities of soil Cd and Pb in wheat grain and eggs of laying hens that ingested the grain for 34 days and in liver and muscle after a 30 day withdrawal period. Soil Cd (0.6 to 2.9 ppm) induced a direct and linear accumulation in grain which ranged from 1.25 to 5.36 ppm. No response to soil Pb (4.0 to 18.7 ppm) was detected in grain which averaged 2.7 +/- 1.5 ppm. Ingestion by hens of 1500 to 11,000 micrograms Cd kg-1 body wt induced 1.87 ppm in dry albumin but Cd was not detectable in yolk, liver or muscle. Lead ingested after 34 days averaged 13,386 micrograms kg-1 body wt induced a mean of 3.88 and 4.71 micrograms Pb g-1 in yolk and albumin, respectively, but none in liver and muscle. From the soil pool 0.004% Cd and 0.02% Pb accumulated in the grain; 1.6% of grain Cd accumulated in the eggs. Only minuscule quantities (1 X 10(-5#of the Cd and Pb in the soil pool were transferred and retained in hen tissues via ingestion of the grain.

Animals↗
PubMed1983

Dieldrin pollution of a human food chain.

1 An incident is described in which excessive mortality amongst a poultry flock alerted veterinarians. Investigation revealed dieldrin in the carcasses and in the wood litter used in the nesting boxes. 2 Because high levels of dieldrin were found also in eggs the Department of Community Medicine was alerted. 3 Those most at risk were the workers who could have absorbed dieldrin by inhalation and percutaneously, and by eating contaminated eggs. A number of other people were at risk having eaten contaminated eggs. 4 Twenty-one workers or members of their families were investigated by case histories and blood levels. They were all clinically well. The highest estimated daily intake of dieldrin in the diet was 3.8 mgm. The highest blood dieldrin level found was 0.016 microgram/ml. This intake was of the same order as the upper limit of no-toxic-effect of long-term daily dosage, but the blood level is well below the level at which symptoms may be expected. The fall in mean blood level over a year is consistent with a long half-life of dieldrin in the human. 5 The conflict of interest in conducting a comprehensive investigation and preventing undue public alarm is discussed, and how this was resolved in this episode is described.

Adolescent↗
PubMed1989

Long-term transfer of I-129 into the food chain.

To investigate the transfer of Iodine-129 along the feed-animal-milk-pig thyroid pathway under conditions of short- and long-term contamination, two feeding experiments with dairy cows were carried out. Pasture grass radiolabelled with I-129 via root uptake was used as labelled feed in both experiments. During the first experiment the transfer of I-129 from feed to milk and the effective removal half-life of I-129 in the milk were determined after constant doses of I-129 in the labelled grass had been administered for a period of 8 days. In the second experiment the long term transfer of I-129 from feed-to-milk-to-cow-meat and to pig thyroid gland was followed for a period of 53 days. The pig was used because of the physiological similarity between pigs and humans. The effective half-life for removal of I-129 from milk was found to be 1.6 days. The values for the transfer factor from feed-to-milk (in units of day kg-1) resulting from the 1st assay ranged between 1.0.10(-3) and 1.7.10(-3). The long term feeding experiment exhibited a middle value for the transfer factor of 2.4.10(-3). The transfer factors pig thyroid/milk (as pig feed) and pig thyroid/cow feed exhibited values of 1.2 and 8.7.10(-3) respectively.

Animal Feed↗
PubMed1980

Negative chemical ionization studied of human and food chain contamination with xenobiotic chemicals.

Negative chemical ionization mass spectrometry with a mixture of isobutane, methylene chloride, and oxygen as the reagent gas has been used to explore contamination of environmental substrates with xenobiotic chemicals. The substrates in question, fish tissue, human seminal plasma, and human adipose tissue, were cleaned up by one of the following three cleanup procedures: (1) continuous liquid-liquid extraction steam distillation; (2) gel-permeation chromatography; and (3) adsorption on activated carbon followed by elution with toluene. The third procedure was used only for the examination of planar polychlorinated aromatic hydrocarbons in environmental samples. Using these techniques, we have found evidence for contamination of fish samples with polychloronaphthalenes, polychlorostyrenes, polychlorobiphenyls, polychlorodibenzofurans, and polychlorodibenzodioxins among other chemicals. The polychlorodibenzodioxins appeared only in the spectra of extracts of fish obtained from the Tittabawassee River at Midland Michigan. The polychlorodibenzofuran ions appeared in NCI mass spectra of fish that were significantly contaminated (above 2 ppm) with polychlorobiphenyls. Toxic substances occurring in human seminal plasma included pentachlorophenol, hexachlorobenzene, DDT metabolites, and polychlorobiphenyls. We have investigated toxic substances in human seminal plasma because of the apparent decrease in sperm density in U.S. males over the last 30 years. Results of screening human adipose tissue for contamination with xenobiotic chemicals have been largely coincident with result of the EPA human monitoring program. Polychlorobiphenyls, DDT metabolites, nonachlor, and chlordane have appeared in most samples examined. Detection limits for all of these chemicals were of the order of 1 ppb.

Adipose Tissue↗
PubMed2004

Campylobacter spp. in Irish feedlot cattle: a longitudinal study involving pre-harvest and harvest phases of the food chain.

The aim of this study was to investigate faecal shedding and transmission of Campylobacter spp. in cohorts of cattle within a feedlot, to assess subsequent contamination of carcasses with this pathogen and to identify risk factors associated with faecal shedding of Campylobacter spp. A cohort of 133 heifers housed in four adjacent pens was examined over a five and a half month period, from entering the feedlot to slaughter. A parallel investigation of individual rectal faecal samples and pen environmental samples were taken at monthly intervals from November to February. The entire outer and inner surfaces of a carcass side of each animal were swabbed immediately following slaughter. Campylobacter spp. were isolated from 322 (54%) of the 600 rectal faecal samples. Campylobacter jejuni and C. coli accounted for 69 and 29.7% of the isolate recovered, respectively. A total of 159 environmental samples were examined, of these Campylobacter spp. was isolated from 46 samples (29%). Campylobacter jejuni and C. coli accounted for 35 and 59% of these isolates, respectively. Campylobacter spp. was not isolated from any of the dressed carcasses. Logistic regression indicated prevalence of Campylobacter spp. faecal shedding within pens was positively correlated to the pen, the month of sampling and the Campylobacter spp. contamination status of the pen dividing bars and the water trough surface. Campylobacter spp. should be considered as a pathogen shed in the faeces of a substantial proportion of feedlot cattle. However, with good hygienic practice during harvest, a very low level of this pathogen can be achieved on dressed carcasses.

Animal Husbandry↗
PubMed1990

Measurements of 129I in human and bovine thyroids in Europe--transfer of 129I into the food chain.

Bovine thyroid glands from different countries in Europe and human thyroid glands from Lower Saxony (Federal Republic of Germany) show isotopic 129I/127I ratios of 2.1 X 10(-9) to 8.2 X 10(-8) for cattle and 2.1 X 10(-9) to 8 X 10(-8) in humans. These values give information about the concentration of fallout 129I in Europe since most of these glands were collected in areas without nuclear facilities. Some of the human thyroids were collected after the Chernobyl accident between May 1986 and February 1988. Results obtained from human thyroids taken in some locations of Lower Saxony show no significant increase of the 129I during this time. Higher concentrations of 129I were only found in cattle grazing in the vicinity of a reprocessing plant in Mol, Belgium. Samples of soil, vegetation, milk, and water from this area contained higher than normal concentrations of 129I. The long-term transfer of radioiodine from the soil to the plant and the translocation within the soil were studied using a soil monolith with a 129I-contaminated surface. During the 4 y of the experiment, the transfer factor plant/soil decreased from 0.3 to 2.2 X 10(-3). Soil samples taken in 5-cm steps to a depth of 30 cm then at 40 and 50 cm depths showed that the transport of radioiodine to lower layers proceeds very slowly. The top 5-cm layer contained about 80% of the total radioactivity 52 mo after contamination. In an in-vivo study with a dairy cow, the transfer of radioiodine from feed to milk to cow meat and to pig thyroid gland was followed for 53 d using 129I-labeled pasture grass contaminated via roots. A part of the milk obtained from the cow was fed to a pig as a substitute for humans. The mean value of the transfer factor milk/feed was 2.4 X 10(-3) d kg-1. The values of the transfer factor cow meat/feed obtained for different muscle cuts and organs (excluding thyroid) ranged between 3.0 X 10(-4) (kidney) and 5.4 X 10(-2) d kg-1 f.w. The transfer factors pig thyroid/milk (as pig feed) and pig thyroid/cow feed exhibited values of 1.2 and 8.7 X 10(-3) d kg-1 f.w., respectively.

Animal Feed↗
PubMed1993

Presentation of a general algorithm to include effect assessment on secondary poisoning in the derivation of environmental quality criteria. Part 1. Aquatic food chains.

Effect assessment on secondary poisoning can be an asset to effect assessments on direct poisoning in setting quality criteria for the environment. This study presents an algorithm for effect assessment on secondary poisoning. The water-fish-fish-eating bird or mammal pathway was analyzed as an example of a secondary poisoning pathway. Parameters used in this algorithm are the bioconcentration factor for fish (BCF) and the no-observed-effect concentration for the group of fish-eating birds and mammals (NOECfish-eater). For the derivation of reliable BCFs preference is given to the use of experimentally derived BCFs over QSAR estimates. NOECs for fish eaters are derived by extrapolating toxicity data on single species. Because data on fish-eating species are seldom available, toxicity data on all birds and mammalian species were used. The proposed algorithm (MAR = NOECfish-eater/BCF) was used to calculate MARS (maximum acceptable risk levels) for the compounds lindane, dieldrin, cadmium, mercury, PCB153, and PCB118. By subsequently, comparing these MARs to MARs derived by effect assessment for aquatic organisms, it was concluded that for methyl mercury and PCB153 secondary poisoning of fish-eating birds and mammals could be a critical pathway. For these compounds, effects on populations of fish-eating birds and mammals can occur at levels in surface water below the MAR calculated for aquatic ecosystems. Secondary poisoning of fish-eating birds and mammals is not likely to occur for cadmium at levels in water below the MAR calculated for aquatic ecosystems.

Algorithms↗
PubMed1996

Accumulation and physiological and biochemical effects of cadmium in a simple aquatic food chain.

The toxicity of cadmium with regard to the vegetative reproduction of duckweed, Lemna gibba, grown in sterile culture, was determined. The EC50 was found to be 800 ppb. Duckweed grown in 2.24 ppm cadmium (supplied as cadmium nitrate) for 7 days accumulated 98.5% of the available cadmium from the growth medium. Plants that had been grown for 7 days in 2.24 ppm cadmium and control plants were fed to red swamp crayfish, Procambarus clarkii, for 14 days. The concentrations of cadmium were measured in hepatopancreata and muscles of crayfish on Day 0 and in crayfish fed duckweed grown in cadmium for 14 days. Accumulation of this metal in hepatopancreata increased 26-fold, i.e., 176.80 ppb on Day 0 to 4657.56 ppb on Day 14, and in muscles almost 7-fold, i.e., 6.75 ppb on Day 0 to 46.28 ppb on Day 14. Crayfish fed cadmium-containing duckweed demonstrated inhibition (55% after 14 days of feeding) of acetylcholinesterase activity in their central nervous tissue compared to crayfish fed cadmium-free duckweed. The ovarian index and total lipids content in the ovaries of crayfish fed cadmium-containing duckweed demonstrated significant increases on Day 14.

Animals↗
PubMed1998

Mercury levels along the food chain and risk for exposed populations.

Mercury was not regarded as a pollutant of primary importance until many deaths due to mercury poisoning occurred in the 1950s. More recently, adverse health effects have been documented at relatively low exposure levels, and monitoring data must now be interpreted in this light. The Mediterranean basin has been studied in great detail over the past 20 years because of the anomalous natural presence of mercury. Marine animals of this basin have higher mercury body burdens than the same (or similar) species in the Atlantic. The mercury found in marine organisms is mainly in the form of methyl mercury. Long-term and frequent intake of seafood with high mercury levels by populations living in coastal fishing villages is associated with a toxic risk, especially in pregnant women. High blood and hair concentrations of mercury have repeatedly been found in fishermen of Tyrrhenian coastal villages. In some cases these concentrations have been associated with an increase in DNA damage in blood cells. High mercury levels in hair and blood of people from a fishing village of Madeira have also been found. This information deserves renewed scrutiny with regard to preventive efforts needed.

Animals↗