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Biomedical subjects

J C Sherlock

Publications and source records attributed to J C Sherlock.

At least 19 recordsLinked to original sources
PubMed1993

Human uptake of 137Cs in mutton.

The uptake of radiocesium from mutton contaminated by fallout from the Chernobyl reactor accident has been studied in eight healthy male volunteers. Each subject consumed, on adjacent days, two meals prepared from the mutton containing a total of 0.8 kBq 137Cs. The elevation and subsequent decline in whole-body content were determined from body radioactivity measurements prior to the meals and at intervals up to 15 wk afterwards. Clearance of 137Cs between 1 and 15 wk showed a biological half-time of 102 +/- 24 (SD) d, (range 84-154 d). The fraction cleared with this half-time was 80 +/- 4% (range 72-85%). No attempt was made to determine the early retention and excretion but, if the ICRP's assumption of 10% clearance with a 2-d half-life were valid, the data would indicate an average uptake (f1) of 89%, i.e., marginally lower than the value of 100% assumed in setting limits on intake.

Accidents↗
PubMed1992

Elevation of lead in human blood from its controlled ingestion in beer.

1. Nine volunteers ingested high levels of lead in beer over a 28-d period. The increase in blood lead varied by a factor of about two. There was a similar two-fold variability in the whole-body uptake (mean 14%) of a single oral dose of the short-lived tracer 203Pb. 2. The average elevations led to estimates of the potential increment from consumption of alcoholic beverages which accord broadly with epidemiological observation and which, if relevant to intakes of lead in table wine, raise the possibility of considerably elevated levels in the blood of avid consumers. 3. Rate constants inferred for removal of stable lead from blood were lower than reported following intake of the tracer, reflecting feedback of lead from other compartments.

Adult↗
PubMed1990

Lead intake and blood lead in two-year-old U.K. urban children.

A comprehensive study of a group of 2-year-old urban children (n = 97), designed to provide quantitative information simultaneously for lead intakes via all identified pathways, has been carried out in Birmingham (U.K.). Results showed that for children whose blood levels and exposure to environmental lead were within the normal range for the U.K., blood lead concentration was significantly related to a combination of house dust lead loading and an overall rate of touching objects, to water lead concentration and to the parents' smoking habits. On the basis of assumptions used by the Royal Commission on Environmental Pollution (RCEP), the estimated average total uptake of lead was 36 micrograms day-1; of this, 97% was from ingestion from dust, food and water and only 3% from inhalation.

Air Pollutants↗
PubMed1990

Human metabolism of arsenobetaine ingested with fish.

1. Six volunteers ingested 74As-labelled arsenobetaine with a fish meal. The retention and distribution of the tracer were studied by body radioactivity measurements. 2. The tracer became rapidly dispersed in soft tissues, with no major concentration in any localized organ or region. 3. In all subjects less than 1% of the ingested activity remained in the body after 24 days. 4. Any losses from the skin were minor in relation to those by other routes of excretion.

Adult↗
PubMed1988

Underestimation of dose--response relationship with particular reference to the relationship between the dietary intake of mercury and its concentration in blood.

Wide discrepancies have been observed between controlled and uncontrolled intake studies of the relationship of blood mercury concentration to intake of mercury. The probable reason for the apparent discrepancies is that the within-subject variation of mercury intake in the uncontrolled studies was almost certainly considerably larger than the within-subject variation in blood mercury concentration; in these circumstances, the apparent slope obtained from a linear regression of blood mercury on intake will invariably be much smaller than the true slope. Studies of the exposure or intake of any substance should therefore include a consideration of the likely within-subject variation in the exposure or intake relative to that in the effect.

Analysis of Variance↗
PubMed1986

Cadmium in foods and the diet.

Information on the sources of cadmium in food are presented and the effects of raised environmental levels of cadmium on the concentration of cadmium in plant based foods, fish and shellfish, meat and offals, and dairy produce are discussed. Information is also presented on normal dietary intakes of cadmium and how these intakes may be elevated by environmental pollution or atypical dietary habits. The estimation of dietary intakes of cadmium using data about extreme intakes of specific foods is described.

Adult↗
PubMed1986

Dietary copper intake in artificially fed infants.

Plasma concentrations of copper and zinc and leucocyte concentrations of zinc were measured in mothers during later pregnancy, at delivery, and 8-10 weeks after birth, and plasma concentrations of copper and zinc were measured in their infants at delivery and 8-10 weeks after birth. The 145 infants were either breast fed or fed one of two milk formulas supplying copper at different concentrations. None of the infants achieved the minimum copper intakes recommended by the World Health Organisation (WHO). At 2 months of age there were no major differences in growth or health detected in infants fed the different copper intakes. Infant birth weight correlated well with the ratio of maternal venous plasma zinc:maternal leucocyte zinc at delivery. Maternal venous plasma copper and zinc concentrations at birth correlated with umbilical venous plasma copper and zinc concentrations. Infants fed the higher copper content formulas had a low mean plasma zinc concentration without a significant increase in the mean plasma copper concentration. The present WHO recommendations regarding minimum copper intakes for infants fed formulas cannot be achieved with currently available formulas and are probably wrong.

Breast Feeding↗
PubMed1985

Blood lead concentrations and lead intake in children of different ethnic origin.

Factors affecting blood lead concentrations in three groups of children of different ethnic origin have been investigated. Dietary lead intakes were similar for the three groups, the average lead intakes lay in the range 110-150 micrograms/week. Blood lead concentrations were not related to ethnic origin when the effect of other factors was allowed for. Children who washed their hands before eating had significantly lower blood lead concentrations than those who did not.

Calcifediol↗
PubMed1984

Cadmium in foods and the diet.

Information on the sources of cadmium in food are presented and the effects of raised environmental levels of cadmium on the concentration of cadmium in plant based foods, fish and shellfish, meat and offals, and dairy produce are discussed. Information is also presented on normal dietary intakes of cadmium and how these intakes may be elevated by environmental pollution or atypical dietary habits. The estimation of dietary intakes of cadmium using data about extreme intakes of specific foods is described.

Animals↗
PubMed1984

Temporal stability of blood lead concentrations in adults exposed only to environmental lead.

The temporal stability of blood lead concentrations of 21 healthy adults (14 men and 7 women) exposed only to environmental lead was assessed by analysis of 253 blood specimens collected serially over periods from 7 to 11 months. Improved analytical sensitivity allowed detection of small (less than 1.0 microgram/100 ml) changes in blood lead concentrations and both within- and between-run analytical errors were minimized by a strict internal quality control protocol. The women had lower blood lead concentrations (mean 8.5, range 7.4-10.8 micrograms/100 ml) than did the men (mean 12.2, range 8.6-15.8 micrograms/100 ml). These are within the expected ranges for non-occupationally exposed persons. Blood lead concentrations in the serial specimens from both men and women changed very little over the study period, with standard deviations of less than 0.5 micrograms/100 ml for the majority of individual mean concentrations: for all except two subjects the standard deviations were less than 0.8 micrograms/100 ml. Two subjects showed significant changes in blood lead concentrations during the study (standard deviations of mean greater than 1.0 micrograms/100 ml). A temporary increase in oral lead intake was identified for one of these subjects. In the absence of substantial changes in lead exposure blood lead levels in adults are remarkably stable and for their environmental monitoring a single blood lead concentration is an excellent biological indicator.

Adult↗
PubMed1984

Reduction in exposure to lead from drinking water and its effect on blood lead concentrations.

The water supply in Ayr (Scotland, UK) was plumbosolvent and many dwellings in Ayr contained lead pipes. In 1981 treatment of the water supply to reduce its plumbosolvency was initiated. Measurements of water and blood lead concentrations were made before and subsequent to the treatment. Most of the measurements made before and after water treatment began were made on water samples from the same dwellings and blood samples from the same women. Water treatment produced a sharp fall in water lead concentrations and a decrease in the median blood lead concentration from 21 to 13 micrograms/100 ml. Two women had higher than expected blood lead concentrations, both these women had been removing old paint. Women who had lead pipes removed from their dwellings all showed substantial decreases in their blood lead concentrations. The curvilinearity of the relation between blood lead and water lead concentrations is confirmed. Even relatively low (less than 40 micrograms/l) water lead concentrations may make a substantial contribution to blood lead concentrations.

Adult↗
PubMed1983

Uptake of lead by humans and effect of minerals and food.

In several series of experiments, volunteers have ingested 203Pb as chloride (a) in distilled water, with or without stable Pb carriers, while fasting, (b) with varying amounts of added mineral Ca and P, (c) with hot or alcoholic beverages between normal meals, (d) in the course of meals. Also, volunteers have eaten lamb's liver and kidney into which 203Pb had been incorporated by injection into the animal before slaughter, and spinach which had taken up 203Pb from its roots. Fasting subjects absorbed 40-50% of the 203Pb, taken in distilled water, irrespective of the addition of Pb carrier up to 100 micrograms per dose. When taken with tea or coffee, uptake averaged 14% and with beer 19%. Much lower uptakes, ranging from 3 to 7%, were found when 203Pb was taken in volunteers with a meal, or incorporated in offal or vegetables which were eaten as part of a meal, or when taken with large amounts of calcium or phosphate.

Adult↗
PubMed1983

Intakes of copper, zinc, cadmium, tin, iron, nickel and arsenic in a population exposed to lead from water.

Adult diets obtained from a population in Ayr, Scotland, U.K., known to be exposed to lead from water were analysed for arsenic, cadmium, copper, iron, nickel, tin and zinc to assess the intake of these elements. With few exceptions, the concentration of each element varied little from diet to diet, and therefore the range of intakes varied only in proportion to the weights of the diets. With the exception of nickel, the difference between the observed average dietary intakes of the metals studied and those expected on the basis of a nationwide Total Diet Study is largely accounted for on the basis of the differences between the weights of the duplicate diet and the weight for the Total Diet Study.

Adult↗
PubMed1983

Dietary surveys on a population at Shipham, Somerset, United Kingdom.

The results are reported of three dietary surveys and crop sampling surveys carried out at Shipham in 1979. Concentrations of cadmium, lead and zinc in crops were higher than would normally be expected. Copper concentrations in crops were normal, and the results for mercury showed that mercury translocation from soil to crops was very low. Although cadmium dietary intakes were found to be greater than those expected from a normal UK diet, dietary lead and zinc intakes were normal. Dietary copper intakes at Shipham were a little lower than national average intakes. Four participants in the duplicate diet study, or 6% of the study population, had cadmium intakes higher than 0.4 mg per week.

Cadmium↗