Biomedical subjects

K C Jones

Publications and source records attributed to K C Jones.

At least 109 records · Page 6Linked to original sources

PubMed1992

Organic chemicals entering agricultural soils in sewage sludges: screening for their potential to transfer to crop plants and livestock.

This paper presents a review and assessment of the pathways and transfers of organic contaminants applied to agricultural soils in sewage sludge. The purpose of the assessment has been to develop a simple screening approach to highlight different chemical fates of organic chemicals in soil and their potential transfers from soil to groundwaters, crop plants and grazing livestock using data on the physico-chemical properties of the compounds of interest. The fate of 46 compounds known to be present in sewage sludges are compared to illustrate the applicability of the procedure. Compounds are screened for their potential to adsorb, volatilise, degrade and leach in soils and to be transferred to plants via retention by root surfaces, root uptake and translocation and foliar uptake and to transfer to animal tissues via soil and herbage ingestion. Recommendations for experimental and field studies are made. It is envisaged that this screening approach can be applied to other chemicals and that it will focus research and aid risk assessments of organic compounds in sewage sludge following land application.

Agriculture↗

PubMed1992

Polynuclear aromatic hydrocarbons in crops from long-term field experiments amended with sewage sludge.

This study reports on the polynuclear aromatic hydrocarbon (PAH) content of crop plants grown at three different field experiments where controlled additions of sewage sludge were made a number of years ago. Archived samples of several crops have been analysed from sludge-amended and unsludged control plots for 15 PAH compounds. Root crops and above ground plant parts were available for several years following the last applications of sludge. Although the soil PAH burden increased substantially due to sewage sludge additions, and residues of these compounds have persisted in the soils for many years, increased PAH concentrations relative to the unsludged controls were not consistently detected in plant tissues. Plant samples were relatively enriched with low molecular weight compounds such as acenaphthene/fluorene nd phenanthrene. Various lines of evidence indicate that PAHs detected in above ground plant parts are chiefly derived from atmospheric inputs, while PAHs detected in root crops probably arise from adsorption to the root surface.

Journal Article↗

PubMed1992

Arrested municipal solid waste incinerator fly ash as a source of heavy metals to the UK environment.

Arrested fly ash samples from most currently operating municipal solid waste (MSW) incinerators in the UK have been analysed for a range of elements. Some of the more important heavy metals ranged in concentration as follows: Cd, 21-4646 (median = 271) mg kg(-1); Cu, 296-1307 (642) mg kg(-1); Cr, 44-1328 (574) mg kg(-1); Ni, 45-2204 (74) mg kg(-1); Pb, 447-9704 (4337) mg kg(-1); and Zn, 2285-13,500 (9232) mg kg(-1). These concentrations represent considerable enrichments relative to median UK soil concentrations. Enrichment ratios (defined as median fly ash: median UK soil) were as follows: Mn 1.6; Co 2.6; Ni 3.3; Ba 11; Sr 11; Cr 15; Cu 35; Pb 108; Zn 113; Cd 387. It is estimated that MSW incinerator ash contributes c. 15 t Cd and 241 t Pb to UK landfill sites per annum. These figures compare with previous studies by Hutton & Symon (Hutton, M. & Symon, C. (1986). The quantities of cadmium, lead, mercury and arsenic entering the UK environment from human activities. Sci. Total Environ., 57, 129-50.) which estimated that annual inputs to UK landfills from coal fly ash are c. 60 t Cd and 1270 t Pb. However, it is argued that metals associated with MSW ashes are potentially of greater environmental significance than in coal ashes, because they are much more available and present at much higher concentrations.

Journal Article↗

PubMed1992

5-Hydroxytryptamine receptor activity of the dopamine receptor agonist fenoldopam in canine tracheal smooth muscle.

Fenoldopam is a new vasodilator undergoing clinical trials for the treatment of hypertensive emergencies. Its pharmacologic effects result from activation of vascular dopamine-1 receptors. In canine tracheal smooth muscle strips, fenoldopam caused a concentration- and calcium-dependent increase in tension, which was not antagonized by atropine, indomethacin or the dopamine-1 receptor antagonist, SCH 23390. The EC50 (1.89 x 10(-6) M) exceeded that of serotonin or acetylcholine (8.38 x 10(-8) and 8.25 x 10(-8) M, respectively). Maximum tension was similar for fenoldopam and serotonin (11.6 +/- 1.5 g, n = 7 and 13.8 +/- 0.8 g, n = 24; P greater than .2) and considerably greater for acetylcholine (20.5 +/- 1.3 g, n = 14; P less than .005). The serotonin antagonists ketanserin and methysergide reversed completely the effect of fenoldopam (5 x 10(-7) M) with IC50 values of 2.5 x 10(-9) and 2.7 x 10(-9) M, respectively. Phentolamine, rauwolscine and chlorpheniramine were also effective, but they were less potent (IC50 values 6.6 x 10(-8), 1.0 x 10(-7) and 1.7 x 10(-7) M, respectively). By contrast, only very high concentrations (IC50, 5.3 x 10(-5) M) of terazosin produced an inhibition of fenoldopam-induced tension increases. The effect of antagonists could be overcome by increasing the fenoldopam concentration. Experiments performed on strips precontracted with serotonin (5 x 10(-8) M) revealed a very similar order of potency for the five antagonists. The addition of serotonin did not increase the tension produced by supramaximal concentrations of fenoldopam (and vice-versa), whereas acetylcholine increased tension further.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1992

Computational fluid mechanical evaluation of steady-flow energy losses in cardiac valve prostheses.

A form of the general integral energy conservation equation is applied to the case of steady flow through a rigid control volume bounded by stationary walls and fixed inflow and outflow control surfaces. The total energy loss due to viscous dissipation in the control volume is then defined as the change in mean (pressure + kinetic energy + shear stress energy) quantities between the inflow and outflow surfaces. Computational fluid mechanical modelling can then be used to provide the extensive flow field data necessary to calculate the integral means of the total energy components--not only at the inflow/outflow surfaces, but throughout the control volume via a series of "cutting surfaces" progressing from the inlet to the outlet. This allows interchanges between the various forms of energy to be examined and provides an insight into the mechanisms responsible for these interchanges. Two illustrative examples are presented: laminar flow through a specially designed ball-occluded conduit valve in a long conduit run, and through a caged-ball annulus valve mounted in a ventricle-aorta model. Analysis of the results suggests that a new energy loss parameter be defined--a "valve only" loss, calculated by subtracting the total energy loss for the system with the valve absent, from the total energy loss for the same system with the valve in place. This developed concept of "valve only" energy loss has the potential of standardising the findings of different research groups by removing the arbitrary selection of measurement points from reported results.

Heart Valve Prosthesis↗

PubMed1991

Unusual product ratios resulting from the gamma-irradiation of cholesterol in liposomes.

Cholesterol in aqueous suspensions of multilamellar vesicles (MLV) was exposed to gamma-irradiation (0.5-10 kGy) at 0-4 degrees C. Cholesterol oxidation products resulting from the irradiation were isolated by dry column extraction followed by preparative thin-layer chromatography (TLC) and were quantitated by on-column gas chromatography (GC). The ratio of 7-ketocholesterol/cholesterol 5,6-epoxides generated by irradiation was less than one, much lower than the ratio of ten commonly produced by autoxidation. Irradiation also produced relatively higher amounts of 7-hydroxycholesterol than did autoxidation. These unique product ratios may be suitable indicators of past exposure to irradiation.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1991

The persistence of polynuclear aromatic hydrocarbons (PAHs) in sewage sludge amended agricultural soils.

In 1968, five metal enriched sewage sludges containing different concentrations of polynuclear aromatic hydrocarbons (PAHs) were applied to different plots on field soils at two experimental sites, Luddington and Lee Valley, in the UK. This resulted in substantial increases in the total PAH soil concentrations in all plots. Since application, losses have occurred, with the high molecular weight PAHs being more persistent. Calculated half-lives range from under 2 years for naphthalene to over 9 years for benzo[ghi]perylene and coronene. The losses of PAH compounds in these field experiments can be related, in part, to their physico-chemical properties, notably the octanol: water partition coefficient.

Journal Article↗

PubMed1991

Contaminant trends in soils and crops.

The evidence for long-term changes in the contaminant content of soils and crops is reviewed. Heavy metals, acidification and trace organic contaminants are each considered separately, with the emphasis placed on changes brought about by inputs from long-term atmospheric deposition. It is argued that effectively all soils in industrialised countries have become contaminated with selected trace substances (notably Pb, Cd, polynuclear aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and -furans) above their true (historical) background level by aerial inputs. In the case of Pb, for example, cumulative deposition inputs over several centuries have probably roughly doubled the Pb burden of contemporary UK surface soils. Despite this, there is little evidence for a concomitant rise in the contaminant content of UK crops through the twentieth century. In fact, the burden of many contaminants in vegetation may well be somewhat lower than in earlier decades of this century because (1) crop composition is strongly influenced by direct deposition onto the above-ground portion of the plant, (2) root uptake and translocation of soil-borne heavy metals and recalcitrant organic contaminants are inefficient processes, and (3) UK air quality has generally improved over the last 10-20 years. Acidification of soils is of considerable regional significance. The evidence for changes in soil pH over this century is reviewed, and it is concluded that atmospheric inputs have enhanced the rate of soil acidification over large areas of Scandinavia and elsewhere.

Journal Article↗

PubMed1989

Human exposure to environmental polychlorinated dibenzo-p-dioxins and dibenzofurans: an exposure commitment assessment for 2,3,7,8-TCDD.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs and PCDFs) are released into the environment from the use of chemicals contaminated with PCDDs/PCDFs, the improper disposal of contaminated production wastes and incineration/other high-temperature processes. Certain congeners are extremely stable compounds which are persistent in the environment once released. An assessment is made of the sources of human exposure to one particular dioxin congener, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD). Representative values of 2,3,7,8-TCDD concentrations in the background environment and in man are selected from available data or, when not available, inferred from other relevant information. A pathway analysis is performed utilizing the exposure commitment method. Normal dietary intake of 2,3,7,8-TCDD is quite variable depending primarily on consumption of contaminated fish. Representative intake for the average adult of 0.1 ng day-1 may be associated with a human body burden of 100 ng (approximately 7 ng 2,3,7,8-TCDD kg-1 adipose tissue). The inferred biological half-time of this compound in the body is approximately 5 years. The exposure evaluation also accounts for secondary pathways to man of 2,3,7,8-TCDD in air and drinking water. Estimates of transfer factors obtained from the representative background levels should be generally relevant and may be applied to more specific cases of exposure.

Air Pollutants↗

PubMed1989

Changes in the polynuclear aromatic hydrocarbon content of wheat grain and pasture grassland over the last century from one site in the U.K.

Crops harvested and stored from two long-term agricultural experiments started in the 1840-1850s at Rothamsted Experimental Station (U.K.) have been analyzed for polynuclear aromatic hydrocarbons (PAHs) because PAHs have increased four-to-five fold in the underlying 0-23 cm depth of soil over the last century due to atmospheric deposition. Bulked samples of herbage and wheat grain were analyzed for 16 compounds by gas chromatography-mass spectrometry for groups of years between 1860 and 1986. The sigma PAH (16 PAH) concentrations in herbage ranged between 110 and 6900 micrograms kg-1 dry weight, with fluoranthene, pyrene, benzofluoranthenes (b + j + k), chrysene and triphenylene consistently the most abundant. Benz[a]anthracene, benzo[ghi]perylene, benzo[a]pyrene, benzo[e]pyrene and indeno(1,2,3-cd)pyrene were also all important constituents. PAH concentrations in wheat grain ranged from 4 to 46 micrograms sigma PAH kg-1; the mixture of individual compounds was similar to that in herbage. Correcting for yield differences these corresponded to 37-1500 and 2.4-8.8 micrograms sigma PAH m-2 for herbage and wheat grain respectively. The lowest values were found in the most recent samples (1980s) and the highest for samples collected in 1879-81. Generally, there was a decline in the PAH burden of the vegetation with time. The temporal trends of PAHs in the samples are discussed in the context of possible sources of PAHs. Various lines of evidence indicate that the PAH concentrations in vegetation are an indication of atmospheric deposition directly onto the above-ground plant portions, and that uptake and translocation of soil-bound PAHs is of minor importance.

Animal Feed↗

PubMed1989

Cadmium in cereal grain and herbage from long-term experimental plots at Rothamsted, UK.

Crop samples harvested and stored from three long-term agricultural experiments started in the 1840-1850s at Rothamsted Experimental Station (UK) have been analysed recently for Cd. Increased Cd burden in the soils of the experiments, which have had a range of treatments, originates mainly from atmospheric deposition. Soils treated with farmyard manure (FYM) or, in some cases, applications of phosphate fertilisers, have increased Cd levels. Herbage, wheat and barley grain from the three experiments were analysed by neutron activation analysis (NAA) and graphite furnace atomic absorption spectrometry (GFAAS). Samples were bulked for groups of years between 1860 and 1986, from variously treated plots in each experiment (control or 'nil' treatment, P-fertilised, FYM-amended, NPK-fertilised-limed and unlimed). There were marked differences in Cd concentrations between treatments. For example, uptake of Cd into herbage was greater where P fertiliser had been applied than not, and was greater from unlimed than limed soils. Offtake of Cd (mg ha(-1) year(-1)) was affected by large differences in yield and probably also by other factors. These include changes in botanical composition in the permanent grassland experiment; cultivar changes in the wheat and barley experiments; changes in soil organic matter and soil pH of some plots; changes in atmospheric deposition of Cd through time. All of these potentially confounding factors make the interpretation of results complicated. It is concluded, however, that, with one exception, there is little evidence of a long-term increase in crop Cd concentrations at Rothamsted.

Journal Article↗

PubMed1989

Polynuclear aromatic hydrocarbons in an agricultural soil: long-term changes in profile distribution.

Soil profile samples collected from the same plot at Rothamsted Experimental Station in southeast England in 1893, 1944 and 1987 have been analysed for polynuclear aromatic hydrocarbons (PAHs). The total PAH burden of the plough layer (0-23 cm) has increased approximately four- to five-fold since the 1890s, with some compounds (notably benzo(b)fluoranthene, benzo(a)pyrene and pyrene) showing substantially greater increases. Average rates of increase in the plough layer for individual PAHs in the Rothamsted plots over the century since c. 1890 vary between 0.01 and 0.67 mg m(-2) year(-1). It is concluded that atmospheric deposition from natural sources has been augmented in recent years by regional fallout of anthropogenically-generated PAHs derived from the combustion of fossil fuels. The total PAH content of the 1893 Rothamsted samples was similar to that observed in soils from contemporary isolated/rural locations in the UK and showed little surface enrichment. By 1987 the surface soil at Rothamsted had been enriched in all PAH compounds measured by a factor of between 1.3 (acenaphthalene) and over 20 (benzo(a)pyrene). Increases in the PAH content of the 23-46 cm subsurface layer indicate migration of PAHs from the plough layer. Net average annual migration rates ranged from 0.01-0.14 mg m(-2) year(-1) for individual PAHs, and the rate appeared to be primarily a function of the plough layer PAH content, rather than physical/chemical properties of the individual compounds. This suggests particle-bound translocation as the dominant mechanism of PAH migration.

Journal Article↗

PubMed1988

Prothrombinase complex assembly. Kinetic mechanism of enzyme assembly on phospholipid vesicles.

The kinetics of the assembly of the prothrombinase complex was studied using factor Xa modified with the active site-directed fluorophore dansylglutamylglycylarginyl chloromethyl ester (DEGR.Xa) as a reporter for the process. Stopped-flow kinetic studies of prothrombinase assembly were undertaken at saturating concentrations of calcium ion, using vesicles composed of phosphatidylcholine and phosphatidylserine (PCPS), factor Va, and DEGR.Xa. The rate of complex formation, studied under pseudo first-order conditions, depended on the premixing protocol used to initiate complex assembly and was most rapid when prothrombinase assembly was initiated by reacting Va with the preformed DEGR.Xa.PCPS complex. Under these conditions, reaction rate was linearly dependent on the concentration of PCPS with no evidence for saturation and was independent of the concentration of VA. Essentially identical reaction rates were observed when the association of Va with PCPS was independently assessed by stopped-flow light scattering. The data indicate that prothrombinase assembly initiated by mixing Va with the DEGR.Xa.PCPS complex is rate limited by the initial reaction between Va and available combining sites on the vesicle surface (k = 5.7 x 10(7) M-1.s-1) followed by extremely rapid reactions (k greater than 1 x 10(9) M-1.s-1) between PCPS-bound DEGR.Xa and PCPS-bound Va. The formation of a separate Va.PCPS complex is therefore required for prothrombinase assembly to proceed. Reaction rates obtained when prothrombinase assembly was initiated by reacting DEGR.Xa with the preformed Va.PCPS complex or by reacting PCPS with a mixture of DEGR.Xa and Va were lower. Under these initiation conditions, reaction rates were inhibited by increasing concentrations of factor Va. These data indicate that the formation of the DEGR.Xa.PCPS binary complex is also a prerequisite for prothrombinase assembly. The second-order rate constant for the reaction between factor Xa and PCPS (k = 2.9 x 10(7) M-1.s-1) and the first-order rates of dissociation of the Va.PCPS complex (koff = 0.17 s-1) and the Xa.PCPS complex (koff = 3.3 s-1) were independently determined by stopped-flow light scattering. Collectively, the data are consistent with the interpretation that prothrombinase assembly proceeds via the initial formation of separate Xa.PCPS and Va. PCPS binary complexes at near diffusion-limited rates on the same vesicle. The lipid-bound constituents then react rapidly via rearrangements on the vesicle surface to form prothrombinase.

Amino Acid Chloromethyl Ketones↗

PubMed1988

Determination of polychlorinated biphenyls in human foodstuffs and tissues: suggestions for a selective congener analytical approach.

Based on a literature review of the occurrence of polychlorinated biphenyl (PCB) congeners in commercial formulations, environmental and biological samples and human tissues, and a consideration of the relative toxicity and persistence of the congeners, suggestions are made as to the most relevant components to be quantified by a selective congener analytical approach to human foodstuffs and tissues. These criteria suggest congener numbers 28, 74, 77, 99, 105, 118, 126, 128, 138, 153, 156, 169, 170, 179 and 180 will give a measure of greater than 70% of the total PCB tissue burden in a sample and be of greatest toxicological significance. Additionally, congeners 8, 37, 44, 49, 52, 60, 66, 70, 82, 87, 101, 114, 158, 166, 183, 187 and 189 are considered because of their reported occurrence or toxicity.

Adipose Tissue↗

PubMed1988

The distribution of metals in the forest floor of aged conifer stands at a plantation in Northern England.

The distribution of the elements Cd, Cr, Cu, Mn, Ni, Pb, Sr, V and Zn has been examined in the horizons of soils under aged Sitka spruce (Picea sitchensis (Bong.) Carr.) stands at a plantation in Northern England. The stands are under first-generation cultivation and are up to 33 years old. Cadmium, Mn, Pb and Zn concentrations were consistently higher in the organic layers than in the underlying mineral soil. This contrasted with the situation for Sr and V. Cadmium, Pb and Zn all showed an increase in concentration in the L + F horizons with stand age and a corresponding increase in the difference between L + F horizon concentrations. Soil pH declined with increasing stand age. Cadmium, Cr, Pb and Zn were all present at higher concentrations in the F horizon than in any other, while Cu and Ni were relatively constant through all the horizons studied. For all nine elements, the H horizon was the largest store of the three organic layers. Calculated rates of accumulation of Cd, Pb and Zn in the L + F horizons gave good agreement with estimated regional atmospheric deposition rates. In comparison to atmospheric deposition, biological mobilisation and deposition of Cd, Pb and Zn make a relatively minor contribution to the surface soil metal burden. Cadmium appeared to be the most readily leached of these three metals from the forest floor, although some transfer of atmospherically-derived Pb to the H+ soil horizons was indicated.

Journal Article↗

PubMed1987

Retrospective analysis of an archived soil collection. II. Cadmium.

Soil samples collected and stored since the mid-1800s to the present day have been analysed recently for Cd. The samples from long-term experiments under permanent grassland or arable crops at Rothamsted Experimental Station (U.K.) were selected to investigate time trends in elemental composition, due either solely to atmospheric deposition or to a combination of atmospheric deposition and various soil treatments. Increases in soil Cd of 27-55% since the 1850s due to atmospheric deposition were observed. This corresponds to an increase in the soil plough layer Cd concentration of between 0.7 and 1.9 micrograms kg-1 year-1 and is equivalent to an increase of 1.9-5.4 g Cd ha-1 year-1. The changes in soil Cd concentrations since 1846 at one control site corresponded well to predicted increases in the plough layer Cd burden based on assumptions about the temporal trends in atmospheric Cd emissions. In addition, sub-samples of a selection of rock phosphates of known origin and superphosphates, mainly from one supplier, collected and stored in the archive from 1925 onwards were also analysed for Cd. The concentrations ranged from 3.6 to 92 (mean 36) mg Cd kg-1 for rock phosphates and from 3.3 to 40 (9.7) mg kg-1 for superphosphates. On the basis of these data and known application rates the estimated input of Cd to P-treated plots at Rothamsted was 2 g ha-1 year-1, but there was little further increase in soil Cd due to this addition in three long-term arable experiments where soil pH was greater than 6.5. On P-treated plots the mean increase in soil Cd was 1.2 micrograms kg-1 year-1, which is equivalent to an increase in the plough layer burden of 3.1 g Cd ha-1 year-1. By contrast, P-treated soils under permanent grassland with a higher organic matter content and lower pH have increased their Cd content by 7.2 g ha-1 year-1. When permanent grassland soils ranging in pH from 5 to 7 were examined it was found that organic matter had a larger effect on Cd concentration than pH and the effects of pH were not consistent. Farmyard manure applied to some experimental plots at Rothamsted appears to have been a more significant source of Cd than combined atmospheric and phosphate fertiliser inputs.

Animals↗

PubMed1986

Reactions of the 4a-hydroperoxide of liver microsomal flavin-containing monooxygenase with nucleophilic and electrophilic substrates.

Liver microsomal flavin-containing monooxygenase (MFMO) has been shown to exhibit a stable 4a-flavin hydroperoxide intermediate in the absence of oxygenatable substrate (Poulsen, L. L., and Ziegler, D. M. (1979) J. Biol. Chem. 254, 6449-6455; Beaty, N. B., and Ballou, D. P. (1981) J. Biol. Chem. 256, 4619-4625). The reaction of this intermediate with an assortment of substrates was studied by stopped flow techniques. The first observed spectral change is a small blue shift in the absorbance peak of the 4a-flavin intermediate. The rate of this spectral change is dependent on the concentration of the substrate. This small spectral change is succeeded by a large increase in the absorbance at 450 nm. The rate of appearance of oxidized flavin is independent of substrate concentration but does increase at higher pH. Steady state turnover rates also greater at higher pH, consistent with earlier observations that the formation of oxidized flavin is rate determining in catalysis. Upon oxygenation by MFMO, thiobenzamide and iodide each undergo a spectral change which is dependent on substrate concentration. The spectral changes corresponding to oxygenation of these substrates occur at the same rates as do the initial small spectral changes contributed by the flavin chromophore as observed with all substrates. However, no substrate tested to date shows any effect on the rate of formation of oxidized flavin. Previous work has shown MFMO to catalyze the oxygenation of a variety of nitrogen- and sulfur-containing hydrophobic compounds. Two new classes of compounds are shown here to be substrates for this enzyme. The nucleophilic anions, iodide and thiocyanate, catalyze the decomposition of the 4a-flavin hydroperoxide. Organic boronic acids (e.g. phenylboronic acid and butylboronic acid) also appear to be oxygenated with no striking differences in kinetic characteristics from those of nucleophilic substrates. These organic boronic acids are classic electrophiles and suggest that like peracids, the 4a-flavin hydroperoxide is capable of oxygenating both nucleophiles and electrophiles (Lee, J. B., and Uff, B. C. (1967) Quart. Rev. 21, 429-457).

Aniline Compounds↗

PubMed1986

Exposure of man to environmental aluminium--an exposure commitment assessment.

Aluminium is one of the most abundant elements in the environment and is released from both natural and anthropogenic sources. Representative values of aluminium concentrations in the background environment and in man are selected from available data and a pathway analysis is performed utilising the exposure commitment method. Using a derived estimate of the body burden (60 mg), a representative value for dietary intake (20 mg day-1) and fractional absorption of 0.01, a mean retention time of A1 in the body of 300 days is obtained. This corresponds to a biological half-time of 210 days. The assessment indicates that an average dietary intake rate of 20 mg day-1 contributes 660 micrograms kg-1 of aluminium to the body, while inhalation of aluminium in air makes, in comparison, a negligible contribution to the body content.

Aluminum↗