Source and Distribution of Heavy Metals in Food†

Diet is the major route of exposure to contaminants, therefore food monitoring programs are essential to estimate the degree of human risk. We present a study undertaken in Austria dealing with the total uptake of mercury, cadmium, arsenic and lead. The dates were calculated from diet as well as from commercial food. Higher contaminated foodstuffs are registered and a comparison was made between body burden of babies and adults on the basis of bodyweight. It was pointed out, that cooked or washed food ready to eat has a lower burden of lead and cadmium than non prepared food due to household processing, which may decontaminate food to some extent’ Arsenic content was not reduced, because it is bound chemically and not primarily deposited on the surface of food such as in the case of lead. It was mentioned that the type of compound plays an important role in the assessment of action of those elements on humans.

Their biological activity is not necessarily related to their concentration in food. As in the case of selenium and chromium one has to take into consideration that there is a narrow range between benefit and harm, toxicity, and minor supply.

Therefore we conclude, that due to interactions of elements, their different biological activity and due to the difference of compounds present in food, we have to relativate the terms toxicity and essentiality. Then we can get a more profound insight into the problems of trace elements in food.     

Low level inhalation experiments with four different cadmium compounds in rats†

This long‐term inhalation study was designed to describe the toxicity and the carcinogenic risk from Cd compounds because it had been shown from former long‐term inhalation studies that cadmium choloride induced primary lung tumors in Wistar rats. It was therefore logical to examine whether other cadmium compounds to which human beings are more frequently exposed have also carcinogenic potency. In a long‐term inhalation study cadmium aerosols consisting of cadmium chloride (CdCl₂), cadmium oxide (CdO) as dusts and fumes, cadmium sulfate (CdSO₄), cadmium sulfide (CdS) and a combination of cadmium oxide/zinc oxide were used. Wistar rats were continuously exposed in inhalation chambers for 18 months 22 hrs a day or for 40 hrs a week. The studies will be terminated at the mean survival life time of the species. The aerosols were generated by several different systems. The particles of the cadmium aerosols have the average mass medium diameters in the range from 0.2 to 0.5 μm.     

Printed in great Britain Cr(VI) and other metallic mutagens in fly ash and welding fumes†

Particulate samples taken from both the indoor (working) and outdoor (community) environments contain a wide range of metallic trace elements most of which are mutagenic in at least one of the short term tests for genotoxicity currently in use. Because of the demonstrated presence of a short lived biologically active species (Cr(VI)), and the uncertainty with which the results of the screening of metallic compounds in short term tests can be interpreted in terms of human risk, great care must be taken to assure the appropriate collection, storage, and chemical and biological assay of such material. The sensitivity of the results for fly ash and welding fumes to variations in these protocols is demonstrated and discussed.     

Analysis of the cyanotoxins anatoxin-a and microcystins in Lesser Flamingo feathers†

Feathers from carcasses of the Lesser Flamingo (Phoeniconaias minor), which had died after ingesting cyanobacterial toxins (cyanotoxins) contained between 0.02 and 30.0?µg microcystin-LR equivalents per gram of feather according to HPLC and ELISA analysis of feather extracts. Anatoxin-a was detected less frequently in the Lesser Flamingo feathers, up to 0.8?µg anatoxin-a per gram of feather being recorded. When feathers from different body regions were analysed and compared for microcystins and anatoxin-a, wing feathers were found to contain the highest concentrations of these cyanotoxins, the order of concentration and frequency of analytical detection being wing?>?breast?>?head. Consistent with the presence of the microcystins and anatoxin-a in gut contents and the livers of the dead birds and negligible in vitro adsorption to feathers, the cyanotoxins associated with the feathers of the dead wild flamingos are inferred to be primarily of dietary origin.     

Cesium inhibition of motor activity in comparison to Lithium and Rubidium †

The biochemical and toxicological significance of cesium is scarcely understood, and could be evaluated in comparison with lithium widely used as a psychotropic drug. Two male Wistar rat groups of 200–220 g are administered independently, lithium, sodium, rubidium and cesium chloride, in doses of 3mEq/Kg/day (0.024 Eq/L drinking water) during 29 days. Motor activity was measured after the injection of 70 mg pargyline/Kg animal i.p. as inhibitor of MAO A + B with an activimeter of Tedeschy type. Accumulative movements per minute are presented in function of time. Total brain proteins, alkaline and acid phosphatases and blood parameters, haematocrit, haemoglobin and erythrocytes, were determined.

The maximal increase of motor activity was seen in rats treated with RbCl 2 h after the pargyline administration and the diminution was Rb>Li>Cs. Cesium induced a decrease of the total serum protein concentration from 6.39 ± 0.1 to 5.8±0.5mg/100ml serum in controls. Acid and alkaline phosphatase were decreased in cesium treated rats. The three determined blood parameters, haematocrit, haemoglobin and erythrocytes, show also a decrement with cesium treatment compared to the control ones.     

Recent advances in arsenic mutagenesis and carcinogenesis†

Arsenic is ubiquitously distributed in nature and is released into the environment through non‐ferrous smelting operations, generation of power from coal, and agriculture.

Epidemiological studies have shown that the incidences of epidermoid carcinomas of the skin and lungs, and of pre‐cancerous dermal keratoses are significantly increased in human subjects exposed to arsenic compounds by oral or respiratory routes. The negative results obtained on animals treated with arsenicals suggest strongly that this metal is probably a cocarcinogen.

The results of the short‐term tests suggest that the cocarcinogenic properties of arsenic could be related to its ability to inhibit DNA repair.     

Suspension feeding in the brittle-star Ophiothrix fragilis : efficiency of particle retention and implications for the use of encounter-rate models

Dense beds of the suspension-feeding brittle-star Ophiothrix fragilis are common in European waters. Their potential importance in benthic–pelagic coupling has been highlighted, but little is known about the feeding dynamics of this species. Encounter-rate models provide a potential mechanism for the estimation of feeding rates on suspended material of varying sizes. This work investigates factors essential to the application of such models. Particle-retention efficiency (RE) converts encounter rate into capture, or clearance rate. Laboratory studies demonstrated that RE varied with the interactive effects of flow velocity and particle size. RE was lowest for large particles, particularly at high flow velocity where RE as low as 59% was observed. This indicates that if RE is not accounted for in encounter-rate models, significant overestimates of feeding rates on large particles may occur. Flow around feeding arms and tube feet was characterised by intermediate Reynolds numbers, precluding application of the most simple encounter-rate models. Complex secondary-flow patterns were observed, which carried particles along the downstream side of the feeding arms, but these did not appear to increase the area available for particle capture. Previously reported particle capture by arm spines was not observed. Evidence of active rejection of large particles by tube feet was recorded. Difficulties in the application of encounter-rate models for prediction of seston-removal rates are highlighted by these results. Predicted encounter rate may deviate from actual clearance rate due to the effects of retention dynamics, localised flow patterns and differential particle handling. Other methods of estimation of seston-removal rates are equally problematic however, so that encounter-rate models are likely to remain a useful tool for such estimates. Received: 23 January 1998 / Accepted: 24 June 1998     

Polychlorinated biphenyls and organochlorine pesticides in amniotic fluids of pregnant women in south-central Turkey†

The concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in amniotic fluid of 200 pregnant women from the Cukurova region of Turkey. The concentrations of OCPs [hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), dichlorodiphenyl trichloroethane (p,p′-DDT), and various metabolites], and different PCB congeners (28, 52, 101, 118, 138, 153, 180) were determined by gas chromatography with electron capture detection as follows: HCB 6.6 ± 4.7, ΣHCH 21.6 ± 14.2, ΣDDT 12.5 ± 7.5, and ΣPCBs 74.0 ± 54 ng mL^?1. Correlations of maternal or gestational age and levels of OCPs and PCBs were not significant. The levels of these organochlorine compounds (OCs) were below detection limit for 5% of the samples, 80% contained more than one OC. This study illustrates that prenatal exposure of a fetus to OCs is prevalent in the Cukurova region.     

Toxic substances: Measures and measurements†

The formulation of a sound policy for environmental protection and toxic substances control requires knowledge of the presence and concentration of environmental contaminants. For this reason monitoring programs have been set up in the Netherlands for water, drinking water, and air pollution. The Netherlands system for air pollution, monitoring of the substances SO2, NOχ, CO, O₃ is now fully automated. Some examples will be given to show the acquisition and management and interpretation of air pollution measurements.

Various smaller projects, supported by the Department of Health and Environmental Protection include measurement of indoor air‐contaminants, contaminants in soil and hazardous waste sites, and contaminants in biotic samples such as for instance PCB's in eels and seals and mussels. Moreover a Coordinating Committee regularly collects measurements from various sources in the Netherlands regarding pesticide residues and contaminants in food.

For cost‐effective monitoring the accuracy of the measurements must be chosen with regard to the biological effect concentration of the pollutant. The necessity of proper control measurements to establish background levels and the necessity of ring‐tests to increase interlaboratory reproducibility is discussed. In cost‐effective monitoring the minimum number of measurements, which are necessary to check the effect of environmental protection measures, must be defined through proper sampling.     

Interrelation of Cd‐lon concentrations and the growth and activities of microorganisms in two growth media†

Partitioning of native or anthropogenic heavy metals in solid and solution phases of soil is a result of network of several physico‐chemical reactions. The attainment of equilibrium between two phases is also regulated by biochemical processes. For practical purposes, the bioavailability of metal present in soil is predominantly regulated by the soil solution phase which is in dynamic equilibrium with the solid phase. The results of a model laboratory and greenhouse growth experiments have been used to investigate the effect of Cd‐ion concentrations (either in soil solution or in nutrient solution) on the growth and activities of microorganisms. The soil solution has been simulated by preparing a suspension of soil with 0.1 M NaNO₃ (1: 2.5) equilibrated for two hours. Important conclusions are as follows:

Increase in Cd‐ion concentration in soil solution or in nutrient solution induces corresponding adverse effect on the growth and activities of microorganisms. Thus, it seems that Cd‐ion concentration is a more sensitive indicator for assessing the effect of metal pollution upon the growth and activities of soil microorganisms in comparison to total Cd contents.

During active microbial growth phase, a large part of the organically bound Cd was released in the soil solution which is largely bioavailable. This process is termed as mobilisation. There was momentary increase of Cd‐ion concentration in soil solution which intoxicated the growing organisms. After this stage, the Cd ions from the solution phase were removed by the newly formed solid phase (nonviable biomass) and were transformed in non‐available form. This process is termed as immobilisation.

The consequences and importance of these results for practical agriculture and in deciding the limits or guidelines on the maximum tolerable metal load in soils are discussed.     

Environmentally significant photochemistry of chlorinated benzenes and their derivatives in aquatic systems†

The pollution of soil and aquatic environments by chlorinated aromatic pollutants (CAPs) such as polychlorobenzenes (PCBzs), polychlorophenols (PCPs), polychloro‐diphenyl ethers (PCDPEs), phenoxyacetic acids, etc., creates growing public anxiety. Phototransformation is an important process for pollutants in aquatic systems. This article extensively reviews the environmentally significant solution phase photochemistry of PCBzs as well as other CAPs derived therefrom. The paper includes photochemical fate of these CAPs at wavelengths >285 nm on the one hand and their photolysis in solution in aquatic systems on the other. In this article, photolytic reductive dechlorination and isomerization of PCBzs are reviewed together with the photoformation of several products including polychlorobiphenyls (PCBs) from PCBzs. Recently developed phenomena of photoincorporation of PCBzs into humic model monomers is also described. This review also describes the environmental photochemistry of chlorobenzene derivatives, namely, α‐substituted p‐chlorotoluenes of the general structure p‐ClC₆H₄CH₂‐X (X = H, Cl, CN, COOH and OH), di‐through pentachlorophenols, PCDPEs (having Cl_1–5 contents) with and without o‐OH substituents, and 2,4‐di‐ and 2,4,5‐trichlorophenoxyacetic acid (2,4‐D and 2,4,5‐T, respectively) as well as their esters and some formulations.     

High genetic diversities and complex genetic structure in an Indo-Pacific tropical reef fish (Chlorurus sordidus): evidence of an unstable evolutionary past?

Historical sea level fluctuations have influenced the genetic structure and evolutionary history of marine species and examining widespread species across their species ranges may elucidate some of these effects. Chlorurus sordidus is a common and widespread parrotfish found on coral reefs throughout the Indo-central Pacific. We used phylogenetic, phylogeographic, and cladistic analyses to examine the genetic composition and population structure of this species across most of its latitudinal range limits. We sequenced 354 bp of the mitochondrial control region I in 185 individuals from nine populations. Populations of C. sordidus displayed high levels of genetic diversity, similar to those recorded for widespread pelagic fish species, but much greater nucleotide diversity values than those previously recorded for other demersal reef fishes. Both phylogenetic and phylogeographic analyses detected strong genetic subdivision at the largest spatial scale (i.e. among oceans). The Pacific Ocean was characterised by weak population genetic structure. Separation of the Hawaiian location from other Pacific and West Indian Ocean sites was evident in phylogenetic analyses, but not from analysis of molecular variance. NCA and isolation-by-distance tests suggested that the genetic structure of this species was the result of multiple contemporary and historical processes, including long-distance colonisation and range expansion arising from fluctuating sea levels, limited current gene flow, and isolation by distance. This pattern is to be expected when historically fragmented populations come into secondary contact. We suggest the patterns of population genetic structure recorded in C. sordidus are caused by large local population sizes, high gene flow, and a recent history of repeated fragmentation and remixing of populations resulting from fluctuating sea levels.Communicated by M.S. Johnson, Crawley     

Biological weighting of ultraviolet (280–400 nm) induced mortality in marine zooplankton and fish. II. Calanus finmarchicus (Copepoda) eggs

The copepod Calanus finmarchicus Gunnerus is a key component of the planktonic food web in the Gulf of St. Lawrence, Canada. In this region, productivity-determining biophysical interactions occur in the upper 0 to 30 m of the water column. The eggs and nauplii of C. finmarchicus are found in this layer. Measurements of the diffuse attenuation coefficients for solar ultraviolet-B radiation (280 to 320 nm, UV-B) at various locations in this region indicated maximum 10% depths (the depth to which 10% of the surface energy penetrates) of 3 to 4 m at a wavelength of 310 nm. This represents a significant percentage of the summer mixed-layer water column: organisms residing in this layer are exposed to UV-B radiation. Laboratory experiments using a Xenon-arc-lamp based solar simulator revealed that C. finmarchicus embryos exposed to UV-B exhibited high wavelength-dependent mortality. The strongest effects occurred under exposures to wavelengths below 312 nm. A significant percentage of nauplii hatched from eggs exposed to these wavelengths exhibited malformations indicative of errors in pattern formation during embryogenesis. At the shorter wavelengths (<305 nm), UV-B-induced mortality was strongly dependent on cumulative exposure. The biological weighting function (BWF) derived for UV-B-induced mortality in C. finmarchicus eggs is similar to that reported for naked DNA. This suggests that the UV-B-induced mortality effect on C. finmarchicus embryos is a direct result of DNA damage. There was no evidence of a detrimental effect of ultraviolet-A radiation (320 to 400 nm). Calculations based upon the BWF indicate that, under current noon surface irradiance, 50% of C. finmarchicus eggs located at or very near (within 10 cm) the ocean surface will be dead after 2.5 h of exposure. Under solar spectral irradiance simulating a 20% decrease in ozone layer thickness, this time drops to 2.2 h. These are first-order estimates based upon irradiance taken at a time of day during which the values would be maximal. Nonetheless, they illustrate the relative changes in UV-B effects that will result from ozone layer depletions expected over the coming decades. It is also important to point out that variability in cloud cover, water quality, and vertical distribution and displacement within the mixed layer, can all have a greater effect on the flux of UV-B radiation to which C. finmarchicus eggs are exposed than will ozone layer depletion at these latitudes. Received: 2 March 1998 / Accepted: 18 December 1998     

Genotoxicity of chromium in vitro on yeast: Interaction with DNA†

The genotoxicity of chromium chloride was investigated in cells of D₇ strain of Saccharomyces cerevisiae harvested either from logarithmic or stationary growth phase.

A weak induction of mifotic gene conversion and point reverse mutation was obtained when the incubations were performed using phosphate buffer. No genetic effect was observed when the incubations were performed using Tris‐HCl buffer.

The experiments with ⁵¹Cr radiotracer demonstrated that Cr³⁺ ion enters the yeast cells and binds to DNA even if the incubation mixture was performed with Tris HCl buffer. This behaviour could be due to the highest concentration of CrCl₃ that cause some damages to cytoplasmatic membrane.     

Biological weighting of ultraviolet (280–400 nm) induced mortality in marine zooplankton and fish. I. Atlantic cod (Gadus morhua) eggs

In the Gulf of St. Lawrence, Canada, productivity-determining biophysical interactions occur in the upper 0 to 30 m of the water column. The eggs and larvae of several commercially important marine invertebrates and fishes (e.g. Gadus morhua L.) are found in this layer. Measurements of the diffuse attenuation coefficients for ultraviolet-B radiation (280 to 320 nm, UV-B) at various locations in this geographic region indicated maximum 10% depths (the depth to which 10% of the surface energy penetrates at a given wavelength) of 3 to 4 m at a wavelength of 310 nm. This represents a significant percentage of the summer mixed-layer water column: organisms residing in this layer are exposed to UV-B radiation. Laboratory experiments using a Xenon-arc-lamp based solar simulator revealed that cod embryos exposed to UV-B exhibited high wavelength-dependent mortality. The strongest effects occurred under exposures to wavelengths below 312 nm. This susceptibility was also dependent upon developmental stage; mortality was particularly high during gastrulation. At the shorter wavelengths (<305 nm) UV-B-induced mortality was strongly dose-dependent, and not significantly influenced by dose-rate. The biological weighting function (BWF) derived for UV-B-induced mortality in cod eggs is similar to that reported for naked DNA – suggesting that the mortality is a direct result of DNA damage. There was no evidence of a detrimental effect of ultraviolet-A radiation (320 to 400 nm). Calculations based upon the BWF indicate that, under current noon surface irradiance, 50% of cod eggs located at or very near (within 10 cm) the ocean surface will be dead after 42 h of exposure. Under solar spectral irradiance simulating a 20% decrease in ozone layer thickness, this time drops to 32 h. These are first-order estimates based upon surface irradiance taken at a time of day during which the values would be maximal. Nonetheless, they illustrate the relative changes in UV-B impacts that will result from ozone layer depletions expected over the coming decades. It is also important to point out that variability in cloud cover, water quality, and vertical distribution and displacement of cod eggs and larvae within the mixed layer, can all have a greater effect on the flux of UV-B radiation to which fish eggs are exposed than will ozone layer depletion at these latitudes. Received: 2 March 1998 / Accepted: 18 December 1998     

Territory and group sizes in Eurasian beavers (Castor fiber): echoes of settlement and reproduction?

According to current theories of territoriality, an animal is expected to defend the smallest area that can provide resources for maximisation of reproduction, known as the economically defendable area. In group territorial species however, the strategies behind resource defence are likely to be more complex with corporate territoriality, cooperative breeding, delayed dispersal and intra-group competition all potentially playing a role. Here we examined group territoriality in a social herbivorous rodent, the Eurasian beaver Castor fiber. Beavers in our study do not inhabit economically defendable territories. Instead the sequence of arrival of pairs into unoccupied areas seems to play a more important role in determining the size of the territory, whereas group size is determined by past reproductive success. We argue that the settlement pattern and reproductive history have a lasting impact in the territorial system of beavers due to a combination of the low adult mortality, high dispersal costs, and avoidance of resource depletion.R.D. Campbell and F. Rosell contributed equally to this work     

Matching and mismatching stable isotope (δ13C and δ15N) ratios in fin and muscle tissue among fish species: a critical review

Using non-lethal tissue sampling for stable isotope analysis has become standard in many fields, but not for fishes, despite being desirable when species are rare or protected, when repeated sampling of individuals is required or where removal may bias other analyses. Here, we examine the utility of fish dorsal fin membrane as an alternative to muscle for analyzing δ¹³C and δ¹⁵N ratios in two reef fish species (blue cod Parapercis colias and spotty Notolabrus celidotus) that have differing feeding modes. Both species exhibited evidence of size-based feeding from fin δ¹⁵N values, but not from muscle. Blue cod fin δ¹⁵N increased steadily throughout the sampled size range (213–412 mm fork length), whereas spotty exhibited a distinct ontogenetic diet shift at approximately 120–140 mm fork length after which size-based feeding did not occur. Fin membrane was higher than muscle in δ¹³C in both species and in δ¹⁵N for blue cod, but fin δ¹⁵N was lower than muscle in spotty. The δ¹³C and δ¹⁵N fin–muscle offsets were constant in spotty regardless of size, while in blue cod, δ¹³C was constant with fish size, but δ¹⁵N offsets increased with increasing fish size. Non-lethal sampling utilizing fin tissue can be employed to estimate stable isotope values of muscle in fishes, but it is necessary to assess relationships among tissues and the effects of fish size on isotope values a priori for each species studied. Our data indicated that fin membrane may be a more sensitive tissue than muscle for detecting size-based feeding in some fish species using stable isotopes. A critical literature review revealed inconsistencies in tissue types tested, little understanding of tissue-specific trophic shift or turnover rates, and pseudo-replicated analyses leading to erroneous postulating of 1:1 relationships between tissues.     

Mutagenic activity of transition‐metal complexes: Relation structure‐mutagenic and antibacterial activity for some Pd(II), Pt(II) and Rh(I) complexes†

The inhibitory and mutagenic action of some Pd(II), Pt(II) and Rh(I) complexes towards various bacterial strains has been evaluated, and some correlations have been found between the chemical behaviour of the complexes and their selective biological activity: most of the complexes cause only a DNA damage repaired by the excision repair system. Particularly, the Rh(I) complexes used in this work show selective antibacterial effects on defective but no effect on wild‐type strains.     

Alkylation of metals and the activity of metal‐alkyls†

The biochemical basis for resistance to metal ion toxicity is emerging though it is complicated by the different resistance mechanisms. Several strategies for resistance to toxic metal ions have been identified:

1. The development of energy driven efflux pumps which keep toxic element levels low in the interior of the cell. Such mechanisms have been described for Cd(II) and As(V).

2. Oxidation (e.g. AsO^2‐ to AsO₄ ^3‐) or reduction (e.g. Hg²⁺ to Hg⁰) can enzymatically and intracellularly convert a more toxic form of an element to a less toxic form.

3. The biosynthesis of intracellular polymers which serve as traps for the removal of metal ions from solution such as traps have been described for cadmium, calcium, nickel and copper.

4. The binding of metal ions to cell surfaces.

5. The precipitation of insoluble metal complexes (e.g. metal sulfides and metal oxides) at cell surfaces.

6. Biomethylation and transport through cell‐membranes by diffusion controlled processes.

In this short review I shall discuss the implications of biomethylation as a detoxification mechanism for microorganisms as well as for certain higher organisms.     

Multielement techniques for determination of Inorganics in Watert†

Several analytical techniques offer the capability of simultaneously determining 5–40 elements. Of those techniques available, two are receiving extensive attention for analysis of water samples. Optical emission spectrometry utilizing plasma excitation has now evolved to a status in which 20–40 elements can be simultaneously determined on a routine basis. Instrumentation which relies on ion exchange chromatography separations is available which allows the routine determination of several cationic and/or anionic species.

The present discussion will briefly describe each of the above multielement analysis systems, summarize their respective capabilities and limitations with respect to water analysis, and project areas of future development.