Increased Cadmium Exposure Research Articles

Evaluating the health impact of increased linseed consumption in the Danish population

Consumption of linseeds has been suggested to have beneficial effects on human health. However, toxic constituents of linseed may compromise these benefits. We conducted a quantitative risk-benefit assessment to evaluate the overall health impact of increasing linseed intake up to 45 g/day in the Danish population (15–74 years). We quantified the risks associated with increased cadmium exposure and the benefits associated with increased intake of dietary fibre. Increased intakes of alpha-linoleic acid (ALA) were included in a sensitivity analysis. The overall health impact of different linseed intake scenarios was estimated in terms of Disability-Adjusted Life Years (DALYs). We found that the beneficial effects of linseed due to increased intake of dietary fibre outweighed the adverse health effects due to increased cadmium exposure in all scenarios. Up to 670 DALYs/100,000 individuals could be averted per year by increasing linseed consumption in the Danish population. The estimated beneficial health impact increased further when including ALA in the assessment. Different sources of uncertainty might affect the results, and more research is needed on both the health effects associated with intake of linseed and its constituents, and the bioavailability of ALA and cadmium from linseed to further improve the risk-benefit assessment.

Probabilistic determination of a maximum acceptable level of contaminant to reduce the risk of overexposure for a novel or emerging food: the case of cadmium in edible seaweed in the French population

European and French populations are overexposed to cadmium (Cd) through their foods. The risk of increased cadmium exposure for consumers needs to be limited by reduced maximum limits (ML) for novel foodstuffs such as edible seaweed in France. The objective was to derive a low and protective cadmium concentration in edible seaweeds to limit cadmium overexposure in consumers. To do so, we applied a probabilistic approach to the data collected on French seaweed consumers, taking into account other sources of exposure for cadmium. This approach led to the identification of a cadmium concentration which should ensure that the seaweed-consuming population does not exceed the tolerable daily intake (TDI) of cadmium according to a probability of cases, when simultaneously exposed to other cadmium dietary sources. Considering the 5% of the population exceeding TDI, the estimated ML is equal to 0.35 mg Cd kg−1 dry matter of seaweed as an unprocessed food with a 95% confidence interval of [0.18,1.09]. The proposed approach is generic and could be applied to other relevant food/substance pairs when considering the setting of MLs in the regulatory system. It ensures better protection of consumer health.

Environmental exposure to cadmium reduces the primary antibody-mediated response of wood mice (Apodemus sylvaticus) from differentially polluted locations in the Netherlands

The Wood mouse (Apodemus sylvaticus) is a widespread mammalian species that acts as a reservoir host for multiple infections, including zoonotic diseases. Exposure to immunotoxins, like for instance trace metals, may reduce the ability of the host to mount proper responses to pathogens, potentially increasing the transmission and prevalence of infections. Antibody-mediated responses are crucial in preventing and limiting infections, and the quantification of the primary antibody response is considered a sensitive predictor of immunosuppression. The current study aims to investigate effects of cadmium exposure on the antibody-mediated responses of wood mice inhabiting polluted and non-polluted areas in the Netherlands. Wood mice were captured alive at different locations and immunized to sheep red blood cells (SRBC) to induce a primary antibody response. SRBC-specific antibody-producing cells, or plaque forming cells (PFC), were quantified and related to kidney cadmium levels. Differential circulating main leukocyte populations were also characterised. Cadmium concentrations in mice kidneys differed between mice captured at different locations, and increased with individual body mass, likely associated with age-related time of exposure. Effect of cadmium was apparent on the percentages of B cell counts in blood. Because of potential natural immune heterogeneity between wild rodent populations, mice immune responses were analysed and compared grouped by captured locations. Capture location had significant effect on the total counts of white blood cells. Increasing cadmium exposure in wood mice captured from polluted sites was associated with a decrease of splenic PFC counts. This field research shows that wood mice antibody responses can be impaired by cadmium exposure, even at low environmental levels, by affecting B cell functioning mainly. Impaired B cell function can make exposed mice more susceptible to infections, potentially increasing the reservoir function of their populations. It also shows that immunomodulatory effects in the field should be assessed site specifically.

Associations between Maternal Cadmium Exposure with Risk of Preterm Birth and Low after Birth Weight Effect of Mediterranean Diet Adherence on Affected Prenatal Outcomes.

Prenatal cadmium exposure at non-occupational levels has been associated with poor birth outcomes. The intake of essential metals, such as iron and selenium, may mitigate cadmium exposure effects. However, at high levels, these metals can be toxic. The role of dietary patterns rich in these metals is less studied. We used a linear and logistic regression in a cohort of 185 mother–infant pairs to assess if a Mediterranean diet pattern during pregnancy modified the associations between prenatal cadmium exposure and (1) birth weight and (2) preterm birth. We found that increased cadmium exposure during pregnancy was associated with lower birth weight (β = −210.4; 95% CI: −332.0, −88.8; p = 0.008) and preterm birth (OR = 0.11; 95% CI: 0.01, 0.72; p = 0.04); however, these associations were comparable in offspring born to women reporting high adherence to a Mediterranean diet (β = −274.95; 95% CI: −701.17, 151.26; p = 0.20) and those with low adherence (β = −64.76; 95% CI: −359.90, 230.37; p = 0.66). While the small sample size limits inference, our findings suggest that adherence to a Mediterranean dietary pattern may not mitigate cadmium exposure effects. Given the multiple organs targeted by cadmium and its slow excretion rate, larger studies are required to clarify these findings.

Cadmium exposure, fasting blood glucose changes, and type 2 diabetes mellitus: A longitudinal prospective study in China

BackgroundCadmium is a recognized human carcinogen, raising global concern for its ubiquitously environmental exposure on public health. Diabetogenic effects of cadmium have been suggested in previous studies, but the longitudinal associations of chronic cadmium exposure with fasting blood glucose changes and type 2 diabetes mellitus have not been fully elucidated. ObjectiveTo investigate the effects of long-term cadmium exposure on the fasting blood glucose changes and type 2 diabetes mellitus risk in a longitudinal prospective study of China. MethodsA total of 3521 urban adults were included as baseline study population from the Wuhan-Zhuhai cohort, and followed up three years later. Urinary cadmium concentrations were determined repeatedly during the follow-up of a three-year period. The within-person and between-person variability of urinary cadmium concentrations over three years was estimated using multilevel random-effects mixed models. Multivariate regression models were performed to evaluate the associations of cadmium exposure with fasting blood glucose changes and type 2 diabetes mellitus risk. ResultsThe geometric means of creatinine-corrected urinary cadmium concentration at baseline were 1.13 μg/g creatinine, which were close to the levels of follow-up (1.14 μg/g creatinine). The intra-class correlation coefficient of creatinine-corrected urinary cadmium concentrations was 0.71, achieving good reproducibility of cadmium over three years. With adjustment for potential confounders, each one-unit increase in log10-transformed cadmium was associated with a 0.11 (95%CI: 0.03 to 0.19) elevation in fasting blood glucose concentration, and was associated with a 42% (95%CI: 1.16 to 1.73) increase in risk of prevalent type 2 diabetes mellitus. Upward trends of fasting blood glucose changes and type 2 diabetes mellitus incidence were observed with increasing cadmium exposure. Individuals with the highest urinary cadmium exposure had a significant increase in fasting blood glucose change at follow-up [β (95% CI): 0.49 (0.31–0.67)]. Risk of incident type 2 diabetes mellitus were gradually elevated across increasing quartiles of cadmium exposure, though associations did not reach statistical significance (P = 0.15). ConclusionsOur findings suggested that relatively high chronic cadmium exposure for general population adults might contribute to elevated changes of fasting blood glucose resulting in the development of type 2 diabetes mellitus.

Avoidance tests with the oribatid mite Oppia nitens (Acari: Oribatida) in cadmium-spiked natural soils

Avoidance behavior can be a useful parameter for assessing the ability of organisms to escape from pollutants in their environment. For soil evaluation, a variety of invertebrates is used including the oribatid mite Oppia nitens. Here, we tested the avoidance behavior of O. nitens using a two-chamber test and an escape test with exposures to different cadmium concentrations of up to 800mg kg-1 dry LUFA 2.2 soil for 2, 4, and6 days, and up to 7 weeks. With the two-chamber method, the oribatid mites had the choice between clean and polluted soils, whereas they were allowed to escape from a box with polluted soil to clean containers without soil with the escape method. Avoidance of cadmium was observed after 2 days in both tests and the net response of the mites in the two-chamber test increased with increasing cadmium exposure concentrations. Mite responses varied through time, especially with the escape method; with the avoidance behavior becoming more variable and overall non-significant with longer test durations. This is the first study investigating the escape test simultaneously with long-term avoidance of cadmium by O. nitens. This mite species is a promising species for avoidance testing in soil ecotoxicology, but more experiments are needed to evaluate the factors that influence its responses in laboratory tests and the consequences for its distribution in contaminated ecosystems.

Placental lncRNA expression associated with placental cadmium concentrations and birth weight.

Heavy metal exposures, such as cadmium, can have negative effects on infant birth weight (BW)—among other developmental outcomes—with placental dysfunction potentially playing a role in these effects. In this study, we examined how differential placental expression of long non-coding RNAs (lncRNAs) may be associated with cadmium levels in placenta and whether differences in the expression of those lncRNAs were associated with fetal growth. In the Rhode Island Child Health Study, we used data from Illumina HiSeq whole transcriptome RNA sequencing (n = 199) to examine association between lncRNA expression and measures of infant BW as well as placental cadmium concentrations controlled for appropriate covariates. Of the 1191 lncRNAs sequenced, 46 demonstrated associations (q < 0.05) with BW in models controlling for infant sex, maternal age, BMI, maternal education, and smoking during pregnancy. Furthermore, four of these transcripts were associated with placental cadmium concentrations, with MIR22HG and ERVH48-1 demonstrating increases in expression associated with increasing cadmium exposure and elevated odds of small for gestational age birth, while AC114763.2 and LINC02595 demonstrated reduced expression associated with cadmium, but elevated odds of large for gestational age birth with increasing expression. We identified relationships between lncRNA expression with both placental cadmium concentrations and BW. This study provides evidence that disrupted placental expression of lncRNAs may be a part of cadmium’s mechanisms of reproductive toxicity.

Denitrification responses to increasing cadmium exposure in Baltic Sea sediments

Benthic ecosystems have come under intense pressure, due to eutrophication-driven oxygen decline and industrial metal contamination. One of the most toxic metals is Cadmium (Cd), which is lethal to many aquatic organisms already at low concentrations. Denitrification by facultative anaerobic microorganisms is an essential process to transform, but also to remove, excess nitrate in eutrophied systems. Cd has been shown to decrease denitrification and sequester free sulfide, which is available when oxygen is scarce and generally inhibits complete denitrification (i.e. N2O to N2). In polluted sediments, an interaction between oxygen and Cd may influence denitrification and this relationship has not been studied. For example, in the Baltic Sea some sediments are double exposed to both Cd and hypoxia. In this study, we examined how the double exposure of Cd and fluctuations in oxygen affects denitrification in Baltic Sea sediment. Results show that oxygen largely regulated N2O and N2 production after 21 days of exposure to Cd (ranging from 0 to 500 μg/L, 5 different treatments, measured by the isotope pairing technique (IPT)). In the high Cd treatment (500 μg/L) the variation in N2 production increased compared to the other treatments. Increases in N2 production are suggested to be an effect of 1) enhanced nitrification that increases NO3− availability thus stimulating denitrification, and 2) Cd successfully sequestrating sulfide (yielding CdS), which allows for full denitrification to N2. The in situ field sediment contained initially high Cd concentrations in the pore water (∼10 μg/L) and microbial communities might already have been adapted to metal stress, making the effect of low Cd levels negligible. Here we show that high levels of cadmium pollution might increase N2 production and influence nitrogen cycling in marine sediments.

Abstract WP178: Combining Novel with Traditional Risk Factors Improves Stroke Prediction in Older Americans: A Systematic Review

Background: The Framingham Risk Score, one validated model for predicting stroke risk in middle age does not perform as well in older cohorts who may have different/novel stroke risk factors. Methods: Two independent raters systematically reviewed (through July 31, 2016) PubMed and Embase, identifying studies including peer-reviewed, original, clinical studies, randomized controlled trials and cited references to assess independent risk factors for first ischemic stroke in older, (&gt; 65 years) Americans using PRISMA guidelines. Results: 467 relevant studies were identified. We extracted data from 42 papers and categorized their aims into 6 sections: Serologic/Diagnostic, Traditional, Psychosocial, Genetic, Cognitive, and Miscellaneous risk factors. Some studies fell into more than one category. Serologic/Diagnostic (11 studies) demonstrated: levels of serum androgens, C-reactive protein, advanced glycation endproducts, thrombin generation and increased left ventricular mass were significant risk factors; adipokines and plasma free fatty acids were not. Traditional (11 studies) risk factors included: age, hypertension (both systolic and diastolic), atrial fibrillation, diabetes, peripheral vascular disease, waist/hip ratio in women, and BMI in men. Two studies showed that risk associated with hypertension and diabetes diminishes significantly over age 75. One study showed the protective effect of physical activity increased with age. Psychosocial (13 studies): 6 studies found depression strongly associated with stroke risk. Also, positive affect and purpose in life protected against stroke. Socioeconomic status did not influence risk in 3 studies. Genetic (5 studies) included: Apolipoprotein E, coagulation factor XII, and phosphodiesterase 4D polymorphisms – all with equivocal results. Cognitive (4 studies): Lower cognitive functioning, increased stroke rates. Miscellaneous (4 studies): Decreased level of functioning and increased cadmium exposure were risk factors. Conclusion: Some traditional and other more novel risk factors emerged as increasing stroke risk in older individuals. Only a few studies evaluated each risk factor. Further studies are warranted to investigate risk factors for stroke in older cohorts.

Role of autophagy in cadmium-induced testicular injury

The testis is sensitive to cadmium, but studies investigating cadmium-induced testicular injury have not yet clearly revealed the underlying mechanisms. This study aimed to investigate the injurious effects of cadmium on rat testes and the role that autophagy plays in this process. Wistar rats were randomly divided into four groups and intraperitoneally injected with 0.2 (low), 0.4 (middle), and 0.8 mg/kg·body weight (high) cadmium chloride for 5 weeks, while the control rats were injected with equal volume of saline. Rats exposed to cadmium appeared inactive and had reduced body weights and increased testicular organ coefficients at the end of treatment compared with control rats. Atomic absorption results showed that cadmium levels increased with increased cadmium exposure. Hematoxylin and eosin staining of testicular sections showed seminiferous tubular atrophy, decreased pipe diameter, spermatogonial stem cells falling off the inner lining, and reduced germ cell layers of disorderly arrangements in cadmium-treated rats. Immunohistochemical and western blot results both showed that levels of the autophagy-related proteins Beclin1 and microtubule-associated protein 1 light chain 3B (LC3B) increased with increased cadmium exposure. We also found that LC3B-II and calcium-sensing receptor (CSR) levels in cadmium-exposed rats significantly increased. By immunofluorescence, we found that the percentage of cells that expressed the CSR was significantly higher in LC3B-positive than LC3B-negative cells. Together, our results showed that cadmium accumulates in the testes causing testicular injury, which may be related to increased autophagy levels. Furthermore, calcium disorders associated with the CSR may reveal a potential way to activate autophagy.

Exposure–dose–response relationships of the freshwater bivalve Hyridella australis to cadmium spiked sediments

To understand how benthic biota may respond to the additive or antagonistic effects of metal mixtures in the environment it is first necessary to examine their responses to the individual metals. In this context, laboratory controlled single metal-spiked sediment toxicity tests are useful to assess this. The exposure–dose–response relationships of Hyridella australis to cadmium-spiked sediments were, therefore, investigated in laboratory microcosms. H. australis was exposed to individual cadmium spiked sediments (<0.05 (control), 4±0.3 (low) and 15±1 (high) μg/g dry mass) for 28 days. Dose was measured as cadmium accumulation in whole soft body and individual tissues at weekly intervals over the exposure period. Dose was further examined as sub-cellular localisation of cadmium in hepatopancreas tissues. The biological responses in terms of enzymatic and cellular biomarkers were measured in hepatopancreas tissues at day 28. H. australis accumulated cadmium from spiked sediments with an 8-fold (low exposure organisms) and 16-fold (high exposure organisms) increase at day 28 compared to control organisms. The accumulated tissue cadmium concentrations reflected the sediment cadmium exposure at day 28. Cadmium accumulation in high exposure organisms was inversely related to the tissue calcium concentrations. Gills of H. australis showed significantly higher cadmium accumulation than the other tissues. Accumulated cadmium in biologically active and biologically detoxified metal pools was not significantly different in cadmium exposed organisms, which suggests that H. australis has some tolerance to cadmium. The metallothionein like protein fraction played an important role in the sequestration and detoxification of cadmium and the amount sequestered in this fraction increased with increased cadmium exposure. The highest percentage of biologically active cadmium was associated with the lysosome+microsome and mitochondrial fractions. Cadmium concentrations in these two fractions of cadmium exposed organisms were significantly higher with respect to controls. Total antioxidant capacity decreased with increased cadmium exposure and tissue dose. Lipid peroxidation increased and lysosomal membrane stability decreased significantly with increased cadmium exposure and tissue dose. Based on exposure–dose–response analysis in this study, H. australis would be a suitable organism for assessing cadmium sediment exposure and toxicity.

Dietary Cadmium Exposure and Risk of Postmenopausal Breast Cancer: A Population-Based Prospective Cohort Study

The ubiquitous food contaminant cadmium has features of an estrogen mimetic that may promote the development of estrogen-dependent malignancies, such as breast cancer. However, no prospective studies of cadmium exposure and breast cancer risk have been reported. We examined the association between dietary cadmium exposure (at baseline, 1987) and the risk of overall and estrogen receptor (ER)-defined (ER(+) or ER(-)) breast cancer within a population-based prospective cohort of 55,987 postmenopausal women. During an average of 12.2 years of follow-up, 2,112 incident cases of invasive breast cancer were ascertained (1,626 ER(+) and 290 ER(-)). After adjusting for confounders, including consumption of whole grains and vegetables (which account for 40% of the dietary exposure, but also contain putative anticarcinogenic phytochemicals), dietary cadmium intake was positively associated with overall breast cancer tumors, comparing the highest tertile with the lowest [rate ratio (RR), 1.21; 95% confidence interval (CI), 1.07-1.36; P(trend) = 0.02]. Among lean and normal weight women, statistically significant associations were observed for all tumors (RR, 1.27; 95% CI, 1.07-1.50) and for ER(+) tumors (RR, 1.25; 95% CI, 1.03-1.52) and similar, but not statistically significant associations were found for ER(-) tumors (RR, 1.22; 95% CI, 0.76-1.93). The risk of breast cancer increased with increasing cadmium exposure similarly within each tertile of whole grain/vegetable consumption and decreased with increasing consumption of whole grain/vegetables within each tertile of cadmium exposure (P(interaction) = 0.73). Overall, these results suggest a role for dietary cadmium in postmenopausal breast cancer development.

Antioxidants and stress-related metabolites in the seedlings of two indica rice varieties exposed to cadmium chloride toxicity

We present here a comprehensive study depicting the differences in biochemical responses to increasing CdCl2 concentrations (0.1, 0.25, 0.5 and 1.5 mM) in the two indica rice varieties, IR-29 (salt-sensitive) and Nonabokra (salt-tolerant), in order to contribute to our understanding of genotypic variation of cadmium tolerance. The oxidative damages in both the varieties enhanced with the increase in CdCl2 concentrations, the susceptibility of IR-29 being more pronounced than Nonabokra. The detrimental effects in IR-29 were reflected in greater chlorophyll loss, higher H2O2 and malondialdehyde content even at lower concentrations and drastically higher lipoxygenase activity, protein oxidation and putrescine accumulation, especially at higher CdCl2 levels. The antioxidants like anthocyanin and carotenoids, antioxidative enzymes like guaiacol peroxidase (GPX) and ascorbate peroxidase (APX), osmolytes like proline, reducing sugars, spermidine and spermine, increased in both the varieties with CdCl2 levels. While anthocyanin, reducing sugars and spermine showed greater increment in IR-29, the GPX/APX activity was more enhanced in Nonabokra; the increase in carotenoids, proline and spermidine being similar in both the varieties. However, reverse trends were noted for cysteine level and CAT activity; IR-29 showed marked decrease in cysteine content and CAT activity with increased cadmium exposure, whereas in Nonabokra, both the parameters increased, particularly at higher cadmium levels. Thus, the detoxification mechanism in the more-susceptible IR-29 was probably rendered by anthocyanin, reducing sugars and spermine in particular, as well as by GPX/APX, rather than cysteine and CAT, which showed cadmium sensitivity. Thus, the CdCl2 stress-dependent comparative biochemical analyses displayed major differences in the two rice varieties in terms of tolerance to Cd toxicity. Our data provides evidence that Nonabokra, which is a well-known variety tolerant to sodium chloride toxicity, also shows promising tolerance to cadmium toxicity, and hints at their possible utilization in Cd remediation.

Exposure–dose–response of Anadara trapezia to metal contaminated estuarine sediments. 1. Cadmium spiked sediments

The relationship between cadmium exposure dose and response was investigated in Anadara trapezia exposed to cadmium spiked sediment (10μg/g and 50μg/g dry mass) for 56 days. A. trapezia reached an equilibrium cadmium tissue concentration (13μg/g and 25μg/g, respectively) by day 42. Gills accumulated significantly more cadmium than the hepatopancreas and haemolymph. After 56 days exposure between 46 and 73% of accumulated gill and hepatopancreas cadmium was detoxified and in the metallothionein like protein fraction. Approximately half of the biologically active cadmium in both tissues was in the mitochondrial fraction which has the potential to cause dysfunction in mitochondrial activity. Cadmium exposed A. trapezia generally had reduced GPx activity with an associated increase in total glutathione concentrations and reduced GSH:GSSG ratios due to a build up of oxidised glutathione. The changes in the glutathione pathway were reflected in the total antioxidant capacity of cadmium exposed A. trapezia which were significantly reduced compared to control organisms. There was a trend of increased lipid peroxidation with increased cadmium exposure but this was not significant. Increased cadmium exposure resulted in significant lysosomal destabilisation and increased frequency of micronuclei. The significant exposure–dose–response relationship for A. trapezia exposed to cadmium enriched sediments indicates that elevated sediment cadmium concentrations have the potential to lead to increased biologically active cadmium burdens and impairment of individual A. trapezia at cellular and subcellular levels.

Cadmium and peripheral arterial disease: gender differences in the 1999-2004 US National Health and Nutrition Examination Survey.

Gender differences in the association of blood and urine cadmium concentrations with peripheral arterial disease (PAD) were evaluated by using data from 6,456 US adults aged ≥40 years who participated in the 1999-2004 National Health and Nutrition Examination Survey. PAD was defined as an ankle-brachial blood pressure index of <0.9 in at least one leg. For men, the adjusted odds ratios for PAD comparing the highest with the lowest quintiles of blood and urine cadmium concentrations were 1.82 (95% confidence interval (CI): 0.82, 4.05) and 4.90 (95% CI: 1.55, 15.54), respectively, with a progressive dose-response relation and no difference by smoking status. For women, the corresponding odds ratios were 1.19 (95% CI: 0.66, 2.16) and 0.56 (95% CI: 0.18, 1.71), but there was evidence of effect modification by smoking: among women ever smokers, there was a positive, progressive dose-response relation; among women never smokers, there was a U-shaped dose-response relation. Higher blood and urine cadmium levels were associated with increased prevalence of PAD, but women never smokers showed a U-shaped relation with increased prevalence of PAD at very low cadmium levels. These findings add to the concern of increased cadmium exposure as a cardiovascular risk factor in the general population.

Urinary Disease Morbidity and Mortality in a Population Environmentally Exposed to Cadmium and Other Nephrotoxic Metals

ISEE-0675 Background and Objectives: Exposure to cadmium and other nephrotoxic metals may cause damage to the urinary system. Food is the main source of cadmium exposure in non-smokers. A lead/zinc smelter in Avonmouth (southwest England) was a major source of environmental cadmium for over 70 years. Emissions from the site may have led to increased cadmium exposure in the local population through inhalation of contaminated air and the ingestion of home-grown vegetables and house dust. A previous study carried out in the area showed a positive dose-response relationship between urinary cadmium and a biomarker of kidney tubular damage. Methods: A validated air dispersion model was used to define high, medium and low exposure groups within the vicinity of the smelter. Routinely collected data were used to assess non-malignant urinary disease morbidity and mortality using the southwest England region as the reference. Relative risks for sub-groups of urinary disease were also calculated. Analyses for men and women were carried out separately and results were adjusted for age and socioeconomic status. Results: The results show a significant trend in urinary disease mortality over exposure categories in women (P = 0.02) and a significantly increased risk in the highest exposure group (RR 1.48 (95% CI 1.09–1.96). For urinary disease morbidity the results show a significantly increased risk across all exposure groups for both sexes with relative risks in the highest exposure group of 1.33 (1.26–1.4) and 1.48 (1.41–1.56) for men and women respectively. The analysis for urinary disease sub-groups also show significantly elevated risks including a relative risk of 3.26 (3.07–3.46) for bladder dysfunction in women. Conclusions: An excess risk of urinary disease mortality and morbidity support the need for measures to reduce environmental cadmium exposure in the Avonmouth area.

The use of bioaccumulation, biomarkers and histopathology diseases in shape Procambarus clarkii to establish bioavailability of Cd and Zn after a mining spill

Individuals of the crayfish Procambarus clarkii (males and females) were exposed simultaneously to cadmium and zinc during 21 days. Exposure concentrations were those determined at the Guadiamar river after the Aznalcóllar mining spill (SW, Spain): 10 and 30 microg L(-1) of cadmium and 1000 and 3000 microg L(-1) of zinc. Three biomarkers (MT: metallothioneins like proteins, VTG: vitellogenin/vitellin like proteins and histopathology) together with heavy metal bioaccumulation were determined in soft tissues of male and female P. clarkii. At the concentrations tested, increasing cadmium exposure resulted in increasing cadmium bioaccumulation and increasing subletal effects (induction of MT, VTG and histopathological damage in tissues). Nevertheless, although increasing zinc exposure showed increasing VTG induction and histopathological damages, not a positive relationship was determined with MT induction. Concerning to responses determined in male and female crayfishes only differences were found between sexes at the highest cadmium exposure concentration related to bioaccumulation in hepatopancreas tissues. Biomarkers responses to heavy metal contamination in this crayfish, even VTG induction not before tested in heavy metal contamination assessment in crustaceans resulted potential tools for the monitoring of heavy metal environmental contamination.

Plant-mediated effects of heavy metal pollution on host choice of a grass miner

We studied the effects of heavy metal exposure on host plant choice and performance of the grass miner Chromatomyia milii (Diptera, Agromyzidae). Cadmium decreased plant growth in a dose-dependent way. C. milii preferred the control to the cadmium-exposed plants for feeding and oviposition. Moreover, preference for the control plants increased with increasing cadmium exposure of the alternative choice. Adult and offspring performance decreased with increasing plant cadmium exposure. This suggests that, at least under our laboratory conditions, host choice of C. milii is adaptive under pollution stress. Foliar cadmium concentration increased and the soluble sugar concentration decreased with increasing cadmium exposure. Regression analysis showed that both latter components might be responsible for the decrease in performance of C. milii on cadmium-exposed plants. The protein and amino acid concentration of the leaves, the amount of structural defenses, and water concentration were not affected by the cadmium treatment.

Environmental exposure and preventive measures in Sweden and EU*

Environmental exposure to cadmium (Cd) gives rise to renal tubular dysfunction at low cumulative doses of Cd. A possible role of Cd in influencing the occurrence of diseases, e.g., bone, reproductive and cancer in the general population groups environmentally exposed to Cd has been reported from Japan, Belgium, Sweden and China. Authorities have to pay attention to this fact and to act in order to prevent serious outcomes and personal suffering in the population groups at risk. A general approach in setting recommended health based limits and to regulate the occurrence of a substance existing in food stuff is to keep low levels -better to be on the safer side than on the risk side. In the case of cadmium it should be most clear that since cadmium has a very long biological half-life of 20 years in humans, increased cadmium exposure due to human activities can never be accepted. In cases where cadmium exposure can not be avoided the approach should be to limit and decrease exposure. Presently FAO/WHO Expert Committee on Food Additives and Food has a PTWI (provisional tolerable weekly intake) value for adult persons of 7 microg/kg body weight for Cd (WHO 2003) a value corresponding to 1 microg/kg body weight for each day of a week. For children and pregnant or lactating women daily intakes should not exceed 1 microg/kg body weight.

Evaluation of Metallothionein Measurement as a Biological Indicator of Stress from Cadmium in Brook Trout

A modification of an established technique for quantifying metallothionein (MT) in mammals was used to evaluate the toxicological importance of MT as a biological indicator of stress from chronic cadmium toxicity in brook trout Salvelinus fontinalis. In a 30-d study, fish mortality was significantly increased but growth was not altered by exposure to 3.6 μg Cd/L or more. After chronic exposure to cadmium, both mortality and whole-body residues showed a dose-response relation over the exposure range of 3.6 to 60.6 μg Cd/L. Concentrations of MT were increased significantly in all exposures that resulted in significant mortality; however, they showed no dose-response relation to cadmium exposure, nor were they correlated with mortality or whole-body cadmium residues. Consequently, measurement of MT alone was not a useful indicator of cadmium toxicity in brook trout. A better biological indicator was the amount of free cadmium in liver tissue. Free cadmium (the difference between the amount of cadmium in the supernatant resulting from centrifugation at 100,000 x gravity and the amount bound to MT in an unsaturated condition) showed a dose-dependent increase with increasing cadmium exposure and was highly correlated with mortality and whole-body residues. Free cadmium concentrations were significantly elevated in all exposures to 3.6 μg Cd/L or greater. The presence of free cadmium in tissues of brook trout from all exposures suggests that MT was not saturated with cadmium before the appearance of pathological effects and thus conflicts with the “spillover” hypothesis. As judged by the results of our toxicity studies, the spillover hypothesis should be redefined as a continuum of toxic responses to varying balances between the relative abundance of metals present and their respective binding affinities for MT.