Self poisoning with oral cadmium chloride

Cadmium transport by mammalian ATP-binding cassette transporters

Cellular responses to toxic metals depend on metal accessibility to intracellular targets, reaching interaction sites, and the intracellular metal concentration, which is mainly determined by uptake pathways, binding/sequestration and efflux pathways. ATP-binding cassette (ABC) transporters are ubiquitous in the human body-usually in epithelia-and are responsible for the transfer of indispensable physiological substrates (e.g. lipids and heme), protection against potentially toxic substances, maintenance of fluid composition, and excretion of metabolic waste products. Derailed regulation and gene variants of ABC transporters culminate in a wide array of pathophysiological disease states, such as oncogenic multidrug resistance or cystic fibrosis. Cadmium (Cd) has no known physiological role in mammalians and poses a health risk due to its release into the environment as a result of industrial activities, and eventually passes into the food chain. Epithelial cells, especially within the liver, lungs, gastrointestinal tract and kidneys, are particularly susceptible to the multifaceted effects of Cd because of the plethora of uptake pathways available. Pertinent to their broad substrate spectra, ABC transporters represent a major cellular efflux pathway for Cd and Cd complexes. In this review, we summarize current knowledge concerning transport of Cd and its complexes (mainly Cd bound to glutathione) by the ABC transporters ABCB1 (P-glycoprotein, MDR1), ABCB6, ABCC1 (multidrug resistance related protein 1, MRP1), ABCC7 (cystic fibrosis transmembrane regulator, CFTR), and ABCG2 (breast cancer related protein, BCRP). Potential detoxification strategies underlying ABC transporter-mediated efflux of Cd and Cd complexes are discussed.

Bio-prospectus of cadmium bioadsorption by lactic acid bacteria to mitigate health and environmental impacts

Foodstuffs and water are the key sources of cadmium biomagnifiaction. The available strategies to mitigate this problem are unproductive and expensive for practical large-scale use. Biological decontamination of metals through environmental microbes has been known since long time, whereas lactic acid bacteria (LAB) have not been extensively studied for this purpose. The LAB are known for maintaining homeostasis and suppression of pathogens in humans and animals. They also play a vital role in bioremediation of certain heavy metals. Recently in-vivo research findings strongly complement the in-vitro results in relation to decreased total body cadmium burden in animal model. This review summarizes the currently available information on impact of toxic metal (Cd) on human and animal health as well as cadmium sequestration through microbes placed broadly, whereas preeminent attention grabbed on LAB-cadmium interaction to explore their possible role in bioremediation of cadmium from foods and environment to safeguard human as well as environment health.

Minimal Risk Level Derivation for Cadmium: Acute and Intermediate Duration Exposures

The Agency for Toxic Substances and Disease Registry (ATSDR) lists cadmium as one of its priority hazardous substances. The agency conducted a comprehensive literature review of cadmium and used the information to develop a toxicological profile that identified the full range of health effects associated with exposure to cadmium. It included an assessment that identified screening levels, termed health guidance values or minimal risk levels (MRLs), below which adverse health effects are not expected. In this paper, we describe how MRLs for cadmium are derived. For the acute inhalation MRL, the traditional no observed adverse effect level or lowest observed adverse effect level (NOAEL/LOAEL) approach is used; for the oral intermediate MRL, the benchmark dose (BMD) approach is used. MRLs were developed for the most sensitive route-specific end points, other than mortality and cancer that were sufficiently supported and justified by the data. These included an acute duration (1-14 day exposure) inhalation MRL of 0.03 µg Cd/m³ for alveolar histiocytic infiltration and focal inflammation in alveolar septa and an intermediate duration (15-365 day exposure) oral MRL of 0.5 µg Cd/kg/day for decreased bone mineral density.

Efficacy of indigenous probiotic Lactobacillus strains to reduce cadmium bioaccessibility - An in vitro digestion model

The toxic heavy metal cadmium (Cd) appears as one of the major global threats to human and animal health. Human being and aquatic life are exposed to Cd by breathing, eating, or drinking when industrial effluents released into environment. The study was aimed to identify cadmium-binding Lactobacillus strain to reduce its bioaccessibility in in vitro digestion model. In this context, forty-eight lactobacilli strains isolated and characterized from fermented dairy products and human origin were screened for their Cd biosorption potential using Flame Atomic Absorption Spectroscopy (FAAS). The present study revealed that Cd biosorption potential of 48 lactobacilli strains ranged from 1.0832 ± 0.012 to 3.562 ± 0.03 mg Cd g^-1 of cells from initial 10 mg L^-1 cadmium chloride (CdCl₂) aqueous solution. Lactobacillus plantarum strain HD 48 demonstrated highest biosorption of 3.562 ± 0.03 mg Cd g^-1 of cells. Lactobacilli-Cd complex stability indicated its strong stability as even after three washes with Milli-Q water metal desorption was nonsignificant (p < 0.05) and further studies to delineate the influence of Cd (100 mg L^-1 CdCl₂) on their growth. Moreover, these strains were able to reduce Cd bioaccessibility in the in vitro digestion model in the range of 24.71 to 41.62 %. Transmission electron microscopy (TEM) investigations on Cd bioadsorption also revealed its surface associated bioadsorption phenomenon. These findings depicted that probiotic strain L. plantarum HD 48 was found to be endowed with remarkable Cd biosorption ability as well as reduction in its bioaccessibility. These results suggest that probiotic strain L. plantarum HD 48 has immense potential to sequester Cd from aqueous solution which could be further explored as a potent source to diminish body Cd burden.

High Cadmium Levels in Cured Meat Products Marketed in Nigeria - Implications for Public Health

Heavy metals are known to disrupt important physiological processes in living cells, and have been responsible for various pathological conditions with possible contributions to cancer development. Food contamination have been identified as one of the ways humans are exposed to heavy metals. In developing countries like Nigeria, the regulatory framework for enforcing compliance with globally acceptable exposure to deleterious contaminants is poor. In the current study, thirteen samples of cured meat products of diverse origin marketed in South-west Nigeria were evaluated for lead, cadmium, chromium and nickel contents using the atomic absorption spectroscopy technique. All the samples analysed contained cadmium between 0.35 and 1.20 ppm, levels considered higher than acceptable limits in consumable products. Lead, chromium and nickel were not detected in any of the samples. As known cumulative poisons, there is the need for stringent regulatory control of these heavy metals in cured meat products imported into or produced indigenously in the country in order to minimize the risks to public health.

Toxic trace elements at gastrointestinal level

Many trace elements are considered essential [iron (Fe), zinc (Zn), copper (Cu)], whereas others may be harmful [lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As)], depending on their concentration and chemical form. In most cases, the diet is the main pathway by which they enter our organism. The presence of toxic trace elements in food has been known for a long time, and many of the food matrices that carry them have been identified. This has led to the appearance of legislation and recommendations concerning consumption. Given that the main route of exposure is oral, passage through the gastrointestinal tract plays a fundamental role in their entry into the organism, where they exert their toxic effect. Although the digestive system can be considered to be of crucial importance in their toxicity, in most cases we do not know the events that occur during the passage of these elements through the gastrointestinal tract and of ascertaining whether they may have some kind of toxic effect on it. The aim of this review is to summarize available information on this subject, concentrating on the toxic trace elements that are of greatest interest for organizations concerned with food safety and health: Pb, Cd, Hg and As.

Lipid metabolism in liver of rat exposed to cadmium

We investigated the effect of exposition to cadmium (Cd, 15ppm for 8 weeks) through drinking water on liver lipid metabolism in adult male Wistar rats. As compared to metal non-exposed (control) rats, the serum triglycerides, cholesterol and LDL+VLDL cholesterol concentrations increased. This was associated to a decrease of lipoprotein lipase activity in post heparinic plasma. The VLDL secretion from liver was not modified. Cd treatment increased triglycerides and decreased esterified cholesterol contents in liver. The high triglyceride mass was related to the increased glycerol-3-phosphate acyltransferase mRNA expression. In addition, the liver fatty acids synthesis increased, as determined by an increment of fatty acid synthetase and isocitrate dehydrogenase activities, and [(14)C]-acetate incorporation into saponifiable lipid fraction. The relative percentage of palmitic acid (16:0) and total saturated fatty acids were increased compared with control. Hepatic glucose-6-phosphate dehydrogenase, malic dehydrogenase and cholesteryl ester hydrolase activities were unchanged. In liver, the Cd treatment decreased triglyceride and cholesterol in mitochondria, also increased triglyceride in cytosol, and cholesterol and phospholipid contents in nuclei, compared with control. In addition, an increase of nuclei phosphatidylcholine synthesis was observed. Cd exposure alters directly or indirectly the serum lipid content and liver lipid metabolism.

Oral cadmium chloride intoxication in mice: effects of dose on tissue damage, intestinal absorption and relative organ distribution

The acute toxicity of soluble cadmium salts has almost exclusively been studied experimentally after parenteral exposures, where acute mortality is caused by hepatic necrosis. This report describes an alternative experimental model using oral exposure. A single oral toxic dose of CdCl2 to mice induced toxic gastroenteritis; subsequent hepatic and renal lesions were also observed. Whole-body gamma-counting after a single oral toxic 109CdCl2 dose to mice showed a dose-dependent delay of the fecal excretion of non-absorbed cadmium. This delay was absent when a low, non-toxic dose was administered. This effect is most likely due to decreased peristalsis and, at higher doses, intestinal atony due to oral cadmium toxicity. After fecal elimination of non-absorbed cadmium, the residual body burden of cadmium expressed as percent of initial dose reflects the fractional intestinal cadmium absorption due to slow reexcretion of absorbed cadmium. The fractional absorption increased with increasing doses of cadmium. The relative cadmium deposition in brain, testes and intestines decreased with increasing dose, whereas the relative liver deposition increased with dose. The delayed fecal elimination and increased fractional absorption of cadmium may significantly contribute to the development of both local and systemic toxicity in oral cadmium intoxication.