Exposure of pregnant mice to chromium picolinate results in skeletal defects in their offspring

Decrypting the skeletal toxicity of vertebrates caused by environmental pollutants from an evolutionary perspective: From fish to mammals

The rapid development of modern society has led to an increasing severity in the generation of new pollutants and the significant emission of old pollutants, exerting considerable pressure on the ecological environment and posing a serious threat to both biological survival and human health. The skeletal system, as a vital supportive structure and functional unit in organisms, is pivotal in maintaining body shape, safeguarding internal organs, storing minerals, and facilitating blood cell production. Although previous studies have uncovered the toxic effects of pollutants on vertebrate skeletal systems, there is a lack of comprehensive literature reviews in this field. Hence, this paper systematically summarizes the toxic effects and mechanisms of environmental pollutants on the skeletons of vertebrates based on the evolutionary context from fish to mammals. Our findings reveal that current research mainly focuses on fish and mammals, and the identified impact mechanisms mainly involve the regulation of bone signaling pathways, oxidative stress response, endocrine system disorders, and immune system dysfunction. This study aims to provide a comprehensive and systematic understanding of research on skeletal toxicity, while also promoting further research and development in related fields.

Association Between Heavy Metals Exposure and Height in Chinese Preschoolers

OBJECTIVES

This study aimed to explore the association between multiple metals' exposure and children's height.

METHODS

We collected urine samples and physical measurement data of 1477 preschoolers in China. Children's actual height was measured, and whether reached target height was also assessed. Logistic regression analysis was performed to explore the association between heavy metals and height. The least absolute shrinkage and selection operator regression was used to select the urinary metals, which were highly correlated.

RESULTS

In the single-metal model after adjusting for potential confounders, urinary iron, aluminum, nickel, chrome, titanium, vanadium, selenium, rubidium, and thallium levels were negatively associated with actual height. Urinary iron, aluminum, nickel, and chrome concentrations were also negatively associated with target height.

CONCLUSIONS

The findings suggested that some urinary metal exposure might be associated with height in preschoolers.

Exposure of suckling rats to hexavalent chromium (CrVI) alters bone formation at the base of the alveolus causing a delay in tooth eruption

OBJECTIVES

Hexavalent chromium (CrVI)-exposure of suckling rats has been shown to delay tooth eruption. However, the effects of CrVI-exposure on bone formation at the base of the alveolus, which provides a motive force for tooth eruption in the early stages of the process, remain unknown. The present work sought to evaluate the effect of CrVI-exposure on bone formation at the base of the alveolus during the intraosseous stage of tooth eruption in suckling rats, using histomorphometric and immunohistochemical studies.

METHODS

Experimental animals received 12.5 mg/kg-bw/day of potassium dichromate dissolved in saline solution by gavage starting on day 4 of the experiment; controls similarly received an equivalent volume of saline. All the animals were euthanized at the age of 9 days. The base of the developing alveolus at the level of the mesial root of the first lower molar was analyzed histomorphometrically and immunohistochemically. Data were statistically analyzed using student's t-test, with statistical significance set at p <0.05.

RESULTS

CrVI-exposed animals showed lower bone volume and height at the base of the alveolus, a significant preponderance of bone rest on the surface adjacent to the dental follicle, and a significantly lower percentage of positive Runt-related transcription factor-2 (RUNX2+) osteoblasts and a significantly higher number of mesenchymal-like RUNX2+ cells at the latter site.

CONCLUSION

CrVI-exposure during lactation affects bone formation at the base of the developing alveolus, delaying tooth eruption. These findings underscore the importance of controlling drinking water levels of toxic substances since their effects can alter the growth and development of individuals exposed during early childhood.

Evaluation of Hypoglycemic Activity and Sub-Acute Toxicity of the Novel Biochanin A–Chromium(III) Complex

The novel biochanin A–chromium(III) complex was synthesized by chelating chromium with biochanin A (BCA). The structure of the complex was determined and the complex ([CrBCA3]) was composed of chromium(III) and three ligands, and the chromium content was 55 μg/mg. The hypoglycemic activity of the complex was studied in db/db mice and C57 mice. The sub-acute toxicity test of the complex was carried out by the maximum limit method in KM mice. The hypoglycemic activity showed that the complex could reduce the weight of db/db mice and lower the fasting blood glucose and random blood glucose levels. The complex also improved the organ index, oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) results of db/db mice, and some of the indicators were similar to those of the positive control group after treatment with the complex. The histopathology study showed significant improvements in the liver, kidney, pancreas and skeletal muscle compared with the diabetes model group. The complex also showed a significant improvement in serum biochemical indices and antioxidant enzyme activities, as well as glycogen levels. The sub-acute toxicity study showed that the complex did not cause death or any dangerous symptoms during the study. In addition, the sub-acute toxicity study showed that the complex had no significant effect on the serum biochemical indices, antioxidant capacity and organs of normal mice. This study showed that [CrBCA3] had good hypoglycemic activity in vivo and had no sub-acute toxicity. This work provides an important reference for the development of functional hypoglycemic foods or drugs.

Anti-diabetic properties of genistein-chromium (III) complex in db/db diabetic mice and its sub-acute toxicity evaluation in normal mice

BACKGROUND

In this study, chromium (III) complex was synthesized from genistein (GEN) which had good hypoglycemic activity and inorganic chromium (III) element, and its hypoglycemic activity and sub-acute toxicity were studied.

METHODS

The genistein-chromium (III) complex was synthesized by chelating chromium with genistein in ethanol and its structure was determined by LC-MS, atomic absorption spectroscopy, UV-vis spectroscopy, infrared spectroscopy, elemental and thermodynamic analysis. The anti-diabetic activity of the complex was assessed in db/db mice and C57 mice by daily oral gavage for 4 weeks. The sub-acute toxicity test was carried out on KM mice with this complex.

RESULTS

The molecular structure of this complex was inferred as a complex [CrGEN₃] formed by three ligands and one chromium element. The complex could significantly improve the body weight of db/db mice, fasting blood glucose, random blood glucose, organ index, glycogen levels and the performance of OGTT (Oral Glucose Tolerance Test) and ITT (Insulin Tolerance Test) in db/db mice (p < 0.05). The morphology of liver, kidney, pancreas and skeletal muscle also had obviously improvement and repairment. Effects on serum indices and antioxidant enzymes activities of db/db mice showed that the serum profiles and antioxidant ability of complex group had significant improvement compared with the diabetic control group (p < 0.05 or p < 0.01), and some indices even returned to normal levels. In addition, this complex did not produce any hazardous symptoms or deaths in sub-acute toxicity test. High dose of [CrGEN₃] had no significant influence on serum indices and antioxidant capacity in normal mice, and the organ tissues maintained organized and integrity in the sub-acute toxicity study.

CONCLUSION

The study of the genistein-chromium (III) complex showed that the complex had good hypoglycemic activity in vivo, and did not have the potential toxicity. These results would provide an important reference for the development of functional hypoglycemic foods or pharmaceuticals.

Assessment of DNA Methylation and Oxidative Changes in the Heart and Brain of Rats Receiving a High-Fat Diet Supplemented with Various Forms of Chromium

Simple Summary

Obesity is one of the most prevalent diseases of civilization in the 21st century. This may be due to an increase in the consumption of high-fat diets. For the treatment of obesity, various supplements with chromium (III) are used. Chromium has the ability to regulate carbohydrate and lipid metabolism, which may result in weight loss. Our studies compared the effects of a high-fat diet supplemented with three different forms of chromium-chromium (III) picolinate, chromium (III) -methionine, and nano-sized chromium on oxidative damage of the DNA, proteins, and lipids in the heart and brain of rats. The conducted study showed that the use of a high-fat diet results in oxidation of the DNA, proteins, and lipids in the brain and heart, and the addition of chromium additionally intensifies these processes, especially when used in the form of nanoparticles. Therefore, the results of these studies suggest that one should be careful when using chromium supplementation to counteract obesity, because it may be associated with the risk of deterioration of the functioning of the heart and brain.

Abstract

The aim of the study was to determine how feeding rats a high-fat diet supplemented with various forms of chromium affects DNA methylation and oxidation reactions as well as the histology of heart and brain tissue. The rats received standard diet or high-fat diet and chromium at 0.3 mg/kg body weight (BW) in form of chromium (III) picolinate, chromium (III)-methionine, or nano-sized chromium. The content of malondialdehyde (MDA), protein carbonyl (PC), and 8-hydroxydeoxyguanosine (8-OHDG), the level of global DNA methylation and the activity of selected DNA repair enzymes were determined in the blood. In the brain and heart, the content of MDA, PC, 8-OHDG, and levels of global DNA methylation were determined. The brain was subjected to histological examination. The use of a high-fat diet was found to intensify epigenetic changes and oxidation reactions in the heart and brain. It was concluded that epigenetic changes and oxidation of lipids, proteins, and DNA in the heart and brain of rats resulting from the use of a high-fat diet cannot be limited by supplementing the diet with chromium. It was established that the use of chromium to supplement a high-fat diet intensifies the negative epigenetic and oxidative changes in the heart and brain, especially in the case of chromium nanoparticles.

Differential DNA methylation in newborns with maternal exposure to heavy metals from an e-waste recycling area

This study explored the effects of maternal exposure to e-waste environmental heavy metals on neonatal DNA methylation patterns. Neonatal umbilical cord blood (UCB) samples were collected from participants that resided in an e-waste recycling area, Guiyu and a nearby non-e-waste area, Haojiang in China. The concentrations of UCB lead (Pb), cadmium (Cd), manganese (Mn) and chromium (Cr) were measured by graphite furnace atomic absorption spectrometry. Epigenome-wide DNA methylation at 473, 844 CpG sites (CpGs) were assessed by Illumina 450 K BeadChip. The differential methylation of CpG sites from the microarray were further validated by bisulfite pyrosequencing. Bioinformatics analysis showed that 125 CpGs mapped to 79 genes were differential methylation in the e-waste exposed group with higher concentrations of heavy metals in neonatal UCB. These genes mainly involve in multiple biological processes including calcium ion binding, cell adhesion, embryonic morphogenesis, as well as in signaling pathways related to NFkB activation, adherens junction, TGF beta and apoptosis. Among them, BAI1 and CTNNA2 (involving in neuron differentiation and development) were further verified to be hyper- and hypo-methylated, respectively, which were associated with maternal Pb exposure. These results suggest that maternal exposure to e-waste environmental heavy metals (particularly lead) during pregnancy are associated with peripheral blood differential DNA methylation in newborns, specifically the genes involving in brain neuron development.

Exposure to heavy metals released to the environment through breastfeeding: A probabilistic risk estimation

Toxic heavy metals released into the environment through various anthropogenic activities, raising concerns over their potential adverse effects on human health and the environment. Biological monitoring studies are of great value in toxicological research for estimation of such health effects. The aim of this study was to evaluate the concentrations of lead (Pb), arsenic (As), and chromium (Cr) in the breast milk of urban mothers in Hamadan city, Iran and the accompanying health risk to infants. A total of 100 lactating mothers were recruited from public health care centers in Hamadan city and breast milk samples were collected at 2, 6, 8, and 12 months postpartum. Inductively coupled plasma mass spectroscopy (ICP-MS) has been used to measure target heavy metal concentrations. The median breast milk concentrations of Pb, As, and Cr were 41.90, 0.50, and 3.95 μg/L, respectively. The highest levels of Pb were observed after two months of delivery (with the mean of 96.69 μg/L and median of 45.70 μg/L). Up to 94% of the breast milk samples exceeded the WHO limit suggested for lead contamination of breast milk (<5 μg/L). The breast milk As and Cr contents were above the limit of detection (LOD) in 19% and 76% of samples, respectively. Unacceptable non-cancer health risk levels or hazard quotient (HQ) were found for Pb and As in 61% and 10% of the samples, respectively. Nevertheless, HQ from Cr was <1.0 for 100% of breastfeeding infants. Finally, our results indicated that there may be a potential risk of toxic metals, especially lead, for infants in Hamadan via the consumption of mothers' breast milk.

Exposure to chromium during pregnancy and longitudinally assessed fetal growth: Findings from a prospective cohort

BACKGROUND

Prenatal exposure to chromium may be associated with reduced birth weight; however, critical windows of such exposure for fetal growth are unclear.

OBJECTIVE

Our study was aimed to assess trimester-specific associations of chromium exposure with fetal growth parameters measured repeatedly by ultrasound and birth size, and to see whether these associations were modified by fetal sex.

METHODS

We conducted a prospective cohort of 3041 women in Wuhan, China, from 2013 to 2016. Chromium concentrations were measured in maternal urine samples collected in the 1st, 2nd, and 3rd trimesters using an inductively coupled plasma mass spectrometry. We calculated standard deviation scores for ultrasound measured head circumference, abdominal circumference (AC), femur length, and estimated fetal weight (EFW) at 16, 24, and 31 weeks of gestation. Linear regressions with generalized estimating equations were used to estimate the associations of specific gravity-adjusted urinary chromium concentrations in each trimester with fetal growth parameters and birth weight, birth length, and ponderal index.

RESULTS

Inverse associations of chromium exposure in the 1st trimester with fetal growth parameters at 31 weeks of gestation were observed, resulting in significant reductions in AC of -5.4% (95% confidence interval [CI]: -9.6%, -1.2%) and EFW of -5.6% (95% CI: -9.8%, -1.4%) per unit increase in natural logarithm transformed urinary chromium concentration. Urinary chromium concentration in the 2nd trimester was also associated with reductions in AC of -7.0% (95% CI: -12.5%, -1.4%) and in EFW of -5.0% (95% CI: -10.6%, 0.6%) at 31 weeks, and these inverse associations were evident in boys (reduction in AC of -13.9% [95% CI: -21.1%, -6.7%]; EFW of -9.5% [95% CI: -16.9%, -2.0%]) but not in girls (increase in AC of 2.9% [95% CI: -5.7%, 11.5%]; EFW of 1.5% [95% CI: -6.8%, 9.8%]) (both p_ineraction < 0.05). Moreover, one-unit increase in urinary chromium concentrations in the 1st and 2nd trimesters were both associated with significant reductions in ponderal index of -0.11 kg/m³ (95% CI: -0.19, -0.03 kg/m³) and -0.15 kg/m³ (95% CI: -0.27, -0.03 kg/m³), respectively.

CONCLUSION

Our findings suggest that chromium may be a toxic metal for fetal growth. Early and mid-pregnancy seem to be the most vulnerable period for fetal exposure to chromium, but these results need further confirmation.

[Cr3O(O2CCH2CH3)6(H2O)3]NO3·H2O (Cr3) Toxicity Potential in Bacterial and Mammalian Cells

Chromium(III) has generally been considered to be essential for proper carbohydrate and lipid metabolism, and, despite recent evidence to the contrary, chromium(III)-containing compounds remain one of the most popular commercial dietary supplements. Cr3, or [Cr₃O(O₂CCH₂CH₃)₆(H₂O)₃]NO₃·H₂O, is a trivalent chromium compound that is a promising chromium nutritional supplement. Studies with Cr3 have indicated that it is non-toxic in developmental and short- and long-term exposure studies in rodents, but the safety of this compound to chromosomes and cells has not been explored. The current study evaluates the mutagenicity, cytotoxicity, and clastogenicity of Cr3 in bacterial and mammalian cells and compares these results with similar studies using the bestselling Cr(III) nutritional supplement, chromium picolinate (CrPic). The mutagenicity of CrPic and Cr3 was tested in Escherichia coli FX-11 and Salmonella typhimurium (TA 98 and TA 100). Cytotoxicity was measured as a decrease in plating efficiency relative to controls after treatment with Cr3 and CrPic for 24 h in CHO K1 cells. Clastogenicity was measured by counting the number of metaphases damaged and of the total number chromosomal aberrations in CHO K1 cells. Mutagenesis assays in E. coli and S. typhimurium were negative. All treatments of Cr3 produced ≥ 84% plating efficiency except 80 μg/cm², which reduced the plating efficiency to 62%. Cr3 at any treatment level did not produce a significant increase in the number of cells with abnormal metaphases, while treatments using ≥ 40 μg/cm² of CrPic elevated the number significantly. These data suggest that Cr3 is significantly less mutagenic in bacteria cells and less clastogenic in CHO K1 cells, while CrPic is clastogenic in CHO K1 cells.

Invited review: Mineral absorption mechanisms, mineral interactions that affect acid-base and antioxidant status, and diet considerations to improve mineral status

Several minerals are required for life to exist. In animals, 7 elements (Ca, P, Mg, Na, K, Cl, and S) are required to be present in the diet in fairly large amounts (grams to tens of grams each day for the dairy cow) and are termed macrominerals. Several other elements are termed microminerals or trace minerals because they are required in much smaller amounts (milligrams to micrograms each day). In most cases the mineral in the diet must be absorbed across the gastrointestinal mucosa and enter the blood if it is to be of value to the animal. The bulk of this review discusses the paracellular and transcellular mechanisms used by the gastrointestinal tract to absorb each of the various minerals needed. Unfortunately, particularly in ruminants, interactions between minerals and other substances within the diet can occur within the digestive tract that impair mineral absorption. The attributes of organic or chelated minerals that might permit diet minerals to circumvent factors that inhibit absorption of more traditional inorganic forms of these minerals are discussed. Once absorbed, minerals are used in many ways. One focus of this review is the effect macrominerals have on the acid-base status of the animal. Manipulation of dietary cation and anion content is commonly used as a tool in the dry period and during lactation to improve performance. A section on how the strong ion theory can be used to understand these effects is included. Many microminerals play a role in the body as cofactors of enzymes involved in controlling free radicals within the body and are vital to antioxidant capabilities. Those same minerals, when consumed in excess, can become pro-oxidants in the body, generating destructive free radicals. Complex interactions between minerals can compromise the effectiveness of a diet in promoting health and productivity of the cow. The objective of this review is to provide insight into some of these mechanisms.

A case-control study of maternal exposure to chromium and infant low birth weight in China

Exposure to chromium is increasing due to environmental pollution from industrial processes. Several epidemiological studies have investigated chromium exposure and reproductive outcomes, but few studies have investigated the association of chromium exposure and low birth weight (LBW). This study was designed to investigate whether maternal exposure to chromium during pregnancy is associated with an increased risk of LBW. Chromium concentrations in maternal urine samples collected at delivery were measured in 204 LBW cases and 612 matched controls recruited between 2012 and 2014 in Hubei Province, China. Risk of LBW was associated with higher levels of chromium in maternal urine [adjusted odds ratio (OR) = 1.77 for the medium tertile, 95% confidence interval (CI): 0.95, 3.29; adjusted OR = 2.48 for the highest tertile, 95% CI: 1.33, 4.61; P trend = 0.01]. The association was more pronounced among female infants (adjusted OR = 3.67 for the highest tertile, 95% CI: 1.50, 8.97) than among male infants (adjusted OR = 1.22 for the highest tertile, 95% CI = 0.48, 3.11) (p heterogeneity = 0.06). Our findings suggest that maternal exposure to higher levels of chromium during pregnancy may potentially increase the risk of delivering LBW infants, particularly for female infants.

Evaluation of 90-day Repeated Dose Oral Toxicity, Glycometabolism, Learning and Memory Ability, and Related Enzyme of Chromium Malate Supplementation in Sprague-Dawley Rats

Our previous study showed that chromium malate improved the regulation of blood glucose in mice with alloxan-induced diabetes. The present study was designed to evaluate the 90-day oral toxicity of chromium malate in Sprague-Dawley rats. The present study inspected the effect of chromium malate on glycometabolism, glycometabolism-related enzymes, lipid metabolism, and learning and memory ability in metabolically healthy Sprague-Dawley rats. The results showed that all rats survived and pathological, toxic, feces, and urine changes were not observed. Chromium malate did not cause measurable damage on liver, brain, and kidney. The fasting blood glucose, serum insulin, insulin resistance index, C-peptide, hepatic glycogen, glucose-6-phosphate dehydrogenase, glucokinase, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride levels of normal rats in chromium malate groups had no significant change when compared with control group and chromium picolinate group under physiologically relevant conditions. The serum and organ content of Cr in chromium malate groups had no significant change compared with control group. No significant changes were found in morris water maze test and superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and true choline esterase (TChE) activity. The results indicated that supplementation with chromium malate did not cause measurable toxicity and has no obvious effect on glycometabolism and related enzymes, learning and memory ability, and related enzymes and lipid metabolism of female and male rats. The results of this study suggest that chromium malate is safe for human consumption.

Persistent hexavalent chromium exposure impaired the pubertal development and ovarian histoarchitecture in wistar rat offspring

Hexavalent chromium (CrVI) is a highly toxic metal and a major environmental pollutant. Several studies indicate that CrVI exposure adversely affects reproductive function. We reported that maternal Cr exposure resulted in Cr accumulation in the reproductive organs of female offsprings. CrVI can cross the placental barrier and also can be passed through breastfeeding. The present investigation aimed to determine the persistent (in utero through puberal period) CrVI exposure-induced toxic effects on the reproductive functions of mother and the offspring. Induction of oxidative stress is one of the plausible mechanisms behind Cr-induced cellular deteriorations. Mother rats exposed to CrVI showed reduced reproductive outcome, while the offsprings showed higher accumulation of Cr in ovary, altered steroid, and peptide hormones. Specific activities of antioxidant enzymes were decreased and associated with increased levels of H2 O2 , and lipid peroxidation. CrVI exposure also damaged the ovarian histoarchitecture in various age groups studied. CrVI exposure also delayed the sexual maturation. Results from the present investigation suggest that CrVI exposure from in utero through puberal period significantly damaged the pubertal development through altered antioxidants, anemia, and altered hormone levels. These changes were associated with damaged ovarian histoarchitecture and extended estrous cycle in developing Wistar rats.

Protective effect of curcumin against heavy metals-induced liver damage

Occupational or environmental exposures to heavy metals produce several adverse health effects. The common mechanism determining their toxicity and carcinogenicity is the generation of oxidative stress that leads to hepatic damage. In addition, oxidative stress induced by metal exposure leads to the activation of the nuclear factor (erythroid-derived 2)-like 2/Kelch-like ECH-associated protein 1/antioxidant response elements (Nrf2/Keap1/ARE) pathway. Since antioxidant and chelating agents are generally used for the treatment of heavy metals poisoning, this review is focused on the protective role of curcumin against liver injury induced by heavy metals. Curcumin has shown, in clinical and preclinical studies, numerous biological activities including therapeutic efficacy against various human diseases and anti-hepatotoxic effects against environmental or occupational toxins. Curcumin reduces the hepatotoxicity induced by arsenic, cadmium, chromium, copper, lead and mercury, prevents histological injury, lipid peroxidation and glutathione (GSH) depletion, maintains the liver antioxidant enzyme status and protects against mitochondrial dysfunction. The preventive effect of curcumin on the noxious effects induced by heavy metals has been attributed to its scavenging and chelating properties, and/or to the ability to induce the Nrf2/Keap1/ARE pathway. However, additional research is needed in order to propose curcumin as a potential protective agent against liver damage induced by heavy metals.

Chromium and diabetes

Chromium enhances glucose control and decreases insulin resistance in type 2 diabetes.

RCT evidence suggests that supplements are safe and will offer some benefit in glucose control for such patients. Further trials are needed to confirm this and to clarify in what dose and form chromium supplements are best given.

Opinion controversy to chromium picolinate therapy's safety and efficacy: ignoring 'anecdotes' of case reports or recognising individual risks and new guidelines urgency to introduce innovation by predictive diagnostics?

Due to the important physiologic function of trivalent chromium in glucose/insulin homeostasis, some commercial organisations promote Cr3+ supplements in maintaining proper carbohydrate and lipid metabolism; regulation of reducing carbohydrate carvings and appetite; prevention of insulin resistance and glucose intolerance; regulation of body composition, including reducing fat mass and increasing lean body mass; optimal body building for athletes; losing weight; treatment of atypical depression as an antidepressant; and prevention of obesity and type 2 diabetes mellitus. On one hand, case reports are commented as 'nonevidence-based anecdotes'. On the other hand, a number of independent studies warn against adverse health outcomes assigned to chromium picolinate (CrPic) dietary application. This review analyses opinion controversies, demonstrates highly individual reactions towards CrPic dietary supplements and highlights risks when the dietary supplements are used freely as therapeutic agents, without application of advanced diagnostic tools to predict individual outcomes.

Comparing anti-hyperglycemic activity and acute oral toxicity of three different trivalent chromium complexes in mice

Three different ligands (rutin, folate and stachyose) of chromium(III) complexes were compared to examine whether they have similar effect on anti-hyperglycemic activity as well as the acute toxicity status. Anti-hyperglycemic activities of chromium rutin complex (CrRC), chromium folate complex (CrFC) and chromium stachyose complex (CrSC) were examined in alloxan-induced diabetic mice with daily oral gavage for a period of 2 weeks at the dose of 0.5-3.0 mg Cr/kg. Acute toxicities of CrRC and CrFC were tested using ICR mice at the dose of 1.0-5.0 g/kg with a single oral gavage and observed for a period of 2 weeks. Biological activities results indicated that only CrRC and CrFC could decrease blood glucose level, reduce the activities of aspartate transaminase, alanine transaminase, alkaline phosphatase, and increase liver glycogen level. In acute toxicity study, LD(50) values for both CrRC and CrFC were above 5.0 g/kg. The minimum lethal dose for CrFC was above 5.0 g/kg, while that for CrRC was 1.0 g/kg. Anti-diabetic activity of those chromium complexes was not similar and their acute toxicities were also different. CrFC represent an optimal chromium supplement among those chromium complexes with potential therapeutic value to control blood glucose in diabetes and non-toxicity in acute toxicity.

Potential of chromium(III) picolinate for reproductive or developmental toxicity following exposure of male CD-1 mice prior to mating

Chromium(III) picolinate, [Cr(pic)(3)], is a commonly used nutritional supplement in humans, which has also been approved for use in animals. Health concerns have arisen over the use of [Cr(pic)(3)]. At high [Cr(pic)(3)] doses, developmental toxicity tests in female mice have shown a higher litter incidence of split cervical arch in exposed fetuses, but this was not consistently reproducible. In the current study, male CD-1 mice were used to further assess the potential for reproductive or developmental toxicity. Four weeks prior to mating, the males were fed a diet providing 200 mg/kg/day [Cr(pic)(3)] for comparison with untreated controls. Females were not treated. Each male was mated with two females, which were sacrificed on gestation day 17, and their litters were examined for adverse effects. Mating and fertility indices were not significantly altered by treatment. Male exposure to [Cr(pic)(3)] also had no effect on prenatal mortality, fetal weight, or gross or skeletal morphology. These results suggest that paternal dietary exposure to chromium(III) picolinate has little potential for adverse reproductive effects, even at exposure levels considerably higher than expected human exposures from nutritional supplements (1 mg of Cr per day or less).

Bioremoval of trivalent chromium using Bacillus biofilms through continuous flow reactor

Present study deals with the applicability of bacterial biofilms for the bioremoval of trivalent chromium from tannery effluents. A continuous flow reactor was designed for the development of biofilms on different substrates like glass beads, pebbles and coarse sand. The parameters for the continuous flow reactor were 20 ml/min flow rate at 30°C, pH4. Biofilm biomass on the substrates was in the following sequence: coarse sand>pebbles>glass beads (4.8 × 10(7), 4.5 × 10(7) and 3.5 × 10(5)CFU/cm(2)), which was confirmed by CLSM. Biofilms developed using consortium of Bacillus subtilis and Bacillus cereus on coarse sand had more surface area and was able to remove 98% of Cr(III), SEM-EDX proved 92.60% Cr(III) adsorption on biofilms supported by coarse sand. Utilization of Bacillus biofilms for effective bioremoval of Cr(III) from chrome tanning effluent could be a better option for tannery industry, especially during post chrome tanning operation.

Embryotoxicity and fetotoxicity following intraperitoneal administrations of hexavalent chromium to pregnant rats

Heavy metals are omnipresent in the environment, and industrial use has greatly increased their presence in soil, water and air. Their inevitable transfer to the human food chain remains an important environmental issue as many heavy metals cause a range of toxic effects, including developmental toxicity. Administration of chromium VI (1 and 2 mg/kg as potassium dichromate) through intraperitoneal (i.p.) injection during organogenesis (days 6 to 15 of gestation) in rats revealed embryo- and fetotoxic effects. Reduced fetal weight, retarded fetal development, number of fetuses per mother and high incidences of dead fetuses and resorptions in treated mothers were also observed. Gross morphological abnormalities, such as displayed form of edema, facial defect, lack of tail, hypotrophy, severs subdermal haemorrhage patches and hypotrophy of placenta were observed in fetuses after chromium VI-treated mothers. A skeletal development of fetuses presented an incomplete ossification in nasal, cranium, abdominal or caudal bones in rats treated with 1 mg/kg of chromium, whereas rats treated with 2 mg/kg showed ossification and absence of the sacral vertebrae compared with the control. At a higher dose of chromium, histological changes were found in fetuses with atrophy of theirs vital organs. Placental histological observations revealed a pronounced morphological alteration, with atrophy of decidual cells, a degenerated of chorionic villi and hypertrophy of blood lacuna. The present study suggests a risk to the developing embryo when the mother is exposed to a high concentration of chromium VI during organogenesis.

Preconceptional paternal exposure to depleted uranium: transmission of genetic damage to offspring

Depleted uranium (DU) is an alpha particle emitter and radioactive heavy metal used in military applications. Due to internalization of DU during military operations and the ensuing chronic internal exposure to DU, there are concerns regarding its potential health effects. Preconceptional paternal irradiation has been implicated as a causal factor in childhood cancer and it has been suggested that this paternal exposure to radiation may play a role in the occurrence of leukemia and other cancers to offspring. Similarly, in vivo heavy metal studies have demonstrated that carcinogenic effects can occur in unexposed offspring. Using a transgenic mouse system employing a lambda shuttle vector allowing mutations (in the lacI gene) to be analyzed in vitro, we have investigated the possibility that chronic preconceptional paternal DU exposure can lead to transgenerational transmission of genomic instability. The mutation frequencies in vector recovered from the bone marrow cells of the F1 offspring of male parents exposed to low, medium, and high doses of internalized DU for 7 mo were evaluated and compared to control, tantalum, nickel, and gamma radiation F1 samples. Results demonstrate that as paternal DU-dose increased there was a trend towards higher mutation frequency in vector recovered from the DNA obtained from bone marrow of F1 progeny; medium and high dose DU exposure to P1 fathers resulted in a significant increase in mutation frequency in F1 offspring (3.57 +or - 0.37 and 4.81 + or - 0.43 x 10; p < 0.001) in comparison to control (2.28 + or - 0.31 x 10). The mutation frequencies from F1 offspring of low dose DU, Ta- or Ni-implanted fathers (2. 71 + or - 0.35, 2.38 + or - 0.35, and 2.93 + or - 0.39 x 10, respectively) were not significantly different than control levels (2.28 + or - 0.31 x 10). Offspring from Co (4 Gy) irradiated fathers did demonstrate an increased lacI mutation frequency (4.69 + or - 0.48 x 10) as had been shown previously. To evaluate the role of radiation involved in the observed DU effects, males were exposed to equal concentrations (50 mg U L) of either enriched uranium or DU in their drinking water for 2 mo prior to breeding. A comparison of these offspring indicated that there was a specific-activity dependent increase in offspring bone marrow mutation frequency. Taken together these uranyl nitrate data support earlier results in other model systems showing that radiation can play a role in DU-induced biological effects in vitro. However, since the lacI mutation model measures point mutations and cannot measure large deletions that are characteristic of radiation damage, the role of DU chemical effects in the observed offspring mutation frequency increase may also be significant. Regardless of the question of DU-radiation vs. DU-chemical effects, the data indicate that there exists a route for transgenerational transmission of factor(s) leading to genomic instability in F1 progeny from DU-exposed fathers.

Chromium(III) propionate complex supplementation improves carbohydrate metabolism in insulin-resistance rat model

The purpose of this study was to evaluate the antidiabetic potential and safety of the chromium(III) propionate complex (CrProp) in insulin resistance induced by a high-fructose diet in rats. The experiment was carried out on 32 nine-week old male Wistar rats divided into 4 groups of 8 rats each. Animals were fed at libitum: the control diet (AIN-93M), and high-fructose diets (HF) containing various levels of Cr(III) given as CrProp (1 mg Cr kg(-1) diet (HF) and supplemented with 10 mg Cr kg(-1) diet (HFCr10), or 50 mg Cr kg(-1) diet (HFCr50), equal to approx. 0.1, 1 and 5 mg kg(-1) body mass per day) for 8 weeks. It was found that supplemental CrProp improved carbohydrate metabolism indices (decreasing serum insulin levels and insulin resistance indices HOMA-IR and HOMA-B, while increasing insulin sensitivity index QUICKI). Supplemental CrProp did not affect overall nutritional indices, blood morphology, most of the toxicity indices, blood glucose and lipids levels, while it increased kidney Cr level (HFCr50), normalized decreased liver Cu concentrations, and decreased kidney Fe and Cu levels (HFCr50). Supplemental CrProp administered at 10- and 50-fold doses of the basal dietary Cr level has a significant antidiabetic effect in insulin resistant rats. However, a prolonged treatment with this compound can affect Fe status.

Chromium ion release from stainless steel pediatric scoliosis instrumentation

STUDY DESIGN

Case-control study.

OBJECTIVE

To determine whether serum metal ion levels and erythrocyte chromium levels in adolescents with stainless steel spinal instrumentation are elevated when compared with 2 control groups.

SUMMARY OF BACKGROUND DATA

Instrumented spinal arthrodesis is a common procedure to correct scoliosis. The long-term consequences of retained implants are unclear. Possible toxic effects related to raised metal ion levels have been reported in the literature.

METHODS

Thirty patients who underwent posterior spinal arthrodesis with stainless steel instrumentation for scoliosis (group 1) were included. Minimum postoperative duration was 3 years. Serum chromium, molybdenum, iron, and ferritin levels were measured. Participants with elevated above normal serum chromium levels (n = 11) also underwent erythrocyte chromium analysis. Comparisons were made with 2 control groups; 10 individuals with scoliosis with no spinal surgery (group 2) and 10 volunteers without scoliosis (group 3). All control group participants underwent serum and erythrocyte analysis.

RESULTS

Elevated above normal serum chromium levels were demonstrated in 11 of 30 (37%) group 1 participants. Elevated serum chromium levels were demonstrated in 0 of 10 participants (0%) in group 2 and 1 of 10 (10%) in group 3. There was a statistically significant elevation in serum chromium levels between group 1 and group 2 participants (P = 0.001). There was no significant association between groups 1, 2, and 3 for serum molybdenum, iron, and ferritin levels. Erythrocyte chromium measurements were considered within the normal range for all participants tested (n = 31).

CONCLUSION

Raised serum chromium levels were detected in 37% of patients following instrumented spinal arthrodesis for correction of scoliosis. This new finding has relatively unknown health implications but potential mutagenic, teratogenic and carcinogenic sequelae. This is especially concerning with most scoliosis patients being adolescent females with their reproductive years ahead.

Predictors of serum chromium levels after stainless steel posterior spinal instrumentation for adolescent idiopathic scoliosis

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

To determine the predictors of serum chromium levels after stainless steel posterior spinal instrumentation for adolescent idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

Abnormally elevated serum chromium levels have been detected in patients with adolescent idiopathic scoliosis after stainless steel instrumentation. To date, the relationship among serum chromium levels, time of implantation, and implant characteristics (including surface area, rod length, numbers of hooks, screws, and cross connectors) has not been studied.

METHODS

Thirty patients with adolescent idiopathic scoliosis undergoing posterior instrumented spinal arthrodesis using stainless steel implants between 1998 and 2002 were prospectively studied. Serum chromium levels were measured between October 2006 and June 2007. Postoperative radiographs were used to measure rod lengths, number of hooks, screws, cross-connectors, and cables. The surface area of each component and the total surface area for each patient were calculated. Possible associations between serum chromium levels, time of implantation, and implant characteristics were investigated.

RESULTS

Implant exposure, whether expressed in the form of total metal implant surface area, rod length, or number of metal interfaces, was found to be positively associated with serum chromium levels. Specifically, chromium levels increased by a multiplicative factor of 1.0060 for every additional square centimeter of total metal implant surface area (P = 0.02). In addition, the chromium level was found to decrease by a multiplicative factor of 0.7766 for every additional year since surgery (P = 0.02).

CONCLUSION

After adjusting for the number of years since surgery, metal implant exposure is positively associated with elevated serum chromium levels in adolescent idiopathic scoliosis patients with stainless steel posterior spinal implants. This is the first study to identify statistically significant positive associations between specific spinal implant characteristics (other than corrosion identified by radiographs) and serum chromium levels.

Evaluation of the acute oral toxicity class of tricentric chromium(III) propionate complex in rat

Chromium(III) is an essential element for carbohydrate and lipid metabolism, and various chemical forms of this element are widely used in dietary supplements. Of particular interest is [Cr(3)O(O(2)CCH(2)CH(3))(6)(H(2)O)(3)](+) cation (CrProp), that has been proposed as an alternative source of Cr. However, its safety has not been studied completely. In this study, we evaluated the acute toxicity class of CrProp in Wistar rats applying the OECD 423 procedure. Male and female Wistar rats (n=12, 6 female symbol and 6 male symbol) were given by gavage either a single dose of CrProp 2000 mg kg(-1) body mass or equivalent volumes of distilled water, and fed Labofeed B diet, and observed carefully for 14 days, than sacrificed to collect samples for biochemical and histologic examination. No death cases were detected, no major abnormalities in animal behaviour, body mass gains, gross organ histology, and blood morphology, and biochemistry were observed, except some changes of liver mass and the activity of ALT in female rats. The results demonstrate that LD(50) of CrProp is greater than 2000 mg kg(-1) when administrated orally to rat, thus this compound appears to be belong the fifth category in the GHS system or the fourth class ("unclassified") in the EU classification system.

Chronic toxicity and carcinogenicity studies of chromium picolinate monohydrate administered in feed to F344/N rats and B6C3F1 mice for 2 years

Trivalent chromium (Cr(III)) has been proposed to be an essential element, which may increase sensitivity to insulin and thus participate in carbohydrate and lipid metabolism. Humans ingest Cr(III) both as a natural dietary constituent and in dietary supplements taken for weight loss and antidiabetic effects. Chromium picolinate (CP), a widely used supplement, contains Cr(III) chelated with three molecules of picolinic acid and was formulated in an attempt to improve the absorption of Cr(III). In order to examine the potential for CP to induce chronic toxicity and carcinogenicity, the NTP conducted studies of the monohydrate form (CPM) in groups of 50 male and female F344/N rats and B6C3F1 mice exposed in feed to concentrations of 0, 2000, 10,000 or 50,000 ppm for 2 years; exposure concentrations were selected following review of the data from NTP 3-month toxicity studies. Exposure to CPM did not induce biologically significant changes in survival, body weight, feed consumption, or non-neoplastic lesions in rats or mice. In male rats, a statistically significant increase in the incidence of preputial gland adenoma at 10,000 ppm was considered an equivocal finding. CPM was not carcinogenic to female rats or to male or female mice.

Effects of pre- and postnatal exposure to chromium picolinate or picolinic acid on neurological development in CD-1 mice

Chromium picolinate, Cr(pic)3, a popular dietary supplement marketed as an aid in fat loss and lean muscle gain, has also been suggested as a therapy for women with gestational diabetes. The current study investigated the effects of maternal exposure to Cr(pic)3 and picolinic acid during gestation and lactation on neurological development of the offspring. Mated female CD-1 mice were fed diets from implantation through weaning that were either untreated or that contained Cr(pic)3 (200 mg kg(-1) day(-1)) or picolinic acid (174 mg kg(-1) day(-1)). A comprehensive battery of postnatal tests was administered, including a modified Fox battery, straight-channel swim, open-field activity, and odor-discrimination tests. Pups exposed to picolinic acid tended to weigh less than either control or Cr(pic)3-exposed pups, although the differences were not significant. Offspring of picolinic acid-treated dams also appeared to display impaired learning ability, diminished olfactory orientation ability, and decreased forelimb grip strength, although the differences among the treatment groups were not significant. The results indicate that there were no significant effects on the offspring with regard to neurological development from supplementation of the dams with either Cr(pic)3 or picolinic acid.

Comparison of the potential for developmental toxicity of prenatal exposure to two dietary chromium supplements, chromium picolinate and [Cr3O(O2CCH2CH3)(6(H2O)3]+, in mice

BACKGROUND

Chromium(III) is generally thought to be an essential trace element that allows for proper glucose metabolism. However, chromium(III) picolinate, Cr(pic)3, a popular dietary supplement form of chromium, has been shown to be capable of generating hydroxyl radicals and oxidative DNA damage in rats. The cation [Cr3O(O2CCH2CH3)(6(H2O)3]+, Cr3, has been studied as an alternative supplemental source of chromium. It has been shown to increase insulin sensitivity and lower glycated hemoglobin levels in rats, making it attractive as a potential therapeutic treatment for gestational diabetes. To date, no studies have been published regarding the safety of Cr3 supplementation to a developing fetus.

METHODS

From gestation days (GD) 6-17, mated CD-1 female mice were fed diets delivering either 25 mg Cr/kg/day as Cr(pic)(3), 3.3 or 26 mg Cr/kg/day as Cr3, or the diet only to determine if Cr3 could cause developmental toxicity. Dams were sacrificed on GD 17, and their litters were examined for adverse effects.

RESULTS

No signs of maternal toxicity were observed. No decrease in fetal weight or significantly increased incidence of skeletal defects was observed in the Cr3 or Cr(pic)3 exposed fetuses compared to the controls.

CONCLUSION

Maternal exposure to either Cr(pic)3 or Cr3 at the dosages employed did not appear to cause deleterious effects to the developing offspring in mice.

Chemical properties and toxicity of chromium(III) nutritional supplements

The status of Cr(III) as an essential micronutrient for humans is currently under question. No functional Cr(III)-containing biomolecules have been definitively described as yet, and accumulated experience in the use of Cr(III) nutritional supplements (such as [Cr(pic) 3], where pic = 2-pyridinecarboxylato) has shown no measurable benefits for nondiabetic people. Although the use of large doses of Cr(III) supplements may lead to improvements in glucose metabolism for type 2 diabetics, there is a growing concern over the possible genotoxicity of these compounds, particularly of [Cr(pic) 3]. The current perspective discusses chemical transformations of Cr(III) nutritional supplements in biological media, with implications for both beneficial and toxic actions of Cr(III) complexes, which are likely to arise from the same biochemical mechanisms, dependent on concentrations of the reactive species. These species include: (i) partial hydrolysis products of Cr(III) nutritional supplements, which are capable of binding to biological macromolecules and altering their functions; and (ii) highly reactive Cr(VI/V/IV) species and organic radicals, formed in reactions of Cr(III) with biological oxidants. Low concentrations of these species are likely to cause alterations in cell signaling (including enhancement of insulin signaling) through interactions with the active centers of regulatory enzymes in the cell membrane or in the cytoplasm, while higher concentrations are likely to produce genotoxic DNA lesions in the cell nucleus. These data suggest that the potential for genotoxic side-effects of Cr(III) complexes may outweigh their possible benefits as insulin enhancers, and that recommendations for their use as either nutritional supplements or antidiabetic drugs need to be reconsidered in light of these recent findings.