Outline of occupational chromium poisoning in China

HK2 and LDHA upregulation mediate hexavalent chromium-induced carcinogenesis, cancer development and prognosis through miR-218 inhibition

Hexavalent chromium [Cr(VI)] is one of the most common environmental contaminants due to its tremendous industrial applications, but its effects and mechanism remain to be investigated. Our previous studies showed that Cr(VI) exposure caused malignant transformation and tumorigenesis. This study showed that glycolytic proteins HK2 and LDHA levels were statistically significant changed in blood samples of Cr(VI)-exposed workers and in Cr-T cells compared to the control subjects and parental cells. HK2 and LDHA knockdown inhibited cell proliferation and angiogenesis, and higher HK2 and LDHA expression levels are associated with advanced stages and poor prognosis of lung cancer. We found that miR-218 levels were significantly decreased and miR-218 directly targeted HK2 and LDHA for inhibiting their expression. Overexpression of miR-218 inhibited glucose consumption and lactate production in Cr-T cells. Further study found that miR-218 inhibited tumor growth and angiogenesis by decreasing HK2 and LDHA expression in vivo. MiR-218 levels were negatively correlated with HK2 and LDHA expression levels and cancer development in human lung and other cancers. These results demonstrated that miR-218/HK2/LDHA pathway is vital for regulating Cr(VI)-induced carcinogenesis and human cancer development.

Supplementation of Micro- and Macronutrients-A Role of Nutritional Status in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a condition in which the pathological cumulation of fat with coexisting inflammation and damage of hepatic cells leads to progressive dysfunctions of the liver. Except for the commonly well-known major causes of NAFLD such as obesity, dyslipidemia, insulin resistance, or diabetes, an unbalanced diet and imbalanced nutritional status should also be taken into consideration. In this narrative review, we summarized the current knowledge regarding the micro- and macronutrient status of patients suffering from NAFLD considering various diets and supplementation of chosen supplements. We aimed to summarize the knowledge indicating which nutritional impairments may be associated with the onset and progression of NAFLD at the same time evaluating the potential therapy targets that could facilitate the healing process. Except for the above-mentioned objectives, one of the most important aspects of this review was to highlight the possible strategies for taking care of NAFLD patients taking into account the challenges and opportunities associated with the micronutrient status of the patients. The current research indicates that a supplementation of chosen vitamins (e.g., vitamin A, B complex, C, or D) as well as chosen elements such as zinc may alleviate the symptoms of NAFLD. However, there is still a lack of sufficient data regarding healthy ranges of dosages; thus, further research is of high importance in this matter.

Associations between multiple metal exposure and fertility in women: A nested case-control study

Metal pollution can cause a decline in female fertility, however, previous studies have focused more on the effect of a single metal on fertility. In this study, we evaluated the effect of metal mixtures on female fertility based on nested case-control samples. The plasma levels of 22 metal elements from 180 women were determined by an inductively coupled plasma mass spectrometer (ICP-MS). Minimum absolute contraction and selection operator (LASSO) penalty regression selected metals with the greatest influence on clinical outcome. Logistic regression was used to analyze the correlation between single metals and fertility while a Bayesian kernel function regression (BKMR) model was used to analyze the effect of mixed metals. Eight metals (Calcium (Ca), Chromium (Cr), Cobalt (Co), Copper (Cu), Zinc (Zn), Rubidium (Rb), Strontium (Sr) and Zirconium (Zr)) were selected by LASSO regression for subsequent analysis. After adjusting for covariates, the logistic model showed that Cu (Odds Ratio(OR):0.33, 95% CI: 0.13 - 0.84) and Co (OR:0.38, 95% CI: 0.15 -0.94) caused a significant reduction in fertility, and identified the protective effect of Zn (OR: 2.96, 95% CI:1.21 -7.50) on fertility. Trend tests showed that increased Cr, Cu, and Rb levels were associated with reduced fertility. The BKMR model showed that Cr, Co, Cu, and Rb had a nonlinear relationship with fertility decline when controlling for the concentrations of other metals and suggested that Cu and Cr might exert an influence on fertility. Analysis showed a negative correlation between Cu, Cr, Co, Rb, and fertility, and a positive correlation between Zn and fertility. Furthermore, we found evidence for the interaction between Cu and Cr. Our findings require further validation and may identify new mechanisms in the future.

Acute Oral Chromium Exposure Resulting in Ulcerative Gastritis and Perforated Ulcers in Swine

Heavy metal poisoning poses a challenge in diagnostic practices and environmental safety. This study describes the epidemiological, clinical, and pathological aspects of a chromium (Cr) poisoning outbreak in growing/finishing pigs housed in pens with bedding of pine wood shavings containing Cr. A visit to the affected farm was conducted. Epidemiological data were collected, and necropsy and histopathological examinations and heavy metal quantifications were performed. Up to 30% of the animals from the affected pens displayed clinical signs 48 h after housing, characterized by apathy, rigid gait, distended abdomen, pain to abdominal palpation, fever, vomiting, and skin cyanosis. The lethality rate reached 76.6%. Main postmortem findings consisted of ulcerative gastritis with perforation of the glandular stomach in all necropsied swine. Heavy metal analysis revealed a higher concentration of Cr in the bedding of the affected pens, along with elevated levels of Cr in the livers of the affected swine. Given that Cr is a known cause of poisoning in humans (with acute oral exposure resulting in corrosive lesions in the gastrointestinal tract), this study marks the first diagnosis of acute oral natural Cr poisoning in animals. This diagnosis was established through the association of epidemiological, pathological, and heavy metal quantification data.

Prediction of Food Safety Risk Level of Wheat in China Based on Pyraformer Neural Network Model for Heavy Metal Contamination

Heavy metal contamination in wheat not only endangers human health, but also causes crop quality degradation, leads to economic losses and affects social stability. Therefore, this paper proposes a Pyraformer-based model to predict the safety risk level of Chinese wheat contaminated with heavy metals. First, based on the heavy metal sampling data of wheat and the dietary consumption data of residents, a wheat risk level dataset was constructed using the risk evaluation method; a data-driven approach was used to classify the dataset into risk levels using the K-Means++ clustering algorithm; and, finally, on the constructed dataset, Pyraformer was used to predict the risk assessment indicator and, thus, the risk level. In this paper, the proposed model was compared to the constructed dataset, and for the dataset with the lowest risk level, the precision and recall of this model still reached more than 90%, which was 25.38-4.15% and 18.42-5.26% higher, respectively. The model proposed in this paper provides a technical means for hierarchical management and early warning of heavy metal contamination of wheat in China, and also provides a scientific basis for dynamic monitoring and integrated prevention of heavy metal contamination of wheat in farmland.

Two-week repair alleviates hexavalent chromium-induced hepatotoxicity, hepatic metabolic and gut microbial changes: A dynamic inhalation exposure model in male mice

Hexavalent chromium [Cr(VI)] has been identified as a "Group I human carcinogen" with multisystem and multiorgan toxicity. A dynamic inhalation exposure model in male mice, coupled with the hepatic metabolome and gut microbiome, was used to explore hepatotoxicity, and hepatic metabolic and gut microbial changes under the exposure scenarios in the workspace and general environment. The present study set up an exposure group (EXP) that inhaled 150 μg Cr/m³ for 13 weeks, a control group (CONT) that inhaled purified air, as well as a two-week repair group (REXP) after 13 weeks of exposure and the corresponding control group (RCONT). Cr(VI) induced elevation of hepatic Cr accumulation, the ratio of ALT and AST, and folate in serum. Inflammatory infiltration in the liver and abnormal mitochondria in hepatocytes were also induced by Cr(VI). Glutathione, ascorbate, folic acid, pantetheine, 3'-dephospho-CoA and citraconic acid were the key metabolites affected by Cr(VI) that were associated with significant pathways such as pantothenate and CoA biosynthesis, hypoxia-inducible factor-1 signaling pathway, antifolate resistance, alpha-linolenic acid metabolism and one carbon pool by folate. g_Allobaculum was identified as a sensitive biomarker of Cr(VI) exposure because g_Allobaculum decreased under Cr(VI) exposure but increased after repair. The gut microbiota might be involved in the compensation of hepatotoxicity by increasing short-chain fatty acid-producing bacteria, including g_Lachnospiraceae_NK4A136_group, g_Blautia, and f_Muribaculaceae. After the two-week repair, the differential metabolites between the exposed and control groups were reduced from 73 to 29, and the KEGG enrichment pathways and differential microbiota also decreased. The mechanism for repair was associated with reversion of lipid peroxidation and energy metabolism, as well as activation of protective metabolic pathways, such as the AMPK signaling pathway, longevity regulating pathway, and oxidative phosphorylation. These findings might have theoretical and practical implications for better health risk assessment and management.

The Impact of Oxidative Stress of Environmental Origin on the Onset of Placental Diseases

Oxidative stress (OS) plays a pivotal role in placental development; however, abnormal loads in oxidative stress molecules may overwhelm the placental defense mechanisms and cause pathological situations. The environment in which the mother evolves triggers an exposure of the placental tissue to chemical, physical, and biological agents of OS, with potential pathological consequences. Here we shortly review the physiological and developmental functions of OS in the placenta, and present a series of environmental pollutants inducing placental oxidative stress, for which some insights regarding the underlying mechanisms have been proposed, leading to a recapitulation of the noxious effects of OS of environmental origin upon the human placenta.

Monitoring of urinary arsenic (As) and lead (Pb) among a sample of pregnant Iranian women

PURPOSE

Heavy metals, as significant toxic environmental contaminants, can cause serious adverse health outcomes on the human body even in trace concentrations. There is limited evidence on heavy metal concentrations existing in the body fluids of pregnant women. This study aims to evaluate the urinary levels of arsenic (As) and lead (Pb), as two main toxic heavy metals, among pregnant women and their lifestyle determinants.

METHODS

The study was performed in 2019-2020 in Isfahan, Iran. A number of 140 urine samples of pregnant women who were in their first pregnancy trimester were examined. Inductively coupled plasma optical emission spectrometry (ICP-OES) was applied to analyze the urinary concentrations of As and Pb. Socio-demographic data including age, pre-pregnancy body mass index (BMI), education status, and family income, as well as the use of cleaning products (cosmetic and household cleaning products), and lifestyle habits (food intake, smoking, and physical activity) were collected using a validated questionnaire.

RESULTS

The mean concentration of As and Pb were 8.14 ± 10.8 and 9.6 ± 7.1 μg/g creatinine, respectively. The mean urinary concentration of Pb indicated significant differences in the levels of cosmetic usage, second-hand smoking exposure, and the use of Copper, Aluminum, Teflon, Steel, and Enameled utensils for cooking (p-value < 0.05). Furthermore, the mean of urinary Pb concentrations at high levels of physical activity and scratched utensils using was significantly different from the other categories (p-value = 0.02). No significant differences were found between As and Pb concentration with other socio-demographic factors.

CONCLUSION

The lifestyle determinants and cosmetic products use are important predictors of urinary heavy metals in pregnant women, rather than sociodemographic characteristics. Additional research is necessary to determine long-term adverse birth outcomes of exposure to these heavy metals.

Prenatal exposure to chromium (Cr) and nickel (Ni) in a sample of Iranian pregnant women: urinary levels and associated socio-demographic and lifestyle factors

Heavy metals have been well documented to pose detrimental health effects. The current study aimed to measure the concentration of chromium (Cr) and nickel (Ni) in urinary samples of Iranian pregnant females and determine their potential correlations with different lifestyle variables. The study was conducted in 2019-2020 in Isfahan, Iran, and the urine samples were collected from 140 pregnant women. The concentrations of Cr and Ni in the urinary samples were measured by inductively coupled plasma optical emission spectrometry (ICP-OES). Data on socio-demographic characteristics, use of cleaning products, and lifestyle profiles was collected by validated questionnaires. Cr and Ni were detected in 100% of urinary samples with the mean concentration of 4.1±3.4 and 7.5±4.8 μg/g creatinine, respectively. Significant associations were found between the mean concentration of Cr and Ni with using cooking utensils made of copper, aluminum, Teflon, steel, and enameled, as well as with cosmetic use, and second-hand smoking exposure during pregnancy. The results also showed that the mean urinary Ni and Cr concentrations were significantly different among individuals who consumed seafood and canned food (p-value <0.05). Furthermore, the mean of urinary Cr and Ni concentrations at high levels of physical activity and scratched utensils used was significantly different from the other categories (p-value <0.05). According to our findings, the lifestyle determinants and cosmetic products had superiority to socio-demographic characteristics in predicting urinary heavy metals in Iranian pregnant women.

Impact of Environmental and Lifestyle Use of Chromium on Male Fertility: Focus on Antioxidant Activity and Oxidative Stress

Male reproductive tissues are strongly susceptible to several environmental and lifestyle stressors. In general, male reproductive health is highly sensitive to oxidative stress, which results in reversible and/or irreversible changes in testosterone-producing cells, spermatogenesis, and sperm quality. Chromium compounds are widely used in the +3 and +6 valence states, as food supplements, and in the industrial field, respectively. Chromium (III) compounds, i.e., Cr(III)-tris-picolinate, [Cr(pic)₃], known as chromium picolinate, are used as nutritional supplements for the control of diabetes, body weight, and muscular growth. However, previous studies showed that animal models exposed to chromium picolinate experienced degenerative changes in spermatogenesis. Contradictory results are documented in the literature and deserve discussion. Furthermore, the long-term effects of chromium picolinate on the antioxidant system of treated subjects have not been properly studied. Comprehensive studies on the role of this compound will help to establish the safe and useful use of chromium supplementation. On the other hand, chromium (VI) compounds are widely used in several industries, despite being well-known environmental pollutants (i.e., welding fumes). Chromium (VI) is known for its deleterious effects on male reproductive health as toxic, carcinogenic, and mutagenic. Previous studies have demonstrated severe lesions to mouse spermatogenesis after exposure to chromium (VI). However, workers worldwide are still exposed to hexavalent chromium, particularly in electronics and military industries. Data from the literature pinpoints mechanisms of oxidative stress induced by chromium compounds in somatic and germ cells that lead to apoptosis, thus underlining the impairment of fertility potential. In this review, we analyze the benefits and risks of chromium compounds on male fertility, as well as the mechanisms underlying (in)fertility outcomes. Although supplements with antioxidant properties may maximize male fertility, adverse effects need to be investigated and discussed.

Hexavalent chromium induces mitochondrial dynamics disorder in rat liver by inhibiting AMPK/PGC-1α signaling pathway

Occupational exposure to hexavalent chromium (Cr(VI)) can cause cytotoxicity and carcinogenicity. In this study, we established a liver injury model in rats via intraperitoneal injection of potassium dichromate (0, 2, 4, and 6 mg/kg body weight) for 35 d to investigate the mechanism of Cr(VI)-induced liver injury. We found that Cr(VI) induced hepatic histopathological lesions, oxidative stress, and apoptosis and reduced the expression of mitochondrial-related regulatory factors such as adenosine 5'-monophosphate-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) in a dose-dependent manner. Furthermore, Cr(VI) promoted mitochondrial division and inhibited fusion, leading to increased expression of caspase-3 and production of mitochondrial reactive oxygen species. Our study demonstrates that long-term exposure to Cr(VI) induces mitochondrial dynamics disorder by inhibiting AMPK/PGC-1α signaling pathway in rat liver.

Effect of industrial wastewater on wheat germination, growth, yield, nutrients and bioaccumulation of lead

Due to fresh water scarcity, farmers are using polluted water for irrigation. This research was conducted to study the bioaccumulation of Pb in wheat (Cv. Shafaq-2006). The experiment was comprised of seven treatments of lead i.e. 0–1,000 mg Pb/kg. The results revealed that lead severely reduces germination (− 30%), seedling fresh weight (− 74%), seedling dry weight (− 77%), vigor index (− 89%), tolerance index (− 84%), plant height (− 33%), number of leaves (− 41%), root fresh weight (− 50%), shoot fresh weight (− 62%), root dry weight (− 63%), shoot dry weight (− 71%), and root length (− 45%). The physiological parameters also respond negatively like stomatal conductance (− 82%), transpiration rate (− 72%) and photosynthetic rate (− 74%). Similarly, biochemical parameters also showed negative impacts, like carotenoids (− 41), total chlorophyll (− 43), chlorophyll a (− 42) and chlorophyll b (− 53). Yield parameters like the number of seed/plant, seed weight/plant, 1,000 seed weight and harvest index were reduced by 90%, 88%, 44% and 61%, respectively in T₆. In addition, protein contents (− 81%), phosphorous (− 60%) and potassium (− 55%) were highly effected in the highest lead concentration (T₆). Lead accumulation was extremely higher in seeds (119%) as compared to control plants. Lead bio-accumulation above threshold concentrations in crop parts is a serious human health concern.

Suburban areas in flames: Dispersion of potentially toxic elements from burned vegetation and buildings. Estimation of the associated ecological and human health risk

The results of the assessment of burned residential and wildland areas associated with the July 2018 western Attica wildfire are summarised. The dispersion of major and trace elements in a fire impacted suburban landscape which is adjacent in the north with a Natura 2000 area is evaluated. The dataset includes 35 elements and 27 sampling sites spatially distributed in wildland and residential areas. Field observations and a macroscopic method were applied for investigating the wildfire severity. Statistical and spatial analysis tools were used for data treatment. Major and trace element contents were compared to levels and criteria provided by the United States Environmental Protection Agency, Canadian Council of Ministers of the Environment and Australian Department of Environment and Conservation. Aluminum, As, Co, Fe, Mn, Ni, Sb and Zn concentrations observed in wildfire ash pose potential risk to human health. Median ash concentrations for Al, As, B, Ba, Cd, Cu, Fe, Mn, Ni, Pb, S, Sb, and Zn exceeds the plant-avian-mammalian screening levels in wildland and residential areas. Geogenic or anthropogenic origin of the elements is discussed. The associated health risk on human health and terrestrial ecological receptors (plant, avian, mammalian) is assessed.

Mild steel and stainless steel welding fumes elicit pro-inflammatory and pro-oxidant effects in first trimester trophoblast cells

Problem

As more women join the skilled‐trade workforce, the effects of workplace exposures on pregnancy need to be explored. This study aims to identify the effects of mild steel and stainless steel welding fume exposures on cultured placental trophoblast cells.

Method of study

Welding fumes (mild steel and stainless steel) were generously donated by Lincoln Electric. Electron microscopy was used to characterize welding fume particle size and the ability of particles to enter extravillous trophoblast cells (HTR‐8/SVneo). Cellular viability, free radical production, cytokine production, and ability of cells to maintain invasive properties were analyzed, respectively, by WST‐1, electron paramagnetic resonance, DCFH‐DA, V‐plex MULTI‐SPOT assay system, and a matrix gel invasion assay.

Results

For all three welding fume types, average particle size was <210 nm. HTR‐8/SVneo cells internalized welding particles, and nuclear condensation was observed. Cellular viability was significantly decreased at the high dose of 100 µg/mL for all three welding fumes, and stainless steel generated the greatest production of the hydroxyl radical, and intracellular reactive oxygen species. Production of the cytokines IL‐1β and TNFα were not observed in response to welding fume exposure, but IL‐6 and IL‐8 were. Finally, the invasive capability of cells was decreased upon exposure to both mild steel and stainless steel welding fumes.

Conclusion

Welding fumes are cytotoxic to extravillous trophoblasts, as is evident by the production of free radicals, pro‐inflammatory cytokines, and the observed decrease in invasive capabilities.

Environmental & occupational exposure & female reproductive dysfunction

All individuals are exposed to certain chemical, physical, biological, environmental as well as occupational factors. The data pertaining to role of these factors on female reproduction are scanty as compared to male. The available data suggest the adverse effects of certain toxicants, viz., metals such as lead, cadmium and mercury, pesticides such as bis(4-chlorophenyl)-1,1,1-trichloroethane and organic solvent such as benzene, toluene and ionizing radiation on the female reproductive system affecting directly the organ system or impacting in directly through hormonal impairments, molecular alterations, oxidative stress and DNA methylation impairing fertility as well as pregnancy and its outcomes. Thus, there is a need for awareness and prevention programme about the adverse effects of these factors and deterioration of female reproductive health, pregnancy outcome and offspring development as some of these chemicals might affect the developing foetus at very low doses by endocrine disruptive mechanism.

Biomarkers of metal toxicity in embryos in the general population

Background

With the development of industrialization, public exposure to toxic metals could occur everywhere, eventually affecting individuals’ reproductive systems and even embryos and leading to early pregnancy loss. The aim of the study was to determine the profile of toxic metal levels in pregnant women in the general population and to identify biomarkers for metal toxicity in embryos.

Methods

A case‐control study with pregnant women was conducted at Peking Union Medical College Hospital in 2016‐2018. Women who experienced spontaneous abortion within 12 weeks of gestation comprised the case group, and women with pregnancies showing fetal cardiac activity who requested an induced abortion almost simultaneously were included in the control group. Blood and urine specimen were tested for concentrations of cadmium, chromium, selenium, arsenic, and mercury.

Results

A total of 195 patients were enrolled, with 95 in the case group and 100 in the control group. Significant differences in gravidity, parity, history of miscarriage, mean blood cadmium levels, and mean urine chromium levels were present between the two groups (P1 = 0.013, P2 = 0.000, P3 = 0.000, P4 = 0.002, P5 = 0.046); the odds ratios in the spontaneous abortion with blood cadmium >0.4 µg/L, urine chromium >2 µg/L, gravity <3, parity <2, and history of miscarriage >1 compared with the induced abortion group were 1.26 (1.09, 1.85), 1.56 (1.23, 2.53), 1.39 (1.17, 1.98), 1.72 (1.21, 4.62), and 1.18 (1.06, 1.65), with P‐values of 0.003, 0.031, 0.003, 0.247, and 0.001, respectively.

Conclusion

Blood cadmium and urine chromium levels are two possible biomarkers of toxic metal embryotoxicity in the general population, which means that in the general population, blood cadmium >0.4 µg/L or urine chromium >2 µg/L might indicate an increased risk of spontaneous abortion.

Trace elements in soil-vegetables interface: Translocation, bioaccumulation, toxicity and amelioration - A review

The contamination of soil and vegetables with trace elements is one of the most severe ecological problems in developing industrialized countries. Trace elements are released into the environment from natural and anthropogenic activities and accumulated in soil and vegetables through various pathways which ultimately affects the human health. The present review aimed at 1) discussing the anthropogenic sources in detail, 2) describing the bioaccumulation, absorption, and transportation of trace elements, 3) exploring the options to reduce the health risk due to consumption of contaminated vegetables, 4) identifying the research and policy gaps related to soil and vegetables contamination with trace elements. Besides these objectives, the present review also detailed the several factors which affect the rate of accumulation, toxicity mechanism, and effects of trace elements on vegetables and humans. Various toxicity indices for health risk assessment have also been described. It is suggested to evaluate the trace metals concentration in irrigation water and soil prior to plant the vegetable to minimize the possible contamination.

Relationship between cadmium content in semen and male infertility: a meta-analysis

Meta-analysis with high-quality studies can provide superior evidence. In this paper, we use meta-analysis to analyze the relationship between cadmium (Cd) content in semen and male infertility, and then objectively evaluate the effect of Cd on sperm quality. The objectives of this study were to update our understanding of infertility and to provide evidence to treat and prevent the infertility. We searched potentially relevant studies that were published from establishing database data to April 2018. Articles came from the databases of CNKI, Wanfang, VIP, PubMed, CMCI, and EMBASE. A total of 11 articles were included. We gathered the mean and variance of the infertility group and the control group to compare the Cd content in two groups. In total, the 11 studies include 1707 subjects, 1093 of which were in the infertility group and 614 of which were in the control group. We can get some information from this meta-analysis: SMD = 0.50 (95% Cl 0.39-0.61), Z = 8.92, P < 0.05; the funnel plot of the meta-analysis shows incomplete symmetry, which may have the publication bias. Therefore, the high content of Cd in semen is a causative factor of infertility. The Cd content in semen can be used as an indicator of sperm quality.

Chromium(VI) promotes cell migration through targeting epithelial-mesenchymal transition in prostate cancer

Chromium (Cr) is widely used in industry, making its toxicity a matter of concern. Although hexavalent Cr [Cr(VI)] can promote cancer cell proliferation in several cancers, there is little evidence implicating Cr(VI) in cancer cell migration, especially in prostate cancer. We show that the Cr concentration is higher in the serum of prostate cancer patients, and is closely associated with unfavorable outcomes for the patients. Additionally, low dose trivalent Cr [Cr(III)] exposure has no obvious carcinogenic effects in prostate cancer. However, Cr(VI) can promote proliferation and invasion of prostate cancer cell line PC3 cells in vitro and in vivo. In seeking the molecular mechanism of Cr(VI) exposure on cancer progression, we found that Cr(VI) could down-regulate the epithelial protein marker, E-cadherin, and up-regulate mesenchymal protein markers, such as N-cadherin and Snail. Together, these data indicate that Cr(VI) is a newly verified carcinogen in prostate cancer, and can promote cell migration by affecting the Epithelial-Mesenchymal Transition (EMT) pathway. Thus, inhibition of Cr(VI)-EMT signaling is a prospective approach toward limiting prostate tumor progression.

Toxicity of formulants and heavy metals in glyphosate-based herbicides and other pesticides

The major pesticides of the world are glyphosate-based herbicides (GBH), and their toxicity is highly debated. To understand their mode of action, the comparative herbicidal and toxicological effects of glyphosate (G) alone and 14 of its formulations were studied in this work, as a model for pesticides. GBH are mixtures of water, with commonly 36-48% G claimed as the active principle. As with other pesticides, 10-20% of GBH consist of chemical formulants. We previously identified these by mass spectrometry and found them to be mainly families of petroleum-based oxidized molecules, such as POEA, and other contaminants. We exposed plants and human cells to the components of formulations, both mixed and separately, and measured toxicity and human cellular endocrine disruption below the direct toxicity experimentally measured threshold. G was only slightly toxic on plants at the recommended dilutions in agriculture, in contrast with the general belief. In the short term, the strong herbicidal and toxic properties of its formulations were exerted by the POEA formulant family alone. The toxic effects and endocrine disrupting properties of the formulations were mostly due to the formulants and not to G. In this work, we also identified by mass spectrometry the heavy metals arsenic, chromium, cobalt, lead and nickel, which are known to be toxic and endocrine disruptors, as contaminants in 22 pesticides, including 11 G-based ones. This could also explain some of the adverse effects of the pesticides. In in vivo chronic regulatory experiments that are used to establish the acceptable daily intakes of pesticides, G or other declared active ingredients in pesticides are assessed alone, without the formulants. Considering these new data, this assessment method appears insufficient to ensure safety. These results, taken together, shed a new light on the toxicity of these major herbicides and of pesticides in general.

CoQ10 Deficiency May Indicate Mitochondrial Dysfunction in Cr(VI) Toxicity

To investigate the toxic mechanism of hexavalent chromium Cr(VI) and search for an antidote for Cr(VI)-induced cytotoxicity, a study of mitochondrial dysfunction induced by Cr(VI) and cell survival by recovering mitochondrial function was performed. In the present study, we found that the gene expression of electron transfer flavoprotein dehydrogenase (ETFDH) was strongly downregulated by Cr(VI) exposure. The levels of coenzyme 10 (CoQ10) and mitochondrial biogenesis presented by mitochondrial mass and mitochondrial DNA copy number were also significantly reduced after Cr(VI) exposure. The subsequent, Cr(VI)-induced mitochondrial damage and apoptosis were characterized by reactive oxygen species (ROS) accumulation, caspase-3 and caspase-9 activation, decreased superoxide dismutase (SOD) and ATP production, increased methane dicarboxylic aldehyde (MDA) content, mitochondrial membrane depolarization and mitochondrial permeability transition pore (MPTP) opening, increased Ca²⁺ levels, Cyt c release, decreased Bcl-2 expression, and significantly elevated Bax expression. The Cr(VI)-induced deleterious changes were attenuated by pretreatment with CoQ10 in L-02 hepatocytes. These data suggest that Cr(VI) induces CoQ10 deficiency in L-02 hepatocytes, indicating that this deficiency may be a biomarker of mitochondrial dysfunction in Cr(VI) poisoning and that exogenous administration of CoQ10 may restore mitochondrial function and protect the liver from Cr(VI) exposure.

Reproductive outcomes after non-occupational exposure to hexavalent chromium, Willits California, 1983-2014

BACKGROUND

From 1963-1995, a factory in Willits, Mendocino County, CA used toxic hexavalent chromium (Cr(VI)) without adequate measures to protect the population. We use longitudinal hospital data to compare reproductive outcomes for two generations in Willits and two generations in the Rest of County (ROC). This is the first study to quantify the reproductive impact of Cr(VI) in a non-occupational population.

METHODS

We searched California hospital discharge data (1983-2014) to find Mendocino County residents born 1950 or later. ZIP-code 95490 identifies Willits residents, with all others living in ROC. We used the Multi-Level Clinical Classification Software (CCS) to classify health outcomes. First, we calculated the crude birth rate using an external census denominator. The next two models used self-contained denominators to assess health of infants and two generations of pregnant women. Finally, we focused on non-pregnant females and, for comparison, males. Here we added admissions for people who moved, linked and summarized admissions to the person level, and calculated rates per census population.

RESULTS

We found 29311 newborn records in ROC and 5036 from Willits. At start of period, Willits birth rate was low and did not recover until 12 years after Plant closure. While the Plant was open, respiratory conditions, perinatal jaundice, and birth defect rates were higher for Willits infants compared to ROC, but improved post-closure. Risk for abnormal birthweight and term was high and remained high over the study period. During the period under study, we identified 31444 admissions of pregnant ROC women and 5558 from Willits. Willits women had significantly higher risk of pregnancy loss compared to ROC, whether stratified by generation, age group, or pre- and post-closure. Regardless of when exposed, Willits women continued to have significantly higher rates of in-hospital terminations, as animal studies of Cr(VI) exposure predict. In life course models, non-pregnant Willits women have significantly higher risk of reproductive organ conditions and neoplasms compared to ROC.

CONCLUSIONS

Adverse reproductive outcomes are elevated and consistent with animal studies. General health outcomes reflect the same broad effect reported for occupationally exposed workers. For the first time, the detrimental reproductive effects of non-occupational Cr(VI) exposure in human females and their infants is reported.

Editor's Highlight: Exposure to CrVI during Early Pregnancy Increases Oxidative Stress and Disrupts the Expression of Antioxidant Proteins in Placental Compartments

Epidemiologic studies document relationships between chromium VI (CrVI) exposure and increased risk of spontaneous abortion, stillbirth, preterm birth, and neonatal death in pregnant women. Environmental contamination with CrVI is a growing problem both in the United States and developing countries. CrVI is widely used in numerous industries. This study was designed to understand the mechanism of CrVI toxicity on placental oxidative stress and antioxidant (AOX) machinery. Pregnant mother rats were treated with or without CrVI (50 ppm K2Cr2O7) through drinking water from gestational day (GD) 9.5-14.5, and placentas were analyzed on GD 18.5. Results indicated that CrVI reduced the trophoblast cell population. CrVI increased reactive oxygen species (ROS) and decreased the expression of AOX proteins. CrVI disrupts the trophoblast proliferation of the placenta. This study provides insight into the critical role of AOXs in placental function.

Trace metal imaging in diagnostic of hepatic metal disease

The liver is the most central organ and the largest gland of the body that influences and controls a variety of metabolic and catabolic processes. It produces inconceivable many essential proteins, is responsible for the recovery of various food components, degrades toxins, mediates the bile production, and is involved in the excretion of unwanted metabolites. Several of these anabolic or catabolic functions of the liver depend on trace elements. These are either integral part of enzymes, cofactors, or act as chemical catalysts. Therefore, a lack of trace elements can lead to organ failure or systemic illness. Conversely, excessive hepatic trace element deposition resulting from genetic disorders, intoxication, extensive dietary supply, or long-term parenteral nutrition may cause hepatic inflammation, fibrosis, cirrhosis, and even hepatocellular carcinoma. Although specific serum parameters currently allow rough assessment of metal deficit and excess, the precise quantification of hepatic metal content in liver is presently only possible by different titration or staining techniques of biopsy specimens. Recently, novel innovative metal imaging techniques were developed that are on the way to replace these traditional methods. In the present review, we summarize the function of different trace elements in liver health and disease and discuss the present knowledge on how quantitative biometal imaging techniques such as synchrotron X-ray fluorescence microscopy, secondary ion mass spectrometry, and laser ablation inductively coupled plasma mass spectrometry enrich diagnostics in the detection and quantification of hepatic metal disorders. We will further discuss sample preparation, sensitivity, spatial resolution, specificity, quantification strategies, and potential future applications of metal bioimaging in experimental research and clinical daily routine. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 35:666-686, 2016.

Chromium VI - Induced developmental toxicity of placenta is mediated through spatiotemporal dysregulation of cell survival and apoptotic proteins

Environmental contamination with hexavalent chromium (CrVI) is a growing problem both in the U.S and developing countries. CrVI is a heavy-metal endocrine disruptor; women working in Cr industries exhibit an increased incidence of premature abortion and infertility. The current study was designed to understand the mechanism of CrVI toxicity on placental cell survival/death pathways. Pregnant mothers were treated with or without CrVI (50ppmK₂Cr₂O₇) through drinking water from gestational day (GD) 9.5-14.5, and placentas were analyzed on GD 18.5. Results indicated that CrVI increased apoptosis of trophoblasts, vascular endothelium of the metrial glands and yolk sac epithelium through caspase-3 and p53-dependent pathways. CrVI increased apoptosis in labyrinth and basal zones in a caspase-3-independent manner via AIF, and through an ATM-p53-NOXA-PUMA-p27 network. CrVI downregulated cell survival proteins Bcl-2, Bcl-XL and XIAP in the placenta. CrVI disrupts placental histoarchitecture and increases cell death by spatiotemporal modulation of apoptotic signaling.

A fetal whole ovarian culture model for the evaluation of CrVI-induced developmental toxicity during germ cell nest breakdown

Prenatal exposure to endocrine disrupting chemicals (EDCs), including bisphenol A, dioxin, pesticides, and cigarette smoke, has been linked to several ovarian diseases such as premature ovarian failure (POF) and early menopause in women. Hexavalent chromium (CrVI), one of the more toxic heavy metals, is widely used in more than 50 industries. As one of the world's leading producers of Cr compounds, the U.S. is facing growing challenges in protecting human health against adverse effects of CrVI. Our recent findings demonstrated that in vivo CrVI exposure during gestational period caused POF in F1 offspring. Our current research focus is three-fold: (i) to identify the effect of CrVI on critical windows of great vulnerability of fetal ovarian development; (ii) to understand the molecular mechanism of CrVI-induced POF; (iii) to identify potential intervention strategies to mitigate or inhibit CrVI effects. In order to accomplish these goals we used a fetal whole ovarian culture system. Fetuses were removed from the normal pregnant rats on gestational day 13.5. Fetal ovaries were cultured in vitro for 12 days, and treated with or without 0.1 ppm potassium dichromate (CrVI) from culture day 2-8, which recapitulated embryonic day 14.5-20.5, in vivo. Results showed that CrVI increased germ cell/oocyte apoptosis by increasing caspase 3, BAX, p53 and PUMA; decreasing BCL2, BMP15, GDF9 and cKIT; and altering cell cycle regulatory genes and proteins. This model system may serve as a potential tool for high throughput testing of various drugs and/or EDCs in particular to assess developmental toxicity of the ovary.

Association between blood arsenic levels and nasal polyposis disease risk in the Tunisian population

Although the pathophysiology underlying nasal polyposis (NP) formation is not fully understood, systemic, local, and environmental factors appear to contribute to NP disease development. This study aimed to explore the relationship between metal blood levels and NP risk. To the best of our knowledge, the current research represents the first scientific contribution reporting levels of Cr and As in blood of NP patients. In this context, 90 NP patients and 171 controls were recruited and blood samples were analyzed to determine the concentrations of As and Cr. Metal blood levels of As in patients (2.1 μg/L) were significantly higher than those of controls (1.2 μg/L). However, no significant difference in blood Cr levels was found between cases and controls. Arsenic blood levels of cigarette smokers were significantly higher than those of non-smokers. Environmental exposure and shisha consumption presented the most significant association with NP disease (OR = 10.1 and 14.1, respectively). High levels of blood As were significantly associated with NP disease (OR = 2.1). Cr blood levels were found to be associated with the four stages of polyps in both nasal cavities. This study found a strong association between nasal polyposis disease and As blood levels. These findings merit further investigation.

Evidence for bystander signalling between human trophoblast cells and human embryonic stem cells

Maternal exposure during pregnancy to toxins can occasionally lead to miscarriage and malformation. It is currently thought that toxins pass through the placental barrier, albeit bi-layered in the first trimester, and damage the fetus directly, albeit at low concentration. Here we examined the responses of human embryonic stem (hES) cells in tissue culture to two metals at low concentration. We compared direct exposures with indirect exposures across a bi-layered model of the placenta cell barrier. Direct exposure caused increased DNA damage without apoptosis or a loss of cell number but with some evidence of altered differentiation. Indirect exposure caused increased DNA damage and apoptosis but without loss of pluripotency. This was not caused by metal ions passing through the barrier. Instead the hES cells responded to signalling molecules (including TNF-α) secreted by the barrier cells. This mechanism was dependent on connexin 43 mediated intercellular ‘bystander signalling’ both within and between the trophoblast barrier and the hES colonies. These results highlight key differences between direct and indirect exposure of hES cells across a trophoblast barrier to metal toxins. It offers a theoretical possibility that an indirectly mediated toxicity of hES cells might have biological relevance to fetal development.

Cadmium and nickel in blood of Tunisian population and risk of nasosinusal polyposis disease

Nasosinusal polyposis (NSP) is a chronic inflammatory disease of the nasal mucosa. Although the pathophysiology underlying NSP formation is not fully understood, environmental factors appear to be contributed the development of this disease. A case-control study of Tunisian patients was examined to assess the levels of cadmium (Cd) and nickel (Ni) in blood and reparse the association between the exposure to these metals and the risk of nasosinusal polyposis disease. Mean blood levels of Cd in patients (2.2 ± 12.8 μg/L) were significantly higher than those of controls (0.5 ± 0.7 μg/L). Levels of blood Cd were positively correlated with tobacco smoking and chewing among controls. The Cd and Ni concentrations among control (p = 0.001) and patient (p = 0.018) tobacco consumers (smoking, chewing, and shisha) were significantly higher than those nonconsumers. Additionally, Ni blood levels of patient and control smokers were significantly higher than those of nonsmokers. Cd levels in blood samples of NSP patients occupationally exposed for more than 14 years were eight times higher than that of nonexposed. Drinking water was also found to be incriminated as exposure sources. Among risk factors, shisha consumption, environmental exposure, and occupational exposure presented the most significant association with NSP disease (odds ratio (OR) = 14.1, 10.1, and 1.7, respectively). High levels of blood Cd (OR = 3.5) were strongly associated with NSP disease (p = 0.027). Ni blood levels were shown to be associated with the four stages of polyps in both nasal cavities (right and left) (p < 0.05). This investigation suggested a potential role of toxic metals in the mechanism of NSP disease development. Exposure assessment investigations encompassing a wider population are needed.

Identifying a novel role for X-prolyl aminopeptidase (Xpnpep) 2 in CrVI-induced adverse effects on germ cell nest breakdown and follicle development in rats

Environmental exposure to endocrine-disrupting chemicals (EDCs) is one cause of premature ovarian failure (POF). Hexavalent chromium (CrVI) is a heavy metal EDC widely used in more than 50 industries, including chrome plating, welding, wood processing, and tanneries. Recent data from U.S. Environmental Protection Agency indicate increased levels of Cr in drinking water from several American cities, which potentially predispose residents to various health problems. Recently, we demonstrated that gestational exposure to CrVI caused POF in F1 offspring. The current study was performed to identify the molecular mechanism behind CrVI-induced POF. Pregnant rats were treated with 25 ppm of potassium dichromate from Gestational Day (GD) 9.5 to GD 14.5 through drinking water, and the fetuses were exposed to CrVI through transplacental transfer. Ovaries were removed from the fetuses or pups on Embryonic Day (ED) 15.5, ED 17.5, Postnatal Day (PND) 1, PND 4, or PND 25, and various analyses were performed. Results showed that gestational exposure to CrVI: 1) increased germ cell/oocyte apoptosis and advanced germ cell nest (GCN) breakdown; 2) increased X-prolyl aminopeptidase (Xpnpep) 2, a POF marker in humans, during GCN breakdown; 3) decreased Xpnpep2 during postnatal follicle development; and 4) increased colocalization of Xpnpep2 with Col3 and Col4. We also found that Xpnpep2 inversely regulated the expression of Col1, Col3, and Col4 in all the developmental stages studied. Thus, CrVI advanced GCN breakdown and increased follicle atresia in F1 female progeny by targeting Xpnpep2.