Ca Minerals and Oral Bioavailability of Pb, Cd, and As from Indoor Dust in Mice: Mechanisms and Health Implications

Assessing the Impact of PM2.5-Bound Arsenic on Cardiovascular Risk among Workers in a Non-ferrous Metal Smelting Area: Insights from Chemical Speciation and Bioavailability

Inhalation of fine particulate matter PM2.5-bound arsenic (PM2.5-As) may cause significant cardiovascular damage, due to its high concentration, long transmission range, and good absorption efficiency in organisms. However, both the contribution and the effect of the arsenic exposure pathway, with PM2.5 as the medium, on cardiovascular system damage in nonferrous smelting sites remain to be studied. In this work, a one-year site sample collection and analysis work showed that the annual concentration of PM2.5-As reached 0.74 μg/m3, which was 120 times the national standard. The predominant species in the PM2.5 samples were As (V) and As (III). A panel study among workers revealed that PM2.5-As exposure dominantly contributed to human absorption of As. After exposure of mice to PM2.5-As for 8 weeks, the accumulation of As in the high exposure group reached equilibrium, and its bioavailability was 24.5%. A series of animal experiments revealed that PM2.5-As exposure induced cardiac injury and dysfunction at the environmental relevant concentration and speciation. By integrating environmental and animal exposure assessments, more accurate health risk assessment models exposed to PM2.5-As were established for metal smelting areas. Therefore, our research provides an important scientific basis for relevant departments to formulate industry supervision, prevention and control policies.

Release mechanism and interactions of cadmium and arsenic co-contaminated ferrihydrite by simulated in-vitro digestion assays

Cadmium (Cd) and arsenic (As) co-contamination is widespread and threatens human health, therefore it is important to investigate the bioavailability of Cd and As co-exposure. Currently, the interactions of Cd and As by in vitro assays are unknown. In this work, we studied the concurrent Cd-As release behaviors and interactions with in vitro simulated gastric bio-fluid assays. The studies demonstrated that As bioaccessibility (2.04 to 0.18 ± 0.03%) decreased with Cd addition compared to the As(V) single system, while Cd bioaccessibility (11.02 to 39.08 ± 1.91%) increased with As addition compared to the Cd single system. Release of Cd and As is coupled to proton-promoted and reductive dissolution of ferrihydrite. The As(V) is released and reduced to As(Ⅲ) by pepsin. Pepsin formed soluble complexes with Cd and As. X-ray photoelectron spectroscopy showed that Cd and As formed Fe-As-Cd ternary complexes on ferrihydrite surfaces. The coordination intensity of As-O-Cd is lower than that of As-O-Fe, resulting in more Cd release from Fe-As-Cd ternary complexes. Our study deepens the understanding of health risks from Cd and As interactions during environmental co-exposure of multiple metal(loid)s.

Sex-dependent effects of rice cadmium exposure on body weight, gut microflora, and kidney metabolomics based on a mouse model

Consumption of cadmium (Cd) contaminated rice is the main dietary source of Cd exposure and toxicity. To protect humans from Cd toxicity, it is pivotal to fully understand the sex-dependent toxicity of subchronic rice-Cd exposure. However, the sex-dependent effects of subchronic rice-Cd exposure on body weight gain, gut microflora, and kidney metabolomics are still unclear. In this study, a Cd-free and a Cd-contaminated rice (0.005 and 0.74 mg Cd kg-1) were fed to both female and male mice for one month, with changes in body weight gain, Cd accumulation in tissue, bone mineral concentration, expression of intestinal channels involving in Cd and calcium (Ca) absorption, gut microbiota, and kidney metabolites assessed for both genders. Results showed that female mice had normal body weight gain after rice-Cd exposure, while body weight of male mice was decreased from 19.8 to 17.5 g over the one-month consumption of the Cd-contaminated rice (0.74 mg kg-1), suggesting specific toxicity on growth of male mice. Rice-Cd exposure had limited effects on gut microbiota for both genders. However, higher Cd accumulation in liver and femur was observed in male mice than in females, which may be due to higher intestinal expression of Ca channels involving in intestinal Cd absorption in male mice with rice-Cd exposure. Greater risk of osteoporosis was also observed in male mice. In addition, kidney metabolomic profiling showed special disruption of adrenocortical hormone homeostasis for male mice with rice-Cd exposure. Particularly, expression of cortisol in kidneys of male mice was elevated 37.1-fold with rice-Cd exposure, likely resulting in Cushing's syndrome and contributing to growth retardation. This study advances our understanding of the sex-dependent toxicity of rice-Cd exposure, and highlights the priority of protecting males from the adrenocortical hormone disrupting effects of rice-Cd exposure.

Early-life exposure to lead changes cardiac development and compromises long-term cardiac function

Lead (Pb) is widely used in industrial and daily-use consumer products. Early-life exposure may increase the risk of lead-related heart problems in childhood. However, the effects of early-life lead exposure on fetal heart development and long-term cardiac outcomes are unknown. In this study, pregnant ICR mice were exposed to lead acetate trihydrate (50 mg/kg/d) via oral gavage from gestation day 1.5 until offspring weaning. Thereafter, the second hit model was established, two groups of offspring (4 weeks old) were either administered sterile saline or Angiotensin II (Ang II) for 4 weeks until euthanasia. We investigated lead-induced offspring heart damage from embryonic period to adulthood by echocardiographic analysis, pathological H&E staining, and ultrastructural examination, as well as mitochondrial function detection. The results showed early-life lead exposure predisposed offspring mice to decreased ejection fraction, increased left ventricular volume, accompanied by hypertrophy and dilation, cardiomyocyte sarcomere dysplasia, abnormal mitochondrial structure, mitochondrial dysfunction, and decreased expression of key sarcomeric and mitochondrial genes, rendering them more susceptible to cardiac hypertrophy, vascular wall thickening, cardiac fibrosis, apoptosis, and heart failure induced by Ang II infusion. This study elucidates early-life low dose lead exposure compromises cardiac development and exacerbates second hit-induced cardiac pathological responses in adulthood, which furnishes crucial scientific evidence pertaining to the cardiac toxicity and risk evaluation associated with early-life exposure to lead.

Dietary Galactooligosaccharides Supplementation as a Gut Microbiota-Regulating Approach to Lower Early Life Arsenic Exposure

Prebiotics may stimulate beneficial gut microorganisms. However, it remains unclear whether they can lower the oral bioavailability of early life arsenic (As) exposure via regulating gut microbiota and altering As biotransformation along the gastrointestinal (GI) tract. In this study, weanling mice were exposed to arsenate (iAsV) via diet (7.5 μg As g-1) amended with fructooligosaccharides (FOS), galactooligosaccharides (GOS), and inulin individually at 1% and 5% (w/w). Compared to As exposure control mice, As concentrations in mouse blood, liver, and kidneys and As urinary excretion factor (UEF) were reduced by 43.7%-74.1% when treated with 5% GOS. The decrease corresponded to a significant proliferation of Akkermansia and Psychrobacter, reduced percentage of inorganic arsenite (iAsIII) and iAsV by 47.4% and 65.4%, and increased proportion of DMAV in intestinal contents by 101% in the guts of mice treated with 5% GOS compared to the As control group. In contrast, FOS and inulin either at l% or 5% did not reduce As concentration in mouse blood, liver, and kidneys or As UEF. These results suggest that GOS supplementation may be a gut microbiota-regulating approach to lower early life As exposure via stimulating the growth of Akkermansia and Psychrobacter and enhancing As methylation in the GI tract.

Mechanistic Insights into Effects of Different Dietary Polyphenol Supplements on Arsenic Bioavailability, Biotransformation, and Toxicity Based on a Mouse Model

Arsenic (As) exposure has been related to many diseases, including cancers. Given the antioxidant and anti-inflammatory properties, the dietary supplementation of polyphenols may alleviate As toxicity. Based on a mouse bioassay, this study investigated the effects of chlorogenic acid (CA), quercetin (QC), tannic acid (TA), resveratrol (Res), and epigallocatechin gallate (EGCG) on As bioavailability, biotransformation, and toxicity. Intake of CA, QC, and EGCG significantly (p < 0.05) increased total As concentrations in liver (0.48-0.58 vs 0.27 mg kg-1) and kidneys (0.72-0.93 vs 0.59 mg kg-1) compared to control mice. Upregulated intestinal expression of phosphate transporters with QC and EGCG and proliferation of Lactobacillus in the gut of mice treated with CA and QC were observed, facilitating iAsV absorption via phosphate transporters and intestinal As solubility via organic acid metabolites. Although As bioavailability was elevated, serum levels of alpha fetoprotein and carcinoembryonic antigen of mice treated with all five polyphenols were reduced by 13.1-16.1% and 9.83-17.5%, suggesting reduced cancer risk. This was mainly due to higher DMAV (52.1-67.6% vs 31.4%) and lower iAsV contribution (4.95-10.7% vs 27.9%) in liver of mice treated with polyphenols. This study helps us develop dietary strategies to lower As toxicity.

Cadmium and lead bioavailability to poultry fed with contaminated soil-spiked feed

Geophagy is common for free-range chickens, however, the relative bioavailability (RBA) of heavy metals in contaminated soils consumed by chickens has not fully investigated. In this work, chickens were fed diets increasingly spiked with a contaminated soil (Cd = 105, Pb = 4840 mg kg^-1; 3, 5, 10, 20 and 30 % of overall feed by weight), or Cd/Pb reagent spikes (from CdCl₂ or Pb(Ac)₂), for 23 d. After the study period, chicken liver, kidney, femur and gizzard samples were analyzed for Cd and Pb concentrations, and organ/tissue metal concentrations were used to calculate Cd and Pb RBA. Linear dose response curves (DRCs) were established for both Cd/Pb reagents-spiked and soil-spiked treatments. Femur Cd concentrations of soil-spiked treatments were two times of Cd-spiked treatments with similar feed Cd levels, while feed spiked with Cd or Pb also resulted in elevated Pb or Cd concentrations in some organ/tissues. Metal RBA was calculated using three different methods. Most Cd and Pb RBA values were in the range 50-70 %, with the chicken gizzard as a potential endpoint for bioaccessible Cd and Pb. Cadmium and Pb bioavailability values can help with more precise estimation of Cd and Pb accumulation in chicken following heavy metal-contaminated soil ingestion, with overall results helping to protect human health.