Toxicological effects and ultrastructural changes induced by lanthanum and cerium in ovary and uterus of Wistar rats

Accumulation, translocation, and fractionation of rare earth elements (REEs) in fern species of hyperaccumulators and non-hyperaccumulators growing in urban areas

The issue of ion-adsorption type rare earth deposits (IADs) in urban areas of South China has garnered significant attention due to its environmental implications. Hyperaccumulator-based phytoremediation is a potentially effective solution for reducing the environmental impact of IADs in urban areas, particularly using ferns as they are known to be REE hyperaccumulators. However, the ability of different fern species to accumulate REEs in urban areas remains unknown. In this study, four fern species, including known hyperaccumulators (Dicranopteris linearis and Blechnum orientale) and other ferns (Pteris ensiformis and Cibotium barometz), were studied to investigate their REE accumulation abilities in the Guangzhou urban area. The aboveground parts of Dicranopteris linearis (848.7 μg g-1) and Blechum orientale (1046.8 μg g-1) have been found to accumulate high concentrations of REEs, demonstrating they probably can be applied for phytoremediation in the natural environments. Despite having lower REE concentrations than REE hyperaccumulators, Pteris ensiformis and Cibotium barometz still probably have the function as phytostabilizers in urban areas, as REEs can be enriched in their roots beyond the normal levels of plants. The enrichment of REEs in ferns is influenced by the availability of various nutrients (K, Ca, Fe, and P), which probably can be associated with different growth processes. The four fern species show LREE enrichment, moderate Eu anomalies and different Ce anomalies. It is difficult to absorb and transfer Ce to the aboveground parts of Blechnum orientale and Cibotium barometz. The study also identified selective enrichment of Ce in Pteris ensiformis, which has potential for comprehensive extraction of REEs when combined with other REE hyperaccumulators. REE fractionations are probably determined by the specific characteristics of different fern parts. Overall, these findings provide insights for addressing potential environmental problems related to IADs and offer guidelines for phytoremediation technology in addressing high REE levels in urban areas.

Maternal cerium nitrate exposure induces developmental immunotoxicity in BALB/c mouse offspring

With the increasing application of cerium and rare-earth elements (REEs), cerium exposure is becoming more widespread. However, there remains a paucity of evidence on developmental immunotoxicity of cerium. This study was designed to examine the developmental immunotoxicity of gestational and postnatal exposure to cerium nitrate (CN) in BALB/C mouse offspring. Dams were given CN by oral gavage at 0, 0.002, 0.02 and 0.2 mg/kg from gestation day 5 (GD5) to postnatal day 21 (PND 21). On PND 21, the highest dose of CN significantly suppressed the NK cell cytotoxicity, and reduced the proportions of NK cells in peripheral blood and spleen of both female and male pups, however, the proportions of monocytes in peripheral blood and macrophages in spleen only increased in female pups. For adaptive immunity, on PND 21, the suppression of T/B lymphocyte proliferation, humoral and cellular immune responses (number of splenic plaque-forming cells, PFC, and delayed-type hypersensitivity, DTH) were observed in both female and male pup mice exposed to 0.2 mg/kg CN. However, the fall of proportions of T/B lymphocytes in peripheral blood (PB), spleen and mesenteric lymph node (MLN) only found in female pups at 0.2 mg/kg on PND 21. Most indications recovered to normal after 3-week cessation of CN exposure, except the reduction of DTH and PFC. From the findings in this study, the lowest-observed-adverse-effect level (LOAEL) of CN for developmental immunotoxicity was estimated to be 0.2 mg/kg bw per day.

Histological and ultrastructural changes observed in testicles, epididymides, seminal vesicles and liver of rat after intraperitoneal administration of aluminum and indium

BACKGROUND

Aluminum (Al) and indium (In) have been largely used in medicine, pharmacy, dentistry, manufacturing, engineering, clothing as well as food processing and packaging. Our previous study showed that In was accumulated as electron-dense materials in lysosomes of Sertoli and Leydig testicular cells and the liver ones, when administered to male rats as soluble form. For this reason, we have undertaken to confirm whether Al have the same behavior as In and to enlarge this behavior to other organs of the male reproductive system: epididymis and seminal vesicle.

METHODS

Experiments were performed on 24 adult male Wistar rat weighing approximately 250 g. Animals were divided to 3 groups, received Al, In or saline solution as 7 chronic intraperitoneal injections over a period of two weeks and were sacrificed 24 h after the last injection. For ultrastructure study we used The Transmission Electron Microscopy (TEM).

RESULTS

The TEM showed the presence of electron-dense granules in lysosomes of testicular cells (Sertoli and Leydig cells), and in the principal epididymal and seminal vesicle cells of Al and In treated rats. Impairments were observed in the endoplasmic reticulum and mitochondria and many vacuoles were identified in the cells cytoplasm. Our results concluded that lysosomes of Leydig and Sertoli cells, principal epididymis, and seminal vesicle cells as well as liver cells, played a central role in the extraction and concentration of Al and In under insoluble form after their introduction into the body as a soluble route. This mechanism intended to protect the organism against exogenous toxic and non-recognized mineral elements after their intrusion into the body.

CONCLUSION

It looks important to proceed with the study of Al and In impact on the endocrine and exocrine functions of the male rat reproductive system.

Environmental risk assessment of the potential "Chemical Time Bomb" of ion-adsorption type rare earth elements in urban areas

Ion-adsorption type rare earth elements (REEs) located in tropical and subtropical zones have abundant movable and bioavailable ion-exchangeable REEs and could be an environmental hazard. However, our understanding of their environmental risk in urban areas is limited. We aimed to determine whether ion-adsorption type REEs in Guangzhou represent a kind of potential "Chemical Time Bomb" (CTB) and assess the environmental risk. We conducted a comprehensive survey of REEs in 181 samples including regolith (n = 70), surface water (n = 55), sediment (n = 25), vegetables (n = 22) and rhizosphere soil (n = 9), collected from five regions around Guangzhou, as a representative city of ion-adsorption type REEs in tropical and subtropical zones. The existing environmental risk was assessed by calculating the estimated daily intake (EDI) of REEs through vegetable consumption, and leaching simulation experiments were used to discuss the factors affecting the long-term stability of REEs. The average REEs concentrations (ΣREEs) in the regolith and sediment were 458.5 and 218.6 μg·g^-1, respectively, which were higher than the background values of regolith (197.3 μg·g^-1) and sediment (173.3 μg·g^-1), and large proportions of ion-exchangeable REEs were observed in regolith and sediment, indicating that ion-adsorption type REEs in Guangzhou are a kind of potential CTB. The average ΣREEs in surface water (3.9 μg·L^-1), rhizosphere soil (466.9 μg·g^-1) and vegetables (25.0 μg·g^-1·dw) suggest that REEs have migrated to the supergene environment even organisms. The average EDI (55.4 μg·kg^-1·d^-1) close to the safety limitation (70 μg·kg^-1·d^-1) suggests that the existing health risk is very worrisome. Human factors, including acid rain, mining and farming, probably ignite the CTB, causing the release of REEs to the urban environment on a large scale. This prospective study demonstrated that REEs exposure problems in urban areas of ion-adsorption type REEs should not be ignored.

Cell and molecular toxicity of lanthanum nanoparticles: are there possible risks to humans?

Lanthanum nanoparticles are widely used in industry, agriculture, and biomedicine. Over 900 kg of lanthanum is annually released into the environment only in Europe, 50 times higher than the metals, mercury, and cadmium's environmental spread. Human health risk associated with long-term exposure to the abundant lanthanum nanoparticles is a concerning environmental issue. Due to lanthanum's ability to disrupt the main biological barriers and interrupt various cells' hemostasis, they seem to cause severe disruptions to various tissues. This review opens a new perspective regarding the cellular and molecular interaction of nanosized and ionic lanthanum with the possible toxicity on the nervous system and other tissues that would show lanthanum nanoparticles' potential danger to follow in toxicological science.

Association between exposure of light rare earth elements and outcomes of in vitro fertilization-embryo transfer in North China

The adverse health effects of rare earth elements (REEs) on reproductive health remain a subject of debate, and few clinical observations are available. This study investigated the association between light REEs (LREEs) exposure and the outcome of in vitro fertilization-embryo transfer (IVF-ET). We recruited a total of 305 women undergoing IVF-ET in Beijing City and Shandong Province of northern China. Their demographic information and lifestyle characteristics were collected using questionnaires at enrollment. Fasting blood samples were collected on the day before the IVF-ET treatment cycle began. Serum concentrations of the LREEs of concern were analyzed using inductively coupled plasma-mass spectrometry, and four LREEs were measured with a high detection rate, including lanthanum (La), cerium (Ce), praseodymium (Pr), and neodymium (Nd). We found that a higher serum La concentration was associated with a 30% increased likelihood of clinical pregnancy failure [relative risk (RR) = 1.30, 95% confidence interval (CI): 1.00-1.67] and a 230% increased likelihood of preclinical spontaneous abortion (RR = 3.30, 95% CI: 1.57-6.94). There was a negative correlation between serum La concentration and the number of good-quality oocytes. For the other LREEs, no statistically significant associations were observed. We concluded that a high serum La concentration may have an adverse effect on IVF-ET outcomes.

The effect of different concentrations of cerium oxide during pregnancy on ovarian follicle development in neonatal mice

OBJECTIVES

Cerium is a member of the rare metals group and widely used in drug delivery, gene therapy, molecular imaging and medicine. In this study, we investigated the effect of different doses of Cerium (IV) oxide (CeO₂ ) during pregnancy on neonatal mice ovaries, as well as its effect on blood biochemical parameters.

METHODS

Thirty pregnant NMRI mice were divided into five groups: Control and 4 groups treated with CeO₂ (10, 25, 80, 250 mg/kg.bw i.p) at the GD7 and GD14. The ovarian histological of neonatal (2 and 6 day-olds), as well as blood serum of neonates at 15-dpp were analyzed.

RESULTS

Count of ovarian primordial follicles in neonates at 2 dpp showed a significant decrease in the groups treated with 80 and 250 mg/kg.bw doses of CeO₂ . There was also a significant decrease in ovarian primordial and primary follicles in neonates at 6-dpp at 250 mg/kg.bw doses of CeO₂ in the control (P < 0.05). There was no significant difference in serum levels of malondialdehyde and total antioxidant capacity between the experimental and control groups.

CONCLUSIONS

Our results suggest that the effects of CeO₂ on the ovarian tissue of neonatal mice during pregnancy may be dose-dependent.

Rare earth elements exposure and the alteration of the hormones in the hypothalamic-pituitary-thyroid (HPT) axis of the residents in an e-waste site: A cross-sectional study

Rare earth elements (REEs) are widely used in electronic products. But the contaminations of REEs in the e-waste sites and the related health effects were barely investigated. In the present study, we analyzed the concentrations of REEs and the hormones of the HPT axis in plasma of subjects recruited from an e-waste area and a reference area in Taizhou, China. The results showed that the concentrations of several REEs like La, Ce were much higher in the exposed group than in the control group (all p < 0.001). The thyroid hormones, FT3 and FT4, and TRH showed no significant difference between the two groups, while the concentration of TSH was significantly higher in the exposed group when compared to the control group (p = 0.002). Separate regression analysis indicated that elevated La and Ce levels were associated with higher TSH concentrations. MDA and 8-iso, the biomarkers of oxidative stress, were also significantly higher in the exposed group than that of the control group (p = 0.002 and p = 0.003, respectively). The increased oxidative stress might be the mechanism underlying the disruptive effects of REEs on TSH. Our results indicated that the quantities of internal exposure of REEs in the subjects in the e-waste area were considerable and the compositional profile of the REEs in the exposed group was different from the control group due to the e-waste dismantling. The expression of TSH were also affected by high La and Ce exposure which showed an endocrine disruption effects of REEs on HPT axis.

The Accumulation and Metabolism Characteristics of Rare Earth Elements in Sprague-Dawley Rats

The current study aims to investigate the influence of five rare earth elements (REEs) (i.e., lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), and gadolinium (Gd)) on the growth of Sprague-Dawley (SD) rats, and to explore the accumulation characteristics of REEs in tissues and organs with different doses as well as the detoxification and elimination of high-dose REEs. Fifty healthy male SD rats (140~160 g) were randomly divided into five groups and four of them were given gavage of sodium citrate solution with REEs in different doses, one of which was the control group. Hair, blood, and bone samples along with specific viscera tissue samples from the spleen and the liver were collected for detection of REEs by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Treated rats expressed higher concentrations of REEs in the bones, the liver, and spleen samples than the control group (P < 0.05). Few differences were found in relative abundance of La, Ce, Pr, Nd, and Gd in the hair and the liver samples, although different administration doses were given. The relative abundance of Ce in bone samples was significantly lower in the low-dose group and control group, whereas the relative abundance of La and Pr in the bone samples were highest among all groups. Although in the REEs solution, which was given to rats in high-dose group, the La element had a higher relative abundance than Ce element, it ended up with higher Ce element relative abundance than La element in the spleen samples. REEs had a hormetic effect on body weight gain of SD rats. The accumulation of the measured REEs were reversible to low concentrations in the blood and hair, but non-reversible in the bones, the spleen, and the liver. Different tissues and organs can selectively absorb and accumulate REEs. Further inter-disciplinary studies about REEs are urgently needed to identify their toxic effects on both ecosystems and organisms.