Abstract
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.
Highlights
With annual increasing amounts exploited and diversity of uses explored, rare earth elements (REEs) are extensively applied to industrial, medical, zootechnical, and agricultural fields [1,2].The REEs are not as rare in geological abundance as other toxic metals, and China has around 90% of the world’s detected REEs [3,4]
Compared to the control group, higher REEs that accumulated in multiple tissues and organs, including the lung, the liver, the kidneys, and nails, were found in the population with REE exposures [13]
Excessive exposure to REEs could impact the intelligence quotients (IQs) of children, showed by studies of children who live in high La element background regions and attained lower IQ scores than those children in non-exposed regions [14]
Summary
With annual increasing amounts exploited and diversity of uses explored, rare earth elements (REEs) are extensively applied to industrial, medical, zootechnical, and agricultural fields [1,2].The REEs are not as rare in geological abundance as other toxic metals, and China has around 90% of the world’s detected REEs [3,4]. With annual increasing amounts exploited and diversity of uses explored, rare earth elements (REEs) are extensively applied to industrial, medical, zootechnical, and agricultural fields [1,2]. Extensive research has proven that REE exposures would increase concentrations of REEs in body organs and tissues [9,10]. The REE accumulations were observed in various organs of human beings who were exposed, long term, to REE particles [6]. Workers in industries such as photoengravers, glass or lens polishers, and movie projectionists who undergo long-term occupational exposures to REE particles have a higher risk to suffer rare earth pneumoconiosis, compared to the control group without REE exposures [6,12]. Compared to the control group, higher REEs that accumulated in multiple tissues and organs, including the lung, the liver, the kidneys, and nails, were found in the population with REE exposures [13]. Less attention has been paid to the re-distribution and accumulation processes of REEs in different organs and tissues
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