As mentioned in the previous blogs, the rapid growth in demand for lithium-ion batteries and low rates of recycling due to the low cost of production has resulted in Li pollution when these batteries are discarded into landfills with other municipal waste. This sudden increase in Li in the environment impacts marine life, plants, animals, and humans. In the next few blogs, I will explore more about the impacts Li have on animals and humans.
With the increasing concentration of Li in the environment, concerns about prolonged exposure to high concentrations of Li are also rising. As more Li leaks into the environment, into water and food sources, Li will enter the food chain as animals and humans consume contaminated plants, animals and water. To understand the impacts consuming Li has on humans and animals, experiments have been conducted on animals such as rats.
Figure 1: (Magazine, 2019)
Experiments on young Wistar male rats conducted by Nciri et al. (2011) have found significant changes to the chemical and biological activities in the kidneys and liver of rats even at low concentrations of Li. Experiment rats were fed food and water with the same concentrations of Li over different periods and changes were observed over a period of up to 28 days (Nciri et al., 2011).
Significant changes observed:
1. Decrease regulating function of liver and kidney
This treatment led to serum concentrations ranging from 0.5 mM (day 7) to 1.34 mM (day 28) and renal insufficiency highlighted by an increase of blood creatinine and urea levels and a decrease of urea excretion. – Nciri et al., 2011
Creatinine is waste matter from muscles that are excreted from the body through urine (American Kidney Fund, 2022). A healthy liver will ensure a sufficient amount of creatinine is excreted out of the body to ensure a healthy level of blood creatinine (American Kidney Fund, 2022). An increase in blood creatinine indicates that the kidney is no longer functioning healthily.
Urea on the other hand is a chemical waste product and an important circulating source of nitrogen compounds that remove waste products from the bloodstream (Weiner et al., 2015). Urea is produced in the liver before being transported to the kidney where it is filtered to remove waste products from the body (Mayo Clinic, 2021). It is essential to the regulatory function of the kidney (Weiner et al., 2015). A decrease in urea excretion will result in a reduction of chemical waste removed from the body.
2. Damage to tissues
Lithium treatment was found to trigger an oxidative stress both in kidney and liver, leading to an increase of lipid peroxidation level (TBARS) and of superoxide dismutase and catalase activities.- Nciri et al., 2011
Oxidative stress occurs when there is a disproportion between antioxidant activity and free radical activity (Dix, 2018). Prolonged/severe oxidative stress can damage renal tissue (HealthMatters.io, n.d.), the connective tissue that surrounds and supports the kidney (Gyurászová et al., 2020; National Cancer Institute, n.d.). Renal tissue will lead to kidney failure and related diseases which will be explored more in the next blog.
Reference List
American Kidney Fund. (2022, January 5). Serum creatinine test. https://www.kidneyfund.org/all-about-kidneys/tests/serum-creatinine-test
Dix, R. M. N. (2018, September 29). Everything You Should Know About Oxidative Stress. Healthline. https://www.healthline.com/health/oxidative-stress
Gyurászová, M., Gurecká, R., Bábíčková, J., & Tóthová, U. (2020). Oxidative Stress in the Pathophysiology of Kidney Disease: Implications for Noninvasive Monitoring and Identification of Biomarkers. Oxidative Medicine and Cellular Longevity, 2020, 1–11. https://doi.org/10.1155/2020/5478708
HealthMatters.io. (n.d.). Lipid Peroxides (Genova) | Healthmatters.io. https://healthmatters.io/understand-blood-test-results/lipid-peroxides-genova
Magazine, S. (2019, February 27). The History of the Lab Rat Is Full of Scientific Triumphs and Ethical Quandaries. Smithsonian Magazine. https://www.smithsonianmag.com/science-nature/history-lab-rat-scientific-triumphs-ethical-quandaries-180971533/
Mayo Clinic. (2021, August 19). Blood urea nitrogen (BUN) test – Mayo Clinic. https://www.mayoclinic.org/tests-procedures/blood-urea-nitrogen/about/pac-20384821
National Cancer Institute. (n.d.). Kidneys | SEER Training. https://training.seer.cancer.gov/anatomy/urinary/components/kidney.html
Nciri, R., Allagui, M. S., Bourogaa, E., Saoudi, M., Murat, J. C., Croute, F., & Elfeki, A. (2011). Lipid peroxidation, antioxidant activities and stress protein (HSP72/73, GRP94) expression in kidney and liver of rats under lithium treatment. Journal of Physiology and Biochemistry, 68(1), 11–18. https://doi.org/10.1007/s13105-011-0113-3
Weiner, I. D., Mitch, W. E., & Sands, J. M. (2015). Urea and Ammonia Metabolism and the Control of Renal Nitrogen Excretion. Clinical Journal of the American Society of Nephrology, 10(8), 1444–1458. https://doi.org/10.2215/cjn.10311013