Pills, Pollution, and Planet: The Hidden Environmental Costs of Birth Control - Blog 02

I went to the pharmacy yesterday and I ordered my birth control pills, those 30 pills I take every month. I could not stop thinking about what would happen to each component of the pill once my body had digested it. After some research, I came to the conclusion that this pill might not only affect my body negatively but also to the environment.

Levonorgestrel is used as a pharmaceutical contraceptive method for avoiding pregnancy. It can be used as a birth control and emergency pill such as "Plan B".

Europe is the largest Levonorgestrel market with about 43 % market share. Globally, it is expected to increase its production going from 46 million USD to 58 USD million of market value by the end of 2027 [1]. With this expected growth which type of pressure on the environment does it mean? What would happen after the intended effect of the pill? and most importantly, why should we care?

This pill affect reproduction in some aquatic species with low level of exposure.

After emission, a certain amount of the chemical can be excreted through the urine and later, be degraded into other toxic compounds. Other sources of emission are pharmaceutical industries with poor infrastructure to degrade fully Levonorgestrel. However, it is known that Levonorgestrel is quite persistent and stable. For instance, low concentrations of 1 ng/L can be enough for it to bioaccumulate in the aquatic food chain [2].

 After their release into the environment, mainly through wastewater treatment plants, trace elements of levonorgestrel can be found at concentrations of 30 ng/L , which are enough to cause negative effects on adult fathead minnows by inhibiting reproduction or affecting male fertility [3]. Other effects studied on fish are growth and development, and masculinization of females [4]. Even at very low trace amounts of Levonorgestrel (1.64 ng/L) it has been found that adult zebrafish became male and no spawning occurred [5], meaning that females could not lay their eggs in water any longer. Although ecosystems are complex and can adapt with different mechanisms, this at a population level, can cause a decline in biodiversity, and effect negatively affect human consumption of fish.

Ecotoxicological studies have also focused on frogs' effects after exposure to trace elements of Levonorgestrel. One main negative effect is at their reproduction level. Adult frogs were found to have impaired oogenesis, meaning that the process by

which female germ cells undergo meiosis and differentiate into mature oocytes was disrupted. Therefore, female fertility of frogs can also be threatened by the presence of Levonorgestrel on water [6].

But .. which negative effects Levonorgestrel can provoke in humans?

Toxicity studies in trial populations have not been fully developed. Results are also very vague and not enough to reach definite conclusions. However, that does not mean necessarily their inexistence. In a systematic review, it was seen that half of the studies revised showed a connection between breast cancer and levonorgestrel uptake through Levonorgestrel intrauterine device while the other half did not [7]. The authors realized the inconsistency among the studies due to the cohorts, women's age, the reason for using the device, and the time period in which they were taken. Another systematic review found the same problem evaluating 96 studies on the topic [8]. They evaluated studies focused on users of 52-mg levonorgestrel-releasing intrauterine system (LNG-IUS) and their association with breast cancer. As the previous study cited, these authors also found many inconsistencies among the reports. While many of the studies evaluated proved the relationship between cancer risk and the use of LNG-IUS, many of them might have been caused by confounding factors. However, they also found that many of the studies showed this positive relationship on women who were users of LNG-IUS for long periods of time. Finally, the authors recommended:

Women with cancer risk factors such as old age, obesity and familial predisposition should take with precaution the use of LNG-IUS

Even though so far there is not a clear connection between the use of Levonorgestrel on human beings, studies on animals clearly showed a negative effect of the presence of these chemicals on the environment. It is expected to have fewer conclusions when we talk about human health effects due to ethical reasons behind each study, however, this is an opportunity to improve methodologies on cohort studies to understand the systemic effect of birth control pills.

References

[1] Business Growth Reports (2023). Analyzing Levonorgestrel Market Trends in 2023: Growth Dynamics, Segmentation, Future Demands, Innovations, Regional Sales Projection by 2030. Extracted from https://www.linkedin.com/pulse/analyzing-levonorgestrel-market-trends-2023-growth/ 

[2] Fick, J.; Lindberg, R. H.; Parkkonen, J.; Arvidsson, B. r.; Tysklind, M.; Larsson, D. G. J. Therapeutic levels of levonorgestrel detected in blood plasma of fish: Results from screening rainbow trout exposed to treated sewage effluents. Environ. Sci. Technol. 2010, 44 (7), 2661− 2666.

[3] Narváez, J. F., Grant, H., Gil, V. C., Porras, J., Sanchez, J. C. B., Duque, L. F. O., ... & Quintana-Castillo, J. C. (2019). Assessment of endocrine disruptor effects of levonorgestrel and its photoproducts: Environmental implications of released fractions after their photocatalytic removal. Journal of hazardous materials, 371, 273-279.

[4] Zeilinger, J., Steger‐Hartmann, T., Maser, E., Goller, S., Vonk, R., & Länge, R. (2009). Effects of synthetic gestagens on fish reproduction. Environmental toxicology and chemistry, 28(12), 2663-2670.

[5] Teigeler, M., Schaudien, D., Böhmer, W., Länge, R., & Schäfers, C. (2022). Effects of the gestagen levonorgestrel in a life cycle test with zebrafish (Danio rerio). Environmental Toxicology and Chemistry, 41(3), 580-591.

[6] Säfholm, M., Norder, A., Fick, J., & Berg, C. (2012). Disrupted oogenesis in the frog Xenopus tropicalis after exposure to environmental progestin concentrations. Biology of reproduction, 86(4), 126-1

[7] Ángel-Parra, C., Pascual-Domenech, A. M., & González-Mirasol, E. (2021). Riesgo de cáncer de mama en portadoras de DIU de levonorgestrel. Revisión sistemática. Clínica e Investigación en Ginecología y Obstetricia, 48(4), 100668.

[8] Conz, L., Mota, B. S., Bahamondes, L., Teixeira Dória, M., Françoise Mauricette Derchain, S., Rieira, R., & Sarian, L. O. (2020). Levonorgestrel‐releasing intrauterine system and breast cancer risk: A systematic review and meta‐analysis. Acta Obstetricia et Gynecologica Scandinavica, 99(8), 970-982.