Emerging Contaminants: A Growing Concern

Emerging contaminants, such as medicines, personal care products, nanomaterials, and microplastics, are compounds that are not routinely monitored in the environment but have the potential to affect the environment and human health. The behavior and fate of these toxins are frequently unknown, making it difficult to forecast how they may interact with changing environmental circumstances caused by climate change.

Interactions between Climate Change and Emerging Contaminants

The relationship between climate change and the water cycle is critical, as it influences the mobility, distribution, and concentration of ECs across vast areas. When climate change causes more rain and floods, it leads to more runoff and leaking of pollutants from land to water. For example, heavy rains and flooding can overwhelm wastewater treatment systems, leading to the discharge of untreated or partially treated effluents containing ECs into water bodies. This spreads ECs further and increases their levels in rivers and underground water sources, which are used for drinking and can harm aquatic life, subsequently incorporating these contaminants into the human food chain [1].

Climate change-induced temperature changes can affect the behavior of ECs, altering their persistence, bioavailability, and toxicity. Elevated temperatures can both accelerate the degradation of some contaminants and increase the stability of others, as well as cause the volatilization of certain compounds. This shifts their distribution across air, water, and soil, creating new exposure pathways. Additionally, the melting of polar ice due to higher temperatures releases ECs long trapped in ice, reintroducing them into the environment and posing new risks to both wildlife and human health [2]. Moreover, variations in temperature, moisture, and other climatic factors can boost or hinder microbial activities, directly affecting the biodegradation and toxicity of ECs. For example, increased temperatures and UV exposure may expedite the breakdown of some chemicals, reducing their environmental persistence, or create new toxic by-products [3].

The agricultural sector is particularly vulnerable, as climate change can affect the prevalence and distribution of contaminants in soil and water, impacting crop quality and food safety. This not only poses health risks but also economic challenges for farmers and communities dependent on agriculture It's important to note that the impact of climate change and emerging contaminants is not uniformly distributed. Urban areas, with their higher industrial and vehicular emissions, might face different challenges compared to rural areas, where agricultural runoff plays a significant role.

In conclusion, the complex relationship between climate change and ECs not only worsens environmental threats but also has significant implications for human health, affecting exposure pathways and risks. Changes in water quality and availability, as well as changes in agricultural practices due to climate variability, can directly impact human exposure to waterborne and foodborne contaminants [4]. Addressing these challenges requires a multidisciplinary approach, emphasizing the importance of enhancing monitoring and research to understand the behavior, fate, and impacts of ECs under changing climatic conditions. Developing effective mitigation strategies that consider the challenges of climate change is crucial for protecting environmental and public health. There are costs associated with mitigating the effects of ECs, such as upgrading wastewater treatment plants, implementing new water quality standards, waste management practices, and emissions controls. Moreover, the implementation of adaptive and forward-looking policies and regulations is essential to manage the evolving threats posed by both climate change and contaminants efficiently.

References

[1]         S. Bolan et al., 鈥淚mpacts of climate change on the fate of contaminants through extreme weather events,鈥� Science of The Total Environment, vol. 909, p. 168388, Jan. 2024, doi: 10.1016/J.SCITOTENV.2023.168388.

[2]         S. A. Snyder et al., 鈥淐limate Change Impacts on Emerging Contaminants,鈥� pp. 311鈥�329, 2012, doi: 10.1007/978-1-0716-2466-1_261.

[3]         K. Mukherjee, 鈥淐limate change as a driving factor for emerging contaminants,鈥� Present Knowledge in Food Safety: A Risk-Based Approach through the Food Chain, pp. 303鈥�308, Jan. 2023, doi: 10.1016/B978-0-12-819470-6.00048-2.

[4]         K. E. Jones et al., 鈥淕lobal trends in emerging infectious diseases,鈥� Nature 2008 451:7181, vol. 451, no. 7181, pp. 990鈥�993, Feb. 2008, doi: 10.1038/nature06536.

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In a world of increasing 鈥渨ants鈥�, lies a parallel increase in 鈥渨astes鈥�. We are observing a record surge in the production of goods for human consumption, and likewise, its wasteful consequences. From wasted agricultural produce, post-consumption or unused food waste, municipal and industrial wastewater, forestry and textile waste, there is a lot that can be recovered or redirected for further use. Historically, this practice of circular economy has been intrinsically bound to our civilizations, cultures and way of life. However, somewhere along the way with industrialization, rapid technology advancements, the hygienist movement etc., we focused on the linear economy a little too much. While ending the circularity of certain goods from the public health perspective was a giant leap towards eradicating some preventable diseases, it also paved the path towards consumerism and the global issue of waste management [1].

Let us look at some interesting numbers. According to the World Food Programme, 鈥極ne-third of food produced globally for human consumption is wasted or lost鈥�. This is about 1.3 billion tonnes per year [2]! One-third of the forest cover has been wiped off the earth to fulfil human needs including expansion of agricultural land [3]. This consequently has increased agricultural waste when production surpasses the needs or rather the disproportionate division of the produce leading to unnecessary spoilage or wastage. Furthermore, the use of wood in a range of other applications, for instance, the pulp and paper industry. On the other hand, municipal waste alone accounts for 2 billion tonnes of it getting diverted to landfills [4].

So much potential 鈥榳asted鈥� indeed. What do we do, moving forward? We go back to our roots of course, with a wealth of knowledge acquired over the years to generate the 鈥榳ealth from waste鈥�. Not just using the resources to expand the technological advancements, but rather using the technologies as well to expand the end-of-life path of those resources.

If we look at the organics, also called as biomass, consisting of food, crops, forestry products, wastewater etc., their complex chemical makeup offers a wide range of possibilities for value-addition. Wastewater and sludge from treatment plants have been widely studied and used for the production of methane and hydrogen gas which are valuable biofuels. The technology used for this conversion is known as anaerobic digestion where the complexity of wastewater or sludge is reduced to a simpler state by harnessing the power of microorganisms. Not just biofuels, a multitude of by-products like fatty acids are also generated in this process which again have a broad range of applications like creating bioplastics, animal feed, fertilizers, flavouring agents, perfumes, and other industrially-relevant chemicals. This bioprocessing is also applicable to other organic matrices from waste streams. Since they all differ in terms of their basic composition, there are different alterations required for the overall process or a shift observed in the final product.

Sludge generated in the wastewater treatment is highly rich in organic matter, especially carbon, which in the absence of oxygen is ideal for reduction to methane gas. If we look at food waste, it has a different chemical makeup with carbohydrates, proteins, and fats. Thus, requiring different conditions than sludge can favour the production of other by-products like volatile fatty acids than biogas. Another commonly practised process of composting results in a nutrient-rich humus-like product suitable for enhancing soil fertility. Moving further to agricultural and forestry waste, they comprise even more complex sugars or carbon sources, that can shift the process towards a specific product and require different conditions for full utilization. As they are rich in cellulose and lignin, these can also be used to generate biochar which is a stable form of carbon useful in improving soil quality. Livestock waste is rich in nitrogen and phosphorus, which when digested or converted to manure is highly useful for soil fertility. Therefore, the suitability of these various waste streams for specific biological processes is dependent on their physical characteristics, chemical composition, nutrient and moisture content etc. A deeper understanding of the intricacies behind these properties and the activity of microorganisms opens more opportunities for designing waste management strategies for their value addition in the economy.

Thus, there is an art behind mindful resourcefulness in our everyday lives, and science supports resourceful recycling for a better future.

References:

[1]         Aggeri and Franck, 鈥淔rom waste to urban mines: a historical perspective on the circular economy,鈥� http://journals.openedition.org/factsreports, no. Special Issue 23, pp. 10鈥�13, Nov. 2021, Accessed: Mar. 14, 2024. [Online]. Available: http://journals.openedition.org/factsreports/6530

[2]         鈥�5 facts about food waste and hunger | World Food Programme.鈥� Accessed: Mar. 14, 2024. [Online]. Available: https://www.wfp.org/stories/5-facts-about-food-waste-and-hunger

[3]         鈥淒eforestation and Forest Loss - Our World in Data.鈥� Accessed: Mar. 14, 2024. [Online]. Available: https://ourworldindata.org/deforestation#article-citation

[4]         鈥淭rends in Solid Waste Management.鈥� Accessed: Mar. 14, 2024. [Online]. Available: https://datatopics.worldbank.org/what-a-waste/trends_in_solid_waste_management.html

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