Emerging Pollutants

Emerging Pollutants (EPs) are defined as synthetic or naturally occurring chemicals that are not commonly monitored in the environment although having the potential to enter into the environment and cause adverse impacts on the environment as well on human health (Geissen., et al 2015). Emerging pollutants encompass chemicals released from the pharmaceutical sector, endocrine disruptors, hormones, toxins, and biological pollutants, such as micropollutants in soils, which include bacteria and viruses.

Many EPs in the form of chemicals and microbial agents are non-degradable and persistent. Due to its persistency, EPs travels in the various matrix of the environment via water and air (Rasheed et. al., 2019). These contaminants also can be found even in those areas where they were never used to exist in the past. EPs increases after enhancement in the industrial sector along with hospitals and other medical centers (Pal et al., 2010; Fatta-Kassinos et al., 2011; Lienert et al., 2011; Verlicchi et al., 2013). The concentration of pollutants also depends upon their concentration in the parent sources.

Life-cycle distribution of emerging pollutants from sources to receptors viewpoint

Source: https://doi.org/10.1016/j.envint.2018.11.038

In other words, emerging contaminants are not emerging from anywhere - they’re here, now its in measurable quantity and cause irreversible damage to the environment as well as on human health. Previously it's in very low concentration and now awareness increases because of its damaging effect to the environment that’s why emerging pollutant, name has been assigned by the researchers.

Globally, the anthropogenic production of chemicals has experienced rapid growth since the 1970s. Global production has been projected to increase annually by 3.4 percent till 2030 and non-OECD countries will be much greater contributors to this production. Production of hazardous chemicals has been reduced over the last ten years; however, the uncertainties that remain and the lack of information from many developing countries make it impossible to conclude that risks to the environment and human health have been successfully reduced.

Fig: Distribution of publications that report emerging contaminants in aquatic sources in India( Khalid et. al., 2017)

Source: https://ascelibrary.org/doi/10.1061/%28ASCE%29HZ.2153-5515.0000348

Effects of Pharmaceuticals and Personal Care Products in Environment

Pharmaceutical and personal care products (PPCPs) are a class of emerging chemical contaminants that have been used extensively for decades.

This includes more than 4000 pharmaceutical drugs, cosmetics, fragrances, nutritional supplements and household cleaning items. Antibiotics persist in agricultural soil for many days. It comes from wastewater and the animal manure as medicines has been a part of life to an animal as well as humans. Manure and sewage sludge used by famers to enrich their land, however, antibiotics-loaded manure degrades soil fertility and crop productivity.

Pharmaceuticals category contains

• Drugs used to cure human as well as animals
• Research and Development sector related with disease prevention and cure

Source: http://k12s.phast.umass.edu/sess/emerging/Overview.ppt

Personal Care Products

This group contain various daily use items in day to day life like soaps, perfumes. Cleani9ng agents, detergent, products related with personal hygiene etc.

Source: http://k12s.phast.umass.edu/sess/emerging/Overview.ppt

Endocrine Disrupting Compounds

• Disrupt normal function of the endocrine system
• Mimic hormones; agonize or antagonize hormone activity, synthesis, or metabolism; modify hormone receptors
• Active at very low levels
• Concern about additive or synergistic effects caused by mixtures of EDCs
• Synthetic Estrogens
  • Ethinyl Estradiol, Bisphenol-A
• Synthetic Androgens
  • 90% of US cattle receive growth hormone implants
  • Synthetic androgens remain environmentally active for months

Fig: Tens of thousands of chemicals are suspected of having the potential to interfere with the endocrine system, resulting in adverse health effects in people and wildlife.

Source: https://www.intechopen.com/media/chapter/61788/media/F1.png

Numerous data showed that biosolids applied to soil even after treatment have introduced PPCPs into the soil environment (Borgman and Chefetz, 2013; Kinney et al., 2006b; Walters et al., 2010; Xia et al., 2010). The waste water treatment focuses on the toxic metal concentration and organic load removal. However, the fate and transport of various EPs yet not fully address. So, EPs (e.g., perfluoroalkyl substances and pharmaceutical and personal care products [PPCPs]) in WWTP emissions are of important concern (Zhou et al., 2019) in today’s world.

Fig: Main Sources and Fates of Pharmaceuticals and Personal-Care Products (PPCPs) in Plants and the Environment (Bartrons et. al., 2017).

Source: https://www.cell.com/trends/plant-science/comments/S1360-1385(16)30226-6

Effect of Emerging Contaminants on Crops

Pesticides have been extensively used in our agricultural system, several new chemicals have been added to the soils which adversely affects the soil microbiota and imbalances the ecological system (Estévez et al. 2005). These chemicals in soil concern with major adverse effects are considered emerging contaminants.

Usually crop agglomerate EP inside their body which in turn affects the productivity and also goes in the food chain that affects human beings and other animal. Shenker et al. (2011) reported that some pharmaceutical compounds like carbamazepine and antimicrobials has been taken up by the plants when irrigated with EP contaminated water.

Fig: Source and fate of contaminants in soils, directly or indirectly, plants become exposed with contaminants through either by foliar spray or soil application. Contaminants present in soil are absorbed through the roots system(Singh et. al., 2020)

Source: https://www.researchgate.net/figure/Source-and-fate-of-contaminants-in-soils-Directly-or-indirectly-plants-become-exposed_fig1_340049982

Removal of Heavy Metals and Emerging Contaminants by Different Plants

An ecofriendly mitigation of EP from the environment is using plants and microbes. Phytoremediation is one such innovative technology utilising the absorption potential of plant to remediate the contaminated soil and water matriz. Plants like jatropha, miscanthus utilised these days for phytoremediation of emerging contaminants (such as pesticides, hormones, and antibiotics) and several heavy metals. More species yet to find which are having potential to work as a hyperaccumulator (Reckson & Raphael, 2017).

While selecting plant species following are the criteria:

1. Non-edible plant should be preferred so that contaminat will not effect human or animals.
2. Plant shold have fast growth, as it accumulates more EP.
3. After harvesting the plants proper disposal method via incineration or can be utilised in biofuel plant.

Plant Type Used	Mechanism	Media and Contaminants	Growth Condition	Main Finding
Amaranthus spp.	Phytoextraction	Pb, Cd, Cu, Zn, and nickel (Ni) in soil contaminated with industrial sewage	Greenhouse demonstration	Young plants have more potential to uptake and accumulate metals than older ones More Pb and Cd were transmitted at pH 6.3–6.5 after 35–45 days of growth
Jatropha curcas	Phytostabilization	Aluminum (Al), Cu, Zn, Pb,and Cd in polymetallic acid mine tailings	Greenhouse pot experiments	Highest accumulation of metals in roots A high tolerance index (>90%), no phytotoxic symptoms and stunted growth in moderately contaminated soil
	Rhizodegradation	Hydrocarbons in soil contaminated with lubricating oil	Room experiments	A large number of hydrocarbon‐utilizing bacteria in the rhizosphere region
	Phytoaccumulation	Cd, Cr, Pb, Zn, Ni, and Cu in contaminated field soils	Field-scale	Best absorption capability for Cd, Cr, Zn, and Ni
	Uptake and translocation	Heavy metals in sawdust sludge contaminated soils		Potential to accumulate high amounts of Cu, iron (Fe), aluminum (Al), Pd and Zn in roots, leaves, and stems
	Rhizoremediation	Lindane in garden soils	Greenhouse experiments	Accumulation of up to 20.85 μg g−1 lindane and reduction of up to 89% applied lindane
Hybrid poplars	Phytovolatization	Tetrachloroethylene (TCE) in water	Cell cultures and greenhouse experiments	Formation of TCE metabolites in tree tissues and cell cultures, Evapotranspiration and incorporation of TCE into an insoluble residue within the trees
Mauritius hemp (Furcraea gigantea Vent.)	Phytostabilization	Cr-contaminated soils	Pot culture experiment	Cr mainly accumulated in the roots with a tolerance of up to 50 mg Cr kg−1 soil

Emerging Contaminants in Our Drinking Water

• The most widespread chemical was chlorate which was measured above reference concentration in 38% of the public water supplies sampled.
• 1, 4-dioxane was found above reference concentration in 7% of public water supplies.
• Perfluorinated compounds PFOS and PFOA were present in 0.9% and 0.3% of public water supplies respectively.
• Chromium was found in only 0.02% of PWS above reference standard.

Challenges with the Emerging Pollutants

Modeling frame work for emertging pollutants has not been well developed till today. The fate and transport of various EPs has been bwwn well elucidated. EPs comes from various sources and depending upon its properties, EP can be transported by different processes like runoff, erosion or leaching and enter into groundwater or surface water. EPs from diffuse can be transported through soil-water system to the water body (i.e. sink) (McGuire & McDonnell, 2006). Once, EP reached to water bodies , they have been further transport to downstream in solution or attached to suspended material. Hence all the national rivers and lakes are contaminated with emerging pollutants. All the parameters related with all the EP has not been parameterized except for pesticides.

What We Know or Don’t Know!

• Certain emerging contaminants have been shown to interact with the endocrine system.
• There is scientific evidence to suggest that aquatic organisms have been effected.
• There is great scientific debate whether humans are effected at the environmental concentrations present today.
• USGS has detected many of these chemicals in water bodies throughout the United States.
• Many of these chemicals are routinely used by the average household.
• The widespread use of these chemicals allows for many points on entry to the environment.
• Wastewater treatment does not completely remove these chemicals from waste streams.