Contaminants of emerging concern

Contaminants of Emerging Concern (CECs) is a term used by water quality professionals to describe pollutants that have been detected in water bodies, that may cause ecological or human health impacts, and typically are not regulated under current environmental laws. Sources of these pollutants include agriculture, urban runoff and ordinary household products (such as soaps and disinfectants) and pharmaceuticals that are disposed to sewage treatment plants and subsequently discharged to surface waters.[1][2]

Examples of emerging contaminants are 1,4-Dioxane, food additives, pharmaceuticals, and natural & synthetic hormones. CECs have the ability to enter the water cycle after being discharged as waste through the process of runoff making its way into rivers, directly through effluent discharge, or by the process of seepage and infiltration into the water table, eventually entering the public water supply system. Emerging contaminants are known to cause endocrine disrupting activity and other toxic mechanisms, some are recognized as known carcinogens by the United States Environmental Protection Agency (EPA).[3]

General problem

For a compound to be recognized as an emerging contaminant it has to meet at least two requirements:

1. Somewhere in the world people are hampered by the effect(s) of the compound.
2. There is an established relationship between the positive and negative effect(s) of the compound.

These contaminants were not previously detected by systems which analyze water quality, or they were found in much smaller concentrations. They are of emerging concern because we do not yet fully understand the risk they pose to human or environmental health.

Hamperings

Somewhere in the world

Due to the large differences in transportability of compounds, there is a great level of variance contaminant to contaminant between the location of contamination and the place of occurring hazards. An example of the a contaminant which can have detected hazards at the point of origin is the effect of municipal solid waste on the environment through seepage and particulate pollution. On the other hand, the effects of water-soluble contaminants may be obscured a long time as they are washed far away from the contamination site and only slowly accumulate in oceans and groundwater to harmful concentrations. The same is true for air "soluble" gasses like carbon dioxide: they dissolve in the vast quantity of the atmosphere, and accumulate over time. Emerging Contaminants pose a danger through drinking water as well as air, the Environmental Protection Agency began researching vapor intrusion in the context of emerging contamination in the past years. Vapor Intrusion occurs when contaminants which are subsurface are vaporized, allowing them to enter into public buildings and homes. VI poses a danger to individuals through worsening indoor air quality as well as near-term safety hazards.[4]

Relation between the compound and effects

There is an overlap of many anthropogenically sourced chemicals that humans are exposed to regularly. This makes it difficult to attribute negative health causality to a specific, isolated compound. EPA manages a Contaminant Candidate List to review substances that may need to be controlled in public water systems.[5] EPA has also listed twelve contaminants of emerging concern at federal facilities, with ranging origins, health effects, and means of exposure.[6]

Selected compounds listed as emerging contaminants

Table 1 is a summary of data on the twelve emerging contaminants currently listed on one EPA website regarding federal government facilities. EPA published a fact sheet about each contaminant which has been summarized in three categories below.[3]

Compound	Uses	Where it is Found	Health Risks
Trichloropropane (TCP)	Chemical intermediate, solvent, and cleaning product	TCPs are denser than water, so they sink to the bottom of aquifers and contaminate them, they also have a low capacity to be absorbed organically and leach into soil or evaporate, contaminating the air	Considered a likely carcinogen by NOAA
Dioxane	Stabilizer of chlorinated solvents, manufacturing of PET, manufacturing by-product	Often at industrial sites, and they move rapidly from soil to groundwater, although it was phased out as part of the Montreal Protocol it is very resistant to bio-degradation and has been found at over 34 EPA sites	Rapid disruption of lung, liver, kidney, spleen, colon, and muscle tissue, may be toxic to developing fetuses and is a potential carcinogen
Trinitrotoluene (TNT)	Pure explosive, military and underwater blasting	Major contaminant of groundwater and soils	Listed as cancer-causing by Office of Environmental Health, may cause carcinoma and bladder papilloma
Dinitrotoluene	Intermediate to form TNT, explosive	Found in surface water, groundwater, and soil at hazardous waste sites, and may be released into the air as dust or aerosols	Considered a hepatocarcinogen and may cause ischemic heart disease, hepatobiliary cancer, and urothelial and renal cell cancers
Hexahydro-trinitro-triazane (RDX)	Military explosive	Exists as particulate matter in the atmosphere, easily leaches into groundwater and aquifers from soil, does not readily evaporate from water	Decreased body weight, kidney and liver damage, possible carcinoma, insomnia, nausea, and tremor
Nanomaterials	Broad classification of ultrafine particulate matter used in more than 1,800 consumer products and biomedical applications	Released as consumer waste or spillage, may be airborne, found in food, or in many diverse industrial processes	May translocate into the circulatory system primarily through the lungs, exposing the body to an accumulation of compounds in the liver, spleen, kidney, and brain
N-nitroso-dimethylamine (NDMA)	Formed in the production of antioxidants, additives, softeners, and rocket fuel, and an unintended byproduct of the chlorination of waste and drinking water at treatment facilities	Broken down quickly when released into the air, but highly mobile when released into soil and will likely leach into groundwater, humans may be exposed by drinking contaminated water, ingesting contaminated food, or using products that contain NDMA	Probable carcinogen, evidence of liver damage, reduced function of kidneys and lungs
Perchlorate	Manufacturing and combustion of solid rocket propellants, munitions, fireworks, airbag initiators, and flares	Highly soluble in water so it can greatly accumulate in groundwater, also accumulates in some food crop leaves and milk	Eye, skin, and respiratory irritation and in high volumes corrosion. Potentially disrupts thyroid hormones
Perfluoro-octane sulfonate (PFOS) and Perfluorooctanoic acid (PFOA)	Used in additives and coatings, non-stick cookware, waterproof clothing, cardboard packaging, wire casing, and resistant tubing	During manufacturing, the compounds were released into the surrounding air, ground, and water, is resistant to typical environmental degradation processes and have been shown to bioaccumulate, found in oceans and Arctic, meaning they have a high capacity for transport	World Health Organization categorized possible carcinogen, may cause high cholesterol, increased liver enzymes, and adverse reproductive and developmental effects
Polybrominated biphenyls (PBBs)	Flame retardant	Detected in the air, sediments, surface water, fish and other marine animals, they do not dissolve so they are not mobile in water but are volatile and prevalent in the atmosphere	Classified by International Agency for Research on Cancer classified as likely carcinogenic, neurotoxic, and thyroid, liver, and kidney toxicity as well as an endocrine disruptor
Polybrominated diphenyl ethers (PBDEs)	Flame retardant and used in plastics, furniture, and other household products	Enter the environment through emissions, and has been detected in air, sediments, surface water, fish and other marine animals	Shown to be an endocrine disruptor as well as carcinogenic, also, may cause neural, liver, pancreatic, and thyroid toxicity
Tungsten	A naturally occurring element which exists in various household products and military manufacturing	Tungsten is water-soluble and may be found in dangerous quantities in water sources	May cause respiratory complications, and investigated as a potential carcinogen by the CDC

Examples from the Past

There have always been, and will likely always be emerging contaminants in our water supplies, because the list is ever-evolving and many compounds that are intensely regulated now due to their harmful nature were in food, water, and the environment casually in the past.

• In the 1950s asbestos was not considered a hampering to personal and environmental health at all. Asbestos was investigated for the first time in 1977 by the National Research Council, and they had completed limited research which suggested the adverse health effects of consuming asbestos fibers in drinking water.[7] Today it has passed the status of concern and entered territory of clear causal relationships with negative health impacts and strict regulation, but it took the compound a long time to move from being a miracle material for construction to its present status of harmful contaminant.
• As recently as the 1970s there was a serious issue with the water treatment infrastructure of some states, notably in Southern California with water sourced from the Bay Delta. Water was being disinfected for domestic use through chlorine treatment, which was effective for killing microbial contaminants and bacteria, but in some cases, it reacted with runoff chemicals and organic matter to form trihalomethanes. Research done in the subsequent years began to suggest the carcinogenic and harmful nature of this category of compounds, but the burden fell to the water treatment plant and providers to clean the water, not the federal government. It took many years to get hard regulation of these chemicals passed federally, in fact, the Maximum Contaminant Level for THMs was lowered again in 2001 as more research continues to become available.

Risks and Regulations

Further information: Water pollution

Emerging contaminants are most often addressed as a hampering in issues concerning water quality. The release of harmful compounds into the environment which find their way into municipal food, water, and homes have a negative externality on social welfare. These contaminants have the capability to travel far from the point-source of their pollution into the environment and accumulate over time to become harmful because they have been left unregulated by federal agencies. These harmful compounds cause damage to environmental and human health, and they are difficult to trace therefore it is challenging to establish who should foot the bill for the damage done by ECs. Because these contaminants were not detected or regulated in the past, existing treatment plants are ill-equipped to remove them from domestic water.[8] There are sites with waste that would take hundreds of years to clean up and prevent further seepage and contamination into the water table and surrounding biosphere. In the United States, the environmental regulatory agencies on the federal level are primarily responsible for determining standards and statutes which guide policy and control in the state to prevent citizens and the environment from being exposed to harmful compounds. Emerging Contaminants are examples of instances in which regulation did not do what it was supposed to, and communities have been left vulnerable to the adverse health effects of ECs. Many states have assessed what can be done about emerging contaminants and currently view it as a serious issue, but only eight states have specific risk management programs addressing emerging contaminants.[9]

Solutions

For some emerging contaminants, the EPA has suggested that the best control for them is through advancing technology at treatment plants[10]. One suggestion is "enhanced coagulation" in which the treatment entity would work to optimize filtration by removing precursors to contamination through treatment. In the case of THMs, this meant lowering the pH, increasing the feed rate of coagulants, and encouraging domestic systems to operate with activated carbon filters and apparatuses that can perform reverse osmosis. Although these methods are effective, they are costly, and there have been many instances of treatment plants being resistant to pay for the removal of pollution, especially if it wasn't created in the water treatment process as many EC's occur from runoff, past pollution sources, and personal care products. It is also difficult to incentivize states to have their own policies surrounding contamination because it can be burdensome for states to pay for screening and prevention processes. There is also an element of environmental injustice, in that lower income communities with less purchasing and political power cannot buy their own system for filtration, and are regularly exposed to harmful compounds in drinking water and food.

See also

• Water pollution

References

1. "Contaminants of Emerging Concern including Pharmaceuticals and Personal Care Products". Water Quality Criteria. Washington, D.C.: U.S. Environmental Protection Agency (EPA). 2019-08-19.
2. "Contaminants of Emerging Concern in the Environment". Environmental Health—Toxic Substances Hydrology Program. Reston, VA: U.S. Geological Survey. 2017-06-16.
3. "Emerging Contaminants and Federal Facility Contaminants of Concern". EPA. 2019-04-04.
4. "What is Vapor Intrusion?". Vapor Intrusion. United States Environmental Protection Agency. 2015-09-23. Retrieved 9 March 2019.
5. "Basic Information on the CCL and Regulatory Determination". EPA. 2019-07-19.
6. One example of a listed chemical is RDX, an explosive. "Technical Fact Sheet – Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)" (PDF). EPA. November 2017. EPA 505-F-17-008.
7. "Epidemiology of the Adverse Health Effects of Arsenic and Asbestos in Drinking Water". Drinking Water and Health. 5. 1983.
8. Gogoi, Anindita (March 2018). "Occurrence and fate of emerging contaminants in water environment: A review". Groundwater for Sustainable Development. 6: 169–180. doi:10.1016/j.gsd.2017.12.009.
9. Anderson, Janet. "EC State Summary Report" (PDF). integral-corp.com. Integral Consulting. Archived from the original (PDF) on 2019-03-31.
10. Fraiese A., Naddeo V., Uyguner-Demirel C. S., Prado M., Cesaro A., Zarra T., Liu H., Belgiorno V., Ballesteros F. "Removal of Emerging Contaminants in Wastewater by Sonolysis, Photocatalysis and Ozonation".CS1 maint: multiple names: authors list (link)