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Contaminant Candidate List (CCL): Definition, Regulations, Content

The Contaminant Candidate List (CCL, for short) is a list of contaminants that are expected to appear in the public water system. These contaminants are not subjected to any drinking water regulations from EPA.

The organization behind the Contaminant Candidate List is the Environmental Protection Agency (EPA). The purpose of EPA is to protect environmental and human health. It offers technical assistance to support the infrastructure and general health through water treatment plants.

EPA makes use of CCL to determine the priority of contaminants. The list will be used for regulatory decision-making as well as for the collection of information. The contaminants present on the CCL may be subjected to further regulation, based on the Safe Drinking Water Act (SDWA).

Water filter producers will ensure that they have the appropriate water filtering systems to remove the classified contaminants. This will ensure that the drinking water is safe for consumption.

The contaminants listed on CCL are as follows:

  1. Acanthamoeba
  2. Aldrin
  3. Dieldrin
  4. Hexachlorobutadiene
  5. Manganese
  6. Metribuzin
  7. Naphthalene
  8. Sodium
  9. Sulfate
  10. Boron
  11. Dacthal mono-acid (MTP) degradate
  12. Dacthal di-acid (TPA) degradate
  13. 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE)
  14. 1,3-Dichloropropene (Telone)
  15. 2,4-Dinitrotoluene
  16. 2,6-Dinitrotoluene
  17. s-Ethyl propylthiocarbamate (EPTC)
  18. Fonofos
  19. Terbacil

1. Acanthamoeba

Acanthamoeba is a free-living ameba of microscopic size. It is a single-celled living microorganism that lives in water and soil, as it is an environment where it can grow. The health effects of the ameba are low. Most people will likely be exposed to Acanthamoeba, but very few will develop symptoms.

Acanthamoeba is only a potential issue for people wearing contact lenses, and it can be avoided with proper contact lens care. The ameba is present on the CCL list because it can cause potential diseases such as Acanthamoeba keratitis.

To clean Acanthamoeba from the water, a UV filter or water filter may be used. The Acanthamoeba size ranges between 12 and 34 micrometers, meaning that a filter with a pore size smaller than that can purify it. Usually, ultrafiltration systems are enough in order to remove the ameba from the water.

2. Aldrin

Aldrin is a pesticide that is usually used in order to control insects from the soil such as worms, termites, grasshoppers, and many more. Aldrin is an organic pollutant that may occur in farm areas. Aldrin exists in the water because the soil absorbs it after the human sprays it on the soil.

In high quantities, aldrin can be very toxic to humans, causing damage to the liver and the nervous system. Municipal filters remove most of the aldrin from the water, which is why it is typically not a concern. In small quantities, aldrin can lead to irritation to the skin and the eyes, similar to Acanthamoeba.

Aldrin is part of the CCL regularly because it commonly occurs in the water and soil. Depending on the presence of aldrin in the water, it may need to be regulated. Carbon block water filters and ultrafiltration systems are typically very good at removing aldrin from the water. Even more efficient is a reverse osmosis water filter.

3. Dieldrin

Dieldrin is an insecticide defined as organochloride. Dieldrin is closely related to aldrin, as aldrin’s reaction in the soil often leads to the formation of dieldrin. Aldrin oxidizes within the insect in the soil, which will create the active compound of dieldrin.

Dieldrin exists within the water and soil as a result of oxidation in the insects and soil. In very small quantities, dieldrin may not prove too harmful, but repeated exposure may have a variety of health effects. Dieldrin’s occurrence is uncommon in municipal water but may appear for homeowners that draw well water.

The health effects of dieldrin can include headaches, dizziness, and stomach problems. Ingested in high quantities, dieldrin may cause cancer and damage to the immune system. Dieldrin is present in the CCL because, like aldrin, dieldrin can commonly occur in drinking water.

A water filter may easily purify the water from remnants of dieldrin. Ultrafiltration systems and carbon block filters are among the most suitable options to remove dieldrin remnants from drinking water. A reverse osmosis system can also be very helpful.

4. Hexachlorobutadiene

Hexachlorobutadiene is a contaminant that is colorless and has a mild odor, similar to turpentine. Hexachlorobutadiene does not occur naturally in the water, and it results only after a mix of other chemicals. Hexachlorobutadiene in drinking water can be very common, although it is only present in low concentrations between 1.9 and 4.7 µg/l.

Hexachlorobutadiene’s occurrence depends on the area, as farming grounds are more likely to have a higher concentration. Hexachlorobutadiene is used as a chemical solvent and as a pesticide, and its liquid state may allow it to enter the soil.

Studies show that exposure to Hexachlorobutadiene may have mild effects on the respiratory system, and kidney function of animals, but there is little information on how it may affect the health of humans. In very low quantities (which often happens with municipal water), it is rarely a matter of concern.

For those who wish to clear their drinking water of Hexachlorobutadiene, carbon filters, ultrafiltration systems, and reverse osmosis systems may be used. The smaller the pore size, the more efficient it will be when it comes to removing the contaminants. Brands such as GE Water for ultrafiltration or iSpring for reverse osmosis are fairly common.

5. Manganese

manganeseManganese is a mineral that is naturally occurring in water and a beneficial nutrient for the body. Manganese in drinking water occurs as the water erodes through the aquifer, taking the minerals from the soil. Manganese is not harmful to humans, but in fact, it is highly beneficial. Manganese helps strengthen the nervous system, the bones, and regulates blood sugar levels.

Manganese is present in the CCL because, while it is not a contaminant harmful to humans, it is still deemed a “contaminant.” For this reason, it may be subjected to regulation. While its presence may not be unhealthy for the human body, high amounts of manganese can turn the water hard and affect your home appliances.

Manganese particles measure between 10 and 15 microns, meaning that manganese can be removed with a sediment water filter or most kinds of filtering systems. A water softener may also be used, as it uses ion exchange to replace the manganese with sodium. This will remove the hardness from the water.

6. Metribuzin

Metribuzin is widely used as an herbicide, and it is a synthetic compound that occurs in waters with farming lands. Metribuzin is mostly detected within the lands and groundwaters of Minnesota, as a result of crop fertilization.

Metribuzin has low toxicity, and although studies on animals show that it may have developmental effects, it is not considered to be harmful and dangerous to humans. The soil filters the groundwater, in which case it is rare for Metribuzin to occur in groundwater in high amounts. Metribuzin has been deemed a Group D chemical, which makes it non-classifiable as a carcinogenic product. One may say that metribuzin has the same toxicity levels as Hexachlorobutadiene.

Metribuzin has an average particle size of 6 microns, which means that Metribuzin may be removed with a variety of filter types. A sediment water filter may be used, but for more efficiency, users may want to try an ultrafiltration system. Carbon block filters are also highly efficient in removing Metribuzin.

7. Sodium

Sodium is an essential mineral for the human diet, and it is a compound that we generally refer to as “salt.” Sodium is essential for the normal functioning of the body, and it naturally occurs in the groundwater as it erodes into the aquifer.

Considering that sodium can be found in all fluids and tissues in the human body, normal intakes of it are not considered harmful. Most of the population gets their highest salt intake from food, so water is not considered a high concern. Sodium levels in drinking water are generally considered low and harmless, even in groundwater.

In many cases, sodium does not have to be removed from the water because its presence is beneficial. If the opposite is desired and people want to remove salt particles, a sediment water filter or an ultrafiltration system may be used. Sodium can measure anything from 0.5 to 100 microns, which makes sediment water filters the most common choice.

8. Sulfate

Sulfates are sedimentation agents that are either added or occur naturally in drinking water. Sulfates are often added to drinking water to control algae formation. In most circumstances, sulfate is not harmful to humans.

However, if it goes over 500 milligrams per liter, sulfate can cause mild discomfort to the stomach (i.e., diarrhea or stomach pain). People with sensitive skin might experience irritation or acne breakouts. This is also the reason why sulfate is present on the CCL list.

Sulfates may be removed from the water through ion exchange, distillation, and reverse osmosis. Sediment water filters may also remove the sulfates to some extent, but they may not remove all of them.

9. Boron

Boron is a contaminant that naturally occurs in water and soil. It is usually mixed with oxygen, creating a compound called a borate (or boric acid). Borate can either form naturally in the soil, entering the water, or it may enter the soil through chemical solutions. This is because borate is often used to make detergents or insecticides.

The concentration of boron in drinking water will depend on the source of the water itself. However, in most cases, the range is between 0.1 and 0.3 mg per liter. This amount poses little to no harm or dangers to the human, as the total daily intake of boron may be between 1.5 and 2 mg.

Consumed above that range, boron can be toxic. Boron toxicity can have symptoms such as headaches, indigestion, renal issues, hypothermia, dermatitis, and alopecia. In most cases, the presence of boron in water is never that high, which means that municipal water and well water rarely lead to boron toxicity.

To clean boron out of the water, one may use a reverse osmosis system. Ion exchange filters that specifically target boron may also be used.

10. Dacthal mono-acid (MTP) degradate

Dacthal mono-acid (MTP) degradate is a herbicide compound that commonly occurs in areas where farming is a common activity. Dacthal mono-acid (MTP) degradate does not occur naturally, as it enters the ground through the farmland fertilization process. Dacthal mono-acid (MTP) is part of a pesticide category called degradates.

In small amounts, dacthal is usually not harmful to the human body. However, consumed in high amounts, it can lead to dacthal exposure toxicity. This can have various side effects such as damage to the liver or immune system. In severe cases, dacthal exposure toxicity might lead to birth defects and even cancer.

Dacthal mono-acid (MTP) degradate is in the CCL because it is commonly present in the water. Depending on the area, the concentrations might depend. This is why it is regularly listed in the CCL, to determine whether regulation is necessary or not.

Dacthal mono-acid (MTP) degradate can range between 1 micron and 40 microns. In most cases, sediment water filters are not enough to clean the water of dacthal mono-acid (MTP) degradate. To remove dachtal from the water, the ideal choice would be to use an ultrafiltration system or a reverse osmosis filter. One more suitable choice would be a carbon block filter system. Users can also opt for distillation in order to clean dacthal mono-acid (MTP) from the water.

11. Dacthal di-acid (TPA) degradate

Dacthal di-acid (TPA) degradate is similar to dacthal mono-acid (MTP) degrade, the only difference between them being a slight chemical structure. Dacthal di-acid (TPA) degradate is also often used as a herbicide, which is why it is a common occurrence in waters of agricultural areas.

The concentration of dacthal di-acid (TPA) degradate usually occurs in areas with a lot of crops and farmlands, but it may also be found in the water plants of the cities. Municipal water often uses sediment water filters, which is why this contaminant may slip into the tap water. Sediment water filters can capture some of the contaminants, but some dacthal di-acid (TPA) degradate compounds may still slip.

In small amounts, the ones normally occurring in water, dacthal di-acid (TPA) degradate is usually not harmful to the health. However, consumed in higher amounts, or for those who are sensitive to the substance, dacthal di-acid (TPA) degradate can lead to gastrointestinal issues, immune system problems or even liver damage.

Like its counterpart, dacthal di-acid (TPA) degradate can be removed from the water through reverse osmosis and ultrafiltration systems. Distillation systems and carbon block filters may also be a good way to remove these contaminants from the water.

12. Dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE)

Dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) is an organochlorine pesticide that commonly occurs in both groundwater and municipal water. DDE is a metabolite of DDT, which was often used as an anti-androgen.

In most cases, dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) does not harm the body if it is ever ingested in the human system. Usually, the amount that occurs in public water is not enough to turn it into a health risk. DDE is on the CCL list because it still occurs to some extent in the water – whether it is in harmful amounts or not.

DDE also naturally occurs in food in quantities up to 0.102ppm, which means that there is little danger if ingested only in small amounts. No long-term effects have been noted after exposure to dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE). Considering it is a pesticide, the EPA still advises that users clean the water before drinking it.

In order to clean the water of DDE, users may use a distiller. Sediment water filters are typically not enough to remove the DDE, as the pores are too large. Ultrafiltration systems may also be used, along with reverse osmosis filters.

13. Dinitrotoluene

Dinitrotoluene is a compound made from combining toluene and nitric acid. Dinitrotoluene is used as a deterrent coating, plasticizer, or modifier within a propellant. It often enters soil and water as a result of pollution.

Dinitrotoluene is considered to be harmful not only to humans but also to most living microorganisms. This is why EPA labels Dinitrotoluene as a priority pollutant, subject to regulation on the CCL document. Ingested even in small amounts, Dinitrotoluene can be toxic to humans. Continuous exposure may lead to damage to all the organs.

If the water tests positive for dinitrotoluene, it is recommended that the water is cleaned using a filtering system. Reverse osmosis filters are the recommended choice, but ultrafiltration systems may also remove the offending contaminant. Compared to the other contaminants occurring in the water, dinitrotoluene is among the most dangerous.

14. s-Ethyl propylthiocarbamate (EPTC)

s-Ethyl propylthiocarbamate (EPTC) is a volatile herbicide that is often used in the fertilization or pest control of farm crops. EPTC controls the germination of weeds, and it is then absorbed into the soil, making its way into the aquifer. s-Ethyl propylthiocarbamate (EPTC) has been labeled as a pesticide that can be fairly harmful to humans when consumed in large amounts, which is why it is present on the CCL.

High amounts of s-Ethyl propylthiocarbamate (EPTC) can cause a variety of side effects to the human body, such as skin irritation, liver damage, and stomach problems. EPTC is less dangerous than dinitrotoluene, but more harmful than metribuzin.

A water filter can clean EPTC from the water. Small-pore water filters represent the best solution, in which case an ultrafiltration system or a reverse osmosis system might be the most appropriate choice.

15. Fonofos

Fonofos is classified as an organothiophosphate pesticide, used mainly in the treatment of corn. Fonofos often enters groundwater through the soil, after the crops have been fertilized. The size of the fonofos particles can go lower than 1 micron, which means that a regular sediment water filter will not be able to capture the contaminant.

Fonofos is highly toxic to the human body, and it has been deemed a potential Carcinogen by the EPA. For that reason, fonofos has been listed as a priority contaminant on the CCL, in a similar manner to dinitrotoluene. Fonofos is a hazardous substance and may cause uncomfortable side effects even in small amounts.

Fonofos exposure may result in tightness in the chest, nausea, headache, blurred vision, skin irritation, and vomiting. If ingested in high amounts, fonofos may even lead to death. It also gives off strong irritating odors, which can make drinking the water dangerous. Compared to other contaminants from the CCL, fonofos has a much higher toxicity level, in which case it should be removed completely from the water.

Reverse osmosis systems are often the best choices to clean the water of fonofos. They have the smallest pore size, which will prevent the contaminant from entering the house system. A combination between an ultrafiltration system and a distiller may also be used to clean the water of fonofos.

16. Tetrachloroethane

tetrachloroethaneTetrachloroethane is a contaminant that is often found in drinking water. Its chemical structure is as an ethane chlorinated derivative. Tetrachloroethane is one of the most powerful solvents within the water and was generally used as a method to clear bacteria, viruses, and other live contaminants from the water.

Tetrachloroethane was also a common method to clean air crafts and other surfaces. This would lead the contaminated water to go straight into the soil. Once absorbed, it would enter the aquifer and contaminate groundwater.

In small amounts, tetrachloroethane is not harmful to humans. People with high sensitivity might experience mild discomforts such as stomach aches, numbness, dizziness, tremors, or skin irritation. At the same time, prolonged exposure to high amounts of tetrachloroethane can be harmful. Tetrachloroethane is a strong hepatotoxicant, which is why it is rarely used in the treatment of water.

Nowadays, its occurrence in water is very small, but certain amounts are still discovered. For this reason, Tetrachloroethane is still in the CCL and subjected to regulation. To prevent any side effects, it is recommended that tetrachloroethane is removed from the water.

Water filters can efficiently clean tetrachloroethane from the water. The most efficient option is an ultrafiltration system that uses a carbon block filter. Reverse osmosis filters are also an efficient option to remove tetrachloroethane, as the small pores can remove most of the contaminants from the water.

What Is the Regulatory Determination for Contaminants in Drinking Water?

The regulatory determination for contaminants in drinking water is a formal decision released by EPA. It decides on whether EPA needs to initiate a process in which they develop new regulations or not. These regulations would concern a contaminant that is part of the list.

To regulate a contaminant from the water, SDWA had to determine whether a contaminant:

  • May have potential health effects on a person
  • It is likely to occur in water at a level that may be a public health concern
  • From the Administrator’s judgment, its regulation has enough opportunity to improve the quality of the water.

The list is regularly updated, maintaining previous contaminants while proposing new ones. From that list, it will be determined whether a contaminant requires regulation or not.

What Is the Regulatory Determination 1 for Contaminants on the Drinking Water Contaminant List (CCL)

The Safe Drinking Water Act (SDWA), which was amended in 1996, required EPA to create a list of contaminants to assist their water treatment efforts. The list was finalized in 1998, after which it was directed towards the next step.

SDWA asked the agency to select more than five contaminants from the existent list and determine whether or not the contaminants were to be regulated with the Regulatory Determination 1 for Contaminants on the Drinking Water Contaminant List (CCL). The deadline for the selection was August 2001.

After EPA finished publishing its protocol and making the primary determinations, the list requested public comment. Later on, through the Regulatory Determination 1 for Contaminants on the Drinking Water Contaminant List (CCL), it was determined that the following contaminants required no regulatory action:

  • Aldrin
  • Acanthamoeba
  • Hexachlorobutadiene
  • Metribuzin
  • Manganese
  • Dieldrin
  • Sodium
  • Naphthalene
  • Sulfate

What Is the Regulatory Determination 2 for Contaminants on the Drinking Water Contaminant List (CCL)

The Regulatory Determination 2 for Contaminants on the Drinking Water Contaminant List (CCL) is a list that was finalized in 2005. In this document, a total of eleven contaminants were selected for regulatory action. In the end, EPA determined that none of the following eleven elements needed regulatory action:

  • Dacthal mono-acid (MTP) degradate
  • Boron
  • Dacthal di-acid (TPA) degradate
  • 1,3-Dichloropropene (Telone)
  • 2,6-Dinitrotoluene
  • 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE)
  • Fonofos
  • 2,4-Dinitrotoluene
  • s-Ethyl propylthiocarbamate (EPTC)
  • 1,1,2,2-Tetrachloroethane
  • Terbacil

What Is the Regulatory Determination 3 for Contaminants on the Drinking Water Contaminant List (CCL)

Regulatory Determination 3 for Contaminants on the Drinking Water Contaminant List (CCL) is a list that was set up in 2009 and finalized in 2016. Four contaminants were nominated for regulation. It was determined on the 4th of January 2016, that the following contaminants would not be subject to regulation:

  • Dimethoate
  • Terbufos
  • Terbufos sulfone
  • 1,3-dinitrobenzene

What Is the Regulatory Determination 4 for Contaminants on the Drinking Water Contaminant List (CCL)

On February 20, 2020, the EPA announced the 4th list for regulatory determination of the contaminants in the water. Eight CCL4 contaminants were nominated for preliminary regulatory determination. Six common contaminants were not regulated, whereas two received regulation.

The following contaminants received preliminary determination to be regulated:

  • Perfluorooctanoic acid (PFOA)
  • Perfluorooctanesulfonic acid (PFOS)

It was determined that the following contaminants would not receive regulation:

  • Nitrobenzene
  • 1,1-dichloroethane
  • Metolachlor
  • Acetochlor
  • Methyl bromide (bromomethane)
  • RDX

What Is the Relation Between Water Pollution and CCL?

The CCL lists unregulated contaminants that may need further investigation. SDWA defines a contaminant as any other chemical that is present in the water, no matter if it is harmless for consumption or not. The CCL presents all elements that are found within the water and regulates the ones that are likely to increase the water pollution levels.

What Is the Dominant Type of Water Contaminant within CCL?

The dominant types of water contaminants within CCL are microorganisms and nitrates, depending on the area of control. In other areas, the dominant water contaminant types may be insecticides, herbicides, and bacteria/virus-control contaminants.

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