Water Quality InformationWritten By Actual Experts

Stephanie Angione, Ph.D.  |  Scientific Contributor

Pesticides are chemicals used to kill environmental pests including insects, weeds, fungi and rodents. These are commonly divided into insecticides (used to specifically target and kill insects) and herbicides (used to kill undesirable plants or “weeds”). The most widely used agricultural pesticides are herbicides, which account for 40% of all pesticide use in the US. In typical agriculture, pesticides are applied to crops in order to provide protection against destructive insects and invasive weeds or fungi. By design, pesticides kill or deter pests and thus are toxic to their intended target organisms. Additionally, many pesticides are toxic to humans, and organochlorine pesticides are 9 of the 12 most toxic organic chemicals, as outlined by the Stockholm Convention in 2001.

Which Pesticides Are Most Commonly Found In US Water Systems?

The most comprehensive information available about pesticide occurrence at the national level is part of a 10-year program by the National Water-Quality Assessment (NAWQA), part of the US Geological Survey (USGS). It provides information about pesticide concentrations in streams and groundwater from data collected between 1991-2001.

Major findings of this study are that pesticides exist in both streams and groundwater throughout the US, in both urban and rural areas, but seldom occur at concentrations that will affect human health. Of the water systems studied, pesticides were found 90% of the time in streams throughout the US in urban and agricultural areas. Groundwater sources were less affected by pesticide contamination, with shallow groundwater sources in agricultural and urban areas having pesticides 61% and 55% of the time respectively.

The most commonly detected pesticides in stream water include five agricultural herbicides, atrazine, metolachlor, cyanazine and acetochlor and five non-agricultural herbicides in urban areas, including simazine, prometon, tebuthiuron, 2,4-D and diuron and three insecticides – diazinon, chlorpyrifos and carbaryl (Figure 1).

Figure 1: Percentage of samples found with pesticide contamination in agricultural and urban stream water (upper) and groundwater (lower).

Additionally, pesticides detected the most frequently in fish and streambed sediment were organochloride pesticides and degradation products (Figure 2). Organochlorides were used heavily in the 1950s and 1960s and were largely abandoned by the 1980s. However these compounds including DDT are very persistent in soils, sediments and animals, and were thus found at high levels in stream sources.

Figure 2: Percentage of samples of fish tissue containing organochlorine pesticides and degradation products in agricultural and urban streambeds

Despite the widespread existence of pesticides in water systems, levels of pesticides only exceeded human health benchmarks in about 10% of agricultural streams, and 7% of urban streams studied. It should be noted that for public water supply intakes that withdraw water from streams in the US, only 12% are from an agricultural land-use areas, and only 1% from an urban land-use areas. As for groundwater, only 1% of wells sampled had pesticide levels above human health benchmarks.

As for the pesticides present at these excessive concentrations, the most commonly found were atrazine, cyanazine, diazinon and dieldrin. Notably, stream contamination was commonly atrazine and cyanazine and well contamination was dieldrin, which is no longer used but is a known persistent pollutant.

While the compounds discussed above were detected the most frequently in the study period from 1992-2001, pesticide usage changes as new pesticides are developed. A new study of streams sampled in the US in 2015 by the USGS indicates the existence of the relatively new class of pesticides- neonicotinoids, in US water systems. The study found at least one neonicotinoid detected in 53% of all samples, with imidacloprid detected the most frequently (37%). Guidelines on the effects of neonicotinoids in humans and safe levels of exposure have not yet been systematically investigated.

In addition, a 2022 study revealed that very high levels of PFAS were detected in 6 of 10 varieties of pesticides commonly used in rural and agricultural environments. 

For more information on tracking of common pollutants and pesticides in drinking water, the USGS has an interactive map to examine levels of pesticides nationwide.

How Is Pesticide Contamination Regulated?

The EPA regulates pesticides nationally under the Federal Insecticide, Fungicide and Rodenticide Act to protect human health and the environment. Aside from the 141 banned and severely restricted pesticides, the EPA has set limits on the allowable amount of pesticides in food and drinking water. Many pesticides including alachlor, atrazine, carbofuran, chlordane, 2,4-D, glyphosate, heptachlor, and simazine are included in the national primary drinking water standards that outline the maximum contaminant level for each compound. Public water suppliers are required to maintain levels below the maximum contaminant level for all compounds listed. The EPA has also established 394 human health benchmarks for pesticides that are registered for use on food crops but are not regulated under the national primary drinking water standards.

How Do I Find Out If My Drinking Water Is Contaminated With Pesticides?

If you are concerned about the effects of pesticides in your drinking water and are served by a public water system, your local water supplier is required to issue a Consumer Confidence Report that lists contaminant levels in the water supply. If you have a private well, a laboratory can test your drinking water.

Although the EPA regulates many pesticides as drinking water contaminants, there are many that are not. Additionally, levels of pesticide contamination can vary widely depending on the agricultural season and pesticides can be used in water systems to control pests like mosquitos.

If you get water from a household well, the local health department should have information about ground water quality and contaminants of concern, but it is often a good idea to have your water tested by a certified laboratory for contaminants. The EPA’s Safe Drinking Water Hotline (800-426-4791) can provide additional resources in your local area. It is also important to consider the proper use of pesticides at home if you have a private well, as pesticide runoff can contribute to well contamination.

How Do I Remove Pesticides From Drinking Water?

A home water filtration system can remove pesticides from drinking water that may not fall under EPA regulation. Water filter systems that use activated carbon as part of the filtration media blend or reverse osmosis can be effective in removing pesticides from water. Contrary to what some people tell you, boiling/freezing water does NOT remove pesticides from drinking water!

Do You Have More Questions About Pesticides In Drinking Water?

At Hydroviv, we make it our business to help you better understand your water. As always, feel free to take advantage of our “help no matter what” approach to technical support! Our Water Nerds will work to answer your questions, even if you have no intention of purchasing one of our water filters. Reach out by dropping us an email (hello@hydroviv.com) or through our live chat. You can also find us on Instagram, Twitter or Facebook!

Aakriti Pandey  |  Contributor

Editor's Note: This article is part of a new initiative to include stories on our blog that link scientific policy to everyday life. Recently, the new administration proposed changes to the EPA budget that would gut the Great Lakes Restoration Initiative (GLRI), which could impact the water quality of major cities (e.g. Chicago, Milwaukee) 

An upward slope

A downward slide

Analies Dyjak  |  Policy Analyst

This past Tuesday, February 20th, 2018, a lengthy lawsuit of eight-years ended in an $850 million settlement in favor of the state of Minnesota.

If you’re unfamiliar with the water crisis in Minnesota, here’s a quick recap:

In 2010 the state of Minnesota filed suit against 3M, a manufacturing company based out of Maplewood, Minnesota. The lawsuit came about because of allegations that 3M had been knowingly and improperly disposing of perfluorinated chemicals (PFC’s) such as perflurooctanoic acid (PFOA), and perfluorooctanesulfonic acid (PFOS) for decades. This probably sounds familiar to GenX contamination in North Carolina. 3M publicly stated their phase-out of PFC-like compounds in 2000. In 2004, 67,000 households in communities such as Lake Elmo, Oakdale, Woodbury and Cottage Grove had traces of PFC’s in their drinking water. In 2010, the state of Minnesota initially asked for $5 billion from 3M for natural resource and environmental degradation. In a last ditch effort to avoid trial, the state of Minnesota was granted an $850 million settlement on behalf of 3M. 3M claims that the settlement doesn’t make them guilty of poisoning thousands of people in Minnesota, but rather to show their commitment to environmental stewardship.

How Did The PFC Contamination Get Into Drinking Water?

3M had been disposing of PFC’s in their privately owned landfills as well as certain public landfills in Washington County since the 1950’s. It’s uncertain if 3M disclosed to the public landfills that PFOA’s and PFOS’s would be a part of their industrial hazardous waste permits. Additionally, cap technology in the in the 1950’s and up to the 1970’s was not nearly as advanced as it is today. Once the chemicals were disposed of in the landfill, over time they leached through the lining and into surrounding groundwater.

Health Effects of PFC’s, PFOA’s and PFOS’s

Health experts in Minnesota have seen higher rates of cancers, leukemia, premature births and lower fertility rates in suburbs near 3M manufacturing. This is a pretty constant trend when looking into long term exposure of perfluorinated chemicals. A University of California, Berkeley professor reported a 30% increase in low birth-weights and premature births between the years of 2001 and 2006 in Oakdale, a suburb of a 3M manufacturing plant.

Where Will the Money GO?

According to the Minnesota Attorney General, the settlement will be used to fund projects involving drinking water and water sustainability (whatever that means). $850 million may seem like a substantial peace offering, but the state came to the conclusive amount of $5 billion for a reason. This was the well-researched amount of money that state experts determined for damage done by 3M. Does this mean that the drinking water problem is completely fixed? No. It’s not guaranteed that every household will receive compensation and funding for a proper filtration system. The same UC Berkeley professor estimated the economic cost of the pollution; $1.5 billion in natural resource damages, $830 million in financial damages to existing households, and $309 million for people moving to the area by 2050. So although the settlement is significant, it won’t nearly be able to remediate all existing damages.

Summary

The settlement in Minnesota is a win for the environmental and the millions of individuals affected by 3M. There is still uncertainty regarding how the settlement money will be allocated, and which projects will be prioritized.

_______________________________________________________________

Brief History of 3M in Minnesota

3M initially began producing PFC’s in the 1950’s. Of course commercial-scale production of PFC’s were almost completely unregulated during this time. The Clean Water Act and National Environmental Policy Act weren’t codified until 1970. Knowledge of PFC-like contaminants was minimal and economic pressure was high.

Prior to any knowledge of PFC’s, 3M focused its attention on remediation efforts to volatile organic compounds (VOC’s). VOC’s were first found in groundwater in Washington County in 1966. Because of this, state permitting agencies and 3M were all aware of the hydrology of this area.

Other Articles We Think You'll Enjoy

Analies Dyjak  |  Hydroviv Policy Analyst

Updated 3/13/2024

What Is Groundwater?

Groundwater is submerged water located among soils, cracks and pores, beneath the surface of the earth. Groundwater travels down a gradient through geological formations and is stored in aquifers. Aquifers act as holding tanks for readily available drinking water. Rain patterns, hydrology, and ice/snow melt are the primary factors that affect how quickly a groundwater supply is replenished, also known as recharge. The recharge rate is how quickly aquifers are able to replenish the groundwater level after an influx of water.

Why Is Groundwater So Important?

It’s simple: It supplies drinking water to millions of Americans whose municipalities draw from groundwater sources (e.g. Miami, Tucson, Lincoln), as well as the 15% of people living in the U.S that use private wells as their drinking water source. In fact, the US Geological Survey estimates that 140 million people, or about 40% of the nation's population get their drinking water from groundwater sources, which include both municipal (city) water and private wells. Groundwater is also a major supplier of surface water in oceans, lakes, streams, ponds and wetlands. Crucial habitats and ecosystems are dependent on an influx of healthy groundwater, as well as surface water for public drinking water usage.

How Can Groundwater Become Polluted?

There are two major ways that groundwater can accumulate toxic chemicals:

1. Natural-occurring chemicals: In some regions of the country, things like arsenic, radium, and uranium are naturally found in the rocks that come in contact with groundwater. 
2. Man-made Pollution: Groundwater can also become contaminated by human activities including: agriculture, industry, landfills, localized pollution, and anything that involves discharging effluent into a surrounding waterway. Polluted water seeps through soil until it reaches the water table, where it can travel freely depending on the hydrology and permeability of an aquifer. Contaminants that are particularly soluble in water (such as PFAS and 1,4-dioxane) can migrate into groundwater aquifers that serve as drinking water sources. Polluted groundwater then slowly travels through aquifers until reaching nearby surface water or being pumped through a well and consumed as drinking water.

Are There Federal Regulations That Protect Groundwater?

The Ground Water Rule was created in 2006 by the U.S Environmental Protection Agency to improve and inspect drinking water sources that may be potentially polluted by fecal contamination. This rule does not address human-made toxic and carcinogenic groundwater contamination. Additionally, the Ground Water Rule is specific to public water systems and excludes private wells.

The Federal Government does not oversee or have anything to do with regulating private wells. In fact, private wells aren’t even regulated by the Safe Drinking Water Act. This means that it’s at the discretion of the homeowner to determine if their private well water is safe for consumption. Testing private well water is extremely expensive and at times ineffective if the contamination type and concentration is continuously changing. Additionally, The Federal Government doesn’t regulate many of the contaminants in questions today.

How Can I Learn More About My Water?

If you have any questions about groundwater and regional water information, we encourage you to take advantage of Hydroviv’s “Help No Matter What” approach to technical support, where we will help you, even if you have no desire to purchase one of our water filters. Truth be told, we have access to a much larger pool of water quality data than is easily accessible to the general public. You can reach our water nerds by emailing hello@hydroviv.com or opening a Live Chat window in the bottom corner of this screen.

Other Articles We Think You'll Enjoy