Toxic Tuesdays

Trihalomethanes (THMs)

Toxic Tuesdays

CHEJ highlights several toxic chemicals and the communities fighting to keep their citizens safe from harm.

Trihalomethanes (THMs)

Trihalomethanes (THMs) are a class of chemical compounds which contain three halogen atoms. Common THMs include chloroform, fluoroform, and chlorodifluoromethane. While THMs are used in some industrial processes like refrigeration, people are most likely to be exposed to them through drinking water. Most water utilities use small amounts of chlorine as a disinfectant to keep water supplies clean. While adding chlorine is generally accepted to be an important practice to protect public health, this chlorine can react with organic matter in the water and create THMs. Drinking contaminated water is generally considered to be the most serious route of exposure to THMs, though one study has found that bathing with contaminated water causes even higher exposure. THMs are odorless and flavorless, so people may not know if they have been exposed.

Many types of THMs have adverse health effects upon exposure, and there are four that are known to be particularly harmful to human health:

  1. Chloroform is known to cause lung, liver, and kidney damage, and in high doses can lead to death. In studies of laboratory animals, drinking chloroform-contaminated water caused liver and kidney cancer. The Environmental Protection Agency (EPA) classifies it as a likely cancer-causing agent in humans. 
  2. Bromoform can cause neurological impairments, unconsciousness, and death. In studies of laboratory animals, drinking bromoform-contaminated water caused liver and kidney cancer. EPA classifies it as a probable cancer-causing agent in humans.
  3. Dibromochloromethane is less well understood, but in studies of laboratory animals, drinking contaminated water caused liver and kidney cancer. EPA classifies it as a possible cancer-causing agent in humans.
  4. Bromodichloromethane is known to cause liver, kidney, and immune system damage. It can also cause reproductive system damage and lead to miscarriage and low birth weight. In studies of laboratory animals, drinking bromodichloromethane-contaminated water caused intestinal, kidney, and liver cancer. EPA classifies it as a probable cancer-causing agent in humans.

Because of the danger of THM exposure, EPA regulates the maximum amount of total THMs allowed in tap water. While this can help keep people safe, regulating the total THMs may not necessarily be effective because each type of THM can cause health effects on their own. Furthermore, little is known about the health effects of simultaneous exposure to multiple THMs. EPA has maximum contaminant level goals (MCLGs) for each of the four THMs listed above, but these goals are not enforced by laws or regulations, so they have no power to keep people safe. Because most people get their water from chlorinated municipal water supplies, and because THMs have such serious health effects, more must be done to keep people safe from exposure. This includes more studies to understand the effects of simultaneous exposure to multiple THMs and enforceable standards for individual THMs in drinking water.

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How AI Can Help Strengthen Grassroots Organizing

Image Credit: Tensorspark

By Gregory Kolen II.

Environmental justice is an issue that affects everyone, but those who bear the brunt of it are often the most vulnerable members of society. Disadvantaged communities, specifically, are often the ones living in areas with poor air quality, contaminated water sources, and unregulated disposal of waste. These challenges have been longstanding and difficult to overcome, as they require significant resources and political will. Yet, in recent years, emerging technologies such as Artificial Intelligence (AI) have emerged to support community leaders and organizations working towards environmental justice.

Boosting activism through data: AI can assess and analyze vast amounts of data to help grassroots organizers tailor their messaging based on the demographics, behavior, and attitudes of their target audience. By better understanding the needs of the communities they serve, organizers can create more effective and convincing campaigns that are more likely to drive action.

Streamlining operations: Organizers can improve the efficiency of their operations and decision-making processes, allowing them to work more effectively and achieve their goals more quickly. AI can help organizers automate routine tasks, which saves time and energy, allowing them to focus on more complicated tasks that require human expertise.

Amplifying voices: Magnify the voices of marginalized communities with AI-powered chatbots. Amplify the stories and experiences of those most affected by environmental injustices. This can help grassroots organizers build empathy and support for their causes among those in power, as well as among the broader public.

Improving outreach: Organizers can reach out to a more extensive and precisley targeted diverse audience. AI-powered tools can help create more targeted promotional materials and reach out to individuals who might not have been reached through traditional methods. This can help organizers increase the reach of their initiatives and attract more support.

Identifying environmental issues in communities: AI tools can help communities identify and monitor environmental hazards in their surroundings. For instance, using machine learning and remote sensing technologies, it is possible to map and classify toxic hotspots or areas with high pollution levels. Real-time air and water quality monitoring sensors can also provide early warning systems that allow communities to take the necessary precautions.

Empower communities through data and citizen science: Citizen science is an approach that empowers communities to gather data, conduct research, and create solutions. AI tools can help democratize scientific research by enabling communities to communicate their findings and analyses. Collectively, high-quality data can be used to ascertain environmental health disparities. For instance, EarthAI, a nonprofit organization, aims to provide equal access to AI-assisted satellite imagery, which can be used to map and track environmental health indicators.

Influencing Policies: AI tools can be used to predict the impact of policies on marginalized communities. For instance, researchers can use machine learning models to identify areas where environmental policy interventions are most needed, based on critical community characteristics and environmental hazards. Such data and insights can be shared with policymakers to develop effective policies that prioritize environmental justice.

There are numerous ways that emerging AI technology can be used to help strengthen grassroots organizing efforts for environmental justice. From boosting activism through data analysis to amplifying voices and improving outreach, AI has the potential to help empower grassroots organizers and create more profound change by identifying environmental hazards, empowering communities through data and citizen science, influencing policies, raising advocacy and awareness, and reducing disparities. While AI is not a magic solution, it has the potential to create a pathway towards a more just future and better outcomes for all communities.

Additional information:

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Health Effects of PFAS in Drinking Water

The glass is always... we're screwed comic.
Image credit: Jim Morissey

By Leila Waid.

As a research project for a university course, I conducted a literature review and systematic analysis of the health effects of PFAS in drinking water. This blog post contains a highlight and broad overview of the health effects discovered.

The systematic analysis included 44 observational epidemiological studies focused on PFAS-contaminated water as the exposure and adverse health effects as the outcome of interest. (For inquiries, references to individual studies, or any other information about the information about the systematic review study, email

The results:

PFAS in drinking water is associated with a variety of different health effects. However, it is important to note that the results included here do not prove causation. In other words, the studies cannot prove that PFAS caused these health issues, only that an increase in PFAS exposure is associated with these health effects.

  • Cardiovascular health: increase in “bad” cholesterol, triglyceride lipids, blood pressure, hypertensive pregnancy disorder.
  • Hormonal health (endocrine system): impaired thyroid function, disruption in the growth hormone IGF-1 in children, lower levels of estradiol and testosterone, increase in Poly-Cystic Ovary Syndrome, fibroids, and testicular cancer.
  • Immune health: increase in adverse health effects from COVID-19, disruption in inflammation production, lower immune cell count and production, increase in ulcerative colitis (stomach ulcers).
  • Urinary system health: kidney function impairment, kidney cancer, bladder cancer
  • Digestive system: esophageal cancer.
  • Neonatal (infant) health: lower birthweight and small for gestational age.
  • PFAS has also been found to cause epigenetic changes, which is a process through which our environment impacts how our genes are expressed. In other words, it does not change the actual DNA structure, but how the body reads the DNA sequence. Specifically, PFAS is associated with DNA methylation (a process through which chemicals attach to a DNA chain and turn a specific gene on or off. This process affects how the gene is read).
  • Mortality: exposure to PFAS associated with all-cause mortality, as well as mortalities from liver cancer, cerebrovascular disease, diabetes, myocardial infarction, kidney cancer, breast cancer, and Alzheimer’s disease.
  • Neurological system: developmental language disorder.
  • Skeletal system: increase in bone fractures (hip, proximal humeral, and distal forearm fractures).
  • Non-regional specific: mesothelioma cancer (affects tissues around organs), increase in multi-morbidity (multiple chronic morbidities occurring at the same time).
  • Mental health: increased anxiety, financial stress around health issues, emotional distress due to worrying about living in PFAS-contaminated region. Also, PFAS was associated with an increase in behavioral problems among children. 

It is important to note that all the adverse health effects discussed above were found from observational studies on human health, not animal or in vitro (cell) studies. Although the findings cannot prove causation, they still paint an alarming picture for human health. The results showcase that urgent and robust policy action is needed at the federal and state levels to protect our waterways from PFAS contamination. This situation is critical because almost half (45%) of all tap water systems in the U.S. have PFAS contamination. And one study found that an estimated 97% of all Americans have PFAS in their blood streams.

Toxic Tuesdays

Metals & Preterm Births

Toxic Tuesdays

CHEJ highlights several toxic chemicals and the communities fighting to keep their citizens safe from harm.

Metals & Preterm Births

Over 10% of births worldwide are preterm, meaning delivery occurs earlier than 37 weeks of pregnancy. It is a leading cause of neonatal mortality, and evidence suggests that exposure to heavy metals from the environment could be a risk factor. In the US, a major source of exposure to metals is private well water. The Environmental Protection Agency (EPA) sets standards and regulates levels of contaminants in public drinking water, but private well water isn’t regulated. This means private well water – which 13% of the US population receives drinking water from – is vulnerable to contamination. Indeed, studies have found metal contamination in private wells and that people who receive drinking water from private wells have more of these metals in their systems.

A recently published study set out to evaluate if exposure to toxic metals from private well water increased the risk of preterm birth. Because North Carolina (NC) has the largest state population using private well water, the researchers studied live births in NC that occurred from 2003-2015. From birth certificates, they could collect each pregnant person’s address at the time they delivered their babies. The researchers also used the NC-WELL database, which is a database of over 100,000 geocoded well water tests conducted from 1998-2019 from almost all census tracts in North Carolina. These tests include measurements of the concentrations of metals. The NC-WELL database allowed the researchers to assign each pregnant person’s address an estimate of their exposure to private well water and the concentrations of metals measured in that well water. Ultimately, the study included over 1.3 million births. This large sample size allowed the researchers to determine if increased metals in well water was associated with preterm birth.

The study found that people living in census tracts where over 25% of NC-WELL water tests exceeded EPA’s safe standard for cadmium had 11% higher odds of preterm birth than people who did not. People living in census tracts where over 25% of NC-WELL water tests exceeded EPA’s safe standard for lead had 10% higher odds of preterm birth than people who did not. These results indicate that cadmium and lead in private well water were each associated with preterm birth.

The study then modeled how the exposure to mixtures of metals was associated with preterm birth. This is particularly important because few studies assess the risks of multiple chemical exposures, even though it is highly likely people are exposed to more than one chemical at a time. When considering exposure to a mixture of seven metals present in private well water, the researchers found that exposure to the combination of cadmium and lead was associated with preterm birth.

In the US and NC, Black and Native American people have much higher rates of preterm birth than white people. Racial disparities in exposure to toxic chemicals could influence racial disparities in birth outcomes. As the study states plainly, “This is especially pertinent to consider when evaluating private well water-based exposure in NC, as structural environmental racism has led to poor and minority communities being more likely to rely on private well water.” This study found that when considering exposure to a mixture of seven metals present in private well water, the effect on preterm birth was most extreme for Native American people. It was associated with 20% higher odds of preterm birth for Native American people. The researchers say this disproportionate effect of metal exposure on preterm birth reflects the multiple environmental hazards and contaminants disproportionately forced on Native American people over several centuries. They also note that other studies have found that Native American pregnant people have higher levels of toxic metals in their systems than the national average.

This study used publicly available birth information and private well water testing to create a large cohort to study the effects of metals in private well water on preterm birth. The results make clear that private well water needs more regulation in order to ensure the levels of dangerous metals like cadmium and lead do not put people at risk. The results also make clear that not all people bear the same risks of exposure or health effects of exposure. People of color bear a disproportionate burden because they are more likely to receive private well water, which may contribute to disproportionate rates of preterm births.

For more information, CHEJ has previously written about the health effects of leadcadmium, and the importance of considering the health effects of exposure to mixtures of chemicals.

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News Archive

Interactive Map Displays Military Bases with PFAS Contamination

The Environmental Working Group has created an interactive map displaying 305 U.S. military sites that are known to have discharged firefighting foam containing PFAS. Each site includes information about the base, key findings associated with PFAS contamination and additional resources. Read More.
View the interactive map here.

Backyard Talk

CAFOs and Environmental Injustice in North Carolina

While the situation in Flint, Michigan has deservedly garnered much of the American public’s attention, it is important to recognize that it is just one example of many minority and low-income communities around the country that are living in a toxic environment. Rural North Carolina is another community that has seen its leaders fail to protect the most disadvantaged citizens, in this case, from the toxic pollution associated with the many hog farms in the region. African American and Native American communities in this region have been dealing with the toxic conditions for decades, since North Carolina saw a boom in the number of concentrated animal feeding operations, commonly known as CAFOs, in the 1980s and 1990s.
These feeding operations, that allow hog farmers to produce thousands of hogs for slaughter on a single farm, also produce millions of tons of waste, pathogens, antibiotic-resistant bacteria, and debilitating odors that damage the health and well-being of the minority families that overwhelmingly makeup the neighborhoods that surround them. As an example of how impactful these CAFOs can be, one 80,000-head facility produced 1.5 times the amount of waste generated by the City of Philadelphia in a single year. Yet, these hog producers lack all of the chemical and mechanical filtration systems that are required to treat human sewage. Instead, waste from these operations end up in unlined and untreated lagoons that leach into groundwater and can even rupture and spill their contents into surrounding landscapes and waterways. In addition, the noxious odors that are generated by CAFOs have also been found to cause respiratory problems, eye irritation, and even high blood pressure among individuals living nearby.
Because the development of this type of farming happened so fast in North Carolina, lawmakers have failed to keep up in implementing the necessary policies and regulations to protect the health of its citizens and environment. Particularly troubling is that despite the fact that CAFOs result in localized health problems, state and local health agencies do not have any authority in regulating them. Instead, natural resource agencies, whose mission is not to protect human health, are left with the responsibility.
While some progress has been made in recent years to improve technology, nearby residents are still struggling with horrible living conditions. This has resulted in a recent complaint filed by the University of North Carolina and Earthjustice in 2014 with the state’s Environmental Protection Agency. The complaint was filed under Title VI of the Civil Rights Act, which says that recipients of federal funds must prevent harm to communities or individuals based on race. Negotiations between community groups and regulators fell apart when regulators invited pork industry representatives to participate in negotiations. This left many community members with the impression that state leaders cared less about the health of its disadvantaged citizens, and instead was looking out for the interests of the pork industry. And much like the U.S. EPA failed to act in order to protect the citizens of Flint, they have also yet to intervene and do an investigation to improve the situation in North Carolina and other regions plagued by the negative effects of CAFOs.
This is just one of many examples of environmental injustice that shows us that if there is pollution generated from industry, or in this case, from the production of our food, it is overwhelmingly impacting the most disadvantaged in our society. We need to make the connection between the atrocities that are occurring in Flint, with the similar injustices that are experienced in North Carolina and all across the country and we need to call on our leaders to do a better job of promoting clean and healthy communities for all its citizens.
To learn more about the effects of hog farming, check out this paper by Environmental Health Perspectives