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Cumulative Risks and Toxicity

Toxic Tuesdays

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

Cumulative Risk and Toxicity

Evaluating the cumulative impacts of exposure to multiple chemicals is perhaps the most difficult task facing toxicologists. The standard approach is to evaluate these risks by conducting a risk assessment or risk evaluation which relies heavily on data from exposure to a single chemical. But this only provides a limited assessment of the risks. Over the years there has been a growing recognition that this approach has many flaws (see previous issues of Toxic Tuesday) and limited application to real world exposures to multiple chemicals at low concentrations. EPA has recognized the need to develop tools to evaluate cumulative risks, but has failed to develop a clear road map for how to do this.

A cumulative risk assessment would analyze the combined risks to health or the environment from exposure to multiple agents or stressors (USEPA 2003). This process includes evaluating the risks posed by exposure to multiple toxic chemicals simultaneously and over time as well as the influence on health of stressors such as genetics, lifestyle choices, income and air quality.

Evaluating cumulative risks requires knowledge of what chemicals a person was exposed to, the concentration of each of the substances in the mixture and how long a person was exposed to each of these substances. It also requires knowledge of how these chemicals in combination react to each other and how these chemical interactions in mixtures potentially impact human health. It also necessitates knowledge about the health status of each person exposed. There is both a natural variability as well as unique susceptibility among a group of people that influences health outcomes. For example, people who are sick or who have existing health conditions such as a weak heart or compromised immune system can influence how a person responds to a mixture of chemicals. Socioeconomic factors such as poverty, unemployment rates, education levels and income also influences how people in a community respond. All of these factors combined would have to be considered to assess the cumulative health impact resulting from exposure to multiple chemicals simultaneously.

What’s become very clear over the years is that the scientific community knows very little about most of these factors. Consequently, risk assessors need to make many assumptions about information that is not known or at best uncertain. This is especially true when it comes to information about exposures (concentration and for how long) as well what level of exposure actually triggers harm in the body. The lack of knowledge and understanding of the molecular interactions have made it very difficult for scientists to forecast what will happen when people are exposed to multiple chemicals at low concentrations over time and why the field of toxicology has struggled to address multiple chemical exposures.

This failure has left community leaders and people in communities exposed to multiple chemicals simultaneously frustrated by the lack of answers and the lack for action by government agencies when addressing multiple chemical exposures. It may also be frustrating for government agencies because they are dependent on a tool (risk assessment) that relies on an antiquated approach that cannot answer the questions that people are asking.

EPA and other public health agencies need to be honest and truthful with the public about what they don’t know about chemical exposure risks. Scientists actually don’t know very much about what happens to people exposed to low level mixtures of toxic chemicals. While this reality may not be reassuring, the truth allows everyone to better understand what they are facing.

There is an alternative that should be considered. EPA should follow the lead of what the government did to take care of Vietnam Veterans who were exposed to Agent Orange and the soldiers exposed to emissions from the burn pits in Iraq and Afghanistan, among others. In these cases, soldiers do not have to prove that their illnesses were caused by their exposure to toxic chemicals. If they can show that they were exposed and that they have an illness associated with the chemicals they were exposed to, that’s sufficient for them to get health care and other compensation.

Communities exposed to toxic chemical mixtures shouldn’t be held to a different standard given that the uncertainties about toxic exposures are driven by the same scientific unknowns. In the absence of a basic understanding of what adverse health effects might result from exposures to the mixtures of toxic chemicals released into a community, the government should take steps to address the needs of the community, whether it’s by providing health care for those who were exposed or establishing a medical monitoring program to follow these people, or both.

These steps will begin the long and difficult process of acknowledging what we know and don’t know about exposes to low level mixtures of toxic chemicals and begin to learn what happens to the people exposed in these situations.

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A New Study on How Communities Experience Government Responses to Environmental Disasters

Toxic Tuesdays

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

A New Study on How Communities Experience Government Responses to Environmental Disasters

In October 2021, residents of Carson, California began smelling odors and experiencing dizziness, headaches, and nausea. The odor was identified as being hydrogen sulfide, and its concentration in the air remained above California’s air quality standards for three months. (CHEJ has previously written about hydrogen sulfide and its health effects here). The government concluded the hydrogen sulfide came from firefighting chemicals used to extinguish a warehouse fire in September 2021. The county government distributed air purifiers and provided hotel rooms for temporary relocation, but many residents felt like the response wasn’t fast or substantial enough. Importantly, Carson is a diverse city with one of the highest pollution burdens in California, making residents particularly vulnerable to health effects from disasters like this one.

A recent study in the journal Environmental Health conducted 6 focus groups with 33 members of the Carson community. It uncovered valuable information about how the community experienced the government response to this disaster and what we can learn from it. It found 5 themes that emerged from these focus groups:

  • Breakdowns in communication between institutions of authority and residents. Participants agreed that they didn’t know the source of the odor and received little information about it from responsible agencies. There was not even common understanding of which agencies were responsible. When residents contacted agencies themselves to get information they were often dismissed or ignored. This led to many receiving information from unofficial sources, but they weren’t sure if that information was accurate. Without clear and accurate information, participants felt abandoned and powerless. Spanish-speaking participants in particular said they felt ignored and left in the dark.
  • Institutions downplaying residents’ concerns. Throughout the disaster, residents reported nausea, headaches, dizziness, nose bleeds, trouble sleeping, and stomach problems. However, they felt that local news, government agencies, and healthcare providers downplayed the risks and dismissed their health problems. This disparity between their lived experience and response from institutions led to participants feeling gaslit, causing them to lose trust in these institutions.
  • Stress of the unknown impacts of the odors on health. Many participants explained how the disaster and lack of information led to severe stress and fear in addition to the health effects of the odor. Some are experiencing long-term physical and mental health effects.
  • Efforts to build community power. The lack of information and transparency from institutions made some residents build their own power through research, information sharing, networking, and activism. Participants described doing research themselves on the health effects of hydrogen sulfide exposure because government agencies didn’t provide that information. They shared this research and county response information in social media groups, homeowners associations, local community organizations, and other social networks. Spanish-speaking participants said they were unaware of the social media community groups and mostly received information from neighbors, highlighting how different communities within Carson experienced the disaster response differently. Participants agreed that community leaders emerged through this process who pressured local leaders to take action. They expressed pride and gratitude for the community power and relationships they built.
  • Long-term impacts. Many participants expressed that this experience made them lose trust in local institutions including news, government, and healthcare. They felt that issues of race, class, and the power of polluting industries in Carson led to the lack of response. Many agreed that they now have increased awareness of odors, pollution, and environmental justice issues.

Other communities that have experienced environmental disasters may recognize the experiences of residents in Carson, California. While it may be a common experience for communities, it’s not often something described in scientific studies. This study helps make researchers, public policy experts, and decision makers aware of the problem and the long-term effect it has on communities.

As seen in Carson, the absence of transparent information and community engagement breeds distrust of institutions, which has broad implications for societal stability and health. But Carson also demonstrates a path forward to strengthen communities: residents have the relationships, drive, and expertise to help protect each other. Government responses should harness this power to better protect public health. Current government responses to environmental disasters are often insufficient, and in imagining better responses systems we must center community needs, expertise, and engagement.

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Di(2-ethylhexyl)phthalate (DEHP)

Toxic Tuesdays

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

Di(2-ethylhexyl)phthalate (DEHP)

Di(2-ethylhexyl)phthalate (DEHP) is a manmade chemical and is the most common member of a class of chemicals called phthalates. DEHP is used as a plasticizer, meaning it is added to plastics to make them more flexible, transparent, and durable. DEHP is commonly used as a plasticizer in consumer products such as tablecloths, shower curtains, rainwear, garden hoses, plastic tubing, upholstery, flooring, and food packaging containers. It can also be used as a fragrance ingredient in personal care products such as perfume, laundry detergent, and air fresheners.

When DEHP is added to plastics, over time it can leach out of those products and into the surrounding environment. For instance, when it is used in plastic food packaging, it can leach out of the plastic and into the food it’s holding. Eating this contaminated food is the most likely way people are exposed to DEHP. When it leaches out of household products like upholstery, flooring, and shower curtains, it sticks to dust particles that people may then accidentally inhale or ingest. DEHP is also added to some medical tubing, so some procedures like blood transfusions and kidney dialysis may also lead to exposure.

Exposure to DEHP is associated with reproductive dysfunction in humans. In men, it is linked to lower testosterone and sperm motility. In pregnant women, it is linked to preterm birth. While it is not known if DEHP causes cancer in humans, in studies of laboratory animals, exposure caused liver, pancreatic, and testicular cancer. The US Department of Health and Human Services classifies DEHP as reasonably anticipated to cause cancer in humans. The US Environmental Protection Agency classifies it as a probable cancer-causing agent in humans.

DEHP exposure is harmful to human health and the US government knows it – in 2008 the Consumer Product Safety Improvement Act made it illegal to sell children’s products that contain more than 0.1% DEHP. However, DEHP is still allowed in a wide variety of products that end up in homes, businesses, healthcare facilities, and landfills. Additional regulation to require products to be free of DEHP would have a crucial impact on limiting exposure and the reproductive and cancer harm that come with it.

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Do Environmental Standards Protect Public Health?

Toxic Tuesdays

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

Do Environmental Standards Protect Public Health?

Federal environmental standards were created to protect the environment and human health. Regulations to limit chemicals in water, air, soil, and food set requirements that must be upheld by all levels of government (local, state, tribal, etc.), ideally creating uniform policy and protections for communities across the country. Examples include the Safe Drinking Water Act, Clean Air Act,  Clean Water Act and the Food, Drug and Cosmetic Act that regulate pollutants in drinking water, air, water and food, respectively. It’s natural to think that these laws would protect people from exposure to toxic chemicals, but this is only partially true. While these regulations have made significant improvements in drinking water, air, water and food quality, there are many gaps and limitations in these regulations that result in people unwittingly being exposed to toxic chemicals, especially in environmental justice communities.

With one exception, a major problem with these laws is that they do not establish legally enforceable standards. Instead, government agencies have developed guidelines and recommendations. Another significant problem is that several key regulations only apply to point-source pollutants (“single, identifiable sources of pollution from which pollutants are discharged, such as a pipe, factory smokestack, ditch, etc.”), leaving non-point source pollutants (“pollution that comes from multiple diffuse sources,”) to state, tribal, or local jurisdiction or without regulations. This gap results in discrepancies in exposures to chemicals and health outcomes of communities based on where people live and work, especially in areas described as Sacrifice Zones – areas that are disproportionately impacted by pollution produced by proximity to intensive, concentrated industry, often in low-income communities of color. Without standards in place to protect these areas, these communities are exposed to abnormally high levels of chemicals which increases their risk of cancer, respiratory illnesses, and other diseases.

Health-based standards are important because they define a level of exposure that’s intended to protect the health of all people. Only the Safe Drinking Water Act, which was passed in 1974, sets a health-based maximum concentration of a chemical allowed in water. This legally enforceable standard sets this rule apart from all other regulations. If the level of chemical exceeds its drink water standard, health agencies will issue orders notifying people to stop drinking the water. And, if a company is found responsible for contaminating the water, they are held liable for treatment costs and any potential adverse health effects that result. This is the way health-based regulations are supposed to work.   

However, this is not how the Clean Air Act, the Clean Water Act, or the Food, Drug and Cosmetic Acts work. For these regulations, similar maximum exposure levels are not defined. There are no air standards that define a “safe” or even “acceptable” concentration of a chemical in the air. The Clean Air Act (CAA), which passed in 1970, established national ambient air quality standards (NAAQS) which include regulations for 6 pollutants: carbon monoxide, lead, nitrogen dioxide, ozone, particle pollution, and sulfur dioxide. This rule sets emissions limits for each of these pollutants for varying periods of time such as one year. Under this system, there is no limit to how much a person could be exposed to in the ambient air. Put another way, no one knows what it means if a person is exposed to 50 parts per million (ppm) of benzene in ambient air.

Similarly, the Clean Water Act, which passed in 1972, also does not define a “safe” or “acceptable” concentration of a chemical in open waters. The Clean Water Act (CWA) regulates contaminants and wastewater only from point source polluters by “prohibiting the discharge of pollutants from a point source into navigable waters.” A National Pollutant Discharge Elimination System (NPDES) permit must be acquired in order to discharge pollutants to water bodies. The permit regulates what can be discharged (and how much) and establishes a monitoring system to track discharges. This regulation does not address non-point source pollutants. As is the case with the CAA, there is no limit to the concentration of a chemical that can be discharged into a body of water. Put another way, no one knows what it means if a person is exposed to 50 ppm benzene in a river.

The situation is even worse when it comes to chemical contamination of soil. In this case, there are no federal standards that protect ambient soil quality. EPA has developed guidelines ad recommendations for determining “acceptable” levels of residual contamination at Superfund sites post-remediation. These Superfund sites use Soil Screening Guidance (SSG) which “presents a framework for developing risk-based Soil Screening Levels (SSLs) that protect human health.” However, these guideline values are not legally enforceable standards. Instead, they are used by state and federal agencies to decide how much residual contamination is “acceptable” in one community versus another. EPA can decide to leave 100 parts per million (ppm) of lead at one site and 1,000 ppm at another by using different risk factors. According to EPA, this “flexibility” is important in managing risks. Practically, this means that the community that’s organized and generates political pressure gets a better cleanup, while the one that doesn’t, gets less protection and higher levels of contamination which is typical in Sacrifice Zone communities.

The same goes for toxic chemicals in food. The Federal Food, Drug, and Cosmetic Act, which was passed in 2002, regulates pesticide levels in foods. These regulations define how much pesticide can be applied to food in the field, how often, and the timing of the application in relation to consumption. There are also guidelines for certain metals. For example, FDA has  seafood intake recommendations intended to limit exposure to metals like mercury. These guidelines and are not legally enforceable. FDA states the reason for this is that metals are often “widespread in the environment and because it is not possible to remove [them] from seafood or grow or produce certain foods completely free of [them].”

It’s reasonable for people to think, and expect, that government wouldn’t allow unsafe levels of toxic chemicals in the air we breathe, the water we swim in, the soil we play in, and in the food we eat. However, that’s not the case. With exception of drinking water, existing environmental and public health regulations do not set health-based standards that define a level of exposure that’s “safe” or even acceptable. Instead, we are left with unenforceable guidelines that give federal agencies enormous power to negotiate with the companies responsible for the contamination. This may be practical, but it’s not protective of public health and it leaves communities vulnerable to toxic exposures that can negatively impact their health.  

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N-nitrosodimethylamine (NDMA)

Toxic Tuesdays

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

N-nitrosodimethylamine (NDMA)

N-nitrosodimethylamine (NDMA) is a chemical in a class of chemicals called nitrosamines. NMDA is a yellow liquid but readily evaporates at room temperature.

Until the 1970s it was used to make rocket fuel, but was then discontinued because of the resulting environmental contamination. In the United States today, NDMA is only made for scientific research purposes. However, NDMA can be formed as a byproduct when its commonly found precursors come into contact with each other.

These scenarios where NDMA forms as a byproduct occur in industrial settings like water treatment plants, pesticide manufacturing facilities, and pharmaceutical manufacturing facilities. This can result in NDMA entering soil, drinking water, and air.

NDMA can also be formed from precursors found in common consumer products like lotion, cosmetics, beer, cured meat, and smoked meat. When we use these products, we can be exposed to the NDMA in them. Furthermore, foods like cured meat, smoked meat, fish, cheese, and beer are high in compounds called nitrates, which our bodies can convert into NDMA once we eat them. These kinds of consumer products are how most of the population is exposed to NDMA.
 
Exposure to NDMA can cause liver damage in humans. Workers exposed to NDMA in industrial settings had higher risks of liver, blood, bladder, stomach, and prostate cancers. Increased NDMA exposure through food is associated with stomach and colorectal cancers. In studies of laboratory animals, NDMA exposure
caused liver injury and stillbirth as well as liver, lung, kidney, and testicular cancers. Based on all of this evidence, the US Environmental Protection Agency and the International Agency for Research on Cancer both classify NDMA as a probable cancer-causing chemical in humans.

Because NDMA can be found in industrial settings and a wide variety of consumer products, it can be hard to know our exposure risk. This makes it particularly important for the federal government to regulate NDMA precursor chemicals in manufacturing, personal care products, and food preservation in order to keep people safe from the adverse health effects of exposure.
 

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Racial Disparities in PFAS Exposure Through Drinking Water

Toxic Tuesdays

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

Racial Disparities in PFAS Exposure Through Drinking Water

Per- and polyfluoroalkyl substances (PFAS) are a class of chemicals used in many consumer products and industrial processes since the 1950s. Because there isn’t federal regulation of their use or disposal, PFAS are commonly released into the environment. When PFAS are released, people can be exposed to them through air, dust, food, and water, so PFAS exposure is common in the United States. Biomonitoring studies have found that certain species of PFAS are present in the blood of almost all US residents.

Many species of PFAS are known to have adverse health effects on humans including increased cholesterol levels, changes in liver enzymes, decreased vaccine response in children, increased risk of high blood pressure in pregnant women, and decreased birth weight. Epidemiologic studies also show a link between exposure to certain species of PFAS and increased rates of kidney, prostate, and testicular cancer.

While there many ways to be exposed to PFAS, one of the most common is through contaminated drinking water. It is estimated that 200 million people in the US receive PFAS-contaminated drinking water. In 2018 New Jersey became the first state to adopt enforceable standards for PFAS in drinking water. It established maximum contaminant levels (MCLs) – which are the highest amount of a contaminant allowed in drinking water – for three of the most common species of PFAS: perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA). In April 2024, the US Environmental Protection Agency (EPA) announced the first federal drinking water standards for six PFAS including PFOS, PFOA, and PFNA.

In establishing MCLs for PFAS, New Jersey mandated statewide testing of all Community Water Systems (CWSs, the government-regulated water utilities) in the state. These CWSs tested by New Jersey serve 77% of the statewide population. A recent study used 2019-2021 CWS testing data along with Census data to evaluate if there are demographic differences in PFAS contamination of New Jersey residents’ drinking water. The study calculated quarterly averages for 491 CWs over this time period. It found that PFAS were detected above New Jersey’s MCL in 14% of CWSs, which serve 23% of the population. 

The study also mapped demographic information from census block groups – which are portions of census tracts and generally contain 600-3,000 people – onto the boundaries of each CWS. This created a map where the demographic makeup and quarterly average PFAS concentrations for each CWS were known. 27% of the non-Hispanic white population were served by CWSs with PFAS above New Jersey’s MCL. In contrast, 52% of the Asian population, 38% of the Hispanic population, and 34% of the Black population were served by CWSs with PFAS above New Jersey’s MCL.

These results demonstrate that not only is PFAS contamination prevalent in drinking water in New Jersey, but that there are racial disparities in PFAS contamination by CWS service area. Compared to white populations, Hispanic, Asian, and Black populations are more likely to receive drinking water that has PFAS contamination above the state’s safe threshold. These racial disparities in drinking water quality mirror racial disparities in the US more generally. Historical and ongoing housing discrimination leads to communities of color being excluded from living in certain areas. Throughout the country, pollution-emitting facilities are disproportionately located in nonwhite neighborhoods, driving health and environmental problems that disproportionately affect people of color. Industrial and military facilities that use PFAS and are located in nonwhite neighborhoods may contaminate the water supplying nearby CWSs, which could explain the racial disparities in drinking water discovered in this study.

It is important to note that EPA’s new MCLs for PFAS species are below New Jersey’s MCLs. Complying with these federal standards could reduce racial disparities in PFAS water contamination in New Jersey, but only with robust federal enforcement. People in New Jersey and across the US – especially people of color who have been disproportionately harmed – need enforceable standards and effective enforcement of those standards in order to be safe from PFAS in their drinking water.

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The Government’s Approach to Evaluating Health Problems in Communities

Toxic Tuesdays

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

The Government’s Approach to Evaluating Health Problems in Communities

Communities exposed to toxic chemicals from industrial pollution struggle to get answers about whether the pollution has caused the health problems in their community. Groups organize to pressure the government to stop the pollution and to clean up the contamination. But these agencies have few answers and often little is done. Frequently states ask the Agency for Toxic Substances and Disease Registry (ATSDR) to investigate the health problems reported in a community. Initially, ATSDR is welcomed because people think that someone is finally going to provide some answers about the health problems in the community.

The Agency for Toxic Substances and Disease Registry (ATSDR) was created in 1980 to address health problems at Superfund sites. Their mission is to protect communities from harmful health effects related to exposure to both natural and man-made hazardous substances. ATSDR is the right agency to evaluate health complaints in a community and they have been doing so for more than 30 years. And for most of this time, the agency has repeatedly failed to answer the questions people raise about whether there’s a link between health problems and the pollution in the community. CHEJ has written much about ATSDR over the years1.

Last month an investigative report by the news service Reuters took an extensive look at ATSDR’s work. The report, “How a US health agency became a shield for polluters,” analyzed 428 reports issued by the agency from 2012 to 2023. Those reports contained 1,582 conclusions about potential harms at contaminated sites. Reuters found that in 68% of its findings, the ATSDR declared communities safe from hazards or did not make any determination at all. That record of finding little harm “strains credulity,” said one former EPA official quoted in the report.

Other key findings included:

  • The agency’s frequent declarations of no harm often are rooted in faulty research. At least 38% of the time, agency reports show, its researchers relied on old or flawed data.
  • At least 20 times from 1996 to 2017 the agency declared that a potential hazard posed no health risk – only to be refuted later by other government agencies or the ATSDR itself. The errors impact communities in AlabamaCaliforniaMissouriNew York and North Carolina.
  • Despite decades of criticism, the agency continues to publish research that relies upon practices its own review board called “virtually useless.”
  • The agency’s common practice of publishing inconclusive reports feeds a long-standing corporate strategy of using scientific uncertainty to deflect regulation and liability for polluted sites.

How is it possible that ATSDR has operated like this for so long? Some answers come from a symposium hosted by ATSDR in 2012 on the Future of Science at ATSDR2:

“In conducting its core work of assessing health risks at contaminated sites, ATSDR has faced a large workload with limited authority and resources to collect needed data. Moreover, concerned communities have voiced legitimate public health questions that ATSDR could not answer fully with existing scientific tools and knowledge.

This meeting documented many scientific limitations and challenges facing the agency. ATSDR’s Board of Scientific Counselors hired a consultant who reviewed the agency’s scientific work and came to these conclusions and observations:

  • An alarming gap persists between public expectations and the limited tools available to scientists to assess the public health effects of hazardous waste sites and uncontrolled releases. This gap is due, in part, to the inherently complex and uncertain relationship between diseases and chemicals emanating from hazardous waste sites and uncontrolled releases. Many substances commonly found at hazardous waste sites and in uncontrolled releases may also emanate from other sources and are routinely detected at low levels in air, water, food, consumer products, or other media. No field-based methods are readily available for measuring the portion of a particular ambient exposure or internal dose that is attributable to a specific hazardous waste site or uncontrolled release.
  • In the absence of scientific methods for assessing the unique contribution of releases from hazardous waste sites and uncontrolled exposures to disease, ATSDR scientists rely upon surrogate methods and designs (e.g., comparing exposures to disease rates in communities with a hazardous waste site with “background” levels). Such approaches, although squarely within the mainstream of environmental science, typically are not robust enough to detect adverse health effects caused by site-specific exposures to toxic chemicals.
  • EPA and ATSDR scientists calculate theoretical risk estimates based on a host of assumptions about contaminant concentrations, exposure duration, characteristics of the exposed population, acute and long-term health risks and other factors.
  • ATSDR relies predominately on environmental data collected by other agencies (primarily EPA and state agencies) for its health assessments. Such data often are not adequate or appropriate for addressing specific questions about current exposures and pathways.

Without good tools to evaluate the impact of chemical exposures on people, ATSDR, EPA and other government agencies will continue to struggle to address pollution and contamination in communities. It’s time to recognize and to acknowledge that scientists know very little about how exposures to toxic chemicals, especially to low level mixtures, lead to adverse health outcomes.

Instead of trying to link cause and effect (the agencies default approach), which is virtually impossible to achieve because of the inherently complex and uncertain relationship between disease and chemical exposure and the limited tools to evaluate health effects, isn’t it time to consider whether there’s enough information and evidence about exposure and adverse health problems in a community to take action to protect people exposed to toxic chemicals?

Until there is a change in how government approaches health problems in a community, you can expect ATSDR to continue to investigate health problems in communities using the same approach that’s reflected in the Reuters article.


(1)  – CHEJ, Assessing Health Problems in Communities, S, Lester, Updated Jan 2010; CHEJ,  ATSDR: Don’t Ask… Don’t tell… Don’t Pursue, S. Lester, 1994 (available from CHEJ).

(2) ATSDR: The Basics, The Future of Science at ATSDR: A Symposium, Atlanta, GA, April 11-12, 2012 (available from CHEJ).

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Acrylamide

Toxic Tuesdays

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

Acrylamide

Acrylamide is a clear, odorless chemical. It has many industrial uses, including treating waste water
discharge from water treatment plants. It is also used in the production of industrial products like dyes,
paper pulp, grout, plastics, and construction materials. Many consumer products are also produced
using acrylamide, such as contact lenses, cosmetics, fabrics, textiles, and sugar. When acrylamide enters
the environment, people are most likely to be exposed to it by drinking contaminated water. Acrylamide
can enter drinking water through the water treatment process or through improper disposal from
industrial facilities that use it to manufacture products.

Exposure to acrylamide can have serious effects on the brain, causing numbness in the hands and feet,
disorientation, loss of balance, and muscle weakness. Skin contact with acrylamide can cause irritation,
dermatitis, and nerve damage. Studies in laboratory animals have found that acrylamide exposure can
also cause defects in the male reproductive system, but it is unknown if it has the same effects in
humans. Based on studies in laboratory animals, the US Environmental Protection Agency classifies
acrylamide as probably causing cancer in humans. The International Agency for Research on Cancer
classifies it as likely causing cancer in humans.

In 2002, acrylamide was discovered to form when foods rich in starch are grilled, baked, or fried above
250°F. This includes foods like potato chips, French fries, and breakfast cereals. The resulting acrylamide
can be found in the dark brown or burnt areas of these foods. Since this discovery, many regulatory and
public health agencies across the world have called for more research into whether this dietary
exposure to acrylamide increases the risk for cancer. The American Cancer Society says that based on
existing studies in humans, dietary acrylamide exposure is unlikely to be linked to increased cancer risk.
However, the ACS says that more research on this topic is needed to fully know if dietary acrylamide
poses a cancer risk. This research will be crucial in understanding how widespread cancerous acrylamide
exposure may be.

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Styrene

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

Styrene

Styrene is a chemical compound that can be linked together with itself or other compounds to create strong, flexible polymers that make up plastics, rubbers, and resins. Many products such as foodware containers, printer toner, shoes, plastic pipes, carpeting, fiberglass insulation, and automobile parts contain styrene.

Styrene can enter the air, water, and soil through manufacturing and disposal of styrene-containing products. Styrene is a colorless liquid but it readily evaporates, so a large portion of styrene that enters water or soil ends up in the air. While manufacturing and disposal can cause exposure, most people are exposed to styrene through their use of styrene-containing products.  For example, people inhale it indoors because styrene-containing building materials and printers release styrene vapors. In addition, the styrene in foodware containers can migrate into the food they hold, causing people to ingest styrene.

Once inhaled or ingested, styrene can have many adverse effects on the body. Many of these effects are in the brain, such as impaired vision, impaired hearing, loss of coordination, slowed reaction time, fatigue, and difficulty concentrating. Studies in laboratory animals have found that styrene exposure can also cause damage to the liver, though it is unknown if it has this effect in humans. The US Department of Health and Human Services classifies styrene as being reasonably anticipated to cause cancer. The International Agency for Research on Cancer classifies styrene as probably causing cancer. The pervasiveness of styrene-containing plastics in consumer and industrial products makes these adverse health effects particularly concerning. Decreasing the reliance on plastics – through government regulation, scientific innovation, and consumer education – would help protect people from styrene exposure and its associated health effects.

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Linking Exposure and Health Outcomes

Toxic Tuesdays

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

Linking Exposure and Health Outcomes

One of the hardest things for a public health scientist to do is to link a specific health problem that a person is suffering from to a specific exposure to a toxic chemical(s). People who have been exposed to toxic chemicals, whether they lived at Love Canal, NY, Flint, MI or East Palestine, OH, want to know if their cancer, diabetes or other illness was caused by exposure to toxic chemicals. This is a reasonable question for people to ask, and it is one we hear all the time from people in the communities we work with. Unfortunately, the answer is not so clear. 

The problem is that scientists know very little about how and why the body responds to toxic chemicals the way it does. While we know a great deal about the mechanism of action for some chemicals such as dioxin and lead, we do not know what is going to happen to an individual who is exposed to 5 parts per trillion (ppt) of dioxin in their food. Or to a child who eats lead paint chips for 3 months. In some cases, scientists can predict what symptoms to expect, but it is rare that they can confidently link specific health outcomes to specific exposures even in obvious situations like the drinking water disaster in Flint, MI.

In fact, there are only two chemicals – asbestos and vinyl chloride – out of the more than 80,000 chemicals in use today, that scientists have been able to clearly link between exposure and specific health problems. In the case of asbestos, if you were exposed to asbestos in the shipping industry and develop a rare cancer of the outer lining of the lungs called mesothelioma, scientists are 99% confident (as close to certain as one can get) that the asbestos caused your lung cancer. In the case of vinyl chloride, if you were exposed to vinyl chloride in a PVC manufacturing plant and develop a rare cancer of the liver called angiosarcoma, scientists are 99% confident that the vinyl chloride caused your liver cancer. In both cases, it was an observant clinician who noticed that the people with these rare cancers all worked at the same place and had similar exposures.   

There are several factors that determine what happens when a person is exposed to chemicals. These factors include an individual’s susceptibility (this varies greatly from person to person), how long exposures occur, how many chemicals a person is exposed to, the concentration of these chemicals, and the toxicity of the chemicals. Add in the reality that people are often exposed to more than one chemical at a time and often repeatedly over time, then the certainty over what is known becomes significantly less. Even if you knew all these factors (which is rare), it is still almost impossible to predict what will happen when a person is exposed. We’ve touched on many of these factors in previous issues of Toxic Tuesday.

In addition, there is no way to fingerprint an exposure to tie it to a specific health outcome. And many symptoms or diseases are not specific to a particular chemical. In most instances, there can be many causes of the symptoms that people are having. And few physicians have experience with exposure to toxic chemicals. Meaning they cannot distinguish whether the headache you are suffering from resulted from the chemicals you were exposed to or whether you had a hard day at work. Often this inexperience leads to blaming the victim for their situation rather than looking at chemicals as a possible explanation. Another problem is determining what the “normal” rate of illness or disease is in a community. Scientists simply cannot decide what is normal. This is in large part because of the many uncertainties already discussed.

Despite the many scientific uncertainties, linking cause and effect has become the standard to achieve before government will take action to address a pollution problem or protect a  community. Over the years, this has meant endless studies and years of research gathering data that has resulted in little or no action on the part of government to protect people and communities exposed to toxic chemicals. This has been the government’s approach since before Love Canal more than 40 years ago. This is what is happening now in East Palestine, OH. This is no longer reasonable nor acceptable.

It is time to acknowledge that scientists do not know very much about how or why exposure to toxic chemicals, especially at low-level mixtures, leads to adverse health outcomes. Instead of trying to link cause and effect, which is virtually impossible to achieve because of the lack of information and understanding, it is time to consider whether there is enough information and evidence about exposure and adverse health problems in a community to take action to protect people exposed to toxic chemicals.

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