Center for Health, Environment & Justice
Donate

Category: Toxic Tuesdays

Categories
Toxic Tuesdays

Acrylamide

Toxic Tuesdays

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

< Back to Toxic Tuesdays

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.

Learn about more toxics

Acrylamide

Acrylamide is a clear, odorless chemical. It has many industrial uses, including treating waste water<br

Read More »
Categories
Toxic Tuesdays

Styrene

Toxic Tuesdays

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

< Back to Toxic Tuesdays

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.

Learn about more toxics

Acrylamide

Acrylamide is a clear, odorless chemical. It has many industrial uses, including treating waste water<br

Read More »
Categories
Toxic Tuesdays

Linking Exposure and Health Outcomes

Toxic Tuesdays

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

< Back to Toxic Tuesdays

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.

Learn about more toxics

Acrylamide

Acrylamide is a clear, odorless chemical. It has many industrial uses, including treating waste water<br

Read More »
Categories
Toxic Tuesdays

Particulate Matter and Mental Health

Toxic Tuesdays

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

< Back to Toxic Tuesdays

Particulate Matter and Mental Health

Outdoor air pollution is one of the biggest environmental threats to public health, causing an estimated 4 million premature deaths worldwide each year. One common component of air pollution is particulate matter (PM), which is a mixture of dust, chemicals, and liquid droplets. PM is primarily released into the air by industrial facilities that perform mixing and combustion. When people inhale PM in the air, it gets into their lungs and bloodstream, worsening existing lung diseases and even causing lung disease, heart disease, and lung cancer. Very fine particulate matter less then 2.5 micrometers in diameter – called PM2.5 – is especially dangerous. It can penetrate deep into the lungs and bloodstream, eventually reaching many other organs. PM2.5 exposure can cause lung and heart diseases and is also associated with diabetes, cognitive impairment, and dementia. PM2.5 exposure also increases the chance of dying from COVID-19 infection.

While the effects of long-term PM2.5 exposure on physical health are well established, less is known about how it affects psychological and mental health. A recent study in the journal Environmental Health used mental health data from The Irish Longitudinal Study on Ageing (TILDA), a nationally-representative study of 8,504 adults age 50 and over in Ireland. Data on TILDA participants has been collected every 2 years since 2009 and includes many health and wellness factors. It also includes information about participants’ residential addresses throughout their lives. The study in Environmental Health matched TILDA participants’ reported residential addresses from 1998 to 2014 with the average annual PM2.5 concentration at those addresses. It then assessed how that average annual PM2.5 exposure was related to participants’ 2014 self-reported mental health indicators in the TILDA: depression, anxiety, worry, stress, and overall quality of life. The study controlled for demographic and socioeconomic factors like age, sex, marital status, employment status, education, and health status to better attribute differences in mental health to PM2.5 exposure.

The study found that higher PM2.5 exposure was strongly associated with higher risk of depression and anxiety. PM2.5 exposure was not associated with differences in worry, stress, or overall quality of life. The authors speculate that different aspects of mental health may be differentially impacted by factors such as length of exposure, age at exposure, and exposure to other pollutants. While the association between PM2.5 exposure and depression and anxiety is striking, it is important to note that the study is not designed to determine if PM2.5 exposure directly caused depression and anxiety.

Several studies in the past few years have suggested that short-term PM2.5 exposure is associated with mental health changes such as depression, anxiety, bipolar disorder, schizophrenia, and suicidality. However, this study is one of the few that has assessed the effects of long-term PM2.5 exposure, which is particularly relevant because most real-life exposure to PM2.5 tends to persist for long periods of time. It adds to a growing body of scientific evidence that environmental hazards are associated with decreased mental health and wellbeing.

This study is also an important advance because it demonstrates that exposure to low PM2.5 levels can still have harmful effects on health. The average annual PM2.5 exposure in this study was 7.67 μg/m3. In contrast, the national average PM2.5 level in the US is 8.4 μg/m3, and 90% of the world population live in areas with average annual PM2.5 levels above 10 μg/m3. (The EPA’s interactive air quality map that shows current PM pollution can be found here.)

The National Ambient Air Quality Standards has determined that the maximum safe concentration of PM2.5 in outdoor air to be 9 μg/m3. The results from this study suggest that this is not a health protective standard, and adverse mental health effects can occur at PM2.5 levels below this value. The World Health Organization’s global air quality guidelines recommend a maximum annual PM2.5 level of 5 μg/m3. This standard is more health protective, but this study demonstrates that long-term exposure to low levels of PM2.5 can still significantly impact health.

Learn about more toxics

Acrylamide

Acrylamide is a clear, odorless chemical. It has many industrial uses, including treating waste water<br

Read More »
Categories
Toxic Tuesdays

Nitrates

Toxic Tuesdays

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

< Back to Toxic Tuesdays

Nitrates

Nitrates are a class of compounds that contain nitrogen. They can occur naturally in air, water, and soil, and living things need them to survive. Nitrates are used for industrial purposes to make fertilizers, ammunition, and explosives. They are also used to preserve food, most commonly in the process of curing meat. Many vegetables we eat are naturally rich in nitrates as well.

When nitrate-containing fertilizers are used on crops or yards, the nitrates can easily migrate into surface water and groundwater. This means that people who work with these fertilizers or live near where they are applied could be exposed to nitrates in their drinking water. For most of the population, nitrate exposure happens through the food we eat. The amount of nitrates consumed in a normal diet is generally considered safe, and much of the nitrates our bodies ingest or make naturally are excreted every day. However, people may be exposed to high levels of nitrates by eating lots of foods rich in nitrates such as spinach, lettuce, cured meat, processed meat, fish, and beer.

Once consumed, the body can convert nitrates into similar compounds called nitrites. High levels of nitrites can decrease the blood’s ability to carry oxygen to our cells. This can cause dizziness, headaches, cramps, vomiting, decreased blood pressure, increased heart rate, and death. Infants seem to be more sensitive to the health effects of nitrite exposure than adults.

Once nitrates get converted into nitrites in the body, they can be further converted into compounds called nitrosamines, which are known to cause cancer. For this reason, the International Agency for Research on Cancer has determined that ingesting nitrates probably causes cancer in humans. Because nitrates occur in nature and are made naturally by our bodies, it can be hard to know our exposure risk from dietary and industrial sources. This makes it particularly important for the federal government to regulate nitrates from sources such as fertilizers and food preservation in order to keep people safe from the adverse health effects of exposure.

Learn about more toxics

Acrylamide

Acrylamide is a clear, odorless chemical. It has many industrial uses, including treating waste water<br

Read More »
Categories
Toxic Tuesdays

How the Duration of Exposure Affects Toxicity

Toxic Tuesdays

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

< Back to Toxic Tuesdays

How the Duration of Exposure Affects Toxicity

CHEJ has previously written about the importance of considering multiple chemical exposures when assessing the toxicity of exposure to toxic chemicals. In addition, it is also important to consider the duration of exposure. How long was a person exposed? What was the concentration of the substance(s) during this period of time are critical to truly understanding the cumulative effects that a person has suffered? Without this information, we can only partially understand the risks of exposure to toxic chemicals. 

Yet when evaluating whether exposures to toxic chemicals pose risks to human health, the government’s approach is usually very narrow: it assumes there is a single chemical from a single source at a single point in time with a single exposure pathway causing a single health effect. This approach makes risk assessment more feasible and understandable, but it does not reflect the reality of our lives.

In reality, we are exposed to multiple chemicals at a time and exposures can happen over a long period of time. This means that considering the potential effects of a single exposure to a single chemical isn’t sufficient for evaluating public health risks. We need to include cumulative risks that account for both multiple chemical exposures and exposure over time in order to begin to understand the risks to public health. But incorporating these parameters into a risk assessment poses significant new challenges that  requires more estimates and generates additional uncertainty than the traditional risk assessment approach.

In many cases, exposure assessments assume that exposure to a chemical happens in a single instant in time. In some cases – like cancer risk – EPA assumes that risk is proportional to the lifetime dose. In general, longer exposure means greater risk, but the relationship between duration of exposure and health risk is complicated. The risk depends on the effects an exposure has on the body and the body’s response to it. In some cases, the body may adapt to exposure and the threat over time may be less than additive. In other cases, the body may become more sensitive and the threat over time may be more than additive. Repeated exposure can also influence health risk: past exposure to some chemicals can make us more vulnerable to subsequent exposure. And how do you consider the effects caused by exposure to multiple chemicals that target the same organ in the body can cause more damage than exposure to any of those chemicals individually?

The effect of exposure over time is important to consider in risk assessments, but agencies like EPA and ATSDR do not have comprehensive frameworks for how to assess this cumulative risk. Part of the reason for this is a lack of data. The guideline values we use to evaluate risks are driven by data generated from exposures to a single chemical for a defined period of time. For common chemicals and chemical mixtures that people are exposed to, we need to know how different concentrations and durations of exposure affect health. There is a need for more scientific study on how exposures to chemicals over long periods of time can impact our risk for adverse health effects. Once people have been exposed to chemicals, we also need better tools to measure their past exposure so it can be accounted for in risk assessments.

While more research and data is crucial, there will always be uncertainty in science and data, and we cannot let uncertainty stop us from taking action to protect health. In addition to more scientific study, we need clearer guidelines from federal agencies regarding how to consider cumulative risk – both from multiple chemical exposures and exposures over time – in evaluating if an environmental hazard is a threat to human health. We also need to acknowledge how poor the tools we have are at considering cumulative risks caused by exposures to multiple chemicals over time.

Learn about more toxics

Acrylamide

Acrylamide is a clear, odorless chemical. It has many industrial uses, including treating waste water<br

Read More »
Categories
Toxic Tuesdays

1,2-dichloroethane (1,2-D)

Toxic Tuesdays

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

< Back to Toxic Tuesdays

1,2-dichloroethane (1,2-D)

1,2-dichloroethane (1,2-D) – also called ethylene dichloride – is a clear, oily liquid with a sweet smell that is man-made and not found in nature. It is used in the production of plastic and vinyl products like polyvinyl chloride (PVC) pipes, upholstery, automobile parts, and housewares. It is also added to the leaded gasoline used in airplanes and racecars. 1,2-D was previously used in some household products like carpet cleaners, but most of these products are discontinued. 1,2-D can enter the environment during its production, disposal, or use. It can enter the water and soil, but because it is volatile (meaning it readily evaporates), most 1,2-D ends up in the air. Once in the air, it can persist for many months and travel long distances.

Because most 1,2-D in the environment ends up in the air, people are most likely to be exposed to it by breathing contaminated air. Exposure can cause damage to many organ systems: brain dysfunction such as nausea and blurred vision; gastrointestinal dysfunction such as vomiting, gastritis, and colitis; respiratory dysfunction such as difficulty breathing and bronchitis; immune system dysfunction such as decreased ability to fight infection and decreased blood clotting; liver damage; and kidney damage. In extreme cases, exposure can cause heart attack and death. In studies of laboratory animals, exposure also caused lung, liver, brain, and reproductive cancers. Based on this research, the US Environmental Protection Agency has determined that 1,2-D probably causes cancer in humans.

1,2-D is known to be a very dangerous chemical with multiple harmful effects on human health. It is a positive development that household products with 1,2-D are largely discontinued. However, its continued use in products like PVC pipes and leaded gasoline mean that 1,2-D and its threats to human health remain pervasive in both household and industrial environments.

Learn about more toxics

Acrylamide

Acrylamide is a clear, odorless chemical. It has many industrial uses, including treating waste water<br

Read More »
Categories
Toxic Tuesdays

Lead in Public Housing

Toxic Tuesdays

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

< Back to Toxic Tuesdays

Lead in Public Housing

Lead is a naturally occurring metal that has been used in many household products like paint and plumbing materials. This makes people most likely to be exposed to lead in their own homes, through ingesting or inhaling contaminated paint, dust, or water. Lead exposure affects all organs but is particularly damaging to the brain, causing defects in learning and memory. Children are especially vulnerable to lead exposure because of their growing brains, and exposure can cause defects in brain development, behavioral problems, and irreversible learning disabilities. Even though it’s been known for over two hundred years that lead is toxic, it is estimated that 800 million children worldwide are exposed to lead today. (CHEJ has previously written about the health effects of lead exposure here.)

A new study has found that access to federal housing assistance is associated with lower blood lead levels (BLLs), demonstrating how housing access influences health. The US Department of Housing and Urban Development (HUD) has three main housing assistance programs that help 5 million low-income households access affordable, high-quality housing:

  1. The public housing program provides subsidized housing units at a specific site that is owned by the local public housing authority.
  2. The multifamily income-restricted housing program provides subsidized housing units at a specific site that is owned by a private entity.
  3. Tenant-based housing choice vouchers (HCVs) provides subsidies for tenants to use towards finding housing in the private market.

The study authors linked HUD administrative records to data from an existing survey that measured people’s health including their BLLs. This allowed the authors to connect people’s BLLs to whether or not they were enrolled in a HUD housing program. To determine if access to HUD housing programs was associated with lower BLLs, the authors compared those who were enrolled in a HUD program to those who were not enrolled but would become enrolled within the next 2 years. This ensured that the groups being compared were similar in their socio-economic status and eligibility for HUD housing assistance. Overall, the study sample included over four thousand people.

The authors found that when controlling for demographic factors like race, ethnicity, sex, age, partnership status, and households size, average BLL was 11.4% lower for people enrolled in HUD housing programs compared to people who were not enrolled at the time. The effect was biggest for people enrolled in public housing programs. The effect was smallest for people enrolled in the HCV program. The authors hypothesize that this protective effect of HUD housing assistance is because HUD has stricter compliance and enforcement of federal lead-paint laws – such as the Lead-Paint Poisoning Prevention Act, the Residential Lead-Based Paint Hazard Reduction Act, and the Lead-Safe Housing Rule – in their public-owned housing units compared to housing units that are privately owned. Because the HCV program has recipients find housing on the private market, this may explain why there was little effect on BLLs for people enrolled in HCV. The authors also note that as housing construction has slowed in the past few decades, affordable housing options on the private market tend to be older construction that are more likely to contain lead-based paint and pipes. HUD’s required inspections, maintenance, abatement, and clearance activities seem to be effective at decreasing people’s exposure to lead. This is consistent with previous studies that have found other positive health outcomes associated with public housing.

The authors found that the association between HUD housing program enrollment and lower BLLs was strongest for non-Hispanic white people. The association was much lower for Black and Mexican American people. While the study cannot explain why this is, the authors offer several explanations rooted in historical and ongoing racism:

“Black households continue to face significant barriers to high-quality housing and high-opportunity neighborhoods that may have fewer lead hazards because of legacies of racist housing policies and urban planning practices in the United States. These practices include redlining, zoning and land use restrictions, gerrymandering of school and census boundaries, predatory lending, and urban renewal initiatives in Black and Brown neighborhoods that displaced families and built highways, airports, and other large pollution-emitting sources in their neighborhoods through eminent domain.”

Overall, this study indicates that housing through HUD programs protects against lead exposure. This is likely a success story of regulations that require inspection, abatement, and removal of lead in public housing; it suggests that requiring units on the private housing market to adhere to these same regulations could have a significant impact on lead exposure in the United States. Because lead is one of the worst toxic chemicals with the potential to do lifelong damage to children, public policy efforts that reduce lead exposure should be a priority. The fact that the lead protective effect of HUD programs is less substantial for nonwhite people demonstrates how systemic racism impacts housing and health. This study shows that housing justice and environmental justice are deeply intertwined: access to high-quality housing is crucial for health and safety. The study also shows that neither housing justice nor environmental justice can be achieved without racial justice.

Learn about more toxics

Acrylamide

Acrylamide is a clear, odorless chemical. It has many industrial uses, including treating waste water<br

Read More »
Categories
Toxic Tuesdays

Dealing with Uncertainty When Evaluating Toxicity​

Toxic Tuesdays

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

< Back to Toxic Tuesdays

Dealing with Uncertainty When Evaluating Toxicity

In a recent issue, we discussed the many challenges in evaluating the adverse health effects that result from exposure to a mixture of toxic chemicals. Despite this, scientists still estimate and assess risks by attempting to compensate for these uncertainties.

This is done by assigning an uncertainty factor (UF) to the different uncertainties. How well these uncertainty factors fill in the gap in what we do not know is a matter of controversy and opinion. Especially when you acknowledge that we only have good toxicity information on about 1% of the more than 80,000 chemicals that are in use.

Consider just a few of the uncertainties. The first step in assessing risks is to determine what substances a person was exposed to, at what concentration and for how long. Rarely is this information ever available, so assumptions need to be made to estimate this critical information. Sometimes, there is limited air, soil or water data. This data is often collected for a different purpose, such as to evaluate the need for remediation as opposed to evaluating public health risks. There are also uncertainties in how the samples were collected, the accuracies of and precision of the analytical measurements and the thoroughness of the sampling (were the samples taken at the right places, analyzed for the right substances and at relevant concentrations). At times, modeling is used to estimate how much of a chemical a person was exposed to (usually after making assumptions about even what kind of chemicals a person was exposed to), how long they were exposed and at what concentration.

The next step is to evaluate the toxicity information available on the chemical in question. This would include information from animal studies, clinical trials and epidemiological studies involving people. Since most of the data that exists is from animal studies, this step already creates enormous uncertainties. These uncertainties include extrapolating results in animals to people; the variability in response among people; the sensitivity in response among people; estimating acute or short-term responses in people when the only data you have is from chronic or long-term exposure, and vice versa. These examples just touch the surface of the many uncertainties in our understanding of how chemicals affect a person’s health. 

Another factor that comes into play is the health status of the individual who was exposed. People who are generally healthy and without pre-existing conditions respond differently to toxic chemicals than people with prior exposures, poor immune or nutritional status, or pre-existing health problems.

To address these many uncertainties, scientists have developed what were originally called safety factors, but now are referred to simply as uncertainty factors (UF). These uncertainty factors can range from 1 to 10 and often are multiplied together to yield a composite uncertainty factor that can be as high as 100 (10 x 10). These UFs are included in the estimate of the risks a person or group of people face.

Scientists give an UF to each specific uncertainty trying to compensate for the uncertainty. Doing this requires making many assumptions about areas of knowledge that very little is known about. These assumptions are made by “scientific experts” who very quickly become convinced that they “know” the health risks that a person or a group of people face. Of course, they do not really know. Instead, what they have is an opinion based on multiple assumptions, typically for a single substance.

What compounds this process is that the people who make these risk assessment estimates are scientific experts, and do not include the people who have to bear the risks of the chemical exposures. That’s not right! The people who bear the risks need to be involved in the risk assessment and health evaluation process because of the many uncertainties that exist in estimating exposures and in extrapolating what little data exist to evaluate adverse health effects resulting from exposures to low level mixtures of toxic chemicals.

For more about uncertainties when evaluating the adverse effects from chemical exposures, see Environmental Decisions in the Face of Uncertainty, by the Institute of Medicine of the National Academies, 2013.

Learn about more toxics

Acrylamide

Acrylamide is a clear, odorless chemical. It has many industrial uses, including treating waste water<br

Read More »
Categories
Toxic Tuesdays

1,4-dichlorobenzene (1,4-DCB)

Toxic Tuesdays

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

< Back to Toxic Tuesdays

1,4-dichlorobenzene (1,4-DCB)

1,4-dichlorobenzene (1,4-DCB) – also known as p-dichlorobenzene (p-DCB) – is a colorless solid chemical that readily evaporates into the air. 1,4-DCB does not occur in nature, and it is often produced for use in deodorants or disinfectants because it has a strong odor that humans can smell at very low concentrations. It is commonly used in household products like mothballs and deodorizing sprays. It also has industrial uses as a pesticide ingredient and a precursor to commercial dyes. 1,4-DCB can enter the environment through its household uses, pesticides, and industrial waste disposal. 1,4-DCB mostly enters the environment as a vapor, and people are likely to inhale it in homes and buildings where it is used. Solid 1,4-DCB can also bind to soil and remain there for long periods of time, but people are less likely to be exposed to it in this way.

Inhaling high concentrations of 1,4-DCB can cause irritation or burning sensations in the eyes and nose. It can also cause coughing, nausea, difficulty breathing, dizziness, headaches, and liver dysfunction. Touching products that contain 1,4-DCB can also cause burning sensations on the skin. In studies of laboratory animals, 1,4-DCB exposure caused liver, kidney, and blood defects as well as liver cancer. The US Department of Health and Human Services and the International Agency for Research on Cancer both classify it as being reasonably anticipated to cause cancer.

Because of the danger to human health, the Environmental Protection Agency has set a maximum 1,4-DCB concentration that can be present in drinking water without observing adverse health effects. The European Union has gone even further, banning use of 1,4-DCB in mothballs and air fresheners because of its potential to cause cancer. Similar regulation in the US could protect more people from the health risks of 1,4-DCB exposure.

Learn about more toxics

Acrylamide

Acrylamide is a clear, odorless chemical. It has many industrial uses, including treating waste water<br

Read More »