Tag Archives: air pollution

 This is a thought-provoking study that looked at environmental quality and cancer incidence in counties throughout the US. The researchers found that the more polluted the county, the higher the cancer incidence. An increase in cancer rates was associated with poorer air quality and the "built environment" (such as major highways). They correctly point out that many things together can contribute to cancer occurring - and this is why looking at how polluted the air, water, etc. together is important.

They looked at the most common causes of cancer death in both men (lung, prostate, and colorectal cancer), and women (lung, breast, and colorectal cancer). They found that prostate and breast cancer demonstrated the strongest associations with poor environmental quality. [Original study.]

The researchers point out that about half of cancers are thought to have a genetic component, but therefore the other half have environmental causes. Other studies already find that environmental exposures (e.g., pesticides, diesel exhaust) are linked to various cancers. But this study was an attempt to look at interactions of various things in the environment with rates of cancer - because we all are exposed to a number of things simultaneously wherever we live, not just to exposures to one thing. Thus this study looked at associations in rates of cancer. 

Of course there is also a lifestyle contribution to many cancers that wasn't looked at here (nutrition, alcohol use, exercise). They also pointed out that many counties in the US are large and encompass both very polluted and non-polluted areas - and that those counties should be broken up into smaller geographic areas when studied. [More air pollution studies.] From Science Daily:

Poor overall environmental quality linked to elevated cancer rates

Nationwide, counties with the poorest quality across five domains -- air, water, land, the built environment and sociodemographic -- had the highest incidence of cancer, according to a new study published in the journal Cancer. Poor air quality and factors of the built environment -- such as the presence of major highways and the availability of public transit and housing -- -- were the most strongly associated with high cancer rates, while water quality and land pollution had no measurable effect.

Previous research has shown that genetics can be blamed for only about half of all cancers, suggesting that exposure to environmental toxins or socioeconomic factors may also play a role. "Most research has focused on single environmental factors like air pollution or toxins in water," said Jyotsna Jagai, research assistant professor of environmental and occupational health in the University of Illinois at Chicago School of Public Health and lead author of the study. "But these single factors don't paint a comprehensive picture of what a person is exposed to in their environment -- and may not be as helpful in predicting cancer risk, which is impacted by multiple factors including the air you breathe, the water you drink, the neighborhood you live in, and your exposure to myriad toxins, chemicals and pollutants."

To investigate the effects of overall environmental quality, the researchers looked at hundreds of variables, including air and water pollution, pesticide and radon levels, neighborhood safety, access to health services and healthy food, presence of heavily-trafficked highways and roads, and sociodemographic factors, such as poverty. Jagai and her colleagues used the U.S. EPA's Environmental Quality Index, a county-level measure incorporating more than 200 of these environmental variables and obtained cancer incidence rates from the National Cancer Institute's Surveillance, Epidemiology, and End Results Program State Cancer Profiles. Cancer data were available for 85 percent of the 3,142 U.S. counties.

The average age-adjusted rate for all types of cancer was 451 cases per 100,000 people. Counties with poor environmental quality had higher incidence of cancer -- on average, 39 more cases per 100,000 people -- than counties with high environmental quality. Increased rates were seen for both males and females, and prostate and breast cancer demonstrated the strongest association with poor environmental quality.

The researchers found that high levels of air pollution, poor quality in the built environment and high levels of sociodemographic risk factors were most strongly associated with increased cancer rates in men and women. The strongest associations were seen in urban areas, especially for the air and built environment domains. Breast and prostate cancer were most strongly associated with poor air quality.

 This post is more on the theme of nanoparticles and human health. My last post was about a study that examined how inhaled nanoparticles  (for example, from air pollution) travel from the lungs to the bloodstream. Well, today's post is about a pretty shocking 2016 air pollution nanoparticle study which examined the brains (brain tissue) of 45 dead people  (ages 3 to 92) who had lived for a long time in two places with heavy  particulate air pollution - Mexico City and Manchester, England. Some of the British people also had Alzheimer's disease or dementia.

The researchers found evidence that minute nano-sized particles of magnetite from air pollution can find their way into the brain. There are 2 forms of magnetite (which is an iron ore) - one naturally occurring (jagged edges in appearance), and one found commonly in air pollution (smooth and rounded - from being created in the high temperatures of vehicle engines or braking systems). The researchers are concerned that the air pollution nanoparticles may increase the risk for brain diseases such as Alzheimer's.

One of the researchers (Prof Barbara Maher) has previously identified magnetite particles in samples of air gathered beside a busy road in Lancaster, England and outside a power station. She suspected that similar particles may be found in the brain samples, and that is what happened. "It's dreadfully shocking. When you study the tissue you see the particles distributed between the cells and when you do a magnetic extraction there are millions of particles, millions in a single gram of brain tissue - that's a million opportunities to do damage."..."It's a whole new area to investigate to understand if these magnetite particles are causing or accelerating neurodegenerative disease." However, it must be stressed that at this time there is no proven link between these magnetite particles and any neurodegenerative diseases. They're just wondering.... they call finding these pollution nanoparticles "suggestive observations".

From Medical Xpress: Toxic air pollution nanoparticles discovered in the human brain

Tiny magnetic particles from air pollution have for the first time been discovered to be lodged in human brains – and researchers think they could be a possible cause of Alzheimer's disease. Researchers at Lancaster University found abundant magnetite nanoparticles in the brain tissue from 37 individuals aged three to 92-years-old who lived in Mexico City and Manchester. This strongly magnetic mineral is toxic and has been implicated in the production of reactive oxygen species (free radicals) in the human brain, which are associated with neurodegenerative diseases including Alzheimer's disease.

Professor Barbara Maher, from Lancaster Environment Centre, and colleagues (from Oxford, Glasgow, Manchester and Mexico City) used spectroscopic analysis to identify the particles as magnetite. Unlike angular magnetite particles that are believed to form naturally within the brain, most of the observed particles were spherical, with diameters up to 150 nm, some with fused surfaces, all characteristic of high-temperature formation – such as from vehicle (particularly diesel) engines or open fires. The spherical particles are often accompanied by nanoparticles containing other metals, such as platinum, nickel, and cobalt.

Professor Maher said: "The particles we found are strikingly similar to the magnetite nanospheres that are abundant in the airborne pollution found in urban settings, especially next to busy roads, and which are formed by combustion or frictional heating from vehicle engines or brakes."

Other sources of magnetite nanoparticles include open fires and poorly sealed stoves within homes. Particles smaller than 200 nm are small enough to enter the brain directly through the olfactory nerve after breathing air pollution through the nose.....The results have been published in the paper 'Magnetite pollution nanoparticles in the human brain' by the Proceedings of the National Academy of Sciences.

A good discussion of the study in The Scientist: Environmental Magnetite in the Human Brain

Fig. S11. Image of magnetite nanoparticles from the exhaust plume of a diesel engine. Credit: Maher et al study, 2016.

09_05_magnetic_01  A microscopic image shows magnetic nanoparticles in the human brain. Credit: Barbara Maher et al study, 2016.

  The use of nanomaterials has been really increasing  in recent years without us really understanding if  nanoparticles have negative health effects, and if they travel to the brain or other organs in the human body. Nanoparticles are used in many  consumer products, including foods (e.g., nano-sized titanium dioxide) and medicines, but they are also found in air pollution  (e.g., tires breaking down, vehicle exhaust). Well..... evidence is starting to appear that YES - nanoparticles can travel  throughout the body, and they can accumulate in the body, including lungs and brain, and they can have negative health effects. For example, inhaled nanoparticles from air pollution are able to deposit deep in the lungs where they cause oxidative stress and inflammation.

Now new research in both humans and mice has shown that inhaled nanoparticles can travel from the lungs into the bloodstream. In this study both healthy males and heart disease patients inhaled gold nanoparticles of varying sizes. The gold was detected in the blood and urine within 15 minutes to 24 hours after exposure, and was still present 3 months after exposure. The levels were greater following inhalation of smaller 5 nanometer (nm) particles compared to the larger 30 nm particles (meaning the body had trouble clearing the smaller nanoparticles). The nanoparticles acculmulated more in inflamed vascular sites, including carotid plaques in patients at risk of a stroke. Showing this is important in explaining how tiny nanosized particles in air pollution are linked to cardiovascular disease and death - for example, why and how they can trigger heart attacks and other "cardiovascular events". Science Daily:

Nanoparticles can travel from lungs to blood, possibly explaining risks to heart

Tiny particles in air pollution have been associated with cardiovascular disease, which can lead to premature death. But how particles inhaled into the lungs can affect blood vessels and the heart has remained a mystery. Now, scientists have found evidence in human and animal studies that inhaled nanoparticles can travel from the lungs into the bloodstream, potentially explaining the link between air pollution and cardiovascular disease. Their results appear in the journal ACS Nano.

The World Health Organization estimates that in 2012, about 72 percent of premature deaths related to outdoor air pollution were due to ischemic heart disease and strokes. Pulmonary disease, respiratory infections and lung cancer were linked to the other 28 percent. Many scientists have suspected that fine particles travel from the lungs into the bloodstream, but evidence supporting this assumption in humans has been challenging to collect. So Mark Miller and colleagues at the University of Edinburgh in the United Kingdom and the National Institute for Public Health and the Environment in the Netherlands used a selection of specialized techniques to track the fate of inhaled gold nanoparticles.

In the new study, 14 healthy volunteers, 12 surgical patients and several mouse models inhaled gold nanoparticles, which have been safely used in medical imaging and drug delivery. Soon after exposure, the nanoparticles were detected in blood and urine. Importantly, the nanoparticles appeared to preferentially accumulate at inflamed vascular sites, including carotid plaques in patients at risk of a stroke. The findings suggest that nanoparticles can travel from the lungs into the bloodstream and reach susceptible areas of the cardiovascular system where they could possibly increase the likelihood of a heart attack or stroke, the researchers say. [Original study.]

 Another study finding a link between air pollution and negative health effects - this time a higher incidence of decline in cognitive functioning  and dementia in older women (65 and older) exposed to fine particles (PM2.5 ). These extremely small particles from vehicle emissions are a major source of urban air pollution throughout the world. These results match other studies finding a link with urban air pollution, especially vehicle traffic, to negative effects on the brain (dementia, cognitive decline, shrinking of the brain, etc.). The researchers also exposed mice to this air pollution for 15 weeks and then studied their brains for evidence of degenerative effects in their brains - and yes, they did find them.

The researchers found that the adverse effects of fine particulate air pollution was stronger in both women and mice who had the APOE4 gene, a genetic variation that increases the risk for Alzheimer's disease. They said that while the air pollution has negative effects in general, that having the APOE4 gene interacted with the air pollution. The researchers also wrote that the mice studies they did showed that "...exposure to urban airborne particulates can intensify amyloid accumulation and neurodegeneration". Medical Xpress:

Air pollution may lead to dementia in older women

Tiny air pollution particles—the type that mainly comes from power plants and automobiles—may greatly increase the chance of dementia, including Alzheimer's disease, according to USC-led research. Scientists and engineers found that older women who live in places with fine particulate matter exceeding the U.S. Environmental Protection Agency's standard are 81 percent more at risk for global cognitive decline and 92 percent more likely to develop dementia, including Alzheimer's.

If their findings hold up in the general population, air pollution could be responsible for about 21 percent of dementia cases, according to the study. "Microscopic particles generated by fossil fuels get into our body directly through the nose into the brain," said University Professor Caleb Finch at the USC Leonard Davis School of Gerontology and co-senior author of the study. "Cells in the brain treat these particles as invaders and react with inflammatory responses, which over the course of time, appear to exacerbate and promote Alzheimer's disease.

The adverse effects were stronger in women who had the APOE4 gene, a genetic variation that increases the risk for Alzheimer's. "Our study .....provides the inaugural scientific evidence of a critical Alzheimer's risk gene possibly interacting with air particles to accelerate brain aging," said Jiu-Chiuan Chen, co-senior author of the study....[Their study] adds to an emerging body of research from around the world that links air pollution to dementia. The offending pollutants—known as PM2.5—are fine, inhalable particles with diameters 2.5 micrometers or smaller. A human hair is about 70 micrometers in diameter, making it 30 times larger than the largest PM2.5. The researchers analyzed data of 3,647 65- to 79-year-old women from the Women's Health Initiative Memory Study (WHIMS). These women lived across 48 states and did not have dementia when they enrolled.

USC scientists chronically exposed female mice carrying the APOE4 gene to nano-sized air pollution for 15 weeks. Compared to the control group, mice predisposed to Alzheimer's disease accumulated as much as 60 percent more amyloid plaque, the toxic clusters of protein fragments that further the progression of Alzheimer's.

In other studies, Chen and his colleagues linked long-term exposure to high PM2.5 levels to smaller gray and white matter volumes in important areas such as the frontal lobe, which carries out thinking, decision-making and planning. For every 3.5 micrograms of PM2.5 per cubic meter of air, white matter (insulated nerve fibers that connect different brain regions) decreased by 6 cubic centimeters, according to one earlier study. [see post]

  Study after study finds negative health effects from air pollution, such as heart disease (here, here, and here). Now two more studies found that living in areas with high air pollution is linked to a higher stroke risk. One study (done in Japan) found an increase of ischemic stroke on the same day as exposure to high levels of air pollution, while the other (done in London, UK) found a higher risk of death after stroke (especially ischemic strokes) in patients who live in areas of high air pollution. This was especially pronounced with exposure to smaller or fine particulate matter (PM2.5)- which is found in high quantities in vehicle exhaust fumes.

It is thought that the fine particles in the air (PM2.5) contribute to the development of potentially fatal diseases various ways - by causing chronic inflammation, and also because they slip past the body's defenses and can be absorbed deep into the lungs and bloodstream. They are not sneezed or coughed out the way larger natural particles, like airborne soil and sand, are removed from the body's airways. What can be done? Other studies have found that when air pollution is reduced, than the risk of death is reduced. So yes, pollution controls on vehicles such as trucks and buses are good. And just think how much air pollution will be reduced when electric vehicles replace current gas powered cars and trucks. From Medscape:

Air Pollution Linked to Higher Stroke Mortality

More evidence showing that living in areas with high levels of air pollution is linked to a higher stroke risk has come from two new studies. Both studies are published online in the journal Stroke. The first, from the United Kingdom, shows a higher risk for death after a stroke in patients who live in areas of high air pollution, and the other, a Japanese study, suggests a higher risk for a new stroke the same day as exposure to high levels of air pollution.

"We have shown a significantly increased risk of death after stroke in patients who had long-term exposure to high levels air pollution before their stroke occurred," senior author of the UK study, Charles Wolfe, MD.... "This was particularly pronounced for high exposure to smaller particulate matter — particles below 2.5 μm in diameter (PM2.5) — which are found in high quantities in exhaust fumes." For the study, Professor Wolfe and colleagues analyzed data from the South London Stroke Register, a population-based register covering an urban, multiethnic population.....Results showed an increased risk for death up to 5 years after stroke in patients living in areas of high air pollution.

"While this study adds to the evidence linking air pollution to cardiovascular disease, it cannot prove causality as it has an observational design," Professor Wolfe commented...."So it is difficult to say for certain that it is the air pollution that is responsible but there are many studies now that have shown similar associations," he said. He noted that the smaller particles (PM2.5) were associated with a worse effect on mortality and this correlated with biological studies that have shown a greater inflammatory effect of small particulate matter vs larger particulate matter on the vessel wall. "Our study suggests that people who have previously had an ischemic stroke, but not a hemorrhagic stroke, may be more vulnerable and at a higher risk of death to chronic, long-term exposure of PM," they conclude.

The Japanese study, by lead author Ryu Matsuo, MD, PhD, Department of Health Care Administration and Management Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan, and colleagues, looked at acute exposure to air pollution and shows a small increase in the risk of having a stroke within a day of high exposure to pollution. For the study, the researchers analyzed data on 6885 ischemic stroke patients from a multicenter hospital-based stroke registry in Japan who were previously independent and hospitalized within 24 hours of stroke onset.

Professor Wolfe said his group have conducted a similar study looking at exposure of air pollution in the year before stroke, which showed a 23% increase in stroke risk in those exposed to higher levels of PM2.5. 

 An new analysis of published studies found that air pollution is linked to high blood pressure. Yes, breathing polluted air has health effects (here, here, and here). From Science Daily:

High blood pressure linked to short-, long-term exposure to some air pollutants

Both short- and long-term exposure to some air pollutants commonly associated with coal burning, vehicle exhaust, airborne dust and dirt are associated with the development of high blood pressure, according to new research in the American Heart Association's journal Hypertension. "In our analysis of 17 previously-published studies we discovered a significant risk of developing high blood pressure due to exposure to air pollution," said Tao Liu, Ph.D., lead study author and deputy director and epidemiologist of the environmental health division at Guangdong Provincial Institute of Public Health in China.

Researchers performed a meta-analysis of available published studies in the world assessing the health effects of all air pollution on hypertension risk. Meta-analyses combine results from previous studies to estimate the overall effect of a particular variable on a result.....researchers focused on these air pollutants: sulfur dioxide (SO2), which mainly comes from the burning of fossil fuel; nitrogen oxide (NOx), which comes from fossil fuels burned at power plants and vehicle exhaust; Particulate matter (PM) are particles found in the air, including dust, dirt, smoke and liquid droplets. (PM 2.5 is smaller than a speck of dust, and the most common and hazardous type of air pollution. PM10 includes both PM2.5 and PM2.5-10).

The meta-analysis found high blood pressure was significantly associated with: short-term exposure to sulfur dioxide (SO2), PM2.5 and PM10; and long-term exposure to nitrogen dioxide (NO2), which is produced from combustion, and PM10. For the portion of the study that assessed short-term effects of ozone and carbon monoxide exposure, no significant associations were found. Researchers said ozone and carbon monoxide's links to high blood pressure requires further study.

Of the 5,687 air pollution studies initially identified, 17 were the focus of this -- which involves more than 108,000 hypertension patients and 220,000 non-hypertensive controls. High blood pressure was defined as systolic blood pressure more than 140 mm Hg and/or diastolic blood pressure over 90 mm Hg or by antihypertensive drug use. Air pollution exposure was assessed by averaging data from nearest air pollution monitoring stations, or using complex dispersion models or land use regression models.

High blood pressure is a major risk factor for cardiovascular disease and stroke. Previous studies have indicated that air pollution might be a risk factor for hypertension but the results were controversial, Liu said. The mechanism by which air pollution could contribute to the development of high blood pressure includes inflammation and oxidative stress, which may lead to changes in the arteries.

 Last fall a study came out that estimated that annually about 3.3 million deaths throughout the world were caused from air pollution. But a study was presented Friday at the American Association for the Advancement of Science (AAAS) that gave a much higher estimate of annual air pollution deaths: 5.5 million. A horrifying number. And yet... governments, companies, and people resist  measures to cut air pollution. Why? It costs money. And also many people are too poor (e.g., China and India) to use cleaner sources of heating and cooking fuel - so they are damaging their own health in their own homes. From Science Daily:

Poor air quality kills 5.5 million worldwide annually

New research shows that more than 5.5 million people die prematurely every year due to household and outdoor air pollution. More than half of deaths occur in two of the world's fastest growing economies, China and India.

Power plants, industrial manufacturing, vehicle exhaust and burning coal and wood all release small particles into the air that are dangerous to a person's health. New research, presented today at the 2016 annual meeting of the American Association for the Advancement of Science (AAAS), found that despite efforts to limit future emissions, the number of premature deaths linked to air pollution will climb over the next two decades unless more aggressive targets are set.

"Air pollution is the fourth highest risk factor for death globally and by far the leading environmental risk factor for disease," said Michael Brauer, a professor at the University of British Columbia's School of Population and Public Health in Vancouver, Canada. "Reducing air pollution is an incredibly efficient way to improve the health of a population."

For the AAAS meeting, researchers from Canada, the United States, China and India assembled estimates of air pollution levels in China and India and calculated the impact on health. Their analysis shows that the two countries account for 55 per cent of the deaths caused by air pollution worldwide. About 1.6 million people died of air pollution in China and 1.4 million died in India in 2013.

In China, burning coal is the biggest contributor to poor air quality. Qiao Ma, a PhD student at the School of Environment, Tsinghua University in Beijing, China, found that outdoor air pollution from coal alone caused an estimated 366,000 deaths in China in 2013....In India, a major contributor to poor air quality is the practice of burning wood, dung and similar sources of biomass for cooking and heating. Millions of families, among the poorest in India, are regularly exposed to high levels of particulate matter in their own homes.

In the last 50 years, North America, Western Europe and Japan have made massive strides to combat pollution by using cleaner fuels, more efficient vehicles, limiting coal burning and putting restrictions on electric power plants and factories. 

Additional facts about air pollution: - World Health Organization (WHO) air quality guidelines set daily particulate matter at 25 micrograms per cubic metre. - At this time of year, Beijing and New Delhi will see daily levels at or above 300 micrograms per cubic meter metre; 1,200 per cent higher than WHO guidelines..... According to the Global Burden of Disease study, air pollution causes more deaths than other risk factors like malnutrition, obesity, alcohol and drug abuse, and unsafe sex.... - Cardiovascular disease accounts for the majority of deaths from air pollution with additional impacts from lung cancer, chronic obstructive pulmonary disease (COPD) and respiratory infections. Video: https://youtu.be/Kwoqa84npsU 

  When we think about air pollution, we usually think about pollutants in the air that we breathe in. But there is a growing body of evidence that some pollutants found in the air, including a group of chemicals called phthalates, can be absorbed directly through the skin (dermal absorption or dermal intake). A recent study has found that the skin absorption of certain phthalates (DERP and DnBP) is comparable to that from inhalation.

Phthalates are linked to a number of negative health effects, and so we should try to minimize our exposure to them.(Oct. 8, 2015 post and Sept. 29, 2015 post). The findings of this study is another strong argument against using scented products in the home, because phthalates are found in fragrances - whether air fresheners, scented candles, perfumes, dryer sheets, etc. Just think of them as indoor air pollution. From Environmental Health Perspectives:

Transdermal Uptake of Diethyl Phthalate and Di(n-butyl) Phthalate Directly from Air: Experimental Verification

Fundamental considerations indicate that, for certain phthalate esters, dermal absorption from air is an uptake pathway that is comparable to or greater than inhalation. Yet this pathway has not been experimentally evaluated and has been largely overlooked when assessing uptake of phthalate esters.This study investigated transdermal uptake, directly from air, of diethyl phthalate (DEP) and di(n-butyl) phthalate (DnBP) in humans.

In a series of experiments, six human participants were exposed for 6 hr in a chamber containing deliberately elevated air concentrations of DEP and DnBP. The participants either wore a hood and breathed air with phthalate concentrations substantially below those in the chamber or did not wear a hood and breathed chamber air. All urinations were collected from initiation of exposure until 54 hr later. Metabolites of DEP and DnBP were measured in these samples and extrapolated to parent phthalate intakes, corrected for background and hood air exposures. For DEP, the median dermal uptake directly from air was 4.0 μg/(μg/m3 in air) compared with an inhalation intake of 3.8 μg/(μg/m3 in air). For DnBP, the median dermal uptake from air was 3.1 μg/(μg/m3 in air) compared with an inhalation intake of 3.9 μg/(μg/m3 in air).

This study shows that dermal uptake directly from air can be a meaningful exposure pathway for DEP and DnBP. For other semivolatile organic compounds (SVOCs) whose molecular weight and lipid/air partition coefficient are in the appropriate range, direct absorption from air is also anticipated to be significant.

Selected phthalates have been associated with multiple health effects, including children’s neurodevelopment (Kim Y et al. 2011; Whyatt et al. 2012), altered genital development (Swan et al. 2005), respiratory problems (Jaakkola and Knight 2008), oxidative stress (Ferguson et al. 2011), obesity (Hatch et al. 2010), and the development of diabetes (Svensson et al. 2011). Phthalates are used in a wide variety of consumer products (Dodson et al. 2012), and their metabolites are commonly found in human urine (Koch et al. 2011; Langer et al. 2014; Zota et al. 2014)..... Numerous experimental studies have demonstrated that certain volatile organic compounds (VOCs) are dermally absorbed from air at rates that are comparable to their intake via inhalation (e.g.,Bader et al. 2008; Piotrowski 1967, 1971; other references in Weschler and Nazaroff 2014).

Diethyl phthalate (DEP) and di(n-butyl) phthalate (DnBP) are among the SVOCs predicted to have substantial dermal uptake directly from air (Weschler and Nazaroff 2012, 2014).... DEP is used in personal care products such as cosmetics, perfumes, and shampoos; it is also used in the automotive sector and food packaging. DnBP is a common ingredient of adhesives and coatings and is used as a solvent for organic compounds, as an antifoam agent, as a fiber lubricant, and as an additive in cosmetics, including nail polish (Bolgar et al. 2008; Dodson et al. 2012; Wypych 2012). DEP and DnBP have been identified in indoor air and dust samples from around the world (e.g., Fromme et al. 2004; Rudel et al. 2003; Wensing et al. 2005; Weschler and Nazaroff 2008). Their metabolites are often the most abundant synthetic chemicals identified in human urine (Koch et al. 2011; Langer et al. 2014; Zota et al. 2014).

The older the participant, the higher were the dermal uptakes of both DEP and DnBP from air. Based on this limited sample of six, the impact of age is surprisingly strong. The uptake of DEP by the 66-year-old is five times greater than that of the 27-year-old, while the uptake of DnBP is seven times greater....They indicate that the trend for increased dermal uptake with increasing age is significant for DEP and DnBP, whereas the trend for increased inhalation uptake is significant for DnBP, but not DEP....In the present study the human participants wore only shorts; the rest of their skin was directly exposed to air.

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  Several people have recently asked me whether scented candles have any health effects. The answer is a big YES - they have many negative health effects, and so do other scented products such as air fresheners and dryer sheets (e,g, Bounce). All of them contain fragrances and other chemicals - all from petrochemicals (which means they are chemical products derived from petroleum). And yes - all 3 products are totally unnecessary, so ditch them for better health. View all of them as sources of indoor air pollution.

Most of the candles on the market are made with paraffin wax, derived from petroleum, and scented with synthetic fragrances, also derived from petroleum. Synthetic fragrances typically also contain phthalates that can interfere with your hormone system (endocrine disruptors).

In one study scientists at the South Carolina State University lit several brands of candles made of paraffin – the most common and inexpensive candle wax – as well as soy candles (thus vegetable based) and burned them for 5 to 6 hours in a chamber. All of the candles were unscented and undyed. They found that the paraffin candle smoke emits varying levels of pollutants, including benzene, toluene and ketones, as well as hydrocarbon chemicals called alkanes and alkenes, which are components of gasoline. They have been linked to cancer, asthma and birth defects. None of the vegetable-based soy candles produced toxic chemicals. From SC State University:  Frequent use of certain candles produces unwanted chemicals

Researchers point out that the emissions from burning an occasional paraffin candle will not likely cause health problems - it's the frequent lighting of scented paraffin candles in indoor rooms, and inhaling the pollutants in the air that may cause health problems, or as Dr. Massoudi of S. Carolina State University stated: "could contribute to the development of health risks like cancer, common allergies and even asthma."

Scented candles are known to release various volatile organic compounds (VOCs) including both pleasant aromas and toxic components both before lighting (unlit) and when lit. When lit, the "highest emission concentration" was of formaldehydeCharacterization of hazardous and odorous volatiles emitted from scented candles before lighting and when lit

By simply touching the candles, one absorbs chemicals through the skin.  Skin contact transfer of three fragrance residues from candles to human hands.

Safe candle alternatives are beeswax candles and unscented soy candles. These do not emit toxic chemicals when burned. However, all burning candles emit soot, which is ultrafine, lung-damaging particulate matter that's capable of penetrating deep into the lungs.

From Huffington Post: The Big Problem With Scented Candles

Scented candles are one of the easiest and most effective ways to mask unpleasant odors in your home....But one of the main problems with scented candles is the scent itself. According to Anne Steinemann, an environmental pollutants expert who is a professor of civil engineering and the chair of sustainable cities at the University of Melbourne, certain candles may emit numerous types of potentially hazardous chemicals, such as benzene and toluene. They can cause damage to the brain, lung and central nervous system, as well as cause developmental difficulties.

"I have heard from numerous people who have asthma that they can’t even go into a store if the store sells scented candles, even if they aren’t being burned," Steinemann added. "They emit so much fragrance that they can trigger asthma attacks and even migraines."

Researchers at South Carolina State University tested both petroleum-based paraffin wax candles and vegetable-based candles that were non-scented, non-pigmented and free of dyes. Their 2009 report concluded that while the vegetable-based candles didn't produce any potentially harmful pollutants, the paraffin candles "released unwanted chemicals into the air," said chemistry professor Ruhullah Massoudi in a statement.

It may be shocking to think that your favorite candles could potentially be bad for you, and made worse by added fragrances. Steinemann said for some people, the effects are "immediate, acute and severe," while others may not realize they are being effected until they gradually develop health issues.

Though the risk to you may be small, there are alternatives. Steinemann suggests going the unscented route, avoiding "even those with essential oils, as they can potentially have hazardous chemicals," she said. "It's almost like air fresheners with the fragrance just sitting there ... permeating surfaces in the room."

Scary study results showing what may scientists have long feared - that carbon nanotubes are being released into the environment and getting into our bodies with unknown health effects. The researchers point out that fine particulate matter (PMs) from air pollution penetrate lower airways and are associated with adverse health effects even with low concentrations and that carbon nanotubes are part of this fine particulate matter. Here they discussed how catalytic converters may convert carbon monoxide into carbon nanotubes during the process of converting carbon monoxide into safer emissions. The problem with carbon nanotubes is that they are so small - so small that we inhale them, but can't cough them out. Carbon nanotubes can be envisioned as one-atom thick sheets of carbon atoms that have been rolled into tubes with diameters as small as 1 nm and lengths up to several centimeters. And scientists are concerned that they may have inflammatory effects on the lungs (similar to what asbestos does). Of course the long-term studies have not yet been done....Because once again, technological advances have outpaced any safety sudies. The researchers studied the lung cells of children with asthma, but it is unclear whether the carbon nanotubes had any effect on or caused their asthma.

Two additional areas of serious concern regarding carbon nanotubes: (1) many tires now contain carbon nanotubes, and with abrasion (wear and tear) the nanotubes are released into the air (air pollution), and (2) the tire crumb fill used in synthetic turf fields. People, including athletes and developing children, are playing on these fields and whatever is in the tires (toxic chemicals, lead, etc. and carbon nanotubes) is being released into the air, and inhaled and ingested by those playing and exercising on the synthetic turf. From Futurity:

Nanotubes Found in Lungs of French Kids

Cells taken from the airways of Parisian children with asthma contained man-made carbon nanotubes—just like the kind found in the exhaust pipes of vehicles in Paris. The researchers report in the journal EBioMedicine that these samples align with what has been found elsewhere in US cities, in spider webs in India, and in ice cores. The research in no way ascribes the children’s conditions to the nanotubes, says Rice University chemist Lon Wilson, a corresponding author of a new paper describing the work. But the nanotubes’ apparent ubiquity should be the focus of further investigation, he adds.

“We know that carbon nanoparticles are found in nature,” Wilson says, noting that round fullerene molecules like those discovered at Rice are commonly produced by volcanoes, forest fires, and other combustion of carbon materials. “All you need is a little catalysis to make carbon nanotubes instead of fullerenes.

samples of carbon nanotubes
Carbon nanotubes (the long rods) and nanoparticles (the black clumps) appear in vehicle exhaust from tailpipes of cars in Paris.
Carbon inside a lung cell vacuole
Carbon inside a lung cell vacuole takes the form of nanotubes (rods) and nanoparticles (black clumps).(Both photos: Fathi Moussa/Paris-Saclay Univ.)

A car’s catalytic converter, which turns toxic carbon monoxide into safer emissions, bears at least a passing resemblance to the high-pressure carbon monoxide, or HiPco, process to make carbon nanotubes, he says. “So it is not a big surprise, when you think about it,” Wilson adds.

The team—led by Wilson, Fathi Moussa of Paris-Saclay University, and lead author Jelena Kolosnjaj-Tabi, a graduate student at Paris-Saclay—analyzed particulate matter found in the alveolar macrophage cells (also known as dust cells) that help stop foreign materials like particles and bacteria from entering the lungs. 

The cells were taken from 69 randomly selected asthma patients aged 2 to 17 who underwent routine fiber-optic bronchoscopies as part of their treatment. For ethical reasons, no cells from healthy patients were analyzed, but because nanotubes were found in all of the samples, the study led the researchers to conclude that carbon nanotubes are likely to be found in everybody.

The study notes but does not make definitive conclusions about the controversial proposition that carbon nanotube fibers may act like asbestos, a proven carcinogen. But the authors reminded that “long carbon nanotubes and large aggregates of short ones can induce a granulomatous (inflammation) reaction.”

The study partially answers the question of what makes up the black material inside alveolar macrophages, the original focus of the study. The researchers found single-walled and multiwalled carbon nanotubes and amorphous carbon among the cells, as well as in samples swabbed from the tailpipes of cars in Paris and dust from various buildings in and around the city. “The concentrations of nanotubes are so low in these samples that it’s hard to believe they would cause asthma, but you never know,” Wilson says. “What surprised me the most was that carbon nanotubes were the major component of the carbonaceous pollution we found in the samples.”

The nanotube aggregates in the cells ranged in size from 10 to 60 nanometers in diameter and up to several hundred nanometers in length, small enough that optical microscopes would not have been able to identify them in samples from former patients. The new study used more sophisticated tools, including high-resolution transmission electron microscopy, X-ray spectroscopy, Raman spectroscopy, and near-infrared fluorescence microscopy to definitively identify them in the cells and in the environmental samples.

“We collected samples from the exhaust pipes of cars in Paris as well as from busy and non-busy intersections there and found the same type of structures as in the human samples,” Wilson says. “It’s kind of ironic. In our laboratory, working with carbon nanotubes, we wear facemasks to prevent exactly what we’re seeing in these samples, yet everyone walking around out there in the world probably has at least a small concentration of carbon nanotubes in their lungs,” he says. The researchers also suggest that the large surface areas of nanotubes and their ability to adhere to substances may make them effective carriers for other pollutants.