Ok. Think. How might cars be dangerous? For starters, you can crash them and kill or maim yourself and others through careless driving or being drunk at the wheel. In fact, let’s stop there, as automotive crashes have accounted for roughly 38,000 deaths each year for the past 10 years. And that’s just the people in the cars. Add on collateral damage to 5,000 – 6,000 pedestrians and cyclists each year. Add to that some three million non-fatal injuries for car occupants and 170,000 for pedestrians.
In light of these statistics, it almost defies reason (and taste) to read on MSNBC that the biggest risk to human health from automobiles is from breathing the air inside them. As the headline of the piece (culled from Men’s Health) proclaims: “Invisible hitchhikers may be lurking in your car: Your biggest threat behind the wheel could be toxins riding shotgun.”
That, dear reader, is flat out wrong (but yes, it probably made you click on the article). Unless you store depleted uranium under your car seat, you are the biggest threat to your health behind the wheel. Especially if you have a drink or three (The Centers for Disease Control estimate that alcohol alone counted for 16,855 traffic fatalities in 2005.) MSNBC/Mens’ Health, instead, misreads research about the chemical content of air in cars – often dubbed “new car smell” – and then accelerates into extrapolated nonsense in order to deliver a tabloid shock, viz:
Emerging research suggests that a car’s capacity to do violence to the human body may not be limited to high-speed collisions. In fact, just sitting in the garage with the ignition off could be risky. Best-case scenario, the fumes wafting from the materials surrounding you might merely exacerbate pre-existing asthma or allergies; on the scarier end of the spectrum, those airborne compounds could be carcinogens. And the absolute worst-case scenario: The dashboard’s to blame for your small penis.
First of all, if we want to talk about allergies, we should focus on particulate pollution from automotive emissions, which have been correlated with higher incidences of asthma, and respiratory problems, particularly the larger size particulates found in diesel exhaust fumes. Hence, for example, the oft-commented upon link between high rates of asthma in the South Bronx and the city’s bus depots. A National Institutes of Health panel estimated that reducing exposure to soot by one microgram (to 14 micrograms per cubic meter of air) would save as many as 24,000 deaths per year – as well as produce significant health benefits to those suffering from lung-related disorders and disease.
But these emissions are outside your car. The release of phthalates from plastics inside the car is highly, highly unlikely to give you cancer or do anything even mildly irritating to you. More to the point, they absolutely will not affect the size of your penis – at least according to current research.
The source for this nonsense is the Ecology Center, a Michigan-based non-profit environmental group that has cornered the market on scare stories about new car smell. Relying on the group’s report Automotive Plastics Report Card, MSNBC/Men’s Health contributor Michael Abrams writes the following:
The report examined two categories of chemicals lurking in car materials: phthalates and brominated flame retardants, such as deca. Phthalates make plastics softer and more elastic. They have also been shown to lead to liver and kidney damage in rodents. As for the flame retardants, they act like rat poison, too, causing brain damage and thyroid problems.
And while the research on humans is more limited, it’s no less alarming. One 2004 study from Sweden showed that children raised in houses with high concentrations of phthalates in the dust were more likely to develop asthma and allergies. Another recent study from the University of Rochester found that men with the most phthalates in their bodies had waists 3 inches wider than those with the least. Still more research suggests that we’re being attacked in utero, too: A 2005 paper in Environmental Health Perspectives reported that mothers with higher levels of phthalates in their urine had sons with less-developed genitalia.
Now here’s what’s missing. There are a variety of brominated fire retardants, but the ones that were a genuine threat to health have been banned or restricted. The European Union conducted a 10-year risk assessment, evaluating 588 studies on deca, and found it posed no health risk.
The damage to rodents from phthalates was at levels far, far beyond anything you are likely to inhale or ingest – and besides, most of our exposure to phthalates is through food and dust and not from offgassing while driving. The Ecology Center determined that phthalates were dangerous not by referencing the Environmental Protection Agency or EU risk assessments, but by citing the OSPAR Commission, which has the goal of protecting marine life in the North East Atlantic from environmental pollution.
OSPAR, for example, notes that in high concentrations the phthalate DBP is toxic to fish and rodents, but it says nothing about its toxicity in humans from environmental exposure. The EPA risk faq, on the other hand, notes that DBP “appears to have relatively low toxicity. Adverse effects have not been reported in humans as a result of exposure to di-n-butyl phthalate.”
While marine exposure and environmental pollution are separate and important issues, it’s a bit of a stretch to warn the public about the inhalation risks of a chemical that has a low toxicity.
As for phthalates and obesity, the study in question found that “several phthalate metabolites showed statistically significant positive correlations with abdominal obesity and insulin resistance in adult U.S. males,” which means that the fatter and more insulin resistant the man, the greater the quantity of phthalate metabolites in his urine.
But the simple fact of a correlation doesn’t mean that phthalates actually cause obesity; it could be the case that men who are fat retain more phthalates than men who are not. Or they simply consumed more food. In fact, the authors of the study listed seven limitations on the interpretation of their findings, among which include the study being cross-sectional, so it is only a snapshot of at a single point in time and cannot determine causality; and the database they used contained no data on sex hormone levels, thereby limiting examination of the mode of action by which they hypothesize that phthalates might cause obesity.
It’s also worth pointing out that sitting in a car all day is hardly a recipe for a svelte lifestyle.
As for Abram’s “less developed genitalia,” one can only speculate as to what he means by such a vague formulation. What the researchers found was that some phthalate metabolites were correlated with a shorter than average anogenital index (the distance between the base of the penis and the anus adjusted for weight differences) and that this biomarker could have an impact on the testicular descent in utero. (To read more about what this means, click here.) None of this means deformed, undeveloped or damaged penises: all the children in study Abrams refers to had normal genitalia and healthy reproductive functioning.
Hyping all this data in such a jaunty – watch out, small penises ahead! – manner is the real toxic offgassing going on here. Especially as it obscures the fact that the research, limited as it is, shows that pthalates and fire retardants are not the chemicals that scientists are measuring or concerned about when it comes to new or old car smell.
For example, in the study Toxicity of Parked Motor Vehicle Indoor Air (Buters et al, Environ. Sci. Technol., 41 (7), 2622-2629, 2007), which measured the air in one three-year old car and one identical but brand new car subjected to temperature conditions which would have maximized off gassing, the overall level was three times that proposed as acceptable for indoor environmental conditions.
The major compounds in the new vehicle were o,m,p-xylenes, C3 and C4-alkylbenzenes, dodecane, tridecane, and methylpyrrolidinone. In the used vehicle they were acetone, methylpyrrolidinone, methylcyclohexane, acetaldehyde, o,m,p-xylenes, ethylhexanol, and toluene.
Similar research in Japan on a much greater sample found similar chemicals.
Buters, a toxicologist at the Technical University in Munich, and an expert on sick building syndrome, also tested these compounds on animal cells and did not find any toxic effects. (The Japanese research did not test for toxicity).
Abrams cites the Ecology Center’s dismissal of Buters research for a small sample size and the fact that leather interiors might have minimized the chemical content of the air (even though the Center didn’t actually measure the content of the air in their study, they took a sample of film from the window):
According to the Ecology Center’s ongoing evaluation of VOCs in cars (posted at healthycar.org), the pricier the car, the less toxic its materials. Luxury cars tend to contain safer flame retardants, leather instead of plasticized vinyl, and more stable plastics overall.
The Japanese research however found the opposite, namely, that air pollution was greater in luxury cars with leather seats and trim.
So, what can we conclude? Americans kill themselves and others in the thousands each year by stepping into a car, either sober or drunk. Driving also pollutes the atmosphere, uses up fossil fuels, and discourages physical activity. Sociologists s have found that long commutes significantly increase drivers’ unhappiness and stress. In sum, you could make a lot of arguments about how cars are a menace to human health and well being, but sniffing the smell given off by the dashboard is not quite the health risk that this sloppily researched article would have you believe.