I’m starting to feel as though the entire internet is preoccupied with what may or may not cause cancer. I have received so many chain e-mails warning against some alleged carcinogen or another that I am starting to feel like a stuck record. Don’t get me wrong, cancer is a devastating disease and I have been deeply affected by its ability to destroy a person’s body and tear families apart. This is not an issue to be taken lightly. But, at the same time, it is essential that we not abandon all critical thinking the minute we are told that substance X “causes cancer”.
Today I received this e-mail about how using the Air Conditioner in your vehicle might cause cancer;
Very important guys,please take time to read it , as it is true
No wonder folks are dying from cancer more than ever before. We wonder where this stuff comes from but here is an example that may explain some of the cancer causing incidents. Please pass this on to as many people as possible. Guess it’s never too late to make some changes!!
|Car A/C (Air Conditioning) MUST READ!!!
Do NOT turn on A/C as soon as you enter the car.
Open the windows after you enter your car and turn ON the air-conditioning
According to research the car dashboard emits Benzene,a Cancer causing toxin into the air of your car. Have you ever noticed the smell of heated plastic in your car?
In addition to causing cancer, Benzene poisons your bones, causes anemia and reduces white blood cells..
Prolonged exposure could cause Leukemia, increasing the risk of cancer.
May also cause miscarriage.
Acceptable Benzene level indoors is 50 mg per sq. ft.
A car parked indoors with windows closed will contain 400-800 mg of Benzene.
If parked outdoors under the sun at a temperature above 60 degrees F,
the Benzene level goes up to 2000-4000 mg, 40 times the acceptable level….
People who get into the car, keeping windows closed will inevitably inhale, in quick succession excessive amounts of the toxin.
Benzene is a toxin that affects your kidney and liver.
What’s worse, it is extremely difficult for your body to expel this toxic stuff.
Thought: ‘When someone shares something of value with you and you benefit from it, you have a moral obligation to share it with others.’
There are a few things about this e-mail which pique my sceptical senses, let’s have a close look at the claims made and try to sift the facts from the fables. This is very important, because the e-mail above does contain some correct information, but it is badly misrepresented. The first thing I’d like to do is get the facts straight.
What is benzene?
Benzene is an organic chemical compound (which means it is a chemical in which the molecules contain carbon) which occurs naturally in crude oil and can be synthesized from other compounds in petroleum. Benzene is made up of six carbon and six hydrogen atoms, it’s molecular formula is C6H6 and it is represented by the following diagram;
How is benzene used?
Benzene was used as an additive in petrol but this practice has been limited due to concerns over it’s known carcinogenic (cancer causing) properties. Benzene is still used in industrial applications, such as the production of drugs, plastics, rubbers and nylon. It is important to note, however, that your nylon shorts don’t have benzene in them, but rather a derived chemical, made from benzene. Here is a very simple diagram which illustrates the industrial uses of chemical derived from benzene.
What effects does benzene have on our health?
Benzene is a very dangerous chemical and its effects on our health are reasonably well understood. Because of this, many products which expose the public to benzene have been re-formulated since the 1970’s to reduce, or eliminate, the chemical. Wikipedia has a thorough list of diseases associated with exposure to benzene; here are the most common;
The short term breathing of high levels of benzene can result in death, while low levels can cause drowsiness, dizziness, rapid heart rate, headaches, tremors, confusion, and unconsciousness. Eating or drinking foods containing high levels of benzene can cause vomiting, irritation of the stomach, dizziness, sleepiness, convulsions, and death.
The major effects of benzene are manifested via chronic (long-term) exposure through the blood. Benzene damages the bone marrow and can cause a decrease in red blood cells, leading to anemia. It can also cause excessive bleeding and depress the immune system, increasing the chance of infection. Benzene causes leukemia and is associated with other blood cancers and pre-cancers of the blood.
How much benzene am I exposed to?
Benzene is a widely used chemical and it is released into the environment in many different ways. The Centre for Disease Control in the United States has a fact sheet about benzene which lists the following routes of benzene exposure;
- Outdoor air contains low levels of benzene from tobacco smoke, gas stations, motor vehicle exhaust, and industrial emissions.
- Indoor air generally contains levels of benzene higher than those in outdoor air. The benzene in indoor air comes from products that contain benzene such as glues, paints, furniture wax, and detergents.
- The air around hazardous waste sites or gas stations can contain higher levels of benzene than in other areas.
- Benzene leaks from underground storage tanks or from hazardous waste sites containing benzene can contaminate well water.
- People working in industries that make or use benzene may be exposed to the highest levels of it.
- A major source of benzene exposure is tobacco smoke.
That makes good sense, considering what we know about how benzene is used. It would be reasonable to assume that your sealed car would contain higher levels of benzene than the outside air, but how much? The e-mail claims that the air in your vehicle would contain 2000 to 4000 mg of benzene per square foot; predictably this figure is completely and utterly unfounded. Research on the subject is extensive and here are some findings from “Volatile organic compounds in new car interiors” by Brown and Cheng;
There have been several investigations into automobile exhaust-related VOCs in car interiors (reviewed in Brown 1999), particularly benzene. These have found car interior benzene concentrations ranging from 10–20 µg/m3 during freeway travel, to 150 µg/m3 in heavy urban traffic. An Australian study by Duffy and Nelson (1996) was consistent with these findings. An environmental goal for benzene has been recommended by the UK Health and Safety Executive as 5 ppb (16 µg/m3) as a one-year average. The impact of car travel to this goal needs to consider the amount of time populations spend in heavy traffic.
Unfortunately, that study measured emissions in traffic, a very different situation than your parked car, yet highly illustrative nonetheless. If the level of benzene in a vehicle in heavy traffic (I assume that means that a lot of benzene laden exhaust fumes are circulating in the vehicle) is substantially lower than the figure claimed for a parked car, one can safely assume that the author of the e-mail is not stating true figures, but is pulling random high numbers out of his butt.
Now that we have a better understanding of what benzene is and how it can affect our bodies, let’s have a look at why we should NOT panic and start e-mailing the car air conditioner chain mail.
The first and most obvious sign that the claims made in this e-mail may not be entirely accurate is the fact that the sender tells us that the claims are true without giving ANY supporting evidence. May I point out that I received this second hand from a colleague who received it from the branch manager of a company which re-sells home loans? What does he know about carcinogens? Now, I am not an oncologist, and my knowledge of carcinogens is limited, but I would never tell you to accept my claims without being critical of them, and to pass them on based on some misguided sense of duty. When I receive an e-mail like this I consider it my moral imperative to investigate the facts before spamming it to my whole address book.
The second obvious red flag in this e-mail is the awful spelling, grammar and formatting. I have reproduced the document in its original form (despite almost having an aneurism at the prospect) so that you can see for yourself. Unfortunately, WordPress automatically changes all the text to black so you can’t see the red and blue fonts. Different colours, different font sizes, entirely different fonts, this is all incredibly unprofessional. And that’s the key here, no professional organization would dream of publishing anything as sloppy as this e-mail, thus, it was not released by any professional organization.
I hear you objecting that even though the details of this e-mail are incorrect, the gist of the message is important. I do not disagree. What I would humbly recommend is that the next time you see this e-mail, or one like it, or are told in conversation that your car air conditioner can cause cancer, pause for a minute and look at the facts. Do a quick google search, look it up on Wikipedia or the CDC website. Don’t believe everything you are told in an e-mail. And if you are still concerned, open your windows and let your car air out a little before driving. You’ll be more comfortable, just don’t do so in heavy traffic.