There are thousands of chemical compounds in cigarette smoke, many of them toxic. But simply displaying a long list of intimidating names, and even pointing out which are harmful, isn't particularly helpful. In medicine, dosage is key.
Many of the compounds in cigarette smoke are found in only trace amounts, in the range of nanograms for one cigarette. A nanogram is one-billionth of a gram. One gram is about 3/100 of an ounce or 1 g = 0.0353 oz. Nevertheless, there are a dozen or so ingredients that are not only potentially toxic, but found in significant quantities.
Tar, for example, is a part of most cigarettes. It is found at different levels, from 10-14 mg per cigarette. Even so-called 'low tar' cigarettes typically contain 8-9 mg. Just like the counterpart which coats chimneys, it produces a black substance that lines the lung. That interferes with the action of the alveoli.
The alveoli are tiny sacs in the lungs that allow for oxygen to be transported into the blood stream. Their life-giving action can also be hindered by very low amounts of carbon monoxide (CO).
Carbon monoxide bonds with hemoglobin in the blood, a molecule that plays a significant role in transporting oxygen in the body. CO interferes with that role, rendering the oxygen unavailable. In concentrations as low as 400 parts per million it can cause headaches. It's present in the average cigarette in the amount of 13.4 mg.
Nicotine, too, is one of the major ingredients. Indeed, it's one of the primary reasons people continue to smoke cigarettes. Nicotine isn't itself directly addictive. But it causes the brain to release dopamine, which produces some of the good feelings associated with the habit. Withdrawal symptoms are in part the result of those falling dopamine levels.
Though it varies by brand, approximately 1.2 mg of nicotine is present in each cigarette. The body absorbs less of a compound than is present in cigarette smoke. But up to about 70% of the total is inhaled. Also, most people smoke more than one cigarette per day. So, the total absorbed will be between 20-40 mg per day for the average smoker.
It's also true that sometimes what sounds like a very tiny amount can do a lot of harm. For example, it may require only a few dozen molecules in the air for a scent to be strong enough to be picked up by a dog's nose. Many of the systems in the human body are similarly sensitive.
There are several organic compounds present in cigarette smoke in even larger quantities. Today, labeling something organic is often a code-word for healthy. But in science, it simply means that something contains carbon (and usually oxygen and hydrogen, as well, often nitrogen, too). In other words, it contains elements often found in living entities. But not all organic compounds are healthy for all living things, particularly humans.
Benzene, for example, is a type of organic solvent, similar to paint thinner. In fact, a common ingredient of paint thinner, toluene, is also present in cigarette smoke. Benzene concentrations are nearly 50 micro grams and toluene's nearly 74 micro grams.
These are only a few of the potentially harmful compounds in cigarette smoke. In sufficient concentration, when they build up in the lungs and elsewhere, that 'potential' is often converted into 'actual'. The National Institute of Cancer estimates that about 87% of lung cancer cases are caused by cigarette smoking (30% of all cancers), many of them preventable.
It's time to re-consider what you're putting into your body.