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Compound Exposures or Combination Cocktails Significantly Increase Risk of Lung Cancer

There are various risk factors that can increase a person’s chance of getting lung cancer. Smoking remains the most significant risk factor, and that risk increases with the number of cigarettes smoked in a day and the number of years a person has smoked. However, there are a number of other factors that are significant causes and contributors to lung cancer, whether alone or in combination with smoking. They include exposures found at work, around the home and in the military. Examples include: radon, asbestos, Agent Orange, beryllium and other chemicals.

There are so many toxic elements in the environment that we often cannot determine which ones we might have been exposed to, or how any given combination may affect us. In many cases, multiple types of exposure are more harmful than just one, because the risk factors join forces and together overwhelm the lungs' defenses – the more risk factors a person has, the higher the risk of lung cancer. For instance, a person with lung cancer who smoked, was exposed to Agent Orange in the military and later worked as an electrician and was exposed to asbestos had at least three risk factors that cumulatively may have increased his risk of lung cancer. While each of these factors in itself could have been responsible, in combination a much higher risk was incurred. In short, while everyone knows that smoking is the leading cause of lung cancer, it may not have been enough to cause the cancer on its own.

Toxic materials, both naturally-occurring and man-made often get into the human body by way of our homes, our workplace or the environment. We may inhale them, swallow them in contaminated food or water or absorb them through our skin. Some of these substances, such as arsenic, remain in the body only for a short period of time before being excreted, while others may remain in our blood, tissues, bones or other organs for years. Whether you have been a smoker or not, it is important to know if certain toxic materials were part of what you were exposed to that could have caused your lung cancer; that could determine whether or not you are eligible for compensation for your disease. Call 1-800-258-1054 to find out if you qualify.

These toxic materials can work together to cause cancer but one can also weaken the immune system allowing others to inflict more damage resulting in cancer. Smoking weakens the immune system which allows other toxins to have much greater impact.

Chemicals that cause cancer are called “carcinogens”. Studies have shown that these carcinogens can enter the body and have an adverse effect on a person’s health, sometimes years after exposure occurs. It has also been proven that different people’s bodies may react in different ways depending on the amount or duration of exposure as well as the specific properties of the chemical they were exposed to. Some chemicals attack the genetic material in the nucleus of a cell, causing damage to the DNA of that cell. This can lead to gene mutation, which can then lead to cancer or other disorders.

Unfortunately, of the tens of thousands of chemicals used today, only a small percentage has ever been screened for potential health effects. Of those that have been screened, few have been studied in enough detail to estimate the potential risks from exposure. Additionally, most are tested individually rather than in combination, not taking into consideration the effects of cumulative exposures.

The study of disease rates, causes and patterns of illness in humans is called “epidemiology”. Because there are so many variables involved in these studies, it is rare that it will be found that a specific chemical causes a particular human disease. Although the government regulates, and thus reduces exposures on a chemical-by-chemical basis, epidemiological studies will almost never be successful in producing primary prevention because it cannot identify and link a specific chemical to a specific disease.

Current regulations of many chemicals were developed well before the science that now shows that even small exposures to chemicals, some of which were at one time considered harmless, are indeed capable of causing subtle changes on the cellular level ultimately raising the risk of cancer. In addition, these regulations are not designed to look at exposures in the cumulative total. Regulations also many times come as the result of a long, tedious process in which special interest groups can exert considerable influence, and industries having a significant financial interest in the continued use of a particular product may be quite successful in limiting regulatory controls.

Chemical Interactions

As human beings, we may be exposed to a wide range of both naturally occurring and man-made carcinogens that at some point create a higher risk for lung cancer. Toxic exposures that occur simultaneously may act independently of each other, or, in many cases the presence of one chemical may dramatically affect the response of another chemical. This is known as an interaction.

There are four basic types of interactions, based on the anticipated effects caused by individual chemicals:

  • Additivity occurs when a combination of two or more chemicals is the sum of the expected individual responses.
    Example: Organophosphate insecticides are known to interfere with nerve conduction. The combination of two organophosphate insecticides is equal to the sum of the toxicity of both.
  • Antagonism occurs when a desirable effect in drug toxicity is achieved, and is the basis for most antidotes.
    Example: Ingested poisons are absorbed by introducing charcoal into the stomach.
  • Potentiation occurs when a chemical that does not have a specific toxic effect makes another chemical more toxic.
    Example: Liver damage caused by carbon tetrachloride is greatly enhanced by the presence of isopropanol.
  • Synergism occurs when exposure to one chemical causes a dramatic increase in the effect of another chemical.
    Example: Exposure to both cigarette smoke and asbestos results in a significantly greater risk of lung cancer than the sum of the risks of each individual chemical.

In a high number of lung cancer patients, synergy plays a significant role. The word “synergy” has its roots in the Greek word “synergos” meaning “to work together”. As it relates to toxicology, it refers to the interaction of two or more agents so that their combined effect is greater than the sum of their individual effects. Simply put, synergism occurs when a mixture of chemicals produces a stronger effect than could otherwise have been predicted.

For example, detrimental health effects may be a consequence of using pesticides. During the regulatory registration process, exhaustive tests are performed to determine what health effects might occur in humans at various levels of exposure. An upper limit for presence in food is then placed on the pesticide. As long as residues in the food remain below the regulatory level, undesirable health effects are deemed unlikely, and the food is considered safe for human consumption.

In normal agricultural practice, however, it is rare that only one pesticide is used during the production of a crop, and therefore, each individual pesticide has its own regulatory level at which it is considered safe. Additionally, many commercial pesticides contain a combination of several chemical agents, and the safety level for these is based on the level of the combined mixture. By contrast, a combination of chemicals created by a farmer has not been tested in that combination. The potential for synergy is then unknown or estimated. This same lack of information applies to occupational exposures.

Today, the combined effects of carcinogens are widely accepted as contributors to lung cancer. While asbestos and radon are the best known factors, additional factors include arsenic, bis-chloromethyl ether, chromium, formaldehyde, ionizing radiation, polycyclic aromatic hydrocarbons, hard metal dust and vinyl chloride. Nonetheless, since tobacco smoking is the single most important risk factor in the general population, any evaluation of occupational carcinogens must take into account tobacco’s compounding effect. The table below is representative of assorted patient histories with their corresponding risk factors.

 

Patient History Risk Ratio
Never-smoker with no occupational contact 1
Cigarette smoker – Less than 1 pack per day 15
Cigarette smoker – Greater than 2 packs per day 40
Heavy smoker – Quit 15 years ago 4 - 8
Asbestos worker – non-smoker 5
Asbestos worker – smoker 90
Emphysema, chronic bronchitis 4
Secondhand smoke 1.2 – 1.3


Read more about:
»
Smoking and Asbestos Together Raise the Risk of Lung Cancer
»Smoking and Radon Together Raise the Risk of Lung Cancer
»Lung Cancer in Never Smokers
»Smoking and Vulnerability to Disease