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Toxin Exposure

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By Lyle L. Sensenbernner, M.D.

In many cases, aplastic anemia has been clearly linked to exposure to certain toxins, although in many cases it is unlikely that a specific case can be identified. Overall there are certain groups of substances which have been clearly shown to be causative agents for aplastic anemia. These include:

• Toxic chemicals

• Drugs and other medications

• Radiation

• Viruses

Although accidental exposure to radiation and viruses are very difficult for an individual to control, certain toxic chemicals and medications can frequently be avoided. All persons should take care not to be unduly exposed to potentially toxic chemicals or drugs, but this is especially important for patients who have recovered from aplastic anemia. The possibility that exposure to the same compound a second time may reinduce aplastic anemia is a very real one. Therefore, it is suggested that all patients avoid the following:

Organic Solvents

Organic Solvents - This is probably the most important group of chemical to avoid. This includes:

Benzene and all of its derivatives - Benzene is the starting compound in the manufacture of many substances. It exists in high amounts in gasoline (especially unleaded gas) moth balls and crystals, many organic solvents such as paint and varnish removers, varsol (oil removing solvent), dry cleaning solutions, some glues and household cleansers. The contents should list Benzene if it is contained in the material.

Toluene - used alone as an organic solvent made from Benzene and frequently contaminated by Benzene.

Carbontetrachloride - used in many dry cleaning solutions.

Dichloro ethane, or dichloro ethylene, or trichloro ethane - frequently used in cleaning fluids, especially fluids made to clean metals, metal parts, automobile engines, computer parts or other metal surfaces which must be very clean.

Insecticides

There are a group of insecticides that have been implicated as potential causes of aplastic anemia. These include:

Chlordane - frequently used to prevent termites.
Dichloro, diethyl, trichlorthane (DDT).
Gammabenzene hexachloride (Lindane).
Organophosphates - Parathion, diazinon, malathion, disyston, methylparathion, trichlorfon, dichlorvos, bromphen vinphos,nuvacron. Œ
Most insecticides pose particular hazards to humans, and great care should be exercised with their use by all people at all times. In addition, there are many drugs (medications) that have been implicated as causes of aplastic anemia, or at least potentiating factors. These include:

• Chloramphenicol (chloromycetin) - all forms, including eye drops.

• Butazolidin (phenylbutazone).

• Gold.

• Colchicine.

• Dilantin (phenytoin, hydantoin).

• Several other anti epilepsy drugs.

• Cancer chemotherapy drugs.

• Thorazine and other phenothiazine.

• Quinidine.

No drug should even be taken that is not absolutely necessary. Although "street" drugs (cocaine, heroine, PCP, etc.) have never been definitely shown to be a cause of aplastic anemia, there are strong statistical correlation between the use of these "drugs" and aplastic anemia. It is possible that these drugs predispose one to be susceptible to other drugs, or these "drugs" might be cut with materials containing toxic substances. They should definitely be avoided.

Certain other chemical substances are also "suspect" as agents causing harm to the bone marrow. These include:

Hair dyes (all types).
Herbicides (all types) - these are the substances that are applied to lawns or fields to kill various types of plants. A wide variety of these substances are now commercially available.
Insect killers that act at a distance such as flea collars for dogs and cats, and the "pest strips" available for room use.
One potential source of some of these compounds (insecticides, some of the organic solvents) has been ground water in areas where wells are used as the source of drinking water. Chemicals which have been found in such drinking water include thehalogenated hydrocarbons (di and tri chloro and fluoro ethane, or ethylene). The presence of these can be tested for if they are in question.