Benzene: THE Method of Choice Used to Induce Leukemia in Rats

From creating new cancer drugs to testing dietary supplements, rats are used as models in medical testing and play a critical role in developing new medical wonders. Actually, approximately 95 percent of all lab animals are rodents. The rat has become a standardized physiological and toxicological model, particularly in the pharmaceutical industry. Using rats in research is critical to scientific understanding of biomedical systems leading to valuable drugs, therapies and cures.


Scientists and researchers rely on rats for several reasons: convenience, size, easy adaptation to new surroundings; but the main reason is that their genetic, biological and behavior characteristics closely resemble those of humans, and many symptoms of human conditions, such as leukemia, can be replicated in rats. Rats are mammals that share many processes with humans and are suitable for use to answer many research questions. Rats have allowed us to build up an incredible wealth of knowledge about basic biology and complex physiological interactions, and have served as a model of human disease and learning, much of which has been translated to greater knowledge about humans.


benzeneBenzene, regarded as “bone marrow poison”, is a toxic and carcinogenic agent widely used for industrial purposes and in the manufacture of various plastics, resins and detergents. It is also emitted in large quantities from refineries and petroleum storage facilities. Occupational exposures to benzene have been known to cause hematotoxicity (toxicity of the blood), “multiple myeloma, non-Hodgkin’s lymphoma, acute and chronic lymphocytic leukemia, chronic myelogenous leukemia”, and at lower exposures, with some signs for lung cancer. Individuals with acute inhalation exposure to benzene may experience drowsiness, dizziness, headaches, as well as eye, skin, and respiratory tract irritations.


Many people are unknowingly exposed to the threat of inhaling benzene through their work environment, but the most common exposures occur through building materials, auto exhaust, industrial emissions, and cigarette smoke. Benzene has been classed as a group A carcinogenic by the Environmental Protection Agency, and those exposed to benzene regularly or in high doses, particularly those frequently exposed on an occupational basis, are at risk from the cancerous effects of benzene. In a recent study, leukemia was successfully induced in Wister rats by “intravenous injection of 0.2 ml of a 1:10 diluted benzene solution (chloroform in water/2-propanol [50/50] v/v)”, given every 2 days for 3 consecutive weeks. The blood was collected and analyzed for “hematological parameters”, and the activity of the cells that absorbed the foreign matter was analyzed.

Given this data, it took only 3 weeks of consistent benzene exposure to induce leukemia in rats. (Indian J Pharmacol. 2015 Jul-Aug; 47(4): 394–397).


Unlike the rats in this study who are exposed to benzene for only 3 weeks, humans can be and often are exposed to benzene over years or even decades. Products as diverse as paint thinner, mineral spirits, gasoline, degreasers and various solvents often contain benzene.

With the amount or concentration of benzene in these often unknown, our office routinely fights with benzene-containing product manufacturers to obtain the benzene content of their products. In nearly every case, the benzene-containing product manufacturer resists disclosing this information and even at times deny that their product contains benzene “as an intended ingredient”, implying that although benzene is in their product—they did not “add” it. This distinction obviously means little to the human cells who encounter the benzene and sometimes leukemia is the result.

Individuals exposed to benzene or those that feel they may have suffered prolonged exposure by other means are strongly advised to immediately seek medical assistance, as well as look into legal assistance to determine compensation. We at the Madeksho Law Firm, PLLC have handled benzene-related leukemia cases for almost two decades. Refinery workers, barge and dock workers, railroad workers and line workers working with degreasing agents and solvents, we have seen many types of cases and are happy to answer questions.