Chemicals in environment may increase drug abuse

provided by Texas A&M University

hen it comes to drug addiction and abuse, a Texas A&M University psychologist believes certain populations may be at more of a risk than others because of what, up until now, has remained an unknown factor chemicals in the environment. “We have to say it's possible that a chemical environment may actually increase drug abuse,” says Texas A&M psychologist Jack Nation, who for the last 15 years has studied the effects of environmental contaminants on drug use.

    “There's an entire chemical soup we all live in that could interact with drugs that have abuse liability,” Nation says. “No one has ever looked at that. We're the only lab in the world that systematically looks at the effects of environmental pollution on drug abuse, using animal models.”

    The contaminants Nations studies are lead and cadmium.

    Through the use of an animal model, Nation has determined both of these environmental contaminants act as antagonists to drugs such as cocaine and alcohol. In other words, they create a tolerance for the drugs that results in the user having to take more of the drug to reach the level he or she is seeking.

    Nation says research indicates the threat of lead poisoning is especially great among economically disadvantaged, nonwhite and inner-city children. A 1999 report places the at-risk figure for children suffering from excessive lead exposure at 70 percent in major metropolitan areas of the United States, he notes.

    Cadmium naturally accrues in tobacco products at a point where it is toxic to humans, and it is present in all tobacco products. Nation notes that almost 20 percent of North American women who are pregnant smoke and transfer cadmium to their babies.

    “What we are seeing is a relatively long lasting and potentially nonreversible effect in adulthood,” he says. “Smoking during pregnancy could put that child at risk for drug abuse later in life.” Nation emphasizes that these contaminants don't cause drug abuse, but instead, they act to augment drug abuse patterns.

    Nation's animal model has produced some alarming results. Rats exposed to lead only during gestation have developed long-term side effects later in life despite having their tissues showing no presence of lead contamination at this time.

    “Here's an animal that has no detectable metal in its tissues, but what we see are dramatic changes in terms of their reactivity to cocaine and opiates like morphine,” Nation explains. “We're seeing, generally, this pattern of antagonism of the dopamine system.”

    Nation notes there is a large amount of literature that documents the validity of animal models as models for human substance abuse.

    “Animals rats and primates will self-administer and abuse pretty much the same drugs that humans do, “ he says. “Some populations that are at risk for lead or cadmium poisoning and drug abuse are fighting biological as well as psychosocial imperatives and if these contaminants are promoting drug use, then you have a relatively high public health risk issue.”