U of M study shows little research is available

Graduating students from the University of Minnesota School of Medicine analyzed and summarized the literature on the health effects of chemical demonstration control agents, such as tear gas, including studies that informed guidelines for existing exhibition. Their study shows that, despite frequent use around the world, few studies have looked at the long-term health and environmental effects of tear gas exposure.

“Tear gas and other chemical demonstration control agents (DCAs) have long been used on the civilian population, even though they have been banned in wartime,” said Jennifer Brown, senior author and graduate student in neuroscience in the Faculty of Medicine, University of Toronto. “Most of the published research on these chemicals was done in the 1960s and 1970s and has not been updated, although DCAs and their methods of deployment have continued to evolve. In our research, we paid particular attention to repeated exposures or longitudinal studies, which could provide insight into the poorly understood long-term effects of these chemicals. “

Published in the journal Inhalation toxicology, the study team found that:

• the research used to determine the current acute exposure guide levels for CS gas – a common type of DCA – were based on lethal dose experiments in animals;
• the results of the lethal dose study in animals have been applied to humans using an inaccurate formula;
• current exposure guidelines do not accurately summarize the circumstances of human exposures, which involve variables such as duration of exposure, individual health status, history of exposure and variety of chemicals in DCAs and solvents; and,
• The EPA does not identify any exposure concentration at which the effects of CS gas could be considered mild – uncomfortable or non-disabling. The lowest exposure listed is already irreversible or severe, long-term effects or impaired ability to escape gas.

“The findings that CS gas does not disproportionately affect vulnerable groups, such as those with asthma or high blood pressure, are based on studies that have largely used exclusively samples of men and very high blood pressure. small samples that did not follow for more than a week after exposure, ”says Brown. “Further, this finding ignores the fact that people with hypertension actually had a larger and more prolonged increase in blood pressure compared to non-hypertensive subjects after exposure to a cesarean section.”

“Additionally, people with asthma have experienced more severe chest symptoms immediately after exposure, and there are even reports of deaths from the combination of asthma and DCA exposure,” Brown added. “Since there is evidence that some symptoms can develop after a certain time, failure to monitor beyond acute exposure could result in underreporting of DCA health effects. “

Brown and colleagues noted that chemical DCA used on civilians are poorly studied and poorly regulated, and more rigorous exposure monitoring is needed before they can be declared safe. In the meantime, the research team says increased regulatory oversight could reduce risks to people and the environment.

“We must continue to raise awareness of this problem and work to improve monitoring of both the use and manufacture of these chemical weapons,” Brown said.

More recent studies and case reports describe significant negative health effects that were either overlooked or not included in the design of past experiments. Some of these impacts included disruption of the menstrual cycle in women, negative effects on mental health, and persistent breathing problems. Additionally, more inclusive research is needed to analyze the effects on different body systems and different demographic groups, including women, pregnant women, children, and people with pre-existing conditions.

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About the University of Minnesota School of Medicine
The University of Minnesota School of Medicine is at the forefront of learning and discovery, transforming healthcare and training the next generation of physicians. Our graduates and professors produce high impact biomedical research and advance the practice of medicine. We recognize that the U of M School of Medicine, both the Twin Cities Campus and the Duluth Campus, is located on the traditional, ancestral and contemporary lands of the Dakota and Ojibwa, as well as dozens of other indigenous peoples , and we affirm our commitment to tribal communities and their sovereignty as we seek to improve and strengthen our relationship with tribal nations. For more information on U of M Faculty of Medicine, please visit med.umn.edu.

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