RIVERSIDE, Calif. — Plastics are a largely inseparable part of most people’s daily lives. Although many plastic products are only with their owners for a short time, it can take years and years for these materials to degrade in landfills. Making matters worse, a team from the University of California-Riverside says exposure to the chemicals which make these plastics increase the risk of heart disease — although the reason for this has been unclear. Now, a new study has discovered the possible trigger for this: a chemical which raises cholesterol.
Biomedical scientist Changcheng Zhou found that a particular phthalate, a chemical that makes plastics more durable, triggers an increase in plasma cholesterol levels.
“We found dicyclohexyl phthalate, or DCHP, strongly binds to a receptor called pregnane X receptor, or PXR,” explains Zhou, a professor in the UCR School of Medicine, in a university release. “DCHP ‘turns on’ PXR in the gut, inducing the expression of key proteins required for cholesterol absorption and transport. Our experiments show that DCHP elicits high cholesterol by targeting intestinal PXR signaling.”
What exactly is DCHP?
Phthalate plasticizers are an ingredient that manufacturers use in a number of consumer products. This includes everything from cosmetics, to plastic piping, to adhesives and detergents. Although it’s in widespread use, the Environmental Protection Agency considers DCHP a “high-priority substance for risk evaluation.” To this point however, study authors say scientists know very little about DCHP’s negative impact on humans.
“To our knowledge, our study is the first to show the effects of DCHP exposure on high cholesterol and cardiovascular disease risk in mouse models,” Zhou adds. “Our results provide insights and new understandings of the impact of plastic-associated chemicals on high cholesterol — or dyslipidemia — and cardiovascular disease risk.”
In experiments with mice, Zhou’s team found exposure to DCHP led to higher levels of circulating “ceramides” in their blood. These are a class of waxy lipid (fat) molecules with a link to higher risk for cardiovascular disease. This connection is also dependent on PXR activity.
“This, too, points to the potentially important role of PXR in contributing to the harmful effects of plastic-associated chemicals on cardiovascular health in humans,” Zhou concludes.
The study is published in the journal Environmental Health Perspectives.