- National Institute of Toxicological Research identifies reproductive effects of tire-derived 6PPD and 6PPDQ

- Study confirms disruption of decidualization, a process key to embryo implantation and early pregnancy

Effects of tire-derived pollutants 6PPD and 6PPDQ on endometrial decidualization. [National Institute of Toxicological Research]
Effects of tire-derived pollutants 6PPD and 6PPDQ on endometrial decidualization. [National Institute of Toxicological Research]

Emerging environmental pollutants generated by automobile tires may disrupt the uterine environment during early pregnancy, according to new research.

The National Institute of Toxicological Research (KIT) announced Wednesday that a joint research team — led by Hyun Moon-jeong, a senior researcher at the institute's Biohealth Research Center under its South Gyeongsang Province Biotech and Environment Research Division, and Lee Jong-geol, a professor at Kyungpook National University's College of Medicine — confirmed that the tire rubber antioxidant 6PPD and its oxidation derivative 6PPD-quinone (6PPDQ) affect the decidualization of endometrial stromal cells in distinct ways.

6PPD is an antioxidant used in automobile tire rubber to prevent degradation from oxygen and ozone. As tires wear down on roads, the compound can be released into the environment, while 6PPDQ forms when 6PPD reacts with ozone and other substances. Both compounds have been detected in road dust, airborne particles, aquatic environments and biological samples.

The research team focused particularly on decidualization, a process critical to embryo implantation and the maintenance of early pregnancy. Decidualization is the transformation of endometrial stromal cells into a state suitable for receiving an embryo and sustaining pregnancy, and it plays a key role in establishing a normal gestational environment.

The study found that cells exposed to 6PPD showed increased expression of some genes associated with decidualization, but decreased expression of several genes necessary for normal cell differentiation. The research team said this indicated not a simple promotion of decidualization but a disruption of the balance in the normal cellular transformation process.

By contrast, 6PPDQ consistently suppressed the expression of multiple decidualization-related genes. The findings suggest that even compounds derived from the same tire — the original chemical 6PPD and its environmentally transformed form 6PPDQ — can affect endometrial cells in fundamentally different ways.

Hyun Moon-jeong (left), a researcher at the National Institute of Toxicological Research, and Lee Jong-geol, a professor at Kyungpook National University's College of Medicine. [National Institute of Toxicological Research]
Hyun Moon-jeong (left), a researcher at the National Institute of Toxicological Research, and Lee Jong-geol, a professor at Kyungpook National University's College of Medicine. [National Institute of Toxicological Research]

However, the research team cautioned against overinterpreting the findings, noting that the study was conducted at the cellular level. As an in vitro study using human endometrial stromal cell lines, it does not directly demonstrate that exposure to 6PPD or 6PPDQ causes infertility or pregnancy complications in women. The team said follow-up research applying real-world exposure levels and a range of experimental models is needed.

"We proactively examined the effects of emerging environmental pollutants closely tied to daily life and established a basis for precise risk assessment," Hyun said. "We will continue to contribute to advancing risk assessment for the protection of public health through research on emerging hazardous agents."

The findings were published July 31 in the Journal of Environmental Sciences, an international journal in the field of environmental science.


nbgkoo@heraldcorp.com