A study from the University of Illinois’ Beckman Institute reveals that exposure to banned carcinogenic chemicals known as polychlorinated biphenyls (PCBs) during fetal development can result in hearing difficulties later in life. Researchers used mice, music, and microscopic imaging to explore the impact of these environmental chemicals on hearing health. The study indicates that mice exposed to PCBs struggled to recover from sound-related trauma, suggesting a long-term effect on hearing due to prenatal exposure.
PCB has high impact on fetal development during the first trimester
PCBs, cancer-causing chemicals once used in various products, remain a threat due to their persistent nature even after a US ban in 1979. Their chemical stability makes environmental elimination challenging. Consumption of polluted fish remains the primary source of ongoing PCB-related harm.
Corresponding author of the study and associate professor in the Molecular and Integrative Physiology Department Dr Daniel Llano said that the most critical phase for developmental impacts due to exposure during pregnancy is usually the first trimester, as chemicals like PCBs which are permeant to various membranes can easily cross the placenta and reach the brain, posing significant risks throughout all stages of pregnancy.
PCB exposure and loud noise damages the inferior colliculus
The study by Llano and colleagues builds upon previous research to investigate the potential impact of prenatal PCB exposure on hearing recovery following later auditory trauma. Contrary to prior research focusing on the auditory cortex, the team examined the inferior colliculus in mice using multiphoton imaging. They discovered that PCB exposure, combined with ongoing high noise levels, led to damage in the inferior colliculus.
Llano explains that their unique microscope and lab are among the few globally engaged in distinct imaging within this brain region. Previous studies have demonstrated that exposing mice to loud noise can lead to increased sensitivity in neurons located in the inferior colliculus. However, new research involving the simultaneous exposure of mice to both PCBs (toxic chemicals) and loud noise, along with advanced imaging techniques, revealed that the heightened neural responsiveness caused by these factors was reversed.
