In a new study from the University of Rochester, researchers found that mercury exposure may disrupt the early development of the connections between muscles and the brain, which could lead to motor control problems later in life.
MeHg enters in the environment in the form of industrial pollution and natural sources, settles in the oceans and is eventually absorbed in plants and other small organisms like plankton.
Mercury bio-accumulates as it moves up the food chain and eventually reaches humans in the form of fish consumption, which is a major food source in many parts of the world.
Much of our understanding of the impact of mercury exposure comes from major 20th century industrial accidents in Japan and Iran, which poisoned thousands of people with high levels of mercury exposure.
Many victims of these accidents exhibited a range of neurological symptoms similar to cerebral palsy, including muscle weakness and impaired motor control.
In the study, the team found the mechanism by which mercury may damage developing muscles and motor control.
The researchers identified a gene called Nlg1 that encodes a protein found in muscles that play an important role in forming the connections between muscles and neurons, known as the neuromuscular junction.
The Nlg1 gene expression is altered when exposed to MeHg in the early development stages.
The analysis of the risk/benefit of fish consumption during pregnancy is complicated. Fish are a rich source of omega-3 acids and other nutrients that are important to brain development.
The U.S. Food and Drug Administration and Environmental Protection Agency currently acknowledges the health benefits of nutrients in fish, but also recommends that pregnant mothers limit consumption and avoid fish with higher concentrations of MeHg.
However, decades of study involving mothers and children in the Seychelles Islands in the Pacific Ocean, where residents consume a wide variety of ocean fish resulting in MeHg exposure that is about 10 times greater than in the populations of the U.S. and Europe, have muddled the scientific consensus.
Researchers found that the fatty acids in fish enhance developmental and educational outcomes and may even help protect the developing brain from the harmful effects of mercury.
They are currently working to translate these new findings and aim to see if muscle weakness, loss of motor skills, and other symptoms can be observed in the mothers and their children.
The study is published in Neurotoxicology and Teratology and Toxicological Sciences. One author of the study is Matthew Rand, Ph.D.
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