Mercury, a toxic heavy metal, is known for its potential to cause harm to human health, particularly during early development. It can be found in various sources such as fish, dental amalgams, and certain vaccines.

Mercury exists in different forms, such as elemental (or metallic) mercury, inorganic mercury compounds, and organic mercury compounds (e.g., methylmercury). Methylmercury, the most toxic form of mercury, is commonly found in fish and seafood. It can accumulate in the aquatic food chain, leading to higher concentrations in larger predatory fish, which can then be consumed by humans.

Research has shown that mercury can cross the placental barrier during pregnancy, exposing the developing fetus to the toxic effects of this heavy metal. Studies suggest that prenatal mercury exposure may be associated with cognitive impairments, language delays, and other neurodevelopmental disorders, including Autism Spectrum Disorder (ASD). In addition, mercury can also be found in dental amalgams and certain vaccines, although the quantities in these sources are significantly lower compared to methylmercury in fish.

The potential mechanisms by which mercury may contribute to ASD include oxidative stress, disruption of cellular signaling pathways, alteration of neurotransmitter function, and damage to the blood-brain barrier. Mercury's neurotoxic effects can lead to inflammation, impaired neuronal communication, and disruption of normal brain development.