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Heavy metals normally occur in nature and are essential to life but can become toxic through accumulation in organisms. Arsenic, cadmium, chromium, copper, nickel, lead and mercury are the most common heavy metals which can pollute the environment. Mercury and lead are among the greatest concern because of their ability to travel long distances in the atmosphere. Many children across Latin America and the Caribbean are regularly exposed to mercury and lead due to the contamination caused by unregulated gold mining and improper waste disposal.

Lead can cause serious damage to the human brain, particularly in young children. A large body of scientific evidence shows an association between lead exposure during childhood and impaired cognitive function. Early lead exposure may also be a risk factor for neurocognitive impairment in adulthood, adult intellectual disability, low economic productivity, delinquency and violent offenses.

Mercury is extremely toxic in the body but especially affects the nervous system. Childhood mercury exposure is correlated with lower cognitive test performance and changes in neurological development. High-level prenatal exposures can also result in cerebral palsy, microcephaly, hyperreflexia, poor motor skills, intelligence, vision and hearing. Even low-level prenatal exposures can cause delays or deterioration of neurobehavioral development particularly in cognitive, language, motor, adaptive behavior, and socio-emotional areas.

Experts say that the current surveillance systems are not equipped to handle these chronic conditions, and new governmental policies are an urgent need to prevent more heavy metal poisoning.