Dark Side Of Manganese

In C&EN’s 80th anniversary “It’s Elemental: The Periodic Table” issue, Joan Selverstone Valentine wrote about the rich complexity of manganese’s biological inorganic chemistry. She also mentioned its darker side: It is toxic. She noted that low-level manganese exposure might accelerate Parkinson’s disease in some susceptible people (C&EN, Sept. 8, 2003, page 76).

I have become convinced that manganese poisoning is a continuing major public health threat.

Recent work shows that manganese in water is the issue. Manganese in food is probably not taken up by the body, a very important finding because the higher levels in food versus water led to high manganese concentrations being allowed in water. The same study in Environmental Health Perspectives showed that manganese in water reduces the IQ of children (DOI: 10.1289/ehp.1002321).

Manganese poisoning can be both acute and chronic. The acute form is widely recognized and is the result of massive exposure to airborne manganese. The chronic form is dose dependent and is seen in children and older people. In children it is almost always the result of manganese in the water supply at concentrations above about 0.1 mg/L of water. It results in neurological symptoms including reduction of IQ.

Lower concentrations of manganese to 0.05 mg/L may be sufficient to cause Parkinson’s in genetically prone older individuals. This is the limit set by some water companies, but it is often exceeded. Manganese exposure occurs worldwide, as does Parkinson’s disease. There is no generally recognized cause of idiopathic Parkinson’s disease. Manganese in water may be that cause.

There is a treatment for the acute form using 4-aminosalicylic acid, a chelating agent and drug used for many years to treat tuberculosis that can pass the blood-brain-barrier to remove manganese from the brain (J. Occup. Environ. Med., DOI: 10.1097/01.jom.0000204114.01893.3e). It is not, however, being used or tested in the U.S. because it is not evident how to make a profit on a new use for an old drug. It has not been tested anywhere for idiopathic Parkinson’s disease.

Many research studies that support this concern can easily be accessed on the Internet.

By John A. Simms
Glen Mills, Pa.