Molybdenum
glass of water
Molybdenum is a naturally-occurring metal that can be found in small amounts in rocks and soil. It is also present in plants, animals and bacteria. Molybdenum is most commonly used in the production of structural steel, stainless steel, cast iron and other alloys. It is also used in the manufacture of a number of electronic components, pigments, and other specialty applications, and it can be used in metal finishing processes as a replacement for hexavalent chromium .

Molybdenum is important to human nutrition, and food is the major source of molybdenum for most people. Many leafy vegetables, legumes, grains and nuts contain molybdenum.

Inhalation of airborne molybdenum has not been found to be a major source of exposure, although workers may be exposed to molybdenum through inhalation of dust and fumes from mining or metalworking. Occupational Safety and Health Administration standards address workplace exposures.

Exposure to molybdenum naturally occurring in food and water at low levels is not known to be harmful.

The U.S. Environmental Protection Agency’s current health advisory levels (HALs) for molybdenum are 40 parts per billion (ppb) for life-time exposure, with one-day and 10-day HALs at 80 ppb. There is some evidence that prolonged, very high level exposure may result in higher serum uric acid levels and gout-like illness.

According to recent World Health Organization studies, molybdenum is present in surface waters used as drinking water supplies, and it can be present in finished water at levels less than 10 ppb. As part of its Third Unregulated Contaminant Monitoring Rule (UCMR3) testing, the EPA is examining how prevalent molybdenum is in U.S. drinking water supplies and at what level it occurs. Under the most recent round of UCMR3 testing, many water utilities nationwide tested for molybdenum.

Contact your public water system to learn more about molybdenum testing and results. You can usually find contact information for your public water system on your water bill.

There is not a federal drinking water standard for molybdenum at this time; however the EPA has set health advisory levels for it. The current lifetime HAL for molybdenum is 0.04 ppm, and the one-day and 10-day HALs are both 0.08 ppm.

According to the EPA, HALs “contain drinking water standards in the form of non-enforceable concentrations of drinking water contaminants.” They are used by federal, state and local officials when making decisions about the safety of the drinking water supply.

If there is scientifically compelling evidence that shows a large number of U.S. drinking water systems have detected molybdenum at levels that exceed the HALs set forth by the EPA, it’s possible the agency may decide to regulate molybdenum in the future. Before regulating a contaminant, EPA considers projected adverse health effects from the contaminant, the extent of occurrence of the contaminant in drinking water, and whether regulation of the contaminant would present a meaningful opportunity for reducing risks to health.
If you get your drinking water from a private well, you should have your water tested by a certified laboratory at least once a year. You can find information on how to sample for molybdenum and where to send samples for analysis by contacting your state water laboratory certification officer. Contact information for your state can be found on EPA’s drinking water lab certification page. Additional information about well water testing from EPA is available on their private drinking water well FAQ page
Ion exchange, reverse osmosis, and distillation systems have been shown to be effective at removing metallic contaminants like molybdenum; however there is not a device currently that has been certified to specifically remove molybdenum.
Bottled water quality can vary. Bottled water in the United States is regulated by the U.S. Food and Drug Administration and is required to meet standards equal to the EPA’s tap water standards. There are also individual state standards. However, in most cases, you must contact the bottled water manufacturer for information about molybdenum levels.