Manganese in Food, Water and Welding Fumes: When a Needed Nutrient Becomes Too Much

Manganese in Food, Water and Welding Fumes: When a Needed Nutrient Becomes Too Much

WellOfNess •
#Manganese exposure health effects#manganese in well water#manganese welding fumes#manganese dietary intake

Manganese turns up on well-water reports, supplement labels and welding-shop safety sheets. ATSDR’s pocket guide sums up when it becomes a problem: health effects are determined by the dose (how much), the duration (how long), and the route of exposure. Manganese you swallow in food is handled very differently from manganese you breathe in as dust or fumes.

A nutrient you need every day

Manganese is a nutrient. ATSDR calls it an essential nutrient, and eating a small amount of it each day is important to stay healthy. The body uses it as a cofactor for a variety of enzymes.

For most people, the main source is the plate. ATSDR says the primary way you can be exposed to manganese is by eating food or manganese-containing nutritional supplements, and the highest concentrations of manganese are found in grains, nuts, legumes, and fruit. EPA’s health advisory puts typical manganese dietary intake for adults at between 0.7 and 10.9 mg/day. It adds that manganese intake from drinking water is normally substantially lower than intake from food. Some people take in more than average: vegetarians, who consume foods rich in manganese such as grains, beans and nuts, as well as heavy tea drinkers.

Should you worry about supplement labels? EPA’s advisory describes a case in which an individual who took large mineral supplements over several years displayed symptoms of manganism. The same document cautions that for oral case reports, the quantitative and qualitative details of exposure necessary to establish direct causation are lacking.

Why breathing it in changes things

The key difference between eating and breathing manganese comes down to one sentence from CDC: inhaled manganese is of greater concern because it bypasses the body’s normal defense mechanisms. CDC notes that a healthy person with normal liver and kidney function can excrete excess dietary manganese. Breathing it in skips those defenses. ATSDR adds that inhaled manganese can be directly transported to the brain.

That is why jobs matter. ATSDR warns that welding or working in a factory where steel is made may increase your chances of being exposed to high levels of manganese. Its pocket guide also lists ferromanganese, iron and steel, dry-cell battery, and welding industries. With manganese welding fumes, exposure can vary considerably depending on the amount of manganese in the welding wire, rods, flux and base metal, and confined space welding can significantly increase exposure.

Among highly exposed workers, the most common health problems involve the nervous system. These include behavioral changes and movements that may become slow and clumsy. When these symptoms are severe enough, the combination is called “manganism”. Lower exposures can still matter: CDC cites studies in which welders exposed to low levels of manganese (<0.2 mg/m3) perform more poorly on tests of brain function and motor skills. The lungs are affected too. High levels of manganese in air can cause lung irritation and reproductive effects.

ATSDR also offers a practical step for families. Manganese-contaminated work clothing should be removed before getting into your car or entering your home.

Reading your well-water report

The guidance for manganese in well water starts with the fact that manganese is routinely contained in groundwater, drinking water, and soil at low levels. ATSDR puts the median level in drinking water at 10 µg/L.

EPA recommends drinking water not exceed 0.05 mg/L, but EPA says that recommendation exists to avoid staining of clothing and fixtures and is believed to be more than adequate to protect human health.

BenchmarkValueWhat it means
EPA drinking water recommendation0.05 mg/LSet to avoid staining; more than adequate for health
FDA bottled water0.05 mg/LBottled water recommendation
EPA lifetime level0.3 mg/LNo adverse effects expected
EPA short-term, child1 mg/L for up to 10 daysNo adverse effects expected
Median U.S. drinking water10 µg/LTypical background

If you’re testing a private well for several metals, our guide to testing for lead in tap water explains how to get a result you can rely on.

What about children?

Here the evidence calls for caution, and ATSDR is open about its limits. Studies in children have suggested that extremely high levels of manganese exposure may produce undesirable effects on brain development, including changes in behavior and in the ability to learn and remember. ATSDR then adds two important caveats: we do not know for certain that these changes were caused by manganese alone, and we do not know if these changes are temporary or permanent. Whether children are more sensitive than adults is also unknown, though there is some indication from experiments in laboratory animals that they may be.

Diet is unlikely to be the problem. Children are not likely to be exposed to harmful amounts of manganese in the diet, although higher-than-usual amounts of manganese may be absorbed if their diet is low in iron. ATSDR’s advice is simple: provide your child with a well-balanced diet. For the wider picture, see our overview of children and heavy metal exposure.

Cancer and testing

On cancer, EPA has not reached a conclusion. ATSDR reports that existing scientific information cannot determine whether or not excess manganese can cause cancer, and EPA classifies it as group D, not classifiable as to human carcinogenicity.

Testing has limits too. Several tests are available to measure manganese in blood, urine, hair, or feces, but because the body naturally contains manganese, some is always found in tissues or fluids. Also, excess manganese is usually removed from the body within a few days, so past exposure is hard to measure with common lab tests. A normal result today doesn’t tell you much about last year.

In short, manganese from food and ordinary water is a nutrient your body is built to handle. The cases that call for action are a well result above EPA’s health benchmarks, or a job where manganese is in the air you breathe.

Sources

← Back to the Journal