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Nickel in the Garden

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Nickels, dimes, and pennies

Coins

Sources of nickel exposure

Nickel is not easily taken up by plants, so direct contact with contaminated soil is the most likely route of exposure in the garden. Low-level exposure from soil or water is not a major concern, but hotspots from man-made sources may also exist. Below are some of the main sources that release nickel into the environment or directly expose people.

Drawing of factory nearby industry Power plant emissions and other industries that use nickel can
release the metal into air, water, and soil.
Garbage truck incinerators Trash incinerators, like other power plants, emit nickel into the air. The metal attaches to small particles and stays in the air for many days.
Man in hardhat on the job Occupational exposure by breathing in high levels of nickel can occur in some industries.
Cigarrette smoking Cigarette smoke typically contains nickel and can contribute to lung cancer.
Fork, spoon, and knife foods – Food contains low levels of nickel but is still the main source for most people. Foods with the highest levels of nickel include chocolate, soybeans, oatmeal, and nuts.

Exposure to nickel in the garden

How am I exposed? Eating or direct skin contact with contaminated soil particles, or eating contaminated produce can cause exposure, but mainly at very low levels.

Are my garden plants safe to eat? Nickel binds very tightly to soil, and is not easily taken up by most plants. Some plants like Indian Mustard and sunflowers take up more nickel than other plants, but most of the metal will stay in the roots.

Should I be worried? When we consume nickel, only about 1% is absorbed by our bodies, which is then quickly excreted. The low levels we may be exposed to from produce is not a major concern, and there are many health benefits from gardening.

Sun

Boy with shovel and bucket

Limit children’s exposure

— Small doses matter. Children breathe, eat, and drink more relative to their size than adults

— Their bodies and brains are still developing

— Children spend more time on the ground and often put things (like dirt) into their mouths

— They have more skin surface area than adults, so skin exposure also matters

Making sense of regulatory standards

No official standards have been established in North Carolina for acceptable levels of nickel in garden soils. For eight different nickel compounds, the preliminary soil remediation goal (PSRG) for residential soils in NC ranges between 140 and 310 ppm. A ninth compound, nickel subsulfide, is considered more toxic and has a PSRG of 0.41ppm.

Health impacts of nickel
People need very low levels of nickel in their bodies, which we get from food, but high levels of exposure can cause health problems.

Occupational exposure to high levels of airborne nickel can lead to chronic bronchitis, reduced lung function, lung and sinus cancers, and more. Nickel in cigarette smoke has also been linked to lung cancer.

Skin contact with nickel, usually from jewelry, can lead to skin irritation. This can occur in 10 to 20 percent of people after prolonged contact. In some people, eating or breathing nickel can lead to similar reactions or asthma attacks, but this is uncommon.

Reduce nickel exposure in the garden

  • Adding compost or other organic matter from a contaminant-free source may help limit nickel uptake by plants. Check the NC Composting Council website to find STA or OMRI certified compost.
  • Adding agricultural lime (to raise soil pH above 6.0) can also limit plant uptake.
  • Thoroughly wash produce grown in nickel-contaminated soil to remove any soil or dust.
  • To reduce nickel particles in air from dust, cover bare soil with mulch and keep the soil moist, but not water-logged.
  • If your soil nickel levels are high, consider not planting root vegetables, since nickel tends to stay in plant roots.
  • Conduct a soil safety training for all garden users on exposure reduction strategies.
  • Visit our website below for our factsheet on 10 Healthy Garden Habits.
Testing resources chart
Hand with plant How to test your soil and interpret the results
Water drop Well water testing for nickel
Question mark Still have questions about nickel soil testing? Email us at superfund@duke.edu.
Plants For more information visit:
Duke Superfund Community Engagement

Print Factsheet

This work was supported through the National Institute of Environmental Health Sciences P42 Multiproject Center Grant program, grant number P42ES010356.