Fact Sheet FS336
Lead (chemical symbol Pb) is a naturally occurring element found in soils normally at low concentrations. Elevated levels of lead in soils are usually due to contamination. Living systems have no known biological use for lead. Exposure to lead-contaminated soils can cause human health problems. Lead poisoning is a common childhood environmental health concern that is preventable. Children who are less than six years old are especially vulnerable to impacts due to the negative effects of lead on brain development. New Jersey law requires physicians to screen all children for elevated blood lead levels. Lead exposure can also cause health problems for adults, and pregnant women can transfer lead to a developing fetus.
Gardening or playing where soils are contaminated can expose humans to lead. Testing soil for lead contamination can help to identify one potential pathway of exposure.
Lead can be transferred from the soil through inhalation as soil dust, absorption through skin, or when directly ingested. While few people deliberately eat soil, young children, especially toddlers, are at the greatest risk of ingesting soil and dust accidentally, from hand-to-mouth activity, or more purposefully as they explore their environment. Pica, an appetite for non-food items, can also cause direct ingestion of soil contaminated with lead.
In 2024, New Jersey Department of Environmental Protection (NJDEP) updated its residential soil remediation standard for lead based on the U.S. Environmental Protection Agency's (USEPA) revisions to its model estimating risk to children's health from lead based on an ingestion-dermal exposure pathway. Compared to its 1994 guidance of 400 mg/kg soil lead limit for residential sites, further research and modeling has narrowed the allowable level to 200 mg/kg soil lead to reduce the potential for children's blood lead levels to reach harmful levels.
Major Sources of Lead Contamination
Paint on older buildings often contains lead. When flakes of the peeling paint fall onto the ground, it contaminates the soil with lead. Photo credit: Joseph Heckman.
Some soils were polluted long ago by lead. The use of leaded gasoline volatilized lead from vehicle tailpipes. This lead was then deposited from the atmosphere onto the soil alongside streets and highways until the use of lead in gasoline was banned in 1986. Lead from automobile emissions binds tightly to soil particles and tends to remain near the surface unless the soil is disturbed. Soils near highways and busy intersections often have historical lead contamination from previous lead uses.
Soils around older homes and buildings are often contaminated from lead-based paints. When this paint weathers and paint chips fall to the ground, the soil becomes contaminated. Lead-containing residential paints were banned in 1978. However, older houses and buildings may still be covered with lead-based paint and the surrounding soils are likely contaminated.
Lead-containing pesticides were in common use in fruit orchards and for other crops before the 1950's. Many of these farmlands contaminated with lead-based pesticides were converted to housing developments. The soil surrounding the homes on former farmland treated with these pesticides often have elevated lead from these pesticide applications and can expose gardeners and children to lead.
Waste incinerators have been known to emit lead into the atmosphere. Therefore, soils in the vicinity of waste incinerators may be contaminated from atmospheric deposition.
The history of a particular site can give clues as to where one might find elevated levels of soil lead contamination. In general, urban areas have higher concentrations of lead in the soil. New Jersey Department of Environmental Protection (NJDEP) has developed an online tool (Potential Lead Exposure Mapping (PLEM) in New Jersey) to help assess potential risk of lead exposure due to lead-based paint, based on age of housing, and due to water service line composition (but not from historical vehicle exhaust).
A 1993 survey of New Jersey soils performed by NJDEP and Rutgers University found background levels of lead in soils where there were no known sources of contamination to average less than 30 ppm. Soils with known sources of lead contamination have a higher concentration and average about 400 ppm lead but can sometimes contain more than 3000 ppm.
Soil Testing
Soil testing can help to identify lead as a significant risk and which actions to minimize exposure are necessary. If you suspect elevated levels of lead in the soils around your home, a soil test for lead is recommended.
New methods and instruments have replaced the traditional laboratory analysis for lead. Rutgers Soil Test Laboratory now uses an X-ray fluorescence (XRF) analyzer to assess lead contamination quickly and accurately in soil samples. Handheld XRF analyzers can also be used in the field to map soil lead contamination.
A soil test for lead gathers different data than a standard soil fertility test, though both are useful for managing lead contamination. Rutgers Soil Testing Laboratory is a public fee-for-service laboratory capable of soil pH, nutrient, and lead analyses.
Rutgers Soil Testing Laboratory
New Jersey Agricultural Experiment Station
57 US Highway 1
New Brunswick, NJ 08901
848-932-9295
extension.rutgers.edu/soil-testing-lab
How to Collect a Soil Sample
Considering the possible sources of contamination, collect the soil sample(s) from the site(s) of concern. If you choose to have more than one area tested (for example, from the garden and from children's play areas), it is important that separate samples be collected from each unique area to identify any hotspots.
At each site, collect about 12 sub-samples of the area to get a representative sample. Use a soil probe or a small shovel to collect the soil. Unlike sampling for fertility where a six-inch root-zone sample is desirable, limit the depth of sub-samples to the surface two-inches of soil because lead is likely to be concentrated near the surface. Mix subsamples thoroughly in a clean, plastic bucket to create a homogenized sample. Send a pint of soil to the laboratory for screening.
If there is more than one sampling site, keep each soil sample separate. Label each soil sample to identify the location. The sample ID on the submission form should match the soil sample label. The submission form and testing fees can be found on the Rutgers Soil Testing Laboratory's webpages.
Interpretation of Soil Test Lead
The USEPA has set the safe lead limit for residential and children's play areas at 200 ppm. Some states have set the guidelines even lower than the USEPA.
| XRF Soil Test Lead Concentration | Interpretation and Action |
| 0–30 ppm | Soil test is at background levels. It is always best to follow good hygiene strategies (listed below) to protect children's health. |
| 30–80 ppm | Soil test slightly above background levels. |
| 80–200 ppm | Soil has elevated levels of lead, though below the recommended action limits. |
| Greater than 200 ppm | Soil test indicates that there is significant contamination with lead. It is suggested that children under the age of six, who may have been repeatedly exposed to the soil, be evaluated for blood lead level and be examined by a physician. Vegetables for food consumption should not be grown in this soil. |
| Greater than 400 ppm | This is the New Jersey Department of Environmental Protection soil clean-up criterion for residential soil. It recommends that children under the age of six, who may have been repeatedly exposed to the soil, be evaluated for blood lead level, and be examined by a physician. Vegetables for food consumption should not be grown in this soil. |
Strategies to Minimize Exposure to Protect Health
Regardless of soil test level, it is always best to follow good hygiene strategies to protect children's health.
The degree of risk from lead on human health is related to the amount of exposure. Absorption of ingested lead by the human body depends on several factors, including the concentration of lead in the soil or dust, the amount of soil or dust that is ingested, and the overall nutrition of the person who is exposed.
A blood test by one's family doctor should be routine for young children. Adults may need to request a blood test if exposure is suspected. Determine the possible sources and extent of lead contamination in and around your home by testing for lead.
Exposure to lead may be from places other than the soil surrounding the home, especially from indoor sources, including paint, food, drinking water, and water pipes. Determine the source of lead before spending time and money for soil clean-up.
Strategies for Outdoor Activities
If the soil is the source of lead, soil removal may be too expensive, so preventing access to contaminated soil in the garden or play areas can provide a safe environment for children. Use the following strategies to minimize exposure:
To limit access to lead in soils, plant shrubs or sod along outside walls of older homes where paint chips would tend to accumulate, and along streets with possible previous contamination by leaded gasoline. Apply mulch over bare soil.
Grow only flowering and ornamental plants, or turfgrass in areas where lead levels are too elevated for vegetable gardening. Wear gloves while working in these soils. If the soil is dusty, wear a face mask or irrigate to minimize dust. Avoid carrying dust or mud into the house.
Do not allow children to play in areas of bare soil that are contaminated with lead. Play areas should be covered with turfgrass and any bare spots should be sodded. With proper soil preparation, sod provides rapid turfgrass establishment and a thin layer of new soil at the surface. Turfgrass also prevents the generation of dust. Keep the turf properly fertilized and irrigated to maintain a healthy lawn.
To manage bare play areas like the ground under a swing set, cover the soil with woodchips, mulch, or clean sand.
Prevent Lead Contact When Vegetable Gardening
It has been considered safe to use garden produce grown on soils with U.S. EPA test total lead less than 200 ppm. The following suggestions also help to minimize lead exposure:
Locate your vegetable garden far away from busy highways and older painted structures.
When necessary, relocate the vegetable garden to an uncontaminated site, or use raised beds filled with uncontaminated soil. (If soil is brought in as replacement, first have it tested for lead.)
Keep dust at a minimum by maintaining soil moisture and using mulch in the garden.
Keep the soil pH from becoming too acidic. Maintaining a soil pH between 6.5 and 7.0 limits solubility of lead and helps to prevent uptake of lead into vegetable plants. In general, plants themselves do not absorb or accumulate large amounts of lead, but uptake tends to increase in acid soils. Applying limestone as recommended by a soil fertility test decreases soil acidity and lead uptake.
When taken up by plants from contaminated soil, lead is most likely to be found in root crops and leafy vegetables. Do not eat the oldest and outer leaves of vegetables, especially of leafy greens such as lettuce or Swiss chard.
Instead of leafy greens or root crops, consider growing only fruiting vegetables. The reproductive structure (fruit) of vegetables (e.g., tomato, peppers, sweet corn, squash, etc.) and fruit (e.g., melon, berries, apple, etc.) poses the least risk of lead contamination.
Wash vegetables carefully to remove soil and dust and peel all root crops. Unpeeled root crops such as potatoes or carrots are likely to have soil attached to them and may lead to accidental ingestion of lead-contaminated soil.
Soil Maintenance Strategies
Problems can be minimized using the following cultural practices:
Have soil tested for fertility and soil pH every three years. Maintain soil fertility and a pH of 6.5 to 7.0.
Fertilize the lawn and garden with adequate amounts of nitrogen, phosphorus, and potassium, and apply limestone, as recommended by a standard fertility test. A soil fertility test service is available to New Jersey residents through Rutgers Cooperative Extension. Sample kits may be obtained at most County Extension offices. Your local Rutgers Cooperative Extension office can be found on the internet at extension.rutgers.edu/county.
Prevent Indoor Contact with Lead
Consider strategies to prevent indoor contact with lead. Lead sources can be indoors, from peeled paint in older homes, or lead dust can be tracked into the house, where small children crawl and play. The high levels of hand-to-mouth activity typical of small children increases the amount of soil and dust that they may ingest.
Avoid transporting soil into the house on shoes and clothing. Rinse harvested vegetables off with water before bringing them indoors. Remove garden gloves outside and designate a storage place (out of the reach of children) for them in a shed or garage.
To keep contaminated soil outside of the house, ask family members to remove their shoes by the door, and/or use an abrasive fiber doormat. Frequent vacuuming or mopping can decrease the amount of lead-contaminated dust in a home. Minimize levels of soil lead in the house by regular cleaning of surfaces, especially windowsills and floors. Carpet often becomes a reservoir for soil lead and dust. Consider replacing wall-to-wall or area carpeting with a flooring type that is easy to clean.
Nutritional Factors
Examine nutritional factors, particularly for children. Good nutrition can have a protective effect against lead toxicity. Diets low in iron and calcium allow higher absorption of lead, and diets low in vitamin C allow increased absorption of lead into the bones. Consult your family doctor or nutritionist about a proper diet or the use of vitamin and mineral supplements that may aid in lessening the impact of lead exposure.
Summary
Lead is naturally occurring in our environment at low concentrations, but lead accumulated from long-ago use of lead-containing paint, gasoline, and pesticides may still be impacting the health of humans, many years after the ban of these products in the United States. Outdoor activities of gardening or playing where soils are contaminated with lead can result in toxicity in humans, with children being more sensitive than adults. Absorption of lead by the human body depends on several factors. These include concentration of lead in the soil and household dust, the amount ingested, the age of the exposed person, and the overall nutrition of that person. By taking appropriate actions and practicing good hygiene, the negative human health impacts from lead exposure can be avoided or mitigated.
References
August 2025
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