Soil Contaminant FAQ
1. How do I find out more about the past or historical land uses at my home, garden site, or elsewhere?
There are several mapping tools available online that may help you to research prior land uses:
North Carolina Department of Environmental Quality (DEQ) Division of Waste Management (DWM) Site Locator Tool. The Site Locator Tool is a compilation of federal, state, and local site data that is collected on polluted sites, waste treatment and storage facilities, and other hazardous site locations.
Sanborn Fire Maps: These maps were created by the Sanborn Map Company to visualize all existing structures on parcels of land across the entire country for fire insurance purposes, in some cases going back as far as the 1800s. They are currently held at the Library of Congress, but UNC has a curated collection of North Carolina maps by county that is open access and has a few more maps than the Library of Congress: https://web.lib.unc.edu/nc-maps/sanborn.php North Carolina State University libraries also has a collection of Sanborn Maps, but access is restricted to researchers within North Carolina, or NCSU affiliates: https://www.lib.ncsu.edu/maps/sanborn.html
Deeds from county or local governments: Sometimes it may be necessary to seek out historical property deeds may be necessary to find out about the previous owners of a site or previous site activity. Any party who has ever dumped waste at a site is technically a “Potentially Responsible Party” who should be involved in cleanup of the site. Checking the county for records including the site’s property values may be a helpful step at this part of the process.
Neighbors and other community members: Your neighbors and other long-time residents of your community may have useful information about how your land was used in the past, some of it might not be found anywhere else.
2. How can I reduce my exposure to soil contaminants?
Our ‘10 Healthy Garden Habits‘ is a great place to learn some of the basic ways to reduce exposure to soil contaminants in the garden and elsewhere.
Even if you do not have reason to suspect that your soil is contaminated, it is always a good idea to try and limit the amount of soil, dirt, and dust that you track in to your home from outside. Leaving shoes at the door, washing your hands regularly, and cleaning floors (especially if you have small children) are all great ways to limit exposure to soil in the home.
Learn more about reducing your exposure to soil contaminants here.
3. What are the most common soil contaminants and where do they come from?
Some common soil contaminants are heavy metals like lead and cadmium, and petroleum-based chemicals. Some of these contaminants are naturally occurring in soils and groundwater, where others result from past or present industrial or agricultural land uses, lead-based paint, heavily-trafficked roads, runoff from other surfaces during storms, and other from other human actions and the built environment.
Learn more about soil contaminants and their sources here.
4. How do I interpret my soil contaminant test results?
For an example of how to interpret common soil testing results for contaminants, check out this Story Map created by the Duke University Superfund Research Center RTC and CEC for Garner Grows garden. We can help you to interpret your specific contaminant test results based on current regulatory guidance for residential soils in North Carolina, if they exist for the contaminant you tested for. Contact SuperfundCEC@duke.edu for more information.
Learn more about soil testing here.
5. What about my water source? Is it contaminant-free?
If you are concerned about contaminants that may be in your garden’s watering/irrigation sources, you can participate in the NC Department of Environmental Health’s well-water testing program through your county’s environmental health department. Visit this page for more information: https://epi.dph.ncdhhs.gov/oee/wellwater/howtotest.html If you are on a grid and get water piped in from a water utility, most utilities are required to post annual water quality reports, where you can learn more about what’s in the water that’s piped to your home.
6. Why are children more at risk from soil contamination exposure?
Small doses matter. Children breathe, eat, and drink more relative to their size than adults. Their bodies and brains are still developing. They spend more time on the ground and often put things (like dirt) into their mouths. They also have more skin surface area than adults.
Learn more about exposure routes and health risks here.
7. What does bioavailability mean?
Bioavailability means how much of a contaminant gets absorbed into the body after exposure (in this case, through eating, or ingestion). Some portion of some contaminants might pass through the body without being metabolized.