Gardenroots

Garden Roots

Gardenroots was developed by Mónica Ramírez-Andreotta, Superfund Research Program Training Core graduate student and former Research Translation Coordinator. She created the project in response to home gardening concerns in the Dewey-Humboldt, AZ community over possible metal contamination from the neighboring Iron King Mine and Humboldt Smelter Superfund site.

The overall objective of Gardenroots was to determine whether home garden vegetables grown in Dewey-Humboldt had elevated levels of arsenic. By building co-created public participation in a scientific research program, this project also looked to educate, build human capacity, and increase community networking in resource-related issues in the community.

 

Objectives/Methods:

Gardenroots combined a home garden experiment with controlled greenhouse studies to meet the following project objectives:

  • Develop a citizen-science program to inform and engage community members
    • Recruit at the local level
    • Provide training and educational activities for participants (see below for timeline)
      • Click here to download the participant instructional manual for collection of soil, water, and vegetable samples (1.17 MB)
  • Characterize arsenic uptake in homegrown and greenhouse-grown vegetables
    • Home gardens (citizen-scientists): collect soil, water, and vegetable samples (of their choice)
    • Greenhouse: grow vegetables in soils with known concentrations of arsenic
    • Analyze water, soil, and vegetable samples for arsenic concentration
  • Estimate arsenic exposure and characterize potential risk
    • Combine measured arsenic concentrations with reported U.S. intake rates
    • Use exposure assessment modeling to estimate average daily dose of arsenic from vegetable, soil, and water (assuming the primary source of water for irrigation is also used for drinking) and associated potential risks
  • Report results back to participants in an effective and meaningful way

For technical details, please refer to Dr. Ramírez-Andreotta’s publications:

A greenhouse and field-based study to determine the accumulation of arsenic in common homegrown vegetables grown in mining-affected soils. Sci Total Environ. 2013 Jan 15;443:299-306. Click here to download PDF (905 KB).

Home gardening near a mining site in an arsenic-endemic region of Arizona: Assessing arsenic exposure dose and risk via ingestion of home garden vegetables, soils, and water. Sci Total Environ. 2013 June 1;454-455:373–382. Click here to download PDF (333 KB).

 

Timeline:

In March of 2008, the Iron King Mine Humboldt Smelter Superfund site in Dewey-Humboldt, AZ was added to the U.S. Environmental Protections Agency (EPA) National Priorities List. At a U.S. EPA meeting in August 2008, members of the community asked whether it was safe to grow and consume vegetables from their garden. To answer this question, former Research Translation Coordinator Mónica Ramírez-Andreotta embarked on her doctoral career and began seeking funding. In 2010, residential soils were collected for greenhouse studies and local recruitment of gardeners to participate in the Gardenroots study began. Training sessions were held in March 2011, to instruct citizen-scientists in the collection of garden vegetables, as well as irrigation water and soil samples. Additional educational activities were offered, such as gardening seminars (May 2011), a community health talk with UA researchers (June 2011), and a tour of the UA laboratories where the concentrations of arsenic in the collected vegetable, water, and soil samples were being measured (Nov 2011). At the “Results for Lunch: Your Soil, Water and Vegetable Outcomes” luncheon (Jan 2012), participants were given personalized booklets showing the results for their individual gardens. Booklets included “raw” data (i.e. milligrams of arsenic per kilogram of vegetable, fresh weight), calculations of how much each participant could eat from his or her own garden at different levels of estimated risk, and estimated risks associated with individual water and soil samples. Handouts with recommended safe practices for gardening were also provided. A complete overview of the project was presented to Gardenroots participants and the Yavapai Master Gardeners (June 2012). In December 2012, overall project results handouts were sent to participants and other interested community members.

News and highlights related to Gardenroots:

Vegetable results: The results of this study showed that in general, arsenic concentrations were higher in Gardenroots vegetables than store-bought vegetables, as compared with the 2010 US Food and Drug Administration (FDA) Market Basket nationwide study.

Twenty different types of vegetables falling into 9 different plant families were grown in the greenhouse and/or Dewey-Humboldt gardens. (For vegetables with an asterisk (*), only one sample of that vegetable was received.)

  • Lettuce, beans, onions, radishes, Brussels sprouts*, broccoli*, cabbage, beets, spinach*, peppers, carrot* celery* and corn* generally had higher arsenic concentrations that the US FDA study.
  • Squash, cucumber*, and tomatoes generally had lower arsenic concentrations that the US FDA study.
  • Kale, swiss chard, amaranth, and garlic were grown by community members, but these vegetables were not tested in the US FDA study, and so cannot be compared.

A major finding of the Gardenroots project is that, when combining greenhouse and home garden data, Asteraceae (lettuce) and Brassicaceae (radish, broccoli, brussels sprouts, kale, and cabbage) families were the top accumulators of arsenic. This finding has been reported in other studies.

 

The Big Picture: Overall, the Gardenroots project showed that homegrown vegetables did take up arsenic.

However, calculations of estimated average arsenic daily dose from the three potential exposure routes measured suggested that arsenic exposure was greatest from drinking water (when assuming the primary source of water for irrigation is also used for drinking), followed by incidental soil ingestion, with a relatively small contribution from homegrown vegetable ingestion. Thus, it is strongly recommended for Dewey-Humboldt community members to test drinking water yearly and to test soils prior to gardening. To be precautious and prudent, gardeners can modify gardening behavior to reduce incidental soil ingestion and limit the use of vegetables from the Asteraceae and Brassicaceae families. See "Recommendations/Resources" tab for more information.

 

Outcomes:

Research: Gardenroots advanced our understanding of soils, uptake of arsenic by vegetables, exposure, and risk. A risk-based estimate of maximum soil arsenic concentration was developed for specific plant families to guide gardeners and farmers.

Individuals: Citizen-scientist participants increased their understanding of soil contamination, food quality, and the scientific process. Surveys showed that after learning their Gardenroots results, the majority of participants will continue to garden, but will change their gardening practices (i.e. following the recommended best practices for gardening handouts).

Community: A community-academic partnership was developed and community capacity was increased, resulting in community networking and participation in resource-related issues. For example, following elevated arsenic results for some participants on municipal water, community members worked together to notify authorities and bring attention to the problem, which is now in the process of being resolved.

 

 

 

For further details about Gardenroots results, please refer to the following:

Click here for an overview of study results (2.4 MB)

For additional technical details about the study and results, please refer to Dr. Ramírez-Andreotta’s publications:

A greenhouse and field-based study to determine the accumulation of arsenic in common homegrown vegetables grown in mining-affected soils. Sci Total Environ. 2013 Jan 15;443:299-306. Click here to download PDF (905 KB).

Home gardening near a mining site in an arsenic-endemic region of Arizona: Assessing arsenic exposure dose and risk via ingestion of home garden vegetables, soils, and water. Sci Total Environ. 2013 June 1;454-455:373–382. Click here to download PDF (333 KB).

Recommendations:

Calculations of estimated average arsenic daily dose from the three potential exposure routes measured suggested that arsenic exposure was greatest from drinking water (when assuming the primary source of water for irrigation is also used for drinking), followed by incidental soil ingestion, with a relatively small contribution from homegrown vegetable ingestion. When combining greenhouse and home garden data, Asteraceae (lettuce) and Brassicaceae (radish, broccoli, brussels sprouts, kale, and cabbage) families were the top accumulators of arsenic. This finding has been reported in other studies.

Thus, it is recommended that Dewey-Humboldt community members:

  • Test drinking water yearly
  • Test soils prior to gardening
  • Modify gardening behavior to reduce incidental soil ingestion
  • Limit the use of homegrown vegetables from the Asteraceae and Brassicaceae families

 

Resources:

Click here for a list of laboratories conducting soil, plant, feed, or water testing (362 KB)

For water sampling, you may also work with the University of Arizona Cooperative Extension of Yavapai County:

Click to download recommended best practices for gardening handouts:

U.S. Environmental Protection Agency: Iron King Mine Humboldt Smelter Superfund site information

If you have comments or questions, or would like additional information about the study, please contact:

 

Sarah T. Wilkinson, PhD
Research Translation Core Coordinator, University of Arizona Superfund Research Program 
(520) 307-3452
 
 
Janick Artiola, PhD
Associate Professor and Water Quality Specialist, Department of Soil, Water, and Environmental Science
Research Translation Core Co-Leader, University of Arizona Superfund Research Program
(520) 621-3516
 
Monica Ramirez-Andreotta, PhD
Now at the Social Science Environmental Health Research Institute, Northeastern University (but always a resource to the Dewey-Humboldt community!)
 
 
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