Safe Sugar for All
Project overview:
Is it safe to make maple syrup from trees growing in cities? That’s what we want to find out!
We are collecting and testing maple sap and soils from around maple trees across the City of New Haven and other sites around New England. We are looking for toxic elements, like lead, arsenic, cadmium, chromium and zinc. We are also testing for Per-and polyfluoroalkyl substances, also known as PFAS or “forever chemicals”.
Toxic elements and PFAS are harmful for human health. We want to understand:
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If maple trees absorb contaminants from the soil (and if those contaminants are present in their sap)
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What happens to those contaminants when maple sap is boiled into syrup
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If it is possible to remove contaminants from maple syrup by filtering
Through this research, we hope to be able to tell people living in cities and other potentially contaminated places if–and how–they can safely tap their maple trees to make maple syrup.
Sap collection tools used for collecting maple sap for analysis.
Project background:
Most maple syrup comes from rural, forested areas. However, mature maple trees grow in many cities, post-industrial areas, and other places with histories of contamination. These trees can be tapped to make maple syrup, representing a potential opportunity to deepen local food knowledge and access. However, if the trees are growing in contaminated soil, there may be a risk that the maple syrup, will also be contaminated, which poses a health and safety risk.
Additionally, PFAS are being widely detected across many landscapes. It is possible that PFAS could be contaminating maple sap in areas not generally considered contaminated. We are therefore also testing for PFAS from different sites to better understand the risks posed.
We also want to understand if it is possible to remove contaminants from maple syrup, and thereby mitigate the health and safety risks that may arise when making syrup from trees grown in contaminated soil.
Chemical analysis lab at the Connecticut Agricultural Experiment Station where maple sap is tested for contaminants.
Project methods:
We are collecting sap and soil samples from trees around New Haven Connecticut, Region 1 EPA Superfund sites, the Yale-Myers Research Forest, and the Dartmouth Forest, along with farms and homesteads in rural parts of Vermont and New Hampshire. All samples are processed and analyzed at the Connecticut Agricultural Experiment Station. There, we will measure the concentration of contaminants at different points in the maple syrup-making process: fresh sap, sap after reverse osmosis (which removes water), syrup after boiling and evaporation. We will also take contaminated syrup and filter it using two different methods, and test the syrup afterward to see if the concentration of contaminants has decreased.
Research team:
Emily Sigman
Emily is a PhD student in the Ecology, Evolution, Environment and Society program at Dartmouth College. Emily has lived in New Haven for 13 years, and is motivated by a desire to serve the community by advancing novel agricultural practices within the city. Emily has a background in forestry and also studies anthropology, public policy, and agroecology.
Dr. Joseph Orefice
Joseph Orefice, Ph.D. serves as the Principal Investigator on this project. He is a Lecturer and Director of Forest & Agricultural Operations at the Forest School at the Yale School of the Environment. He teaches courses in agroforestry and forest management and leads students on international and domestic forestry field trips. His other hat is to oversee forestry operations and applied educational opportunities on the 10,880 acre Yale Forests system. His research focus is in temperate agroforestry and applied forest management. Joe’s most recent work has been in quantifying carbon stocks in temperate silvopasture, forest farming of understory medicinal plants, and maple syrup production systems.
Dr. Maron Greenleaf
Maron is a cultural anthropologist, political ecologist, and legal scholar studying human-environment relations in this time of environmental change and crisis. Her research centers on how efforts to address linked environmental crises—like climate change, biodiversity loss, and contamination—shape everyday life. Topics of focus include efforts to protect and restore landscapes, make nature valuable, and create “green” economies, as well as related issues of environmental justice and land rights. Her published work has centered on carbon credits, deforestation, tree planting, postindustrial restoration, and energy transitions in Brazil, the US, and the UK. This work includes her book—Forest Lost: Producing Green Capitalism in the Brazilian Amazon—and collaborative work on energy justice in the United States and South America. Her current research centers on tree planting and environmental restoration in postindustrial England. Maron has a BA in Political Science from Yale University, a JD from New York University, and a PhD in Anthropology from Stanford University.
Dr. Christian Dimkpa
Christian Dimkpa is Chief Scientist and Department head of Analytical Chemistry at CAES, a position he has held since 2020. Prior, he was a development scientist at the International Fertilizer Development Center in Muscle Shoals, Alabama. At CAES, Christian oversees activities to assist state regulators in several aspects of food and environmental safety, including analyzing pesticides, mycotoxins, toxic elements, PFAS, and PCBs in human food, animal feed and environmental samples. He also conducts fundamental and applied research on the implications and applications of nanotechnology in agriculture, including the use of nanomaterials to manage plant nutrient efficiency, plant disease, and abiotic stresses such as drought and salinity. Christian holds a PhD in Natural Sciences (Bioenvironmental Science) from the Friedrich Schiller University/Max Planck Institute for Chemical Ecology Jena, Germany.
Frequently Asked Questions:
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Does sampling hurt the tree? No. We collect a small amount of soil at the base of the tree, and we drill a small hole in the tree (3/8” diameter) which will heal after we remove the sap collection device.
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Where can I find the study results? If you would like to be notified about publications and other announcements, please email emily.sigman.gr@dartmouth.edu to be added to our communications list.
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Where can I find more information about contamination in my area? See our list of resources below to find resources on lead abatement, PFAS and more.
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Who is funding this research? This research is funded by a United States Department of Agriculture (USDA) Agricultural Marketing Service’s Acer Access Grant
Additional resources
Resources for Lead:
EPA Guidance on Lead Abatement – [link to: https://www.epa.gov/lead/lead-abatement-inspection-and-risk-assessment]
City of New Haven Lead Program – [link to: https://www.newhavenct.gov/government/departments-divisions/economic-development-administration/housing-administration-and-development/homebuyers/lead-program]
Connecticut State Department of Health Lead Resources – [link to: https://portal.ct.gov/dph/environmental-health/lead-poisoning-prevention…
Vermont Department of Health Lead Resources – [link to: https://www.healthvermont.gov/environment/healthy-homes/lead-hazards-and-lead-poisoning]
New Hampshire Department of Health and Human Services Lead Resources – [link to: https://www.dhhs.nh.gov/programs-services/environmental-health-and-you/lead-poisoning-prevention-program]
Resources for Other Heavy Metals:
EPA Heavy Metals Guidance: [link to: https://www.epa.gov/caddis/metals]
FDA Heavy Metals Guidance: [link to: https://www.fda.gov/food/guidance-documents-regulatory-information-topic-food-and-dietary-supplements/chemical-metals-natural-toxins-pesticides-guidance-documents-regulations]
Resources for PFAS:
EPA Guidance on PFAS [link to: https://www.epa.gov/pfas]
National Institutes of Health PFAS resources [link to: https://www.niehs.nih.gov/health/topics/agents/pfc]
Overview of PFAS regulations in Connecticut [link to: https://portal.ct.gov/dph/drinking-water/dws/per–and-polyfluoroalkyl-substances]
PFAS resources in Vermont [link to: https://dec.vermont.gov/pfas]
New Hampshire PFAS Response [link to: https://www.pfas.des.nh.gov/]
General resources:
FDA overview of Environmental Contaminants in Food [link to: https://www.fda.gov/food/chemical-contaminants-pesticides/environmental-…
EPA Brownfields Program for Region 1 (Connecticut, Maine, Massachusetts, Rhode Island Vermont, New Hampshire) [link to: https://www.epa.gov/brownfields/r1]
Acknowledgement:
We acknowledge that maple sugaring has been practiced by many Indigenous communities across North America since before the arrival of Europeans. Maple sugaring is deeply rooted in Indigenous knowledge, and continues to be an important Indigenous practice today. We also acknowledge the contributions made by sugar makers from many walks of life, whose place-based knowledge has sustained maple sugaring and stewarded its adaptation across changing social and ecological dynamics. We embark on this research with the intent to honor the generations of people and communities that have taught us how to make this special food, and to expand access to maple sugaring knowledge and practices to persons and places that have historically been excluded.
Contact:
Emily Sigman