Quantifying Outgassing from Plastics Used in Plastics for High or Low Tunnel Systems

Graduate Student Final Report – Ceres Trust Research Grant

Graduate Student: Andrew Petran

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Organic farmers use plastic in their production systems, such as mulch and coverings on low and high tunnels. However, this increase in use of plastics has taken place without considering the potential risk of contamination from molecules released, or outgassed, from plastics exposed to high light, high temperature environments. There is a presumption of safety, contrary to the precautionary principle used to decide if a new product should be allowed in certified production systems. Outgassing from plastics is a well-documented problem, and the plastic coverings used in high and low tunnel season extension in organic production systems could be a source of outgassed contaminates. These contaminates, if absorbed by the plant, might adversely affect yield and/or be a source of low level unwanted synthetic compounds in organically grown vegetables. The nature of the plastics used in these systems need be better understood so organic farmers can make informed decisions.

One of the most difficult aspects of this project was developing a methodology to determine if there are outgassed volatile organic compounds (VOCs) coming from plastics routinely used in organic production. I devised a way to capture VOCs in a controlled environment to help answer if VOCs are indeed released from agricultural plastics used in organic production and if so, identify them to determine if they potentially are a risk of contamination. Plastic outgassing is well documented in other systems, and capturing, identifying and analyzing compounds has been performed before; combining both of these ideas into an assay required novel modifications of other methodologies to fit the needs of this particular project.

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