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Abstract The application of agricultural plastic products such as mulch, greenhouse covers, and silage films is increasing due to their economic benefits in providing an early and better‐quality harvest. However, mechanical abrasion of these plastic materials by soil particles could result in generation of microplastic (MP) pollutants that could harm soil organisms and impact food safety. This study aims to better understand the physicochemical mechanisms resulting in the fragmentation of low‐density polyethylene (LDPE). Herein, we used pellets and films to study the impacts of abrasive wear forces on their surface morphology variations and fragmentation behavior. An innovative laboratory approach was developed to abrade the plastic surface under controlled normal loadings and abrasion durations. The investigation of the plastics’ surface morphology variations due to the abrasion process revealed microcutting as the dominant process at low normal force (4 N). However, a combination of microploughing and microcutting occurred for new LDPE films by increasing the normal force to 8 N. Despite the significant surface morphology variations of the new LDPE film due to the abrasion process; the water contact angle did not alter. Furthermore, the fragmentation behavior of photodegraded LDPE pellets and films was compared to the new plastics. The extent of MPs (3 µm < dp < 162 µm) generation due to fragmentation was studied using fluorescence microscopy imaging. The localized stress and strains at the contact sites of plastic and sand particles resulted in abrasion of the plastic surface. According to the results, the normal loadings and duration of abrasion played a significant role in the degree of fragmentation of plastics. Increasing the normal loading applied during the abrasion process from 2 to 8 N linearly increased the number of generated plastic fragments by more than five times for pellets and more than three times for film. Photodegradation significantly enhanced the extent of MPs fragmentation. Moreover, the limitations of this study and the implications for agricultural soil health were discussed.
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Past, present, and possible future policies on plastic use in the United States, particularly microplastics and nanoplastics: A review
Abstract As the levels of plastic use in global society have increased, it has become crucial to regulate plastics of all sizes including both microplastics (MPs) and nanoplastics (NPs). Here, the published literature on the current laws passed by the US Congress and regulations developed by various federal agencies such as the US Environmental Protection Agency and the US Food and Drug Administration (FDA) that could be used to regulate MPs and NPs have been reviewed and analyzed. Statutes such as the Clean Water Act, the Safe Drinking Water Act, the Toxic Substances Control Act (TSCA), the Resource Conservation and Recovery Act, and the Clean Air Act can all be used to address plastic pollution. These statutes have not been invoked for MP and NP waste in water or air. The Federal Food, Drug, and Cosmetic Act provides guidance on how the FDA should evaluate plastics use in food, food packaging, cosmetics, drug packaging, and medical devices. The FDA has recommended that acceptable levels of ingestible contaminant from recycled plastic are less than 1.5 µg/person/day, which is 476 000 times less than the possible ingested daily dose. Plastic regulation is present at the state level. States have banned plastic bags, and several cities have banned plastic straws. California is the only state beginning to focus on monitoring MPs in drinking water. The future of MP regulation in the USA should use TSCA to test the safety of plastics. The other statutes need to include MPs in their definitions. For the FDA, MPs should be redefined as contaminants—allowing tolerances to be set for MPs in food and beverages. Through minor changes in how MPs are classified, it is possible to begin to use the current statutes to understand and begin to minimize the possible effects of MPs on human health and the environment. Integr Environ Assess Manag 2023;19:474–488. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
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- Award ID(s):
- 1828942
- PAR ID:
- 10565493
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Integrated Environmental Assessment and Management
- Volume:
- 19
- Issue:
- 2
- ISSN:
- 1551-3777
- Format(s):
- Medium: X Size: p. 474-488
- Size(s):
- p. 474-488
- Sponsoring Org:
- National Science Foundation
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