ORCID
- De Falco, Francesca: 0000-0003-3782-4540
- Thompson, Richard: 0000-0003-2262-6621
- Hanley, Mick: 0000-0002-3966-8919
Abstract
In response to the plastic waste crisis, teabag producers have substituted the petrochemical-plastic content of their products with bio-based, biodegradable polymers such as polylactic acid (PLA). Despite widespread use, the degradation rate of PLA/PLA-blended materials in natural soil and their effects on soil biota are poorly understood. This study examined the percentage mass deterioration of teabags with differing cellulose:PLA compositions following burial (−10 cm depth) in an arable field margin for 7-months, using a suite of analytical techniques, such as size exclusion chromatography, 1H nuclear magnetic resonance, dynamic scanning calorimetry, and scanning electron microscopy. The effect of 28-d exposure to teabag discs at environmentally relevant concentrations (0.02 %, 0.04 % and 0.07 % w/w) on the survival, growth and reproduction (OECD TG 222 protocol) of the key soil detritivore Eisenia fetida was assessed in laboratory trials. After 7-month burial, Tbag-A (2.4:1 blend) and Tbag-B (3.5:1 cellulose:PLA blend) lost 66 ± 5 % and 78 ± 4 % of their total mass, primarily attributed to degradation of cellulose as identified by FTIR spectroscopy and a reduction in the cellulose:PLA mass ratio, while Tbag-C (PLA) remained unchanged. There were clear treatment and dose-specific effects on the growth and reproductive output of E. fetida. At 0.07 % w/w of Tbag-A adult mortality marginally increased (15 %) and both the quantity of egg cocoons and the average mass of juveniles also increased, while at concentrations ≥0.04 % w/w of Tbag-C, the quantity of cocoons was suppressed. Adverse effects are comparable to those reported for non-biodegradable petrochemical-based plastic, demonstrating that bio-based PLA does not offer a more ‘environmentally friendly’ alternative. Our study emphasises the necessity to better understand the environmental fate and ecotoxicity of PLA/PLA-blends to ensure interventions developed through the UN Plastic Pollution Treaty to use alternatives and substitutes to conventional plastics do not result in unintended negative consequences.
DOI
10.1016/j.scitotenv.2024.172806
Publication Date
2024-07-15
Publication Title
Science of the Total Environment
Volume
934
ISSN
0048-9697
Organisational Unit
School of Biological and Marine Sciences
Keywords
Plastic alternative, Plastic substitute, Microplastic, Ecotoxicology
Recommended Citation
Courtene-Jones, W., Burgevin, F., Munns, L., Shillam, M., De Falco, F., Buchard, A., Handy, R., Thompson, R., & Hanley, M. (2024) 'Deterioration of bio-based polylactic acid plastic teabags under environmental conditions and their associated effects on earthworms', Science of the Total Environment, 934. Available at: https://doi.org/10.1016/j.scitotenv.2024.172806
