Systematic review and meta-analysis of bacterial biodegradation of low-density polyethylene (LDPE): degradation rates, moderating factors, and geographic gaps in the global evidence base

LDPE is among the most recalcitrant and widely accumulated synthetic polymers in global waste streams, yet no quantitative synthesis of the bacterial biodegradation literature currently exists. Individual studies report highly variable percentage weight loss values that range from below 1% to over 15% under similar experimental timeframes. However, methodological inconsistency across studies prevents meaningful comparison or pooled estimation of degradation rates. This project would examine the rate and extent of bacterial LDPE biodegradation under laboratory conditions, with the primary objective being to calculate a pooled mean percentage weight loss of LDPE film attributable to bacterial activity, with 95% confidence intervals, from all included published experimental studies. Other objectives will be to identify moderators of degradation rate through pre-planned subgroup analyses and meta-regression, including the effect of ultraviolet pre-treatment of LDPE, bacterial genus and inoculum source environment, incubation temperature and duration, and geographic and climatic context of the inoculum source. Also, there will be a quantification of the geographic distribution of existing evidence, with particular attention to sub-Saharan African environments, a region characterised by acute LDPE waste accumulation.