Polyethylene Mailer Bags

Material Composition Assumptions

The default reference product is a standard polyethylene mailer bag (e-commerce poly mailer) weighing approximately 50 g, composed of:

• PE film body: Co-extruded LDPE/HDPE blend film, typically 60-80 microns thick, approximately 40-45 g. The outer layer provides printability and puncture resistance; the inner layer provides tear strength and sealing properties.
• Self-seal adhesive strip: Hot-melt or pressure-sensitive adhesive on a silicone-coated release strip, approximately 2-3 g.
• Printing ink: Flexographic ink (1-6 color process for branding), approximately 0.5-1 g.
• Grey/white pigment: Titanium dioxide or calcium carbonate opacifier blended into the PE film.

Poly mailers have become the dominant e-commerce shipping format for non-fragile goods due to their light weight (~50 g vs. ~200-300 g for a corrugated box) and low material cost. The weight advantage means lower per-shipment packaging emissions than corrugated boxes, though poly mailers have much lower recycling rates.

Manufacturing Geography

Poly mailer production is heavily concentrated in China:

• China: Produces the vast majority of global poly mailers, particularly for e-commerce platforms (Amazon, Shein, Alibaba). Major production in Guangdong, Zhejiang, and Jiangsu.
• USA: Some domestic production (Novolex, Sealed Air) for major e-commerce fulfillment.
• EU: Smaller volumes, primarily for European e-commerce.
• Grid intensity (China): 565 gCO2e/kWh (IEA 2024).
• Rationale: Blown film extrusion and bag making are automated, high-speed processes with moderate energy consumption. Upstream PE resin production (Scope 3) dominates.

Regional Variation

Manufacturing Region	Estimated CCI Score	Adjustment
China (default)	1.0 kgCO2e	Baseline
USA	0.8 kgCO2e	-20%
EU	0.7 kgCO2e	-30%

Provenance Override Guidance

1. EPD or PCF for the specific mailer product.
2. Recycled content: Post-consumer recycled PE mailers (30-100% PCR content) reduce resin-stage emissions. Major brands like Amazon are transitioning to paper-padded mailers.
3. Compostable alternatives: PLA or PBAT-based mailer bags have different emission profiles (~3-4 kgCO2e/kg).
4. Film gauge data: Thinner film (downgauging from 80 to 50 microns) directly reduces per-unit emissions.

Methodology Notes

• CCI score of 1 kgCO2e per mailer is a conservative estimate for a 50 g PE mailer produced in China. Based on PlasticsEurope PE resin data (~2 kgCO2e/kg) scaled to unit weight plus converting energy.
• Scope breakdown: Scope 3 at 90% (0.9 kgCO2e) from PE resin and ink production. Scope 2 at 10% (0.1 kgCO2e) from extrusion and bag making. Scope 1 negligible.
• Confidence: Low — limited published LCA data specific to poly mailers. Estimate derived from PE film LCA data.
• Functional unit: One poly mailer bag (~50 g), cradle to gate.
• Included: PE film extrusion, printing, bag making, adhesive strip. Excluded: Contents, end-of-life disposal.
• Comparison: A corrugated cardboard shipping box (~200-300 g) has approximately 0.3-0.5 kgCO2e. A poly mailer (~50 g) has ~0.1 kgCO2e per unit. Per-shipment, poly mailers are lower-emission but have far lower recyclability.