Abstract

Thermal food labels remain an overlooked but significant source of human exposure to bisphenol-based color developers. This paper synthesizes findings from a 2025 global survey of 247 labels across 15 countries, evaluating the occurrence of Bisphenol S (BPS), Bisphenol A (BPA), and emerging alternatives such as NKK-1304, DBSP, D-90, and D-8. Using LC-qTOF-MS and controlled 10-day migration experiments, the study demonstrates that BPS has largely replaced BPA worldwide, though BPA persists in select markets. Packaging material exerts a decisive influence on developer migration: PVC cling films permit substantial transfer of BPS (up to 63% of extractable content) and D-90 (31%) into fatty simulants, whereas polyethylene (PE) and paper act as effective barriers (<0.1 µg/cm²). Despite regulatory shifts—including the EU’s 2025 bisphenol ban in food-contact materials—health and environmental concerns endure, particularly given the endocrine-active properties of BPS and the limited toxicological data for newer substitutes. The findings underscore the need for comprehensive risk assessment, improved material selection, and phenol-free innovation in label technology.

Keywords

Thermal food labels; Bisphenol S (BPS); Bisphenol A (BPA); color developers; chemical migration; PVC film; polyethylene barrier; endocrine disruption; packaging safety; NKK-1304; DBSP; D-90.

1. Introduction

Thermal printing technology has long relied on bisphenol-type color developers, most notably Bisphenol A (BPA), to activate leuco dyes under heat. Concerns regarding BPA’s endocrine-disrupting properties have prompted global regulatory action and widespread reformulation of thermal papers. While receipts were historically the primary focus, thermal food labels—applied directly onto PVC or polyethylene wraps that contact meat, cheese, produce, and ready-to-eat foods—represent a direct pathway for dietary exposure.

Following the European Union’s 2020 restriction on BPA in thermal papers and the upcoming 2025 ban on bisphenols in food-contact materials, manufacturers have increasingly moved toward alternatives. Bisphenol S (BPS) has emerged as the predominant substitute, though it exhibits toxicological behaviors similar to BPA. Even newer developers such as NKK-1304, DBSP, D-90, and D-8 have entered the market, but their health profiles remain poorly characterized.

This paper consolidates data from the 2025 global survey conducted by Xu, Goodyer, Hales, and Bayen, extending its implications with updated regulatory and toxicological insights. The objective is to evaluate the global prevalence of color developers in thermal labels, quantify their migration across common packaging materials, and interpret the findings in a broader health and policy context.

2. Materials and Methods

2.1 Sample Collection

A total of 247 thermal food labels were collected from 41 retail shops across 15 countries, representing North America, Europe, Asia, Africa, and Oceania. Labels were obtained from wrapped foods including raw meats, seafood, cheeses, vegetables, and prepared items.

Each sample was cut into exact 1 cm² sections, including both the printed label and the underlying packaging film.

2.2 Analytical Screening

Color developers were screened using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-qTOF-MS).
A suspect list of 28 color developers was evaluated; nine were confirmed and quantified:

• BPA
• BPS
• BPS-MAE
• NKK-1304
• DBSP
• PF-201
• TGSA
• D-8
• D-90

Instrument performance met analytical standards with:

• mass accuracy within 6 ppm,
• linearity r² > 0.98,
• method detection limits <1 ng/cm²,
• repeatability <10% RSD.

Polymer identification for films directly beneath labels was performed via ATR-FTIR, achieving a match quality >0.80.

2.3 Migration Experiments

Migration testing followed EU Regulation 10/2011 guidelines.

A commercially available label formulation containing BPS and D-90 served as the model system. Labels were applied to:

1. PVC cling film (two brands)
2. PE cling film (two brands)
3. Paper interlayer on PVC film

Migration cells (MigraCell chambers) were filled with 100 mL of food simulants:

• 95% ethanol (fatty foods)
• 50% ethanol (mixed foods)
• 10% ethanol (aqueous foods)

Exposure duration: 10 days at room temperature.
Migration was expressed as µg/cm² of label area, normalized against maximum extractable developer.

3. Results

3.1 Global Occurrence of Color Developers

Across all regions, BPS dominated, appearing in 48% of labels, with an average surface loading of 59.3 μg/cm².
Regional distribution:

• Asia: 70%
• Oceania: 54%
• North America: 44%
• Europe: 42%
• Africa: 8%

Although global regulations have curtailed BPA use, BPA persisted in 2% of labels, mainly in Asia, with surface loadings reaching up to 397.5 μg/cm².

Newer developers showed region-specific adoption:

• NKK-1304: frequent in Oceania (46%) and Africa (44%)
• DBSP: most common in Africa (48%)
• D-8: present in 8% but at notably high concentrations (mean 129.3 μg/cm²)

Only 8% of labels were found on paper wraps; 92% were applied to plastic films, predominantly PVC (80%).

3.2 Migration Through Packaging Films

BPS Migration

• PVC films permitted significant migration:
  • Up to 130.7 μg/cm² in 95% ethanol (63% of extractable BPS)
  • 23.7 μg/cm² in 50% ethanol
  • 0.9 μg/cm² in 10% ethanol
• PE films functioned as near-total barriers:
  • BPS migration <0.1 μg/cm² across all simulants
• Paper interlayers similarly prevented migration:
  • BPS migration <0.1 μg/cm²

D-90 Migration

The migration profile mirrored BPS:

• PVC: up to 8.5 μg/cm² in 95% ethanol (31% of extractable D-90)
• PE and paper: <0.01 μg/cm²

4. Discussion

The global shift from BPA to BPS in food labels has reduced BPA exposure but created parallel concerns, as BPS exhibits endocrine activity and environmental persistence comparable to BPA. The detection of BPS in human matrices—including breast milk—underscore its relevance to public health.

The rise of NKK-1304, DBSP, and D-8 represents an emerging class of color developers with minimal toxicological evaluation. Their rapid market adoption suggests manufacturers are reacting to regulatory pressure without long-term safety validation—a textbook example of “regrettable substitution.”

Migration tests highlight the critical influence of packaging materials.

• PVC films, widely used in supermarkets, enable substantial transfer of bisphenols into foods, especially fatty items.
• PE films and paper layers effectively block this migration.

This indicates that safer packaging decisions can mitigate exposure irrespective of label chemistry.

However, no solution is entirely hazard-free: PVC, PE, and paper can each leach other contaminants (phthalates, plasticizers, PFAS), requiring comprehensive risk assessment rather than single-compound substitution.

Regulatory momentum continues to accelerate:

• The EU’s 2025 ban on bisphenols in food-contact materials
• Washington State’s 2026 prohibition of BPS
• Industry movement toward phenol-free developers, such as vitamin-C-based formulations

Yet, global enforcement remains uneven, leaving regions vulnerable to outdated or unreviewed chemistries.

5. Conclusion

This synthesis demonstrates that while BPA use in thermal food labels has declined, the global market has transitioned toward BPS and a growing array of newer bisphenol-type developers. Migration experiments confirm that packaging material—not just label composition—is pivotal for consumer exposure. PVC films enable high bisphenol transfer, whereas PE and paper provide significant protection.

The findings underscore three priorities:

1. Comprehensive toxicological evaluation of emerging alternatives such as NKK-1304 and DBSP.
2. Material-specific migration standards that consider both label and film composition.
3. Development of phenol-free, low-migration labeling technologies supported by regulatory incentives and global harmonization.

As the food packaging sector evolves, a shift from reactive substitutions to proactive hazard-based design is essential for safeguarding public health and environmental integrity.

References

1. Xu, Z.; Goodyer, C.G.; Hales, B.F.; Bayen, S. Global survey of bisphenol color developers in thermal food labels and migration through packaging films. SSRN Preprint, 2025.
2. European Commission. Ban on bisphenols in food-contact materials, January 2025.
3. Washington State Legislature. Restriction on BPS in thermal papers, 2026 enactment.
4. McGill University. Endocrine activity of BPA substitutes, 2025.
5. Food Packaging Forum. Bisphenols background report, 2025.
6. ACS Environmental Science & Technology. Migration of BPS from food labels, 2023.
7. EU Regulation No. 10/2011 on food-contact plastics.
8. Industry reports on phenol-free thermal developer technologies, 2024–2025.

Last Updated on 12/12/2025 by Jota Machinery