World Health Organization (WHO / IARC)
IARC Monographs on the Identification of Carcinogenic Hazards to Humans: Antimony Trioxide
IARC Monograph Vol. 47
What is Antimony Trioxide in Mattress Flame Barriers?
Investigates antimony trioxide (Sb2O3) chemical synergists in modacrylic flame socks, toxicology, and exposure risks.
Chemical Synergist
Direct answer summary
Antimony trioxide ($Sb_2O_3$) is an inorganic chemical flame-retardant synergist frequently co-polymerized into modacrylic fibers or applied to cotton batting. When exposed to heat, it reacts with halogenated compounds to form antimony halides that quench gas-phase free radicals in fire flames. Because antimony trioxide is classified as a possible human carcinogen (IARC Group 2B), health-conscious consumers seek out organic wool, thistle, or silica-rayon barriers.
Key points
Acts as a catalytic flame retardant synergist in modacrylic textile fibers.
Classified as a possible human carcinogen (IARC Group 2B) and skin/respiratory irritant.
Premium brands eliminate antimony in favor of mechanical barriers like wool or silica.
Interactive example
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Verified Law Label
Interactive Visual Tool
Law Label & Material Audit
Inspect the physical law label tag, decode the state Uniform Registry Number (URN), and review certified material percentages under CPSC 16 CFR Part 1633.
What the law tag tells you
Uniform Law Label & Material Deconstruction
Under FTC 16 CFR Part 303 and IABFLO uniform law label standards, bedding manufacturers must disclose exact net filling weights using standardized generic fiber terms. Marketing buzzwords are prohibited under federal penalty.
▲ Sewn Into Seam (Tyvek Substrate) ▲
UNDER PENALTY OF LAW THIS TAG NOT TO BE REMOVED EXCEPT BY AUTHORIZED OFFICIAL
SEIZED / QUARANTINED - UNLAWFUL TO SELL OR REMOVE
UNCERTIFIED POLYURETHANE FOAM80%
GLASS FIBER KNIT SLEEVE (FIBERGLASS)20%
Net Filling Weight (Excluding Steel Springs)
Uniform Registry Number (Click to decode)
REG. NO. CA-000000 (CN)
Certification is made by the manufacturer that the materials in this article are described in accordance with law.
Manufacture Date:01/2025
Plant Facility:Port of Long Beach Inspection Depot, CA
Legal Entity:Unregistered Overseas Importer
16 CFR Part 1633 Prototype: FAILED-NON-COMPLIANTInspect →
Physical Tag Dimensions: 3" × 4.5" (Meets IABFLO 2.5" × 3.0" min)
What the tag number means
REG. NO. CA-000000 (CN)
Issuing State
CA (California)
Registry Sequence
#000000
Plant Location
CN (China)
IABFLO 31-State Reciprocity: The issuing state (CA) participates in the Uniform Law Label system. This single registration permits lawful commercial distribution across all 31 regulated US bedding jurisdictions without duplicate state tags.
Specifications
Recorded specifications
Values and benchmarks recorded for this question.
| Specification | Measured value | Benchmark | Status |
|---|---|---|---|
| Chemical Formula | Sb2O3 (Antimony Trioxide) | Heavy Metal Chemical Retardant | warning |
| IARC Carcinogen Rating | Group 2B (Possibly Carcinogenic) | Preferred Non-Carcinogenic | warning |
| Action Mechanism | Halogen Quenching in Gas Phase | Chemical Suppression | neutral |
| Alternative Barrier | Pure Wool / Hydrated Silica Viscose | Zero Heavy Metal Additives | pass |
Standards reference: Benchmarks derived from ASTM D3574 (flexible cellular foam), CPSC 16 CFR 1633 (open flame flammability), and clinical capillary closing thresholds (32.0 mmHg).
Checklist
Consumer Safety & Chemical Verification Protocol
Step-by-step physical inspection procedure for flame barrier integrity and law label compliance.
- 01
Review Law Label Disclosures
Inspect filling breakdown for modacrylic fiber or treated cotton batting.
Watch for: Avoid mattresses that emit sharp metallic chemical odors when unboxed.
- 02
Check OEKO-TEX Certification
Verify OEKO-TEX Standard 100 Class 1 certification, which bans antimony exceeding 10 ppm.
Watch for: Do not expose treated covers to acidic washing agents that leach antimony.
- 03
Opt for Natural Char Barriers
Select mattresses utilizing certified organic wool, natural thistle, or hydrated silica.
Watch for: Never buy uncertified budget import memory foam mattresses lacking chemical disclosures.
Sources
Sources for this answer
Read the source documents behind the thresholds, measurements, and policy details used here.
View source
Agency for Toxic Substances and Disease Registry (ATSDR)
Toxicological Profile for Antimony and Compounds
ATSDR Toxicological Profile