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HSChapter 39
U.S. imports of natural and modified natural polymers (nesoi), in primary forms (HS 391390) totaled $37.4M in July 2026, traded with 44 countries.
Importers of Natural and Modified Natural Polymers (NESOI), in Primary Forms paid $3.8M in duties in July 2026 — an effective duty rate of 12% on $32.5M in dutiable value, based on actual customs collections rather than the published tariff schedule. Natural and Modified Natural Polymers (NESOI), in Primary Forms imports of $37.4M in July 2026 ran 20% above the year-to-date monthly average of $31.1M.
Last updated: July 2026 dataA broad residual heading covering biopolymers and chemically modified natural polymers not classified elsewhere, including xanthan gum (3913902015), chemical derivatives of natural rubber (3913901000), and other polysaccharides and their derivatives (3913902090). Xanthan gum — a fermentation-derived thickener critical to food, oilfield drilling fluids, and personal care products — is among the most commercially significant lines, with China the leading supplier across most subheadings. Importers should note that food-grade xanthan gum and other edible polysaccharides are subject to FDA review, while industrial grades used in drilling or coatings face different compliance considerations. Classification disputes can arise at the boundary between this heading and Chapter 35 (modified starches) or Chapter 13 (natural gums), making precise product specification documentation essential.
AI-written summary of the official U.S. Census Bureau trade figures on this page — verify before relying on it.
921 shipments/mo
Xanthan gum is specifically identified by its own 10-digit line (3913902015) and is classified there regardless of end use — food, oilfield, or cosmetic. Other microbial or plant-derived polysaccharides not specifically named fall under 3913902090. The key is confirming the chemical identity of the polymer; a technical data sheet or certificate of analysis identifying the substance as xanthan gum (produced by Xanthomonas campestris fermentation) supports the specific line.
Chapter 13 covers natural gums, resins, and vegetable saps in their unmodified state, while Chapter 39 applies once those substances have been chemically modified or processed into primary polymer forms. A certificate of analysis showing the degree of chemical modification (e.g., carboxymethylation, esterification) and a product specification sheet are the most effective documents for supporting a Chapter 39 classification and defending it during CBP review.
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Subheading 1 of 2 in heading 3913
Subheading 391390 · $37.4M of $43.7M
HS10 import codes under this HS6 parent, each with its own page. Source: U.S. Harmonized Tariff Schedule.
| Code | Description | Import Value | Effective Tariff % | Dutiable Share | Duty Collected |
|---|---|---|---|---|---|
| 3913902090 | Polysaccharides & Their Derivatives, NESOI | $26.5M | 8.58% | 85.45% | $2.3M |
| 3913902015 | Xanthan Gum | $7.2M | 16.41% | 98.47% | $1.2M |
| 3913905000 | Natural Polymers & Modif Nat Polymrs,Prim Fm,NESOI | $3.5M | 8.64% | 75.88% | $306K |
| 3913901000 | Chemical Derivatives of Natural Rubber | $100K | 10.00% | 100.00% | $10K |
HS10 export codes under this HS6 parent, each with its own page. Source: U.S. Schedule B export classification.
| Code | Description | Export Value |
|---|---|---|
| 3913908000 | Natural Polymers & Modif Nat Polymrs,Prim Fm,NESOI | $25.6M |
| 3913901000 | Chemical Derivatives of Natural Rubber | $1.1M |
Import lines come from the U.S. Harmonized Tariff Schedule and export lines from Schedule B. The two are numbered by different agencies, so the same 10-digit code can appear in both tables describing a different product.
ImportsExports
Imports
$37.4MYoY · Pro
Exports
$26.7MYoY · Pro
12-mo low · imports
YoY · ProThrough July 2026. Source: U.S. Census Bureau.
Imports · July 2026
origin
Sweden and China together supply 45% of it.
customs district
destination
entry
rate provision · imports
12.7% enters free of duty; the effective duty rate is 10.10%.