n-Hexane — biological monitoring
When to suspect: Solvent glues/adhesives (shoe, leather, furniture), printing inks, vegetable-oil extraction, degreasing, lamination. Risk of peripheral polyneuropathy.
Urinary 2,5-hexanedione (free) (mg/L)
| Level | Interpretation |
|---|---|
| < 0.3 | Non-exposed background (free 2,5-HD) |
| 0.4 | ACGIH BEI — end of shift at end of workweek |
Assay FREE 2,5-HD — do NOT acid-hydrolyse (hydrolysed values are ~10× higher and not the BEI basis). MnBK shares this metabolite.
Biological exposure index
ACGIH BEI = 0.4 mg/L free 2,5-hexanedione (without hydrolysis), EOS at end of workweek (TLV-TWA 50 ppm).
Basis: ACGIH BEI.
Sample collection & preparation
- Spot urine, end of last shift of workweek; plain container.
- Assay FREE 2,5-HD (no acid hydrolysis).
- Freeze if delayed.
Statutory basis. Factories Act 1948 sets only AIR limits (Second Schedule TWA/STEL, s.41F) and mandates the hazardous-process exam (s.41C, ≤12-monthly); it gives NO blood/urine values. The ranges below are ACGIH BEI / OSHA / clinical benchmarks (India has not adopted biological limits into law).
Reference information for occupational-health professionals — not medical advice, and not a substitute for examination by a qualified physician.
All 27 agents — toxicology & biological monitoring
MedFactory — Occupational Health Centre software for Indian factories