Xylene — biological monitoring
When to suspect: Paints / varnish, histology labs, printing, adhesives, petrochemical, cleaning / degreasing.
Urine methylhippuric acids (o-, m-, p-) (g/g creatinine)
| Level | Interpretation |
|---|---|
| Negligible | Non-exposed (essentially not detectable) |
| 1.5 | ACGIH BEI — end of shift |
Best collected at the end of the second day of exposure.
Biological exposure index
ACGIH BEI = 1.5 g/g creatinine (sum of o-, m-, p-methylhippuric acids), end of shift.
Basis: ACGIH BEI (lab catalogs + peer-reviewed).
Sample collection & preparation
- Clean plastic urine container → standard transport tube.
- END OF SHIFT; creatinine-corrected.
- Avoid ambient solvent contamination. No seafood/fasting requirement.
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