Urinary formic acid as a dose biomarker for Occupational Exposure to Formaldehyde

摘要

Aim: This paper explores the possibility to assess occupational or environmental exposure to Formaldehyde (FA) by biomonitoring, on an accessible matrix like urine. FA is a common contaminant recently recognized as a carcinogen by IARC. Occupational exposure occurs in anatomical pathology, engineering industries, furniture and plastic utensils production, beauty salons and gasoline station. The SCOEL recommends a Limit Value of 0.3 ppm (8 h TWA) with a STEL limit of 0.6 ppm. Inhaled FA is oxidized and excreted as formic acid in the urine; formic acid can derive from other metabolic sources. Methods: A bibliographic search was performed on Scopus and PubMed, retrieving papers published from 2006 to 2015, using key words or strings pertinent to biomonitoring for formaldehyde exposure: 17 papers were selected and read and the use of urinary formic acid as biomarker is discussed. Sampling and analysis of airborne FA content were also conducted in indoor and outdoor air in non-occupational settings, according to the NIOSH method n.2016. Results: Formic acid stays stable in urine up to 13 days at room temperature: its concentration is used as biomarker of exposure to FA in 5 papers, analyzed by headspace GC-FID or HPLC/UV. In all papers measured concentrations of airborne FA were well below the SCOEL Limit Value of 0.3 ppm, ranging from 0.009 to 0.09 ppm, while formic acid was between 17 and 42 mg/L. In exposed workers levels were statistically significant higher than in controls, and one paper reports higher values in gasoline station female workers than in males. In beauty salons a background median level of formic acid is measured of 11.05 mg/L, and a post exposure of 15.22. When if data are put together a linear relationship between airborne FA and urinary formic acid is found (figure). The formic acid concentration corresponding to the SCOEL Limit Value of 0.3 ppm can be extrapolated, being 84.42 mg/L, and a background level of 9.00 mg/L for no exposure. Airborne FA levels measured in non-occupational settings would correspond to formic acid levels very close to the calculated background. Conclusions: Few papers were published in the last 9 years reporting the use of urinary formic acid as a biomarker for FA exposure. Urinary formic acid seems a promising biomarker for the measure of occupational exposure, but non for environmental. Further investigations is needed on this subject, a growing need, as exposure assessment is compulsory for carcinogenic substances like FA.