Biological monitoring of aromatic diisocyanates in workers exposed to thermal degradation products of polyurethanes

Abstract

Exposure to diisocyanates was assessed by biological monitoring among workers exposed to the thermal degradation products of polyurethanes (PURs) in five PUR-processing environments. The processes included grinding and welding in car repair shops, milling and turning of PUR-coated metal cylinders, injection moulding of thermoplastic PUR, welding and cutting of PUR-insulated district heating pipes during installation and joint welding, and heat-flexing of PUR floor covering. Isocyanate-derived amines in acid-hydrolysed urine samples were analysed as perfluoroacylated derivatives by gas chromatography mass spectrometry in negative chemical ionisation mode. The limits of quantification (LOQs) for the aromatic diamines 2,4- and 2,6-toluenediamine (2,4- and 2,6-TDA) and 4,4'-methylenedianiline (4,4'-MDA) were 0.25 nmol l(-1), 0.25 nmol l(-1) and 0.15 nmol l(-1), respectively. The LOQ for the aliphatic diamines hexamethylenediamine (HDA), isophoronediamine (IpDA) and 4,4'-diaminodicyclohexyl methane (4,4'-DDHM) was 5 nmol l(-1). TDA and MDA were detected in urine samples from workers in car repair shops and MDA in samples from workers welding district heating pipes. The 2,4-TDA isomer accounted for about 80% of the total TDA detected. No 2.6-TDA was found in the urine of non-exposed workers. The highest measured urinary TDA and MDA concentrations were 0.79 nmol mmol(-1) creatinine and 3.1 nmol mmol(-1) creatinine, respectively. The concentrations found among non-exposed workers were 0.08 nmol mmol(-1) creatinine for TDA and 0.05 nmol mmol(-1) creatinine for MDA (arithmetic means). Exposure to diisocyanates originating from the thermal degradation of PURs are often intermittent and of short duration. Nevertheless, exposure to aromatic diisocyanates can be identified by monitoring diisocyanate-derived amines in acid-hydrolysed urine samples.

Role of dermal exposure in systemic intake of methylenediphenyl diisocyanate (MDI) among construction and boat building workers

“…The detection limit was 0.1 mg/l or lower (0.04-0.1 mmol mol À1 creatinine, depending on the amount of creatinine in the urine). The workup procedure and analytical conditions are described in detail by Rosenberg et al (2002).…”

Hemoglobin adducts in workers exposed to 1,6-hexamethylene diisocyanate

“…1, 6-Hexamethylene diamine (HDA) in biological media (e.g., urine, plasma) has been utilized as a biological marker for occupational exposure to 1,6-hexamethylene diisocyanate (HDI) (Maître et al 1996, Williams et al 1999, Rosenberg et al 2002, Pronk et al 2006, Flack et al 2010a). During automotive spray painting, workers may be exposed to HDI present in paint formulations via skin or inhalation routes.…”

Absorption, distribution, metabolism and excretion of an inhalation dose of [14C] 4,4'-methylenediphenyl diisocyanate in the male rat

“…These approaches address potential biomarkers that may be applicable to assessment of isocyanate exposure in workers (Dalene 1995, Rosenberg 2002) rather than providing quantitative assessments of uptake, distribution and biotransformation.…”