A new specific and sensitive method has been used to monitor workers from five different factories where 4,4'-diaminodiphenylmethane (methylene dianiline) (DDM) was being used. The isolation and identification of an N-acetyl conjugate of DDM, a major metabolite of DDM found in human urine, is reported for the first time. The use of this biological monitoring method will allow the assessment of the absorption of DDM and help in monitoring improvements in work practices, particularly where exposure may occur through pathways other than inhalation.4,4' Diaminodiphenylmethane (DDM) is a commercially important aromatic amine used in the production of isocyanates, polyisocyanates, polyurethane foams, and elastomers and as an epoxy resin hardener.' It is commonly referred to as methylene dianiline (MDA) (CAS 101-77-9). Several workers have studied the toxicity of DDM. It has been reported to be hepatoxic in rats,2 3 dogs,4 and man.5 It is mutagenic in the Ames test in the presence, but not in the absence, of an S9 metabolising system9 and has been reported to be carcinogenic in rats and mice.'0 " I As a result of these findings and the close chemical similarity of DDM to other aromatic amines, which are proved or suspect human carcinogens, DDM is under scrutiny by regulatory bodies in the United States.Occupational exposure to DDM may be assessed by measuring DDM concentrations in the work environment and by biological monitoring. DDM, like 3,3'-dichloro 4,4'-diaminodiphenylmethane (commonly known as 4,4' methylene bis 2-chloroaniline or MBOCA) and other aromatic amines, has the potential for considerable skin absorption. Analysis of urine samples from workers exposed to MBOCA is helpful in assessing absorption and in monitoring improvements in occupational hygiene.'2 Analytical methods have been reported for the analysis of DDM in workplace air using high performance liquid chromatography (HPLC) with ultraviolet detection'3 and in blood using gas chromatography (GC) with elecAccepted 3 March 1986. tron capture detection.'4 The work reported here describes the use of a new sensitive and specific gas chromatographic-mass spectrometric (GCMS) method for measuring DDM in urine. This approach was adopted after we had used HPLC and GC methods and had noted that occasionally interfering peaks were present in urine. We also describe for the first time the isolation and identification of N-acetyl DDM, a major metabolite of DDM found in human urine. These findings are used to devise a biological monitoring method for monitoring workers exposed to DDM. Materials and methods URINE SAMPLESUrine samples were collected from 111 workers at five factories using DDM. Factories A and B were packaging DDM as a component of a hardener in a two part epoxy resin formulation, factories C and D were using DDM and other compounds to impregnate carbon fibre mats, and factory E used DDM as a component in a screen printing process for seals and gaskets. Urine samples were collected in polycarbonate bottles towards the end of a working sh...

The development and use of a gas chromatographic method for monitoring workers who are occupationally exposed to 4,4'-methylenebis(2-chloroaniline) (MBOCA) is reported. The increase in ether-extractable MBOCA on mild hydrolysis is determined. The analytical conditions for a specific and sensitive electron capture gas chromatographic method that will measure both "free" MBOCA and "total" MBOCA are established. It is suggested that workers should be monitored by the measurement of "total" urinary MBOCA.

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