Assessment of occupational exposure to 4,4'-diaminodiphenylmethane (methylene dianiline) by gas chromatography-mass spectrometry analysis of urine.

Abstract

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...

Acute respiratory disorder, rhinoconjunctivitis and fever associated with the pyrolysis of polyurethane derived from diphenylmethane diisocyanate.

“…The 4,4'-MDI-related amine , MDA , was detected in hydrolyzed serum and urine . In workers exposed to MDA as such, much higher levels (in urine) have been reported (17).…”

Determination of urinary 4,4′-methylenedianiline and its acetylated metabolites by solid-phase extraction and HPLC analysis with UV and electrochemical detection

“…Tanaka et al ( 1985) found no significant mutagenicity of N-acetyl MDA and N,N'-diacetyl MDA towards Salmonella typhimurium TA 98 and TA 100 They also found, after examination of acetylation in vivo, that N-acetyl MDA predominated over the corresponding N,N'-diacetyl MDA and unmetabolized MDA in the urine of rats orally dosed with high amounts of MDA ( 50 mg/kg) This lack of mutagenicity of the acetyl derivatives of MDA, unlike those of benzidine, which is a well-known bladder carcinogen, may have implications for the slow acetylator phenotype in exposed workers, as noted by Cocker et al ( 1986 The N-acetyl MDA that they found in significant proportion in urine samples of exposed workers was shown to appear, at least in part, in the form of heatlabile conjugates Although the ratio N-acetyl MDA/ MDA, after heat treatment, was given for a number of workers, the proportion of N-acetyl MDA over total MDA was not determined, and the relative contribution of N,N'-diacetyl MDA could not be assessed Moreover, it appeared that MDA was not stable enough in unprotected urine to be analysed with satisfactory precision and accuracy The presence of labile conjugates in the urine of exposed workers reinforces the difficulty of precise analyses, not only of MDA itself, but also of its direct derivatives such as acetyl MDA Furthermore, the analytical determination of urinary aromatic amines is often considered to be a time-consuming and difficult operation.…”

“…Chemicals cording to the procedure described by Cocker et al ( 1986): acetylation of MDA (Merck) with acetic anhydride in pyridine and purification by liquid chromatography on a glass column ( 500 x 40 mm) packed with Silicagel 60 ( 70-230 mesh) (Merck) and eluted with 4 % methanol in dichloromethane MDA, MAMDA and DAMDA were recrystallized in ethanol The identity and purity of the N-acetyl derivatives of MDA were checked by Fourier transform infra-red spectrophotometry, mass spectrometry and HPLC.…”

“…A 20-ml urinary sample was vortexed with 4 g sodium hydroxide until dissolution in a 40-ml glass tube The solution was then heated in a water bath at 800 C for 60 min according to the procedure of Cocker et al ( 1986): for a complete hydrolysis of MDA conjugates these conditions are sufficient and were confirmed during this work After cooling to room temperature, the hydrolysed solution was submitted to the same procedure as previously described for isolation of MDA and MAMDA; the washing step of the CBA cartridge ( 3 ml methanol followed by 3 ml distilled water) was also applied but the resulting solution was discarded.…”

“…Although several airborne threshold limit values were recommended, occupational exposure is frequently assessed by biological monitoring due to preponderant skin penetration in most cases (e g Vaudaine 1981 ;Porst 1986 ;Cocker et al 1986 ;Trippel-Schulte et al 1986 ;Boeniger 1987 ;Tiljander and Skarping 1990 ;Hathaway et al 1991 ;Peterson et al 1991 ;Neumeister 1991 ;Kusters 1992 ;Selden et al 1992 ;Brunmark et al 1992) The analytical methods described for this purpose were mostly designed to determine urinary MDA after either strong acid or alkaline hydrolysis, hydrolysed MDA being used as a suitable determinant to assess absorption and to monitor improvements in factories Among the different works reported in the literature, Cocker et al ( 1986) described the presence of N-acetyl MDA as a major metabolite in human urine for the first time.…”