4,4'-Methylenedianiline (MDA) and 4,4'-methylenediphenyl diisocyanate (MDI) are important intermediates in the production of polyurethanes. In order to biomonitor people exposed to low levels of MDA or MDI we have developed sensitive methods to measure hemoglobin (Hb) adducts and urine metabolites. Adducts and metabolites from 33 workers exposed to MDA and 27 workers exposed to MDI were analyzed by gas chromatography-mass spectrometry after hydrolysis, extraction and derivatization with heptafluorobutyric anhydride. Hb adducts of MDA were detected in 31 out of the 33 MDA workers and both MDA and N-acetyl-MDA (AcMDA) were found in 20 of these individuals. The detection limit for MDA was 20 fmol and for AcMDA 100 fmol/sample, which correspond to an absolute detection limit of approximately 1 fmol MDA and 5 fmol AcMDA, respectively. In the urine of workers exposed to MDA both MDA and AcMDA were found in all samples, with the exception of five where only MDA was detected. Acid hydrolysis of the urine samples yielded an approximately 3-fold higher concentration of MDA than the sum of MDA and AcMDA found after base hydrolysis. MDA but not AcMDA found in urine and in Hb correlate well, except for three outliers. In one workers the Hb adduct level of MDA was very low compared to the urine levels. Two workers had very high levels of MDA as Hb adducts but very low levels as urine metabolites. The former case indicates that the workers were recently exposed to higher levels of MDA. The latter case suggests a relatively low recent exposure. The air levels of MDA, monitored using personal air monitors, were below the detection limit. It was possible, however, to determine exposure to MDA for all workers with the methods presented in this publication. Workers exposed exclusively to MDI were studied. Exposure levels, as monitored using personal air samplers, were below the detection limit of 3 micrograms/m3, with the exception of three individuals. In 10 of the MDI workers, hydrolyzable Hb adducts of MDA (57-219 fmol/g Hb) were found. Except for four subjects, the presence of MDA (0.007-0.14 nmol/l) and AcMDA (0.08-3 nmol/l) was detected in all urine samples after base treatment. Following acid hydrolysis of the urine, higher levels of MDA (0.7-10 nmol/l) were found than the sum of free MDA and AcMDA. According to the present data, it was possible to detect exposure to MDI in a greater number of individuals by analyzing urinary metabolites than by measuring Hb adducts or air monitoring.

4,4'-Methylenediphenyl diisocyanate (MDI) is the most widely used isocyanate in the manufacture of polyurethanes. MDI has been implicated as one of the major causes of occupational asthma. Hydrolysis of MDI can yield 4,4'-methylenedianiline (MDA), which is a suspected human carcinogen. Thus the need to monitor occupational exposure to MDI is of great significance. The use of air monitors alone has been found to be insufficient and there is a need for sensitive markers of recent and long-term exposure. We obtained biological samples from a group of 20 workers exposed to MDI vapor during the manufacture of polyurethane products. The air levels of MDI in the factory were measured using personal, work room and work station monitors. In most cases the levels were below detection limits. The blood and urine samples were analyzed for the presence of adducts and metabolites using GC-MS methods. Urinary base-extractable metabolites were found above control levels in 15 of the 20 workers and ranged from 0.035 to 0.83 pmol MDA/ml. The level of the acetylated metabolite N'-acetyl-4,4'-methylenedianiline (AcMDA) ranged from 0.13 to 7.61 pmol/ml. The amount of MDA released after acid hydrolysis was on average 6.5 times higher than the amount of free MDA and AcMDA present in urine. MDA was detected as a hemoglobin (Hb) adduct in all of the 20 subjects. The level ranged from 70 to 710 fmol/g Hb. In one individual the Hb adduct of AcMDA was detected. This is the first time a Hb adduct of AcMDA has been detected after occupational exposure to MDI. This is a further piece of evidence for the biological availability of the suspected human carcinogen MDA from in vivo hydrolysis of MDI. Plasma albumin conjugates of MDI can cause the onset of respiratory disorders in both man and animal models. Thus we investigated the presence of plasma protein adducts. The plasma MDA levels ranged from 0.25 to 5.4 pmol/ml. Up to 120 fmol/mg were found to be covalently bound to albumin.

4,4'-Methylenediphenyl diisocyanate (MDI) is the most important of the isocyanates used as intermediates in the chemical industry. Among the main types of damage after exposure to low levels of MDI are lung sensitization and asthma. Protein adducts of MDI might be involved in the etiology of sensitization reactions. It is therefore necessary to have sensitive and specific methods for monitoring the isocyanate exposure of workers. To date, urine metabolites or protein adducts have been used as biomarkers in workers exposed to MDI. However, with these methods it is not possible to determine if the biomarkers result from exposure to MDI or to the parent aromatic amine 4,4'-methylenedianiline (MDA). This work presents a procedure for quantitating isocyanate-specific hemoglobin adducts. Blood proteins are used as markers of exposure and possibly as markers of dose size for the modifications of macromolecules in the target organs where the disease develops. For the quantitation of hemoglobin adducts, N(1)-[4-(4-isocyanatobenzyl)phenyl]acetamide (AcMDI) was reacted with the tripeptide valyl-glycyl-glycine and with valine yielding N-[4-(4-acetylaminobenzyl)phenyl]carbamoyl]valyl-glycyl-glycine and N-[4-[4-(acetylaminobenzyl)phenyl]carbamoyl]valine, respectively. N-[4-[4-(Acetylamino-3,5-dideuteriobenzyl)-2, 6-dideuteriophenyl]carbamoyl]valine was synthesized from valine, as was N(1)-[4-(4-isocyanato-3,5-dideuteriobenzyl)-2, 6-dideuteriophenyl]acetamide, for use as an internal standard. These adducts were cleaved in 2 M HCl to yield the corresponding hydantoins, 3-[4-(4-aminobenzyl)phenyl]-5-isopropyl-1, 3-imidazoline-2,4-dione (MDA-Val-Hyd) and 3-[4-(4-amino-3, 5-dideuteriobenzyl)-2,6-dideuteriophenyl]-5-isopropyl-1, 3-imidazoline-2,4-dione, respectively. In globin of rats exposed to MDI, MDA-Val-Hyd could be found in a dose-dependent manner. The adduct was identified by HPLC/MS/MS and quantified by GC/MS after derivatization with heptafluorobutyric anhydride. The amount of MDA-Val-Hyd found after acid hydrolysis of globin at 100 degrees C is about 12 times larger than the sum of N-acetyl-4, 4'-methylenedianiline (AcMDA) and MDA obtained from mild base hydrolysis of hemoglobin. The MDA-Val-Hyd is an isocyanate-specific adduct. MDA and AcMDA released after mild base hydrolyses result most likely from a sulfinamide adduct which is a typical adduct of arylamines. According to these results, higher amounts of isocyanate adducts than arylamine adducts should be expected in workers exposed to isocyanates.

Industrial "chlorine chemistry" is accused of polluting the environment with its products and having adverse effects on health. The accusation has been followed by the demand that this ill-defined branch of chemistry be simply abolished. a demand which has been repeated vigorously now for years. It grew out of misgivings such as those summarized here: 1. A number of polychlorinated cyclic compounds are very stable and highly lipophilic so that they accumulate in the environment and affect mankind through the food chain. Prominent examples are chlorinated pesticides, biphenyls, dibenzodioxins, and dibenzofurans. 2. Many chlorinated compounds are toxic for man and animals. Their genotoxicity (mutagenicity and carcinogenicity) plays a role in risk assessment; more and more chlorinated organic compounds are being shown to be carcinogenic and classified accordingly.To date there are no comprehensive reviews of the toxicology of chlorinated organic compounds. The present treatise is the result of an attempt to analyze the situation systematically. It makes generalizations as to the kind and degree of toxicity of the most important classes of chlorinated organic compounds and elaborates recommendations for reduction and avoidance of risk during production, occupational handling. and general use.

1. Allyl and allylic compounds may exert alkylating activities by SN1, SN2 and SN2' mechanisms. This direct alkylating potential can be determined quantitatively by a modified 4-NBP (4-nitrobenzyl pyridine) test. 2. The alkylating activities in a systematically selected series of allyl and allylic compounds correlate well with the direct mutagenic potential as determined in the Ames test using Salmonella typhimurium TA 100 as tester strain. 3. The allylic structure is a prerequisite for these types of activities since structurally related molecules lacking the allylic moiety are inactive in this respect. 4. The potency of both the alkylating and mutagenic activity is determined by the strength of the leaving group: --OSO2CH3 greater than I greater than Br greater than Cl greater than--NCS. 5. Indirect mutagenicity, through metabolic activation of the olefinic bond (by addition of S9 mix to the tester medium), can be ruled out for practically all compounds, the only exception found being 2,3-dichloro-1-propene where an increase of mutagenicity is encountered after addition of S9 mix; mechanistic explanations for this exception are provided. 6. Analogous activation is demonstrated for benzyl halides, the alkylating potency of which is even higher than that of genuine allylic compounds. 7. A variety of methyl- and chlorine-substituted allyl compounds has been included in the study: both groups increase activity, either by +I (CH3) or by +M effects (Cl). 8. alpha, beta-Unsaturated carbonyl compounds, e.g. acrolein and crotonaldehyde, also display direct mutagenic activity which is due to a completely different mechanism: covalent binding to nucleophilic sites of DNA bases by Michael addition. Methyl and other alkyl substitutions decrease the mutagenic potential in this type of compound. The corresponding alcohols, also displaying mutagenic activity but to a lesser degree, are metabolically activated by ADH (alcohol dehydrogenase) of the tester strain microbes to the aldehydes or ketones.