Increased risk of acute myelogenous leukemia (AML) and chronic myelogenous leukemia (CML) in a county of Hesse, Germany

Environmental persistence, hazard, and mitigation challenges of nitroaromatic compounds

Nitroaromatic compounds (NACs) are extensively used in different industries and are synthesized in large quantity due to their heavy demand worldwide. The broad use of NACs poses a serious pollution threat. The treatment processes used for the removal of NACs are not effective and sustainable, leading to their release into the environment. The nitro group attached to benzene ring makes the compounds recalcitrant due to which they persist in the environment. Being hazardous to human as well as other living organisms, NACs are listed in the USEPA's priority pollutant group. This review provides updated information on the sources of NACs, prevalence in different environmental matrices, and recent developments in methods of their detection, with emphasis on current trends as well as future prospects. The harmful effects of NACs due to exposure through different routes are also highlighted. Further, the technologies reported for the treatment of NACs, including physico-chemical and biological methods, and the challenges faced for their effective implementation are discussed. Thus, the review discusses relevant issues in detail making suitable recommendations, which can be helpful in guiding further research in this subject.

[Vitamin B12 deficiency in the elderly]

The prevalence of vitamin B12 deficiency increases with age. Patients with dementia and spouses of patients with dementia are at special risk for the development of vitamin B12 deficiency. In a normal diet this vitamin is present only in animal source foods; therefore, vegans frequently develop vitamin B12 deficiency if not using supplements or foods fortified with cobalamin. Apart from dementia, most of these manifestations are completely reversible under correct therapy; therefore it is crucial to identify and to treat even atypical presentations of vitamin B12 deficiency as early as possible. This article deals with the physiology and pathophysiology of vitamin B12 metabolism. A practice-oriented algorithm which also considers health economic aspects for a rational laboratory diagnosis of vitamin B12 deficiency is presented. In cases with severe neurological symptoms, therapy should be parenteral, especially initially. For parenteral treatment, hydroxocobalamin is the drug of choice.

Genotoxicity of nitrosulfonic acids, nitrobenzoic acids, and nitrobenzylalcohols, pollutants commonly found in ground water near ammunition facilities

2-Amino-4,6-dinitrobenzoic acid (2-A-4,6-DNBA), 4-amino-2,6-dinitrobenzoic acid (4-A-2,6-DNBA), 2,4,6-trinitrobenzoic acid (2,4,6-TNBA), 2-amino-4, 6-dinitrobenzylalcohol (2-A-4,6-DNBAlc), 4-amino-2,6-dinitrobenzylalcohol (4-A-2,6-DNBAlc), 2,4-dinitrotoluol-5-sulfonic acid (2,4-DNT-5-SA), 2,4-dinitrotoluol-3-sulfonic acid (2,4-DNT-3-SA), and 2, 4-dinitrobenzoic acid (2,4-DNBA) are derivatives of nitro-explosives that have been detected in groundwater close to munitions facilities. In the present study, the genotoxicity of these compounds was evaluated in Salmonella/microsome assays (in strains TA100 and TA98, with and without S9 and in TA98NR without S9), in chromosomal aberration (CA) tests with Chinese hamster fibroblasts (V79), and in micronucleus (MN) assays with human hepatoma (HepG2) cells. All compounds except the sulfonic acids were positive in the bacterial mutagenicity tests, with 2,4,6-TNBA producing the strongest response (8023 revertants/micromol in TA98 without S9 activation). 2-A-4,6-DNBA was a direct acting mutagen in TA98, but negative in TA100. The other positive compounds were approximately 1-3 orders of magnitude less mutagenic than 2,4,6-TNBA in TA98 and in TA100; relatively strong effects ( approximately 50-400 revertants/micromol) were produced by the benzylacohols in the two indicator strains. With the exception of 2,4-DNBA, the mutagenic responses were lower in the nitroreductase-deficient strain TA98NR than in the parental strain. 2,4-DNBA produced a marginally positive response in the V79-cell CA assay; the other substances were devoid of activity. Only the benzoic acids were tested for MN induction in HepG2 cells, and all produced positive responses. As in the bacterial assays, the strongest effect was seen with 2,4,6-TNBA (significant induction at >or=1.9 microM). 4-A-2,6-DNBA was positive at 432 microM; the weakest effect was observed with 2,4,-DNBA (positive at >or=920 microM). The differences in the sensitivity of the indicator cells to these agents can be explained by differences in the activities of enzymes involved in the activation of the compounds. The strong responses produced by some of the compounds in the human-derived cells suggest that environmental exposure to these breakdown products of nitro-explosives may pose a cancer risk in man.

Hemoglobin adducts, urinary metabolites and health effects in 2,4,6-trinitrotoluene exposed workers

2,4,6-Trinitrotoluene (TNT) is an important occupational and environmental pollutant. In TNT exposed humans, the notable toxic manifestations have included aplastic anemia, toxic hepatitis, cataract, hepatomegaly and liver cancer. Therefore, we developed methods to biomonitor workers exposed to TNT. The workers were employed in a typical ammunition factory in China. The controls were recruited from the same factory. We determined hemoglobin (Hb) adducts and urine metabolites of TNT. Hb-adducts of TNT, 4-amino-2,6-dinitrotoluene (4ADNT) and 2-amino-4,6-dinitrotoluene (2ADNT), and the urine metabolites of TNT, 4ADNT and 2ADNT were found in all the workers and in a few controls. 4ADNT was the main product. Although the levels of 2ADNT correlated well with 4ADNT, 2ADNT was not found in all the samples. Therefore, 4ADNT was the best marker of exposure for Hb-adducts and urine metabolites. The levels of the urine metabolites and Hb-adducts were related to the health status of the workers. The Hb-adduct 4ADNT was statistically significantly associated with risk of hepatomegaly, splenomegaly and cataract. The odds ratio (OR) for cataract, splenomegaly and hepatomegaly were 6.4 [95% confidence interval (CI) = 1.4-29.6], 9.6 (1.1-85.3) and 7.6 (1.3-43.7), respectively. No correlation was found between urine metabolites and health effects. These results were tested for confounding factors like age, workyears, smoker status, smoke years, cigarettes per day and hepatitis B status using stepwise forward logistic regression analysis. In the case of splenomegaly, hepatitis B status is a confounder. In the case of cataract, age is a confounder. The Hb-adduct, 4ADNT, is a good biomarker of exposure and biomarker of biological effect.

Exposure to armament wastes and leukemia: a case-control study within a cluster of AML and CML in Germany

An unusually high incidence of acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) concentrated in a specific locality of a region in Germany motivated a descriptive incidence study in that region which showed a near 10-fold increased risk of CML among males but not among females (Kolb G, Becker N, Scheller S, Zugmaier G, Pralle H, Wahrendorf J, Havemann K. Increased risk of acute myelogenous leukemia (AML) and chronic myelogenous leukemia (CML) in a County of Hesse, Germany, Soc Prev Med 1993;38:190-195). Since a serious environmental contamination of areas in this locality with armament wastes containing toluene-derivatives has been known for a long time, the hypothesis arose that TNT production and the related severe contamination of soil and water might be responsible for the observed higher risk. We carried out a case-control study within the cluster to test this hypothesis. Overall, the results do not confirm the hypothesis. There is an indication of a relationship of an increased odds ratio with the exposure for a small group of persons who lived at a particular site in one of the two communities involved during the peak phase of TNT production during the 1940s. However, this finding is spurious and cannot explain the large majority of cases which occurred in that area in the 1980s. At the moment, no other explanation can be given for the increased risk of leukemias in that area.

Cytotoxic and genotoxic effects of energetic compounds on bacterial and mammalian cells in vitro

The mutagenicity and toxicity of energetic compounds such as 2,4, 6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), hexahydro-1,3, 5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3, 5,7-tetrazocine (HMX), and of amino/nitro derivatives of toluene were investigated in vitro. Mutagenicity was evaluated with the Salmonella fluctuation test (FT) and the V79 Chinese hamster lung cell mutagenicity assay. Cytotoxicity was evaluated using V79 and TK6 human lymphoblastic cells. For the TK6 and V79 assays, TNB and 2, 4,6-triaminotoluene were more toxic than TNT, whereas RDX and HMX were without effect at their maximal aqueous solubility limits. The primary TNT metabolites (2-amino-4,6-dinitrotoluene, 4-amino-2, 6-dinitrotoluene, 2,4-diamino-6-nitrotoluene and 2, 6-diamino-4-nitrotoluene) were generally less cytotoxic than the parent compound. The FT results indicated that TNB, TNT and all the tested primary TNT metabolites were mutagenic. Except for the cases of 4-amino-2,6-dinitrotoluene and 2,4-diamino-6-nitrotoluene in the TA98 strain, addition of rat liver S9 resulted in either no effect, or decreased activity. None of the tested compounds were mutagenic for the V79 mammalian cells with or without S9 metabolic activation. Thus, the FT assay was more sensitive to the genotoxic effects of energetic compounds than was the V79 test, suggesting that the FT might be a better screening tool for the presence of these explosives. The lack of mutagenicity of pure substances for V79 cells under the conditions used in this study does not preclude that genotoxicity could actually exist in other mammalian cells. In view of earlier reports and this study, mutagenicity testing of environmental samples should be considered as part of the hazard assessment of sites contaminated by TNT and related products.

Biological monitoring of dinitrotoluene by gas chromatographic-mass spectrometric analysis of 2,4-dinitrobenzoic acid in human urine

The method of analysis described permits the determination of 2,4-dinitrobenzoic acid down to the lower microg l(-1) range in the urine of persons exposed to dinitrotoluene. 2,4-Dinitrobenzoic acid is the main metabolite of 2,4-dinitrotoluene and technical dinitrotoluene. After acidic hydrolysis, which served to release the conjugated part of the 2,4-dinitrobenzoic acid, the analyte was selectively separated from the urine matrix via various extraction steps and then derivatised to the methyl ester. Quantitative analysis was carried out using capillary gas chromatography and mass selective detection. 3,5-Dinitrobenzoic acid was used as an internal standard. The detection limit was 1 microg l(-1) urine. The relative standard deviations of within-series imprecision were between 5 and 6%. The relative recoveries were between 91 and 110% depending on the concentration. The analytical method developed as part of this study was used to investigate a collective consisting of 82 urine samples from persons working in the area of explosives disposal. The concentrations of 2,4-dinitrobenzoic acid determined ranged from the detection limit to 95 microg l(-1) urine. The method allowed the quantification of low-level internal exposure to dinitrotoluene.

Toxic equivalence factors, problems and limitations

It is a particular problem to set tolerance levels for mixtures containing chemicals classified as carcinogens. In the case of chlorinated dioxin and furan congeners, 'toxicity equivalence factors' (TEFs) were introduced. This concept has problems in itself and cannot be readily transferred to other mixtures, such as those of monocyclic nitroarenes in wastes of trinitrotoluene (TNT)-based explosives. The difficulties in finding suitable endpoints to compare the components are discussed (methaemoglobin formation; quantitative structure-activity relationships; mutagenicity; carcinogenicity). An alternative approach for the development tolerance levels in this instance is based on results obtained by measuring haemoglobin adducts as biomarkers of the most prevalent mixture components in humans.

The implications for risk assessment of measuring the relative contribution to exposure from occupation, environment and lifestyle: hemoglobin adducts from amino- and nitro-arenes

Recent progress in biomonitoring allows measurement of internal exposure of individuals ranging from occupational and life style exposures to environmental levels. Ten specific hemoglobin adducts generated by polycyclic and monocyclic nitro-arenes were measured in coke oven workers and residents living on ground contaminated with explosive wastes, respectively. Consistently, adducts were found in most 'exposed' as well as control individuals, interindividual variation being great. Adduct levels in the majority of exposed individuals were within the range of reference values (95 percentile). Although hemoglobin adduct levels do not directly reflect genotoxic potential and potency of the parent compounds, they correlate with the biologically active dose. On the basis of such target doses, the contribution of specific exposures relative to 'background' and to related chemicals can be assessed. The impact of 'relative risk' on risk perception and risk management is to provide a rationale for the application of the ALARA principle (As Low As Reasonably Achievable).