3.3- Dichlorobenzidine, concentration

Diehlorobenzidine in lake water samples was not metabolized by mieroorganisms over a 4-week period (Sikka et al. 1978) although 1 lake sample of the 2 tested eontained approximately 5 million microorganisms per mL. The composition of the biologieal eommunity was not described. Minor decreases in 3,3 -dichlorobenzidine concentrations were attributed to adsorption onto suspended sediment. 

Activated sludge did not degrade 3,3 -dichlorobenzidine after weekly subculturing. The sludge was not described or chemically characterized. Observed decreases in 3,3 -dichlorobenzidine concentration were attributed to adsorption by the sludge. 

Analytical identification of monoazo colorants and the other decomposition products requires effective (analytical) methods of concentration, which is made possible by high performance liquid chromatography (HPLC). Prior to HPLC analysis, the pigmented medium was extracted for 20 hours with toluene in a soxhlet extractor. These analytical methods also showed that above 240°C, especially after prolonged exposure of the pigmented polymer material to heat, dichlorobenzidine (DCB) is also formed. 

No adverse health effects were observed in male rats exposed by inhalation to 3,3 -dichlorobenzidine free base (23,700 mg/m ) 2 hours per day for 7 days (Gerarde and Gerarde 1974). In another study, 10 rats were exposed to an unspecified concentration of 3,3 -dichlorobenzidine dihydrochloride dust particles for 1 hour and then observed for 14 days. Slight-to-moderate pulmonary congestion and one pulmonary abscess were observed upon necropsy (Gerarde and Gerarde 1974). The effects observed in the study using the ionized (hydroehloride) form of 3,3 -dichlorobenzidine may have been due to the irritative properties of hydrochlorie aeid released from the salt in combination with particulate toxicity. 

While hemoglobin adduct formation does not imply altered or abnormal hemoglobin function, adduct formation may be a suitable biomarker of human exposure to 3,3 -dichlorobenzidine (see Section 2.7). Hematological variables (erythrocyte count, hemoglobin concentration, hematocrit, and leucocyte count) were found to be normal in dogs exposed to 10.4 mg/kg/day 3,3 -dichlorobenzidine for 7 years (Stula et al. 1978). 

In animals, absorption of 3,3 -dichlorobenzidine from the gastrointestinal tract is rapid. Following a dose of 40 mg/kg, the plasma level of imchanged 3,3 -dichlorobenzidine attained a peak concentration of 1.25 g/mL at 4 hours in Sprague Dawley rats. Further, about 90% of the administered radioactivity was excreted in feces (via bile) and urine within 72 hours largely as metabolites, indicating a high bioavailability, typical of primary aiylamines. The elimination is biphasic, with half-lives of 6 hours and 14 hours in plasma for the rapid and slow phases, respectively (Hsu and Sikka 1982). 

It has been speculated that aqueous solutions of aromatic amines can be oxidized by organic radicals, but there are no actual data on reaction rates. Based on a study of reaction rate data for compounds with structures similar to 3,3 -dichlorobenzidine, an estimate of the half-life of aromatic amines in water is approximately 100 days, assuming a peroxy radical concentration of 10 mole/L in simlit, oxygenated water (EPA 1975). Based on the oxidation rates of similar compounds, the direct oxidation of 3,3 -dichlorobenzidine by singlet oxygen in solution may be treated as a first-order reaction, to arrive at an estimated reaction constant of <4xlOVmole-hour (Mabey et al. 1982). The oxidation rate constant with... 

Dichlorobenzidine was not deteeted in the ambient air at production facilities at deteetion limits of 0.1-5.0 ng/m (Narang et al. 1982 Riggin et al. 1983). The median concentration of 3,3 -diehloro-benzidine in waste effluents (<10 ppb), groundwater (<10 ppb), surface water (<10 ppb), and soils (<1 ppb) is very low, although significant contamination may be associated with hazardous waste sites (Staples et al. 1985). Moreover, the production and use of 3,3 -diehlorobenzidine-based dyes has decreased to zero over the last 30 years, while environmental and health regulations have been implemented to reduce the release of 3,3 -dichlorobenzidine to the environment. 

The concentration of 3,3 -dichlorobenzidine in the Canadian environment was estimated by Liteplo and Meek (1994) by applying the Level III Fugaeity Computer Model of Maekay and Paterson (Maekay and Paterson 1991). Assuming that 1% of the total amount produced in and imported to Canada is released into various media in proportions similar to those given in the U.S. TRI, the average concentration of 3,3 -dichlorobenzidine in air, as estimated by the model, is 7.6x10 g/m. ... 

Capillary gas chromatography/mass spectrometry (GC/MS) was used to identify, but not quantify, 3,3 -dichlorobenzidine in the dissolved phase (that is, smaller particles and dispersed eolloids not retained by the filter) of water concentrates from the Besos River in Spain (Grifoll et al. 1992). Vails et al. identified 3,3 -dichlorobenzidine in urban wastewater in the same region (Vails et al. 1990). 

The estimated median concentration of 3,3 -dichlorobenzidine in sediments in the United States has been reported to be <1 ppm on a dry sediment basis (Staples et al. 1985). Of the 34 sediment or soil measurements recorded in the STORET database, none of the samples contained detectable concentrations of 3,3 -dichlorobenzidine. 

Environmental Fate. It is not known if 3,3 -dichlorobenzidine, like benzidine, is oxidized by clay minerals or if cations in water ean have the same oxidizing effect. 3,3 -Dichlorobenzidine does not appear to biodegrade easily, but the few studies in this area did not state the type(s) or concentrations of mieroorganisms used in eaeh study. More systematic studies with other organisms may prove useful. A reeent study (Nyman et al. 1997) provides evidence that in the span of a year up to 80% of 3,3 -dichloro-benzidine can degrade to benzidine in anaerobic mixtures of sediment/water. Further research to identify the pathways and produets of deeomposition of 3,3 -dichlorobenzidine in various soils is needed. The toxieologieal profile for benzidine eontains information on the environmental fate of that compound (ATSDR 1995). 

Exposure Levels in Environmental Media. There were no quantitative data on current atmospheric levels of 3,3 -dichlorobenzidine emissions or on the chemical s potential to act as a surface eontaminant of soil environments. It is difficult to determine 3,3 -dichlorobenzidine levels in the aquatic environment because the concentrations tend to be at or below analytical detection limits. In general, it may only be possible to ascertain fully the environmental fate of 3,3 -dichlorobenzidine as analytical advances permit the routine determination of very low concentrations. Moreover, determination of the nature and environmental fate of breakdown products of 3,3 -dichlorobenzidine would be useful. 

Nony et al. 1980 Zwimer-Baier and Neumann 1994). Some of the methods have been shown to be suitable for the determination of the aeetylated metabolites (Bowman and Nony 1981 Nony and Bowman 1980 Nony et al. 1980). The methods of Bimer et al. (1990), Joppieh-Kuhn et al. (1997), and Zwimer-Baier and Neumann (1994) permit the analysis of hemoglobin adduets of 3,3 -diehlorobenzidine and its monoacetyl metabolite. Limits of deteetion for 3,3 -diehlorobenzidine in mine and semm were reported to be as low as 1 to 5 ppb (Bowman and Rushing 1981 Hoffman and Sehmidt 1993 Roberts and Rossano 1982), with detectable concentrations of the aeetylated metabolites somewhat higher. Most of these studies were performed with samples from rats the methods should be tested to determine if they are applieable to samples of human origin. In addition, the levels of these biomarkers associated with exposures to 3,3 -dichlorobenzidine of toxicological concern should be defined in order to increase their utility. 

The precision and accuracy data are not available for all the urea pesticides listed in the Table 2.19.3. However, a matrix spike recovery between 70 and 130% and a RSD below 30% should be achieved for aqueous samples. Samples should be spiked with one or more surrogates. Compounds recommended as surrogates are benzidine-d8, 3,3-dichlorobenzidine-d6, and caffeine-15N2. Surrogate concentrations in samples or blank should be 50 to 100 pg/L. 

Small Quantities. Wear butyl rubber gloves, laboratory coat, and eye protection. Work in the fume hood. To a 50-mL, three-necked, round-bottom flask equipped with stirrer, thermometer, and dropping funnel, add 1 mL of water, 3 mL of concentrated hydrochloric acid, and 2 g (0.008 mol) of 3,3 -dichlorobenzidine. The temperature is maintained at -5 to OX by a cooling bath, while 0.2 g (0.0084 mol) of 97% sodium nitrite dissolved in 1.4 mL of water is added dropwise to the solution or slurry of dichlorobenzidine hydrochloride. Stirring is continued an additional 30 minutes after addition is complete. While maintaining the temperature at -5 to 0°C, 16.6 mL (0.16... 

To each 9 mg of dichlorobenzidine, add 10 mL of 0.1 M hydrochloric acid (slowly add 1 mL of concentrated acid to 119 mL of cold water). Mix to dissolve. Add 5 mL of 0.2 M potassium permanganate solution (0.3 g of solid KMn04 dissolved in 10 mL of water) and 5 mL of 2.0 M sulfuric acid (prepared by carefully adding 1 mL of concentrated acid to 8 mL of cold water). Mix and let stand overnight (at least 10 hours). Decolorize if necessary with sodium metabisulfite or ascorbic acid. Neutralize by careful addition of 5 M sodium hydroxide solution (20 g of NaOH dissolved in 100 mL of cold water). Discard the remaining solution into the drain with at least 50 times its volume of water.6... 

In Class II, where a maximum concentration of 1 mg/m is set for a mass flow of 5 g/h or above, the only compound included from the range of aromatics is 3,3 -dichlorobenzidine. 

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