<b>Bijsluiter</b>. De hyperlink naar het originele document werkt niet meer. Daarom laat Woogle de tekst zien die in dat document stond. Deze tekst kan vreemde foutieve woorden of zinnen bevatten en de opmaak kan verdwenen of veranderd zijn. Dit komt door het zwartlakken van vertrouwelijke informatie of doordat de tekst niet digitaal beschikbaar was en dus ingescand en vervolgens via OCR weer ingelezen is. Voor het originele document, neem contact op met de Woo-contactpersoon van het bestuursorgaan.<br><br>====================================================================== Pagina 1 ======================================================================

<pre>3-Nitrotoluene
(CAS No: 99-08-1)
Health-based Reassessment of Administrative Occupational Exposure Limits
Committee on Updating of Occupational Exposure Limits,
a committee of the Health Council of the Netherlands
No. 2000/15OSH/135 The Hague, November 9, 2004
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<pre>Preferred citation:
Health Council of the Netherlands: Committee on Updating of Occupational
Exposure Limits. 3-Nitrotoluene; Health-based Reassessment of Administrative
Occupational Exposure Limits. The Hague: Health Council of the Netherlands,
2004; 2000/15OSH/135.
all rights reserved
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<pre>1     Introduction
      The present document contains the assessment of the health hazard of 3-
      nitrotoluene by the Committee on Updating of Occupational Exposure Limits, a
      committee of the Health Council of the Netherlands. The first draft of this
      document was prepared by AAE Wibowo, Ph.D. (Coronel Institute of the
      Academic Medical Centre, University of Amsterdam, the Netherlands).
           In February 1998, literature was searched in the databases Medline, Embase,
      and Chemical Abstracts, starting from 1966, 1988 and 1970, respectively, using
      the following key words: m-nitrotoluene, nitrotoluene, methylnitrobenzene,
      nitrotoluol, and 99-08-1. HSELINE, CISDOC, MHIDAS, and NIOSHTIC
      (covering the period from 1985/87 up to 1997) and Poltox (Toxline, Cambridge
      Scient Abstr, FSTA) (from 1990 up to and including 1994), databases available
      from CD-ROM, were consulted as well.
           In February 2001, the President of the Health Council released a draft of the
      document for public review. No comments were received.
           An additional search in Toxline and Medline in September 2004 did not
      result in information changing the committee’s conclusions.
2     Identity
      name                       :  3-nitrotoluene
      synonyms                   :  m-nitrotoluene; 1-methyl-3-nitrobenzene; 3-methylnitrobenzene;
                                    3-nitrotoluol
      molecular formula          :   CH3C6H4NO2
      structural formula         :
      CAS number                 :  99-08-1
135-3 3-Nitrotoluene
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<pre>3     Physical and chemical properties
      molecular weight          :   137.14
      boiling point             :   232.6oC
      melting point             :   16oC
      flash point               :   106oC (closed cup)
      vapour pressure           :   at 20oC: 16 Pa
      solubility in water       :   not soluble (at 20oC: 0.05 g/100 mL)
      log Poctanol/water        :   2.45 (experimental); 2.36 (estimated)
      conversion factors        :   at 20oC, 101.3 kPa: 1 mg/m3 = 0.18 ppm
                                                         1 ppm = 5.7 mg/m3
      Data from ACG02, Lun92, NLM04, http://www.syrres.com/esc/est_kowdemo.htm.
      3-Nitrotoluene is a yellowish liquid at room temperature (ACG02).
           Odour thresholds of 0.045 and 1.74 ppm (0.26 and 9.9 mg/m3) have been
      reported (ACG02, Amo83).
4     Uses
      Like the two other isomers, 3-nitrotoluene is used in the manufacture of other
      substances such as pigments and explosives (Lun92).
5     Biotransformation and kinetics
      The committee did not find quantitative data on the uptake, biotransformation,
      and excretion of 3-nitrotoluene in humans.
           The metabolism and kinetics of nitroaromatic compounds, including 3-
      nitrotoluene, have been investigated in male and female Fischer 344 rats at the
      Chemical Industry Institute of Toxicology (CIIT, USA) (Chi84, Chi85, deB84,
      Ric84; see also review in Ric87). A metabolism scheme for 3-nitrotoluene is
      presented in Figure 1 (see Annex I).
           Seventy-two hours after oral administration of 200 mg/kg 14C-ring-labelled
      3-nitrotoluene, 68, 12.5, and 1% of the dose were recovered in the urine, faeces,
      and expired air, respectively. 3-Acetamidobenzoic acid (12%), 3-nitrobenzoic
      acid (21%), and 3-nitrohippuric acid (24%) were the main metabolites identified
      in the urine. About 1.5% of the dose was excreted as S-(3-
      nitrobenzyl)glutathione, presumably formed via the O-sulphate of the 3-
      nitrobenzyl alcohol. This indicates a major role of oxidation of the 3-nitrobenzyl
135-4 Health-based Reassessment of Administrative Occupational Exposure Limits
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<pre>      alcohol (Chi84). In bile-cannulated male rats, 11% of the dose was recovered in
      12-hour bile, 27% (i.e., 2.8% of the dose) of which consisted of the glucuronide
      of 3-nitrobenzyl alcohol; in bile-cannulated females, 4.3% was found in 12-hour
      bile, 16% (i.e., 0.7% of the dose) of which was this glucuronide. During the same
      period, about 45% and 0.5% of the dose were excreted in the urine and faeces of
      sham-operated male and female controls, respectively. This indicates almost
      complete intestinal absorption of 3-nitrotoluene and a minor extent of biliary
      excretion of the nitrobenzylic glucuronide (Chi85). This conclusion is confirmed
      by metabolic studies using freshly isolated hepatocytes, where 3-nitrotoluene
      was also predominantly oxidised into the corresponding nittrobenzoic acid as
      compared with glucuronidation of the nitrobenzylic OH-group (deB84). Hepatic
      covalent macromolecular binding of 3-nitrotoluene was 50% inhibited by bile
      cannulation. DNA binding was negligible as compared with 2-nitrotoluene. Both
      parameters were not modified by inhibitors of sulphation, indicating that
      bioactivation via the pathways described above is of negligible importance for 3-
      nitrotoluene (Chi84, Ric84). On the other hand, for 2-nitrotoluene, these
      pathways proved to be important determinants for its binding to DNA. This is in
      agreement with the observation that 2-nitrotoluene, but not 3-nitrotoluene,
      induced unscheduled DNA excision repair in the in vivo-in vitro Fischer 344 rat
      hepatocyte assay, an effect that depends on the intestinal microflora (Doo83).
          3-Nitrotoluene was found to bound to haemoglobin, forming haemoglobin
      adducts, in female rats 24 hours after oral (gavage) administration (doses not
      presented). The haemoglobin index (i.e., [mmmol compound/mol Hb]/[mmol
      compound/kg bw]) was calculated to be 1.0 (Sab95).
6     Effects and mechanism of action
      Human data
      The committee did not find human data on the effects of (occupational) exposure
      to 3-nitrotoluene.
      Animal data
      Irritation and sensitisation
      Application of 0.5 mL of undiluted 3-nitrotoluene to the clipped intact and
      abraded skin of rabbits was not irritating (mean Draize score 0.37; maximum
      possible score: 8.0).
135-5 3-Nitrotoluene
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<pre>           No irritation (all scores: 0) was seen following instillation of 0.1 mL of 3-
      nitrotoluene into the eyes of rabbits (Cis81).
           It is not known whether the compound produced any sensitisation to the skin.
      Acute toxicity
      LC50 values of 693 and 425 mg/m3 were listed for rats and mice, respectively
      (duration not indicated) (NIO04). Oral LD50 values for rats were 1072 (NIO04)
      and 2200 (males) and 2000 (females) mg/kg bw (Cis80a). Ciss et al. reported that
      agitation, increased respiration rate, prostration, brief convulsions, weakness,
      and atony occurred immediately after administration. Animals died between 18
      and 48 hours post-administration (Cis80a). For mice, rabbits, and guinea pigs,
      oral LD50 values of 330, 1750, and 3600 mg/kg bw, respectively, were listed
      (NIO04).
           3-Nitrotoluene, like most other aromatic nitro compounds, may cause
      elevation of blood methaemoglobin levels in cases of acute poisoning (Lun92).
      However, the increase produced by 3-nitrotoluene is relatively small compared
      to that produced by other methaemoglobin-forming agents. French et al.
      conducted in vitro tests, using Dorset sheep erythrocytes, to compare the
      methaemoglobin-forming capacity of various agents. In the absence of
      bioactivation, 3-nitrotoluene at concentrations of 2.5, 5.0, 7.5 and 10.0 mM,
      produced methaemoglobin levels of 2.5, 3.7, 4.5, and 5.0%, respectively. With
      NADP bioactivation, the corresponding methaemoglobin levels were statistically
      significantly increased when compared to control values (2.5, 4.7, 5.6, and 6.4%,
      respectively, vs. <3% in controls) (Fre95).
      Repeated-dose toxicity
      Rats (n=10/sex/group) were given oral doses of 0, 500, or 1000 mg/kg bw/day, 5
      days/week, for 4 weeks. In the animals of the low-dose group, no compound-
      related mortality occurred. Irregular breathing, convulsions, weakness, and atony
      were observed in the first treatment week. Thereafter, the behaviour of the
      treated animals was generally comparable with that of controls. Apart from the
      first days, there was no difference in food intake and body weight gain between
      low-dose and control animals. At post-mortem macroscopic and microscopic
      examinations, there were increased spleen weights and sizes and decreased
      testicular weights and sizes, which were accompanied by histological changes
      such as splenic haemosiderosis and seminiferous tubular atrophy with reduction
      or absence of mature spermatids. Treatment of the high-dose animals was
135-6 Health-based Reassessment of Administrative Occupational Exposure Limits
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<pre>      terminated after the first week, because of severe toxic effects including
      increased respiratory rate, convulsions, prostration, body weight loss, and
      mortality in 6 males and 6 females. Post-mortem examinations showed similar
      effects as found in the low-dose animals, but more prominently present (Cis80a).
      In a subsequent experiment, oral (gavage) doses of 3-nitrotoluene (vehicle: olive
      oil) of 300 mg/kg bw/day administered to male and female rats, 5 days/week, for
      6 months, did not affect survival, behaviour, or body weights. Symptoms
      observed were limited to alopecia in females. When compared to controls, there
      were no effects on red and whit blood cell counts, but total haemoglobin levels
      were decreased by ca. 15 and 7% in males and females, respectively. Clinical
      chemistry parameters changed included increases in serum alkaline phosphatase,
      serum cholinesterase, and creatine phosphokinase activities. Following post-
      mortem macroscopic and microscopic examinations, only lesions of the spleen
      were seen (increased weight and size) (Cis80b).
           In a range-finding study, rats (F344/N; n=5/sex/group) were given 3-
      nitrotoluene in the diet at concentrations of 625-10,000 ppm, resulting in daily
      doses of 61-881 and 58-754 mg/kg bw for males and females, respectively, for
      14 consecutive days. There were no clear compound-related clinical signs in any
      of the treated groups, other than decreased body weights at doses of 259, 431,
      and 881 mg/kg bw in males (by 9, 12, and 15%, respectively, compared to
      controls) and at doses of 420 and 754 mg/kg bw in females (by 7 and 14%,
      respectively). Feed consumption was decreased at these levels. Post-mortem
      findings were limited to effects on testes and uterus in the animals given 10,000
      ppm (see ‘Reproduction toxicity’) (Dun92). In the subsequent 13-week study,
      rats (F344/N; n=10/sex/group) were given 3-nitrotoluene in the diet at
      concentrations of 0, 625, 1250, 2500, 5000, and 10,000 ppm resulting in daily
      doses of 46-661 and 48-638 mg/kg bw for males and females, respectively.
      Animals were observed twice daily for mortality/moribundity. Body weights and
      clinical observations were recorded weekly and at necrospy; feed consumption
      was measured weekly. Blood and serum samples were taken and analysed at
      week 1, 3, and 13. At study termination, complete necropsy was performed on all
      animals and reproductive system evaluation on all animals of the 3 higher dose
      groups. All animals survived treatment. Decreased final body weights and feed
      consumption were seen in males given 661 mg/kg bw/day (by 19%, compare to
      controls) and in females at 336 and 638 mg/kg bw/day (by 9 and 14%,
      respectively). No clinical signs were observed in any of the treated groups.
      Clinical chemistry/haematology evaluations at week 1 showed only changes in
      the high-dose animals, including mild increases in erythrocyte counts and
      haemoglobin concentrations in males and in haematocrit in males and females,
135-7 3-Nitrotoluene
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<pre>      and further mild decreases in reticulocyte and platelet counts, and alkaline
      phosphatase activity and mild increases in urea nitrogen, creatinine, and
      albumine. At week 3, erythrocyte counts, haemoglobin concentrations, and
      haematocrit were decreased in most male dose groups and in the high-dose
      female group. Increased reticulocyte, nucleated erythrocyte, and platelet (males
      only) counts and methaemoglobin levels were seen in the male and female
      animals of the highest dose groups, as well as increased lymphocyte counts in
      high-dose males and females and increased leukocyte counts in high-dose
      females. Clinical chemistry changes included minimal decreased urea nitrogen
      levels in male rats and increased creatinine levels in male and female rats, as well
      as mild increased alanine aminotransferase activity in females of the 3 highest
      dose groups. At study termination, decreased erythrocyte counts, haemoglobin
      levels, and haematocrit were reported for females of the highest 1 or 2 dose
      groups and decreased erythrocyte counts in males of the highest dose group. In
      males and females given 5000 and 10,000 ppm, mean corpuscular volume, mean
      corpuscular haemoglobin, reticulocyte and platelet counts, and methaemoglobin
      concentrations were increased. Clinical chemistry changes were limited to mild
      to moderate increases bile acid concentrations in male and female animals dosed
      with 5000 and/or 10,000 ppm. Post-mortem evaluations showed moderately
      increased relative liver weights in 10,000-ppm males and females, increased
      relative kidney weights in males and females given 5000 and 10,000 ppm, and
      decreased absolute and relative testis weights in 10,000-ppm males. Gross
      examination only revealed smaller testes and epididymis in 4/10 rats of the
      10,000-ppm group. Upon microscopic examination (see Table 1), there were
      increases in the incidences of haemosiderin pigment and congestion of the spleen
      - mostly of minimal severity - in male and female animals when compared to
      controls. Kidney lesions were seen in males only and included a hyaline-droplet
      nephropathy in almost all treated animals, characterised by the presence of
      eosinophilic protein droplets in the renal tubular epithelium and tubule lumen.
      The droplets were irregularly shaped and increased in size and number as
      compared to the protein ‘resorption droplets’ typically present in the kidney of
      the male controls. The nephropathy was of minimal severity but the number of
      protein droplets increased with dose. The amount of α2µ-globulin was not
      measured. However, in concomitant studies with 2- and 4-nitrotoluene, similar
      hyaline-droplet nephropathy appeared to be associated with increased α2µ-
      globulin levels. There was no evidence of renal necrosis or proliferative lesions.
      Examination of the reproductive system (see ‘Reproduction toxicity’) revealed
      reduced testis sizes and testicular degeneration in all male animals given 661
135-8 Health-based Reassessment of Administrative Occupational Exposure Limits
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<pre>               mg/kg bw/day and effects on the oestrus cycle in female animals given 420 and
               754 mg/kg bw/day (Dun92, Dun94).
Table 1 Incidence and severitya of lesions in rats orally dosed with 3-nitrotoluene for 13 weeks (Dun92, Dun94).
                                            0 ppm          625 ppm        1250 ppm     2500 ppm    5000 ppm      10,000 ppm
                                                                                      males
kidney
- hyaline-droplet nephropathy               0              9 (1.0)        10 (1.0)     10 (1.0)    10 (1.0)      10 (1.0)
spleen
- haemosiderin pigment                      0              1 (1.0)        0            2 (1.0)     5 (1.0)       10 (1.4)
- congestion                                1 (1.0)        0              0            1 (1.0)     0             9 (1.0)
testis
- degeneration                              0              0              0            0           0             9 (2.2)
                                                                                     females
spleen
- haemosiderin pigment                      1 (1.0)        9 (1.1)        10 (1.1)     10 (1.2)    8 (1.5)       10 (1.2)
- congestion                                0              0              0            0           2 (1.0)       9 (1.0)
a
      everity scores (between brackets) are based on a scale of 1 to 4 (1=minimal, 2=mild, 3=moderate, 4=marked) and averages
      from the number of animals with lesions from groups of 10.
               The committee considers the kidney lesions found in this study in male rats as a
               α2µ-globulin-induced, typical male rat event and, therefore, not relevant for
               human risk assessment. The committee could not establish a no-adverse-effect
               level, since there was an increased incidence of spleen lesions (haemosiderosis of
               minimal severity) in female animals at 48 mg/kg bw/day, the lowest dose tested.
                    Mice (B6C3F1; n=5/sex/group) were given dietary concentrations of 3-
               nitrotoluene of 388-5000 ppm for 14 days, resulting in daily doses of 66-779 and
               92-901 mg/kg bw for males and females, respectively. Treatment did not affect
               survival, body weight (gain), or feed consumption, and no clinical signs were
               observed. At necropsy, there were increased relative liver weights in females at
               doses of 164 mg/kg bw (i.e., 675 ppm) and more and in males at doses of 409
               and 779 mg/kg bw (i.e., 2500 and 5000 ppm) (Dun92).
                    In the subsequent 13-week study, mice (B6C3F1;n=10/sex/group) were
               treated with dietary concentrations of 0, 625, 1250, 2500, 5000, and 10,000 ppm,
               resulting in doses of 114-1422 and 139-1550 mg/kg bw/day. All animals
               survived treatment. Body weight decreases, accompanied by decreased feed
               consumption, were observed in the animals given 5000 and 10,000 ppm (by 12
               and ca. 24-28%, respectively, when compared to controls). There were no
               clinical signs of toxicity in any of the treated groups. At post-mortem
               examinations, dose-related increased relative liver weights were seen in male and
135-9          3-Nitrotoluene
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<pre>       female mice and increased relative lung weights in male and females of the
       10,000-ppm group. However, there were no macroscopic or microscopic changes
       in these or other organs, including the reproductive system (Dun92, Dun94).
           Burns et al. conducted extensive studies of 3-nitrotoluene immunotoxicity in
       female B6C3F1 mice. Mice were exposed to 3-nitrotoluene by gavage at doses of
       200, 400 and 600 mg/kg bw/day for 14 consecutive days. The liver and kidney
       weights of high-dose animals were increased whereas thymus weights were
       decreased at the mid and high doses. The spleen, lungs, thymus, kidneys, and
       mesenteric lymph nodes were histologically normal at all doses. In the livers,
       hepatocytes adjacent to central veins showed mild cellular swelling at all doses.
       There was no evidence of necrosis and the swellings seemed to be reversible.
       The haematological parameters (erythrocytes, leukocytes, haemoglobin,
       haematocrit, mean corpuscular volume, mean corpuscular haemoglobin, mean
       corpuscular haemoglobin concentration, differential counts) and serum
       chemistry (alanine aminotransferase, urea nitrogen, glucose, albumin and total
       protein levels) were unaffected although there was a modest decrease in the
       percentage of polymorphonuclear leukocytes and eosinophils in the differential
       counts. Bone marrow cellularity and the colony-forming ability were unaffected.
       However, 3-nitrotoluene suppressed the IgM response to sheep red blood cells
       and the delayed hypersensitivity response to keyhole-limpet haemocyanin at the
       two higher doses. There was a slight (8%) decrease in the percentage of B
       lymphocytes in the spleen. The response to the T cell mitogens was suppressed
       by as much as 39%. Fluorescent covasphere-mediated adherence and
       phagocytosis of chicken erythrocytes, as well as natural killer cell activity
       showed dose-dependent increases. Several immune parameters were unaffected
       by exposure to 3-nitrotoluene, including the IgG response to sheep reed blood
       cells, responses to B-cell mitogen lipopolysaccharides and to allogeneic cells,
       and serum interferon levels. Resistance to Streptococcus pneumoniae and
       Plasmodium yoelii were also unaffected. Resistance to the tumour model PYB6
       was increased. Exposure of mice to 3-nitrotoluene decreased resistance to
       Listeria monocytogenes, which might be related to an effect on T cells,
       evidenced by a decrease in T cell numbers and in the delayed hypersensitivity
       response (Bur94). The committee concludes that the liver and immune system
       may be target organs in mice, 200 mg/kg bw, the lowest dose tested, being an
       effect level.
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<pre>       Carcinogenicity
       The committee did not find data from long-term studies on 3-nitrotoluene.
       However, no neoplasia or pre-neoplastic lesions were observed in rats and mice
       of both sexes in the 13-week oral NTP studies (Dun92, Dun94). Although this
       exposure period is too short to assess the carcinogenic potential, 2-nitrotoluene
       induced 2 - rare - mesotheliomas of the tunica vaginalis of the epididymis of
       male rats exposed to 353 mg/kg bw/day and - preneoplastic - hyperplasia (but no
       mesotheliomas) at the same location in males at 696 mg/kg bw/day (Dun92,
       Dun94).
       Mutagenicity and genotoxicity
       IARC (IARC96) summarised studies on the mutagenicity and genotoxicity of
       3-nitrotoluene:
       • 3-Nitrotoluene was negative in several mutation assays in S. typhimurium
           strains TA92, TA94, TA98, TA100, TA1535, TA1537, and TA1538, both in
           the presence and absence of metabolic activating systems.
           The compound was negative in a differential killing-rec assay in B. subtilis
           strains H17 (rec+) and M45 (rec-), an indicator for DNA damage.
       • In mammalian cell systems, 3-nitrotoluene weakly induced sister chromatid
           exchanges (SCE) in Chinese hamster ovary cells (positive in the absence,
           negative in the presence of a metabolic activating system). It did not cause an
           increase in chromosomal aberrations in Chinese hamster ovary cells (tested
           with and without metabolic activation) or Chinese hamster lung fibroblasts
           (tested without metabolic activation only).
           3-Nitrotoluene did not induce unscheduled DNA synthesis (UDS) in rat
           hepatocytes and rat spermatogonia (both tests without metabolic activation
           only).
       • In vivo, 3-nitrotoluene was negative in a micronucleus test in mice.
           It did not induce UDS in hepatocytes obtained from male rats after a single
           oral dose of 500 mg/kg bw. It did not covalently bind to male rat liver DNA
           at a single oral dose of 200 mg/kg bw.
       Additional information included a positive result in an in vitro chromosomal
       aberration test in human peripheral lymphocytes in vitro (Hua95, Qin96) and a
       negative result in in vitro UDS test in primary rat hepatocytes following culture
       in serum-free defined media (Par95).
135-11 3-Nitrotoluene
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<pre>       Reproduction toxicity
       Ciss et al. studied the reproduction toxicity of 3-nitrotoluene (see ’Repeated-dose
       toxicity’). Doses of 3-nitrotoluene in olive oil of 300 mg/kg bw were orally
       (gavage) given to groups of male and female Wistar rats, 5 days/week, for 3
       months. Thereafter, the rats (n=5/sex/group) were mated in 4 groups: (1) exposed
       males and exposed females, (2) exposed males and unexposed females, (3)
       unexposed males and unexposed females, and (4) unexposed males and exposed
       females, and treated for another 3 months. The treatment did not affect the
       number of pups born or pup survival or behaviour. No organ damage was seen in
       the pups at post-mortem examinations, apart from spleen lesions, which were
       less severe than in the parents, in pups from 3-nitrotoluene-treated females
       (Cis80b). Because of the small sizes of the mated groups, the committee
       considers this study of limited importance.
            In the NTP studies (see ‘Repeated-dose toxicity’), 3-nitrotoluene was found
       to induce reduced testis sizes and testicular degeneration characterised by mild to
       moderate degeneration with loss of germinal epithelium and the presence of
       abnormal spermatids in the lumen of the seminiferous tubules and ducts of the
       epididymis in rats orally (diet) dosed with 881 mg/kg bw/day for 14 days. No
       such effects were seen at 431 mg/kg bw/day. Daily administration of 661
       mg/kg bw for 13 weeks caused smaller testes and epididymis in 4/10 rats.
       Histological examination showed mild to moderate degeneration of the testis in
       all 10 animals with reduction of germ cells and mature spermatids in the
       seminiferous tubules and cellular debris in the epidydimal ducts. This was
       accompanied by reduced epidydimal sperm count and concentration. These
       abnormalities were not seen at 342 mg/kg bw/day. In female rats, administration
       of oral (diet) doses of 754 mg/kg bw for 14 days resulted in smaller uteri with
       thinner muscular walls and less development of the endometrium compared to
       controls and groups treated with doses of 58-420
       mg/kg bw/day. Thirteen-week treatment with doses of 336 and 638 mg/kg
       bw/day caused changes in the length (increase) and stages (decreased oestrus and
       increased dioestrus as percentage of cycle) of the oestrus cycle while the number
       of cycling animals diminished. The no-effect level was 172 mg/kg bw/day. There
       were no macroscopic or microscopic effects on uterus or ovaries. In male and
       female mice, no changes were found in the reproductive system evaluations at
       doses of 1422 and 1550 mg/kg bw/day, respectively (Dun92, Dun94).
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<pre>7      Existing guidelines
       The current administrative occupational exposure limit (MAC) for 3-nitrotoluene
       in the Netherlands is 6 mg/m3 (1 ppm), 8-hour TWA, with a skin notation.
           Existing occupational exposure limits for 3-nitrotoluene in some European
       countries and the USA are summarised in Annex II.
8      Assessment of health hazard
       The committee did not find data on the biotransformation and kinetics of 3-
       nitrotoluene following inhalation or skin exposure. Data from oral adminstration
       to male rats and from studies in isolated rat hepatocytes indicated almost
       complete intestinal absorption of 3-nitrotoluene and minor biliary excretion (of
       the nitrobenzylic glucuronide) and the major pathway for metabolism through
       oxidation of the methyl group into nitrobenzyl alcohol which is converted
       further. Following administration of 200 mg/kg bw, 68% of the dose was
       excreted in the urine within 72 hours with 3-nitrobenzoic acid (21%), 3-
       nitrohippuric acid (24%), and 3-acetamidobenzoic acid (12%) as major
       metabolites.
           The committee did not find data on the toxic effects of 3-nitrotoluene in
       humans.
           Experimental animal data showed that 3-nitrotoluene is not irritating to the
       skin and eyes. LC50 values were 693 and 425 mg/m3 for rats and mice,
       respectively (duration not indicated); oral LD50 values 330 mg/kg bw for mice,
       1072 and ca. 2100 mg/kg bw for rats, 1750 mg/kg bw for rabbits, and 3600
       mg/kg bw for guinea pigs. The compound is a methaemoglobin-forming agent
       with a low potency.
           The committee did not find data from repeated inhalation studies. In 13-week
       oral toxicity studies 3-nitrotoluene affected body weights (decreases), liver
       (increased relative weights; changes in serum bile acid levels and liver-specific
       enzyme activities), kidneys (increased relative weights; male rat-specific, α2µ-
       globulin-induced hyaline-droplet nephropathy), spleen (haemosiderosis,
       congestion, haematological effects), and reproductive system (decreased testis
       sizes; testicular degeneration; oestrus cycle) in male and/or female rats. Apart
       from the kidney and spleen lesions, these effects were generally observed at
       doses of ca. 340 and 650 or ca. 650 mg/kg bw/day. The male rat-specific
       nephropathy occurred at all doses tested, i.e., as low as 42 mg/kg bw/day. The
       spleen lesions, which were mostly of minimal severity, were found in all female
135-13 3-Nitrotoluene
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<pre>       dose groups, i.e., as low as 48 mg/kg bw/day. In mice, the only effects observed
       were decreased body weights at daily doses of 779 (males) and 901 (females)
       mg/kg bw and increased relative liver weights, which were not accompanied by
       macroscopic or microscopic changes, at all doses tested, i.e., as low as 66 (males)
       and 92 (females) mg/kg bw/day. In separate studies, 3-nitrotoluene affected the
       humoral and cell-mediated immunity in mice at 200 mg/kg bw, the lowest dose
       tested, and more.
           The committee did not find data on long-term toxicity and carcinogenicity of
       3-nitrotoluene.
           The genotoxicity data showed that the compound is a weak inducer of sister
       chromatid exchanges, but did not cause mutations or DNA damage in bacteria or
       chromosome or DNA damage in mammalian cell systems. In vivo, it did not
       induce micronuclei in mice; it did not bind to male rat liver DNA.
           The committee considers the spleen to be the critical organ and takes the
       lowest-observed-adverse-effect level (LOAEL) of 48 mg/kg bw/day from the 13-
       week oral rat study (Dun92, Dun94) as a starting point in deriving a health-based
       recommended occupational exposure limit (HBROEL). Since workers are
       exposed for 5 days/week, this LOAEL from a continuous feeding study (i.e., 7
       days/week) is adjusted by multiplying with a factor of 7/5, resulting in a lowest
       adverse effect level (LAEL) of 63 mg/kg bw. For the extrapolation to a
       HBROEL, a factor of 4 for allometric scaling from rats to humans, based on
       caloric demand, and an overall factor of 36, covering the absence of a NOAEL,
       inter- and intraspecies variation, and differences between experimental
       conditions and the exposure pattern of the worker, are applied. This results in a
       NAEL for humans of 0.44 mg/kg bw/day. From this, a health-based occupational
       exposure limit of 2 mg/m3 is recommended for 3-nitrotoluene, assuming a 70-kg
       worker inhales 10 m3 of air during an 8-hour working day and a retention of
       100%, and applying the preferred-value approach.
       The committee recommends a health-based occupational exposure limit for 3-
       nitrotoluene of 2 mg/m3 (0.4 ppm), as an 8-hour time weighted average (TWA).
       Because of lack of quantitative data on skin absorption, the committee could not
       assess the need for a skin notation.
135-14 Health-based Reassessment of Administrative Occupational Exposure Limits
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<pre>       References
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<pre>       Triangle Park NC, USA: National Toxicology Program, 1992; NTP Technical Report Series No 23;
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<pre>Swe00  Swedish National Board of Occupational Safety and Health. Occupational exposure limit values and
       measures against air contaminants. Solna, Sweden: National Board of Occupational Safety and
       Health, 2000: 62 (Ordinance AFS 2000:3).
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       the Netherlands: Sdu Uitgevers, 2004: 37.
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135-17 3-Nitrotoluene
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<pre>       Annex I
       Figure 1 Metabolic pathway of 3-nitrotoluene (adapted from Cis84).
       Structures between brackets are postulated intermediates or inconclusively identified metabolites.
       S-G=glutathione; S-Cys(Ac)=N-acetylcysteine; Gl=glucuronide
135-18 Health-based Reassessment of Administrative Occupational Exposure Limits
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<pre>              Annex II
Occupational exposure limits for 3-nitrotoluene in various countries.
country                               occupational               time-weighted       type of          notea     referenceb
- organisation                        exposure limit             average             exposure limit
                                      ppm         mg/m3
the Netherlands
- Ministry of Social Affairs and      1           6              8h                  administrative   S         SZW04
Employment
Germany
- AGS                                 5           28             8h                                   S         TRG04
                                      20          112            15 min
- DFG MAK-Kommission                  5           28             8h                                   S         DFG04
                                      10          56             15 minc
Great Britain
- HSE                                 5           29             8h                  OES              S         HSE02
                                      10          57             15 min
Sweden                                1           6              8h                                   S         Swe00
                                      2           11             15 min
Denmark                               2           12             8h                                   S         Arb02
USA
- ACGIH                               2           -              8h                  TLV              S         ACG04b
- OSHA                                5           30             8h                  PEL              S         ACG04a
- NIOSH                               2           11             10 h                REL              S         ACG04a
European Union
- SCOEL                               -           -                                                             EC04
a
     S = skin notation; which means that skin absorption may contribute considerably to body burden; sens = substance can
     cause sensitisation.
b
     Reference to the most recent official publication of occupational exposure limits.
c
     Maximum number per shift: 4, with a minimum interval between peaks of 1 hour.
135-19        3-Nitrotoluene
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<pre>135-20 Health-based Reassessment of Administrative Occupational Exposure Limits</pre>

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<br><br>