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EC number: 210-871-0 | CAS number: 624-92-0
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
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- Nanomaterial pour density
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- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Repeated dose toxicity: inhalation
Administrative data
- Endpoint:
- sub-chronic toxicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 1988
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- comparable to guideline study
Cross-reference
- Reason / purpose for cross-reference:
- reference to same study
Reference
- Endpoint:
- immunotoxicity
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- test procedure in accordance with generally accepted scientific standards and described in sufficient detail
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- no guideline available
- Principles of method if other than guideline:
- This study was conducted to determine the inhalation immunotoxicity of Dimethyl disulfide (DMDS) in 3 treated and one control groups of male rats following administration 6 hours/day, 5 days/week over a thirteen-week period and followed by a four-week recovery period . The animals used formed part of a general toxicity study reported in IUCLID section 7.5.3 (Collins, 1992).
- GLP compliance:
- yes
- Remarks:
- for components of the study conducted at Hazelton UK and BIBRA.
- Limit test:
- no
- Species:
- rat
- Strain:
- Sprague-Dawley
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- TEST ORGANISMS:
- Source: Charles River UK Ltd., Margate
- Age at reception: 4-6 weeks
- Weight at reception: 120-140 g
- Weight at the start of the treatment: 185-256 g
- Acclimatation period: 14 days
HOUSING
The animals were housed in group of 5 in suspended stainless steel cages.
FOOD and WATER
- Food: SZQC rat and Mouse Maintenance Diet No. 1 ad libitum excepted during exposure
- Water: filtered tap water, ad libitum excepted during exposure
ENVIRONMENTAL CONDITIONS
- Temperature : 19-25°C
- Relative humidity : 40-70%
- Light/dark cycle : 12h/12h
- Ventilation : 15 air changes/hour - Route of administration:
- other: whole-body inhalation exposure to vapour
- Vehicle:
- unchanged (no vehicle)
- Details on exposure:
- Five horizontal flow, recirculating exposure chambers were used. Each was made of stainless steel with perspex (Plexiglas) doors and a fan to mix the atmospheres by recirculation. The compressed air supply was from a clean, dry, filtered source. The total volume of the animals did not exceed 5% of the volume of the test chamber. The four concentrations of test article vapour were produced by passing metered flows of air through sintered glass frits immersed in separate containers of test article. The resulting outputs of vapour were introduced to the diluent air inlet duct of each test chamber. Mixing, within the duct and recirculation system, ensured the production of homogeneous atmospheres for animal exposure. The chambers were ventilated at a rate of at least 12 air changes per hour. Air flows were monitored continuously and recorded twice hourly during exposure. The exhaust streams were purified with activated charcoal and vented to the outside of the building.
- Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- * Measured concentration Samples for analysis were withdrawn from the exposure chambers twice hourly through sample lines leading from each chamber through a sampling valve into a total hydrocarbon analyser. The analysis was performed with an Analysis Automation total hydrocarbon analyser type 523 Detector with a Flame ionisation detector (FID)
* Nominal concentration The total weight of test article used and total volume of diluent air were measured for each exposure.
Target / Nominal / Analytical concentrations:
0
10 / 20 / 10.17 ppm
50 / 81 / 50.25 ppm
250 / 373 / 246.59 ppm
A simslin II dust monitor was used pre-dose, and during the study at week 1, 4, 8, and 12, at each exposuire levels to confirm all the test article was in a vapour phase. - Duration of treatment / exposure:
- 13 weeks
- Frequency of treatment:
- 6 hours/day, 5 days/week
- Remarks:
- Doses / Concentrations:
10, 50 and 250 ppm
Basis:
analytical conc. - No. of animals per sex per dose:
- 20
- Control animals:
- yes, sham-exposed
- Details on study design:
- - Post-exposure recovery period in satellite groups: yes, 4 weeks
- Observations and clinical examinations performed and frequency:
- The animal observations (mortality, clinical condition, body weight, food consumption, et c... made in connection with the general toxicity study are presented in section 7.5.3. (Collins, 1992). The procedures associated with the inmunotoxicity study are described below.
HAEMATOLOGY
Blood samples were obtained for the haematological studies from the ten male main study animals in 0, 10, 50 and 250 ppm groups at week 12 and the corresponding recovery males at week 17 for the following examinations:
. total white cells
. total lymphocytes
. pan B-cells
. pan T-cells
. T helper cells
. T suppressor cells - Sacrifice and pathology:
- MYELOGRAMS
A femoral bone marrow smear was taken from all animals at necropsy and examined by a haematologist and full myelograms performed.
ORGAN WEIGHTS:
Popliteal, submandibular and mesenteric lymph nodes, thymus.
GROSS PATHOLOGY: Yes
Reported in section 7.5.3 (Collins, 1992)
HISTOPATHOLOGY: Yes
Lymph nodes (popliteal, mesenteric and submandibular), mid colon lymphoid tissue, spleen, thymus. - Humoral immunity examinations:
- SERUM IMUNOGLOBULIN STUDIES
Whole blood samples were obtained from the aforementioned main study animals at necropsyl for the determination of IgG and IgM titres. - Positive control:
- None
- Statistics:
- - ANOVA, Regression and Dunnett's: Immunoglobins (IgG, IgM), Mylograms, Necropsy body weight (terminal kill), Organ Weights (relative and absolute) terminal kill - Popliteal Lymph Node, Mandibular Lymph Node, Mesenteric Lymph Node, Thymus, Adrenals, Spleen, Brain (absolute only).
- Kruskal Wallis, Terpstra-Jonckheere, Wilcoxon Rank Sum Test : Organ weights (relative and absolute) - terminal kill - Brain (relative only).
- Unpaired t test (two-tailed) and Mann-Whitner U test: lymphocytes and lymphocytes sub-populations.
- Histophatology: the statistical analysis was achieved according to the test-t In order to compare the means values betwen the control group and the treated groups and the regression coefficient analysis between the dose and the different measured values. - Details on results:
- HAEMATOLOGY
The treated groups showed lymphocyte counts at week 12 that were reduced compared with the control group (Table 1). The reduction was greatest in the low dose group where the reduction was approximately 20% and did achieve statistical significance. The reductions in absolute lymphocyte counts were primarily attributable to a specific reduction in T-suppressor cells of 20 to 40% and were inversely proportional to dose level; the differences compared with the concurrent control group were statistically significant for the low and intermediate dose group but not for the high dose group.
The reduction in T-suppressor cells persisted to the end of the recovery period at week 17 (Table 2) and statistically significant differences in absolute cell counts compared with the concurrent control group were present in all treated groups. There were no other statistically significant differences.
There was no evidence of any treatment-related changes in T-helper cells or B-cells at either time point.
SERUM IMMUNOGLOBULIN ANALYSIS
There were no statistically significant differences from the control group and no evidence of any treatment-related differences in serum concentrations of IgG or IgM in the samples taken at the terminal kill at week 14.
Groups n Concentration of Protein mg/L
IgG IgM
Control 10 6646 ± 1185 1229 ± 175
10 ppm 9 6664 ± 1550 1223 ± 116
50 ppm 10 6167 ± 1825 1242 ± 238
250 ppm 10 6678 ± 1687 1150 ± 124
MYELOGRAMS
The only treatment-related change in the myelograms taken at necropsy was a trend towards decreased lymphocytes in the treated groups. However, the routine examination of bone marrow conducted as part of the sub-chronique toxicity study (Collins, 1992, section 7.5.3) had not revealed any unusual abnormalities.
ORGAN WEIGHTS
There were no organ weight differences except for minor changes attributable to non-specific stress or reduced body weights in the high dose group.
IMNUNOHISTOPATHOLOGY
QUALITATIVE PATHOLOGY
Two cases of thymic atrophy were observed: one minimal in a high dose animal, the other moderate in a control animal.
Most of the mandibular lymph nodes exhibited inflammatory reaction revealed by various degrees of sinus histiocytosis (SH) and/or medullary plasmacytosis (MP). Hemosiderosis, generally minimal, was present in some of them. The distribution of inflammatory reactions was as follows:
Group...............Minimal.............Moderate..........Marked.............Very marked or severe
........................SH..MP..............SH..MP...............SH..MP..............SH..MP
control..............2.....3................7.....2.................0....0.................0....0
10 ppm.............1.....0................6.....2.................3....2.................0....0
50 ppm.............0.....0..............10.....7.................0....2.................0....0
250 ppm...........2.... 0................4.....1.................3....3.................0....1
Inflammatory reactions seemed to be more frequent and more severe in the treated groups compared with the control group.
This inflammation may result from nasal injury associated with inhalation of the test article.
In addition, in one high dose animal, a cortical and paracortical atrophy of the mandibular lymph made was observed.
Inflanmatory lesions (mainly sinus histiocytosis) were also observed in the mesenteric lymph mode and had the following distribution in the various groups:
Group........... Minimal...........Moderate...........Marked.........Very marked or severe
control..............1.......................9........................0........................0
10 ppm.............0.......................5........................5........................0
50 ppm.............0.......................e........................2........................0
250 ppm...........6.................. ....4.......................0.........................0
There was no evidence of a treatment-related effect.
Inflammatory reaction was also observed in the popliteal lymph nodes especially sinus histiocytosis and less frequently medullary plasmacytosis. Sinus histiocytosis had the following distribution in the various groups:
Group............Minimal............Moderate...........Marked..........Very marked or severe
control..............2........................8.......................0........................0
10 ppm.............0........................6.......................4........................0
50 ppm.............0........................8.......................2........................0
250 ppm...........4........................6.......................0........................0
There was no evidence of a treatment-related change. Hemasiderosis of both red and white splenic pulp was a frequent finding but is commonly observed in rodent spleen. Various levels of atrophy of the white pulp were observed in some animals. Lymphoid atrophy could be best characterized in the peri-arterial lymphoid sheath and had the following distribution in the various groups:
Group............Minimal...........Moderate............Marked..........Very marked or severe
control..............1.......................1........................0........................0
10 ppm.............0.......................4........................0........................0
50 ppm.............0.......................2........................0........................0
250 ppm...........0.......................8........................0........................0
The distribution suggested a treatment-related change.
Mid-colon
The gut associated lymphoid tissue was missing in must of the samples.
Modification of gut associated lymphoid tissue was not observed by one of the pathologists. The other observed moderate hypertrophy of gut associated lymphoid tissue in the low dose group (1/4), the intermediate group (3/5) and the high dose group (1/5).
These results were considered to be insignificant.
HISTOMETRY OF SPLEEN AND STATISTICAL ANALYSIS
The histometric evaluation of total surface of spleen cross section. white pulp surface, periarteriolar lymphoid sheath surface, and marginal zone surface was performed together with the statistical analysis. Pairwise statistical comparison of the control group and treated group showed:
- no significant difference between control group and the 10 ppm group.
- significant decrease of the spleen total cross section surface in the 50 ppm group without significant peri-arterial lymphoid sheath, marginal zone, red pulp.
- significant decrease of the spleen total cross section surface. white pulp. peri-arterial lymphoid sheath and marginal zone surfaces in the 150 ppm group, without significant difference for red pulp surface.
Regression analysis compared the site of the various measured components between the different groups. These results confirm the observations obtained by microscopic examination of the spleen sections and confirms that a significant atrophy of the lymphoid structure of the spleen is present in 250 ppm group.
For the white pulp, the periarteriolar lymphoid sheaths and the marginal zone, the slope value of the regression line is significantly negative demonstrating a reduction in the various lymphoid compartments of the spleen in the treated groups, with a dose-effect relationship.
The slope value of the regression line is almost zero for the red pulp (not statistical effect of treatment) and non-significant for the whole surface - Dose descriptor:
- NOAEC
- Effect level:
- 250 ppm (analytical)
- Sex:
- male/female
- Basis for effect level:
- other: No dose responsive and no treatment-related effects on the immunologic parameters
- Conclusions:
- The immunologic phase of the study suggests that lower lymphocyte counts were noted for the DMDS exposed groups. However, the finding was not dose responsive and not treatment-related as the only statistically significant difference was noted for the low exposed group. The lower lymphocytes counts appear to be result of higher than historical control value for the control group and the method used for determining the total lymphocytes. Evaluations of the percentage of lymphocytes to leukocytes showed that all DMDS exposed groups were similar to control. Based on the evaluation above, it can be concluded that DMDS is not immunotoxic.
- Executive summary:
The inhalation immunotoxicity of dimethyl disulfide (DMDS) was assessed in the male Sprague-Dawley rat following exposure, 6 hours/day, 5 days/week over a thirteen week period to vapor concentrations of 0, 10, 50 or 250 ppm. The animals used formed part of a subchronic toxicity study reported separately (see section 7.5.3, Collins, 1992). Blood samples were obtained at week 12 and corresponding recovery animals at week 17. The following parameters were evaluated for these samples: total white cells, total lymphocytes, pan B-tells, pan T-cells. T helper cells and T suppressor cells. In addition, IgG and IgM titres were determined in serum from these samples. Organ weights were determined for the popliteal lymph node, submandibular lymph node, mesenteric lymph node and thymus prior to fixation. Histologic evaluations were performed on the popliteal lymph node, suhmandibular lymph node, mesenteric lymph node, mid colon lymphoid tissue, spleen and thymus following staining with hematoxylin-eosin saffron, with slow Giemsa and with immunocytochemical staining.
B and T cell analysis did not show any evidence of treatment-related changes in T-helper or B-tells. Reductions in absolute lymphocyte counts at week 12 in treated groups were primarily attributable to a specific reduction in T-suppressor cells and were inversely proportional to dose level. The reduction in T-suppressor cells persisted to the end of the recovery period. There was no evidence of any treatment-related differences in serum concentrations of IgG or IgM in the samples taken at the week 14 necropsy. The only treatment-related change in the myelograms taken at necropsy was a trend towards decreased lymphocytes in the treated groups.
There were no organ weight differences except for minor changes attributable to non-specific stress or reduced body weights in the high dose group.
The immunohistopathology study of a range of lymphoid organs showed various inflammatory lesions in the three examined lymph nodes. For mandibular nodes, the inflammatory reaction was greater in the high dose group compared with the control group. This difference was considered to be attributable to treatment.
Atrophy of the white pulp of the spleen was observed in most animals, including two controls. Nevertheless histometry demonstrated a significant atrophy of the white pulp and marginal zone in the high dose group. The regression line of the atrophy was significantly negative indicating a dose-response.
The report concluded that the reduced lymphocyte counts even et 10 ppm were attributable to a reduction in T-suppressor cells, which were inversely related to dose level and persisted to the end of the recovery period. This finding was confirmed by the trend to reduced Lymphocytes in the myelograms. The immunohistopathology revealed an increase in Inflammation of the mandibular lymph nodes at the high dose level of 250 ppm and a dosage-related increase in splenic lymphoid atrophy that were attributed to treatment. Histometry confirmed significant atrophy of the spleen white pulp and marginal Zone in the high dose group. There was no evidence of sensitization. The immunologic phase of the study suggests that lower lymphocyte counts were noted for the DMDS exposed groups. However, the finding was not dose responsive and not treatment-related as the only statistically significant difference was noted for the low exposed group. The lower lymphocytes counts appear to be result of higher than historical control value for the control group and the method used for determining the total lymphocytes. Evaluations of the percentage of lymphocytes to leukocytes showed that all DMDS exposed groups were similar to control. Based on the evaluation above, it can be concluded that DMDS is not immunotoxic.
Table 1 : Absolute white blood cell (WBC) counts, % of lymphocytes, absolute lymphocytes counts, percentage of CD4+ T-helper, CD8+ T-suppressor and SIg-kappa+ B-cells and absolute numbers of T-cells, CD4+ T-helper cells, CD8+ T-suppressor cells and SIg-kappa+ B-cells at week 12.
Mean ± sd |
Control |
10 ppm |
50 ppm |
250 ppm |
n |
10 |
10 |
10 |
10 |
Total WBC count (109/L) |
13.4 ± 30. |
10.9 ± 1.9 |
13.1 ± 3.6 |
12.4 ±2.1 |
% lymphocytes |
86.1 ± 3.3 |
82.2 ±8.4 |
83.9 ± 10.2 |
84.8 ± 4.02 |
Absolute lymphocyte count (10e9/L) |
11.5 ± 2.7 |
9.1 ± 2.2* |
11.0 ± 3.3 |
10.5 ± 1.8 |
% CD4+ |
46.1 ±3.5 |
49.9 ± 4.1* |
48.9 ± 3.8 |
45.0 ± 3.9 |
% CD8+ |
30.1 ± 5.8 |
23.4 ± 3.3* |
23.2 ± 4.8* |
27.4 ± 4.3 |
%Sig-kappa+ |
19.4 ± 2.9 |
24.2 ± 4.0** |
23.1 ± 4.0* |
19.9 ± 3.6 |
Absolute T-cell count (109/L) |
8.82 ± 2.16 |
6.63 ± 1.66* |
7.89 ± 2.28 |
7.60 ± 1.42 |
Absolute T-helper count (109/L) |
5.31 ± 1.30 |
4.52 ± 1.19 |
5.41 ± 1.82 |
4.77 ± 1.12 |
Absolute T-suppressor count (109/L) |
3.51 ± 1.11 |
2.11 ± 0.53* |
2.48 ± 0.67* |
2.83 ± 0.40 |
Absolute B-cell count (109/L) |
2.25 ± 0.65 |
2.19 ± 0.66 |
2.52 ± 0.84 |
2.10 ± 0.58 |
* p< 0.05
** p < 0.01
Table 2 : Absolute white blood cell (WBC) counts, % of lymphocytes, absolute lymphocytes counts, percentage of CD4+ T-helper, CD8+ T-suppressor and SIg-kappa+ B-cells and absolute numbers of T-cells, CD4+ T-helper cells, CD8+ T-suppressor cells and SIg-kappa+ B-cells at week 17.
Mean ± sd |
Control |
10 ppm |
50 ppm |
250 ppm |
n |
10 |
10 |
10 |
10 |
Total WBC count (109/L) |
9.6 ± 2.6 |
7.4 ± 1.6* |
7.8 ± 2.4 |
9.2 ± 1.8 |
% lymphocytes |
83.9 ± 6.9 |
83.1 ± 12.3 |
85.1 ± 2.4 |
81.3 ± 5.3 |
Absolute lymphocyte count (109/L) |
7.7 ± 2.0 |
6.2 ± 1.7 |
6.6 ± 2.1 |
7.4 ± 1.4 |
% CD4+ |
42.6 ± 4.5 |
46.9 ± 6.2 |
46.3 ± 5.1* |
51.1 ± 5.0*** |
% CD8+ |
21.3 ± 5.2 |
18.5 ± 6.1 |
20.4 ± 5.8 |
16.4 ± 4.2* |
%Sig-kappa+ |
22.4 ± 3.3 |
25.9 ± 6.4 |
25.9 ± 4.0 |
24.1 ±3.8 |
Absolute T-cell count (109/L) |
4.89 ± 1.33 |
4.07 ± 1.28 |
4.37 ± 1.35 |
4.98 ± 0.88 |
Absolute T-helper count (109/L) |
3.32 ± 1.21 |
2.96 ± 1.10 |
3.07 ± 1.05 |
3.81 ± 0.87 |
Absolute T-suppressor count (109/L) |
1.57 ± 0.31 |
1.11 ± 0.37* |
1.30 ± 0.47* |
1.18 ± 0.22** |
Absolute B-cell count (109/L) |
1.71 ± 0.43 |
1.59 ± 060 |
1.74 ± 0.69 |
1.78 ± 0.37 |
* p< 0.05
** p < 0.01
*** p < 0.001
Data source
Reference
- Reference Type:
- study report
- Title:
- Unnamed
- Year:
- 1 992
- Report date:
- 1992
Materials and methods
Test guideline
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)
- GLP compliance:
- yes
- Limit test:
- no
Test material
- Reference substance name:
- Dimethyl disulphide
- EC Number:
- 210-871-0
- EC Name:
- Dimethyl disulphide
- Cas Number:
- 624-92-0
- Molecular formula:
- C2H6S2
- IUPAC Name:
- (methyldisulfanyl)methane
- Details on test material:
- Source: Atochem
Batch: 82551
Purity: 99.88%
Constituent 1
Test animals
- Species:
- rat
- Strain:
- Sprague-Dawley
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- TEST ORGANISMS:
- Source: Charles River UK Ltd., Margate
- Age at reception: 4-6 weeks
- Weight at reception: 120-140 g for males, 80-100 g for females
- Weight at the start of the treatment: 185-256 g for males, 121-169 g for females
- Number of animals: 100 rats : 20 males + 20 females / dose group (4 dose groups + 1 control group)
- Acclimatation period: 14 days
HOUSING
The animals were housed in group of 5 in suspended stainless steel cages.
FOOD and WATER
- Food: SZQC rat and Mouse Maintenance Diet No. 1 ad libitum excepted during exposure
- Water: filtered tap water, ad libitum excepted during exposure
ENVIRONMENTAL CONDITIONS
- Temperature : 19-25°C
- Relative humidity : 40-70%
- Light/dark cycle : 12h/12h
- Ventilation : 15 air changes/hour
Administration / exposure
- Route of administration:
- inhalation
- Type of inhalation exposure:
- whole body
- Vehicle:
- air
- Remarks on MMAD:
- MMAD / GSD: A simslin II dust monitor was used pre-dose, and during the study at week 1, 4, 8, and 12, at each exposuire levels to confirm all the test article was in a vapour phase.
- Details on inhalation exposure:
- Five horizontal flow, recirculating exposure chambers were used. Each was made of stainless steel with perspex (Plexiglas) doors and a fan to mix the atmospheres by recirculation. The compressed air supply was from a clean, dry, filtered source. The total volume of the animals did not exceed 5% of the volume of the test chamber. The four concentrations of test article vapour were produced by passing metered flows of air through sintered glass frits immersed in separate containers of test article. The resulting outputs of vapour were introduced to the diluent air inlet duct of each test chamber. Mixing, within the duct and recirculation system, ensured the production of homogeneous atmospheres for animal exposure. The chambers were ventilated at a rate of at least 12 air changes per hour. Air flows were monitored continuously and recorded twice hourly during exposure. The exhaust streams were purified with activated charcoal and vented to the outside of the building.
- Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- * Measured concentration Samples for analysis were withdrawn from the exposure chambers twice hourly through sample lines leading from each chamber through a sampling valve into a total hydrocarbon analyser. The analysis was performed with an Analysis Automation total hydrocarbon analyser type 523 Detector with a Flame ionisation detector (FID)
* Nominal concentration The total weight of test article used and total volume of diluent air were measured for each exposure.
- Group Target Nominal Analytical concentrations:
1 0
2 10 20 10.17 ppm
3 50 81 50.25 ppm
4 150 223 150.62 ppm
5 250 373 246.59 ppm - Duration of treatment / exposure:
- 90 days
- Frequency of treatment:
- 6 h/day; 5 d/week
Doses / concentrations
- Remarks:
- Doses / Concentrations:
10, 50, 150, 250 ppm
Basis:
analytical conc.
- No. of animals per sex per dose:
- 20
- Control animals:
- yes, concurrent vehicle
- Details on study design:
- Four groups of 20 male and 20 female Sprague-Dawley were exposed 6 hours/day, 5 days/week to 0, 10, 50, 150, or 250 ppm DMDS. The exposure of the 150 ppm group was terminated after 6 weeks and its treatment-free subgroup necropsied 2 weeks later. The remaining groups received a 13 week exposure period followed by four weeks for the treatment-free subgroups.
- Positive control:
- Not appropriate
Examinations
- Observations and examinations performed and frequency:
- - Clinical observations
* Morbidity and mortality All animals were examined twice daily to detect any which were dead or moribund.
* Clinical signs All animals were examined once daily for signs of ill health or overt toxicity. In addition each animal was given a detailed clinical examination at weekly intervals. An individual record was maintained of the clinical condition of each animal.
* Functional observation tests Observations were carried out on all animals prior to beginning treatment and again during weeks 1, 4, 13 and the treatment-free animals in week 17. The observations were made prior to and following any exposure that day. Observations were recorded for the following parameters: ease of removal from home cage, ease of handling, appearance of eyelids, lacrimation, colour of tears, salivation, respiration, appearance of fur, piloerection, writhing, vocalisation.
- Body weight Individual body weights were recorded before exposure on the first day of the study, at weekly intervals thereafter and at necropsy.
- Food consumption The amount of food consumed by each cage of animals was determined weekly.
- Ophthalmoscopy The eyes of all animals were examined pre-dose and all control and high dose animals in week 12.
- Laboratory investigations
Blood samples were obtained from groups 1, 4 and 5 for haematology and clinical chemistry in week 6 and groups 1 and 5 for haematology and clinical chemistry in week 12. The samples were collected from the main study animals.
* Haematology: Haemoglobin, mean cell volume, red blood cell count and indices: mean cell haemoglobin, mean cell haemoglobin concentration packed cell volume, total and differential white blood cell count platelet count.
* Clinical chemistry: aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, sodium, potassium, chloride, calcium inorganic phosphorus, glucose, urea, total bilirubin, creatinine, total protein, albumin, albumin/globulin ratio total cholesterol. - Sacrifice and pathology:
- - Pathology
* Necropsy
Full internal and external examination at sacrifice
* Organ weights
adrenals, brain, kidneys, liver, lungs, ovaries, pituitary, spleen, testes.
* Histology
adrenals, femur (including articular aorta surface)#, brain (including brain stem), heart, caecum, ileum colon, jejunum duodenum, kidneys, epididymides#, lachrymal gland#, eyes (with optic nerves), larynx, liver, sciatic nerve, lungs (with mainstem bronchi), skeletal muscle (quadriceps)#, lymph nodes (bronchial with tracheal bifurcation and mesenteric), skin and mammary gland#, spinal cord (lumbar, cervical, thoracic)#, nasal passages, spleen, nasopharyngeal duct, sternum (and bone marrow), oesophagus, stomach, ovaries, testes, pancreas, thymus, pituitary, thyroids (with parathyroids), prostate#, tracheal bifurcation, rectum, urinary bladder, salivary glands (submaxillary, sublingual), uterus and all gross lesions. Samples of all tissues (except those annotated # above) from all main study animals in the control and high dose group, the lungs and all gross lesions of all main study animals and the nasal cavities of groups 2 and 3 terminal kill and groups 1, 2, 3 and 5 treatment-free animals were evaluated by the study pathologist. - Statistics:
- * ANOVA, T-test
Body weight: week 0
* ANOVA, Regression and Dunnett's
Body weight gains: weeks 0 to 6, 0 to 13, 13 to 17 weeks 6 to 8 (group 1 v group 4 only)
Total food consumption: weeks 1 to 5, 7 to 12
Necropsy body weight: terminal kill and treatment-free
Clinical chemistry: weeks 6, 12 AST, ALT, ALK PROS, Na, K, Cl, Ca, P, GLUCOSE, UREA, T BILI, CREAT, T PROT, ALBUMIN, AG RATIO, TOT CHOL Clinical chemistry: week 13 ALT, ALK PHOS (males), T BILI Clinical chemistry: week 17 ALT, ALK PHOS, T BILI
Haematology: weeks 6, 12 Hb, RBC, PCV, MCV, MCH, MCHC, PLAT, WBC, Neutrophils and Lymphocytes
- absolute and percentages
Haematology: week 13 Hb, RBC, PCV, MCV, MCH, MCHC
* ANCOVA, Dunnett's Organ weights (adjusted for necropsy body weight)
- terminal kill and treatment-free: adrenals, kidneys, spleen, liver, ovaries, gonads, lung, brain, pituitary
* Kruskal-Wallis, Terpstra-Jonckheere, Wilcoxon Clinical chemistry
week 13 females ALK PHOS
No statistical analysis was considered necessary to interpret the results of the functional observation tests.
Results and discussion
Results of examinations
- Clinical signs:
- effects observed, treatment-related
- Description (incidence and severity):
- The only clinical signs attributable to treatment were salivation, lacrimation or reduced activity during exposure 1 and 2 of the 150 and 250 ppm groups and a low incidence of dyspnoea or wheezing in the early part of the study, particularly in the 250 ppm animals at week 1.
- Mortality:
- mortality observed, non-treatment-related
- Description (incidence):
- There was no treatment-related mortality.
Two female animals, 145 (50 ppm) and 163 (150 ppm), showed ulcerative sores on the neck in week 1 of the study attributed to the ear tattooing procedure and were therefore removed from study and replaced with two spare animals designated 145Rl and 163Rl. Male animal 59 (50 ppm), treatment-free subgroup) died during anaesthesia for blood sampling in week 17. This death was considered to be incidental. - Body weight and weight changes:
- effects observed, treatment-related
- Description (incidence and severity):
- There was a dosage-related decrease in body weight gain (Tables 1 and 2) over the treatment period in treated groups compared with controls. Differences were statistically significant except for the 10 ppm group which was only significant for males over weeks 0 to 6. Improvements in the rate of body weight gain were observed in the test groups in the treatment-free period.
- Food consumption and compound intake (if feeding study):
- no effects observed
- Description (incidence and severity):
- Differences in food consumption (Table 3) paralleled those of body weight gain except the numerical differences did not achieve statistical significance in the 50 ppm males or the 10 ppm groups.
- Food efficiency:
- not specified
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- no effects observed
- Description (incidence and severity):
- The eyes of the animals were unremarkable.
- Haematological findings:
- effects observed, treatment-related
- Description (incidence and severity):
- No effect was observed on the haematological profiles of the males on week 6 (0, 150 and 250 ppm groups). In females, a slight statistically significant decrease of MCV (58.7 vs 60.4 fl) and MCH (20.1 vs. 21.1 pg) was observed at 150 ppm and of MCHC (34.1 vs. 34.8 g/dl) at 250 ppm when compared to the control group.
Haematological profiles on week 12 (0 and 250 ppm groups, Table 4)) suggested a possible small reduction in Hb, RBC and PCV in the 250 ppm female group only. Haematological profiles on week 13 (0, 10 and 50 ppm groups, Table 5) were unremarkable (data not shown) - Clinical biochemistry findings:
- effects observed, treatment-related
- Description (incidence and severity):
- Blood chemistry examinations performed on week 6 (0, 150 and 250 ppm groups) showed in males a statistically significant increases of ALT (62 vs. 45 Iu/l) at 150 ppm and Alk. Phos. (450 vs. 338 Iu/l) and total bilirubin (5.2 vs. 3.9 µmol/l) at 250 ppm when compared to the control group. In females, significant increases of total bilirubin (4.1 vs. 3.1 µmol/l) was observed at 150 ppm and of alk. phos. (329 vs. 242 Iu/l) at 250 ppm. A decrease of the urea level was also observed at 150 ppm (6.6 vs. 7.7 mmol/l).
Blood chemistry examinations performed on week 12 (0 and 250 ppm groups, Table 6) and 13 (0, 10 and 50 ppm groups, Table 7) showed treatment-related changes in ALT, alkaline phosphatase and bilirubin. The changes did not include the 10 ppm group except for elevated ALT in occasional animals at week 13 and after the treatment-free period. Any changes in alkaline phosphatase and bilirubin in the 50 ppm group were equivocal.
Blood chemistry examinations performed on week 17 (0, 10, 50 and 250 ppm groups) did not show any treatment related effects on ALT, alk. phos. and total bilirubin. - Urinalysis findings:
- not examined
- Behaviour (functional findings):
- effects observed, treatment-related
- Description (incidence and severity):
- Functional observation tests indicated treatment-related changes in response to handling and respiration, and in incidence of salivation, soiling of the fur and piloerection but no evidence of neurotoxicity.
- Organ weight findings including organ / body weight ratios:
- no effects observed
- Description (incidence and severity):
- There were no changes in organ weights that were considered to be treatment-related. Statistically significant elevations in lung weights in the 250 ppm males and females were of doubtful toxicological importance.
- Gross pathological findings:
- no effects observed
- Description (incidence and severity):
- There were no treatment-related macroscopic abnormalities at necropsy.
- Neuropathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- In the 10, 50 and 250 ppm animals examined microscopically there was a dose-related effect on nasal mucosa characterised by squamous metaplasia of the respiratory epithelium accompanied in 50 ppm and 250 ppm groups by atrophy and microcavitation in the anterior olfactory epithelium. In the 10 ppm group the effects were limited to a local, minor degree of squamous metaplasia of the anterior nasal cavity. The changes were still present in the 50 and 250 ppm groups after the treatment-free period but the 10 ppm group was generally unremarkable.
- Histopathological findings: neoplastic:
- not examined
Effect levels
open allclose all
- Key result
- Dose descriptor:
- NOAEC
- Remarks:
- Systemic toxicity
- Effect level:
- 10 ppm (analytical)
- Sex:
- male/female
- Basis for effect level:
- other: no adverse effect
- Dose descriptor:
- LOAEC
- Remarks:
- Systemic toxicity
- Effect level:
- 50 ppm (analytical)
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- body weight and weight gain
- clinical signs
- food consumption and compound intake
- Key result
- Dose descriptor:
- LOAEC
- Remarks:
- Nasal irritation
- Effect level:
- 10 ppm (analytical)
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- histopathology: non-neoplastic
Target system / organ toxicity
- Key result
- Critical effects observed:
- yes
- Lowest effective dose / conc.:
- 10 ppm (analytical)
- System:
- respiratory system: upper respiratory tract
- Organ:
- nasal cavity
- Treatment related:
- yes
- Dose response relationship:
- no
- Relevant for humans:
- yes
Any other information on results incl. tables
Table 1: Group mean body weight gains (g), males
Week of study |
Concentration (ppm) |
|||||
0 |
10 |
50 |
150 |
250 |
||
Start |
Mean |
227.3 |
224.5 |
228.6 |
225.2 |
227.1 |
S.D. |
15.69 |
13.15 |
13.36 |
14.36 |
14.82 |
|
0 to 6 |
Mean |
160.2 |
139.0* |
128.7** |
115.2*** |
106.3*** |
S.D. |
31.86 |
24.03 |
28.84 |
24.99 |
21.50 |
|
6 to 8 |
Mean |
32.5- |
- |
- |
47.5*** |
- |
S.D. |
10.67 |
- |
- |
8.68 |
- |
|
0 to 13 |
Mean |
233.0 |
225.6 |
181.8*** |
- |
148.3*** |
S.D. |
45.31 |
34.38 |
42.47 |
- |
37.83 |
|
13 to 17 |
Mean |
10.8 |
25.9 |
29.5 |
- |
41.8** |
S.D. |
18.17 |
23.94 |
17.62 |
- |
21.01 |
* p<0.05** p<0.01*** p<0.001
Table 2: Group mean body weight gains (g), females
Week of study |
Concentration (ppm) |
|||||
0 |
10 |
50 |
150 |
250 |
||
Start |
Mean |
149.6 |
146.0 |
144.9 |
145.6 |
144.2 |
S.D. |
7.53 |
8.62 |
5.47 |
10.88 |
10.9 |
|
0 to 6 |
Mean |
88.0 |
77.0 |
73.0** |
68.1*** |
74.2** |
S.D. |
14.97 |
15.00 |
10.72 |
15.86 |
13.51 |
|
6 to 8 |
Mean |
14.8 |
- |
- |
20.3* |
- |
S.D. |
5.22 |
- |
- |
5.30 |
- |
|
0 to 13 |
Mean |
117.8 |
119.8 |
97.5** |
- |
93.2*** |
S.D. |
22.69 |
22.63 |
17.13 |
- |
17.99 |
|
13 to 17 |
Mean |
3.0 |
5.5 |
9.5 |
- |
9.6 |
S.D. |
8.86 |
12.91 |
11.08 |
- |
11.67 |
* p<0.05** p<0.01*** p<0.001
Table 3:mean food consumption (g/animal) over specified periods
Week of study |
Concentration (ppm) |
|||||
0 |
10 |
50 |
150 |
250 |
||
Males |
||||||
1 to 5 |
Mean |
810.2 |
779.4 |
752.3 |
772.4* |
700.4** |
S.D. |
33.85 |
46.25 |
36.88 |
40.86 |
18.17 |
|
7 to 12 |
Mean |
991.7 |
996.1 |
944.0 |
— |
866.8*** |
S.D. |
12.46 |
42.34 |
39.49 |
— |
24.38 |
|
Females |
||||||
1 to 5 |
Mean |
585.5 |
558.5 |
527.5** |
516.1** |
535.6* |
S.D. |
17.77 |
19.63 |
14.23 |
31.86 |
19.34 |
|
7 to 12 |
Mean |
741.1 |
728.4 |
674.2*** |
— |
691.1** |
S.D. |
3.54 |
27.29 |
9.63 |
— |
21.2 |
* p<0.05** p<0.01*** p<0.001
Table 4: Group mean haematology, Occasion: Week 12
Group |
Hb |
RBC |
PCV |
MCV |
MCH |
MCHC |
PLAT |
|
Sex |
g/dl |
mil/cmm |
% |
fl |
pg |
g/dl |
1000/cmm |
|
Males |
||||||||
0 ppm |
Mean |
15.0 |
8.16 |
45.9 |
56.4 |
18.4 |
32.6 |
926 |
S.D. |
0.7 |
0.56 |
1.9 |
2.0 |
0.7 |
0.4 |
147 |
|
250 ppm |
Mean |
14.4 |
7.76 |
44.0 |
56.7 |
18.5 |
32.7 |
936 |
S.D. |
0.8 |
0.44 |
2.5 |
1.3 |
0.5 |
0.3 |
128 |
|
Females |
||||||||
0 ppm |
Mean |
14.4 |
7.44 |
43.4 |
58.4 |
19.4 |
33.2 |
967 |
S.D. |
0.7 |
0.34 |
2.1 |
1.5 |
0.6 |
0.3 |
140 |
|
250 ppm |
Mean |
13.5* |
6.88** |
41.0* |
59.6 |
19.7 |
33.0 |
947 |
S.D. |
0.8 |
0.42 |
2.3 |
1.7 |
0.6 |
0.4 |
73 |
* p<0.05 ** p<0.01 *** p<0.001
Table 5: Group mean haematology, Occasion: Week 12
Group |
WBC 1000 / cmm (%) |
||||||
Sex |
TOTAL |
N |
L |
M |
E |
B |
|
Males |
|||||||
0 ppm |
Mean |
13.2 |
1.71(13) |
11.23(85) |
0.12(1) |
0.12(1) |
0.00(0) |
S.D. |
4.5 |
0.71(-) |
3.91(-) |
0.13(-) |
0.14(-) |
0.00(-) |
|
250 ppm |
Mean |
11.7 |
1.31(11) |
10.33(88) |
0.01(0) |
0.04(0) |
0.00(0) |
S.D. |
3.5 |
0.50(-) |
3.23(-) |
0.04(-) |
0.06(-) |
0.00(-) |
|
Females |
|||||||
0 ppm |
Mean |
11.0 |
1.25(12) |
9.22(84) |
0.28(3) |
0.20(2) |
0.00(0) |
S.D. |
2.7 |
0.82(-) |
2.51(-) |
0.15(-) |
0.23(-) |
0.00(-) |
|
250 ppm |
Mean |
10.8 |
1.30(12) |
9.13(85) |
0.28(3) |
0.10(1) |
0.00(0) |
S.D. |
1.7 |
0.43(-) |
1.45(-) |
0.18(-) |
0.08(-) |
0.00(-) |
Table 6: Group mean clinical chemistry, Occasion: Week 12
Group |
AST |
ALT |
ALK |
Na |
K |
Cl |
Ca |
P |
|
Sex |
Iu/l |
Iu/l |
Iu/l |
mmol/l |
mmol/l |
mmol/l |
mmol/l |
mmol/l |
|
Males |
|||||||||
0 ppm |
Mean |
96 |
51 |
222 |
143 |
3.9 |
108 |
2.41 |
1.8 |
S.D. |
13 |
11 |
50 |
1 |
0.2 |
2 |
0.10 |
0.1 |
|
250 ppm |
Mean |
78** |
47 |
302* |
143 |
3.8 |
106 |
2.44 |
1.8 |
S.D. |
9 |
7 |
82 |
1 |
0.3 |
2 |
0.09 |
0.1 |
|
Females |
|||||||||
0 ppm |
Mean |
86 |
39 |
168 |
141 |
3.4 |
107 |
2.46 |
1.7 |
S.D. |
9 |
6 |
37 |
1 |
0.2 |
1 |
0.09 |
0.1 |
|
250 ppm |
Mean |
84 |
51* |
264* |
139* |
3.4 |
106 |
2.38* |
1.7 |
S.D. |
9 |
14 |
108 |
2 |
0.3 |
3 |
0.06 |
0.1 |
* p<0.05 ** p<0.01*** p<0.001
Group |
GLUC |
UREA |
T BILI |
CREAT |
T PROT |
ALBUMIN |
AG RATIO |
TOT CHOL |
|
Sex |
mmol/l |
mmol/l |
µmol/l |
µmol/l |
g/l |
g/l |
mol/l |
||
Males |
|||||||||
0 ppm |
Mean |
5.9 |
6.0 |
3.7 |
62 |
62 |
34 |
1.3 |
1.7 |
S.D. |
0.7 |
1.0 |
0.6 |
3 |
4 |
1 |
0.1 |
0.3 |
|
250 ppm |
Mean |
6.0 |
6.1 |
4.8* |
59* |
62 |
36* |
1.4 |
1.5 |
S.D. |
0.5 |
0.9 |
1.2 |
2 |
3 |
1 |
0.1 |
0.3 |
|
Females |
|||||||||
0 ppm |
Mean |
6.2 |
7.0 |
3.5 |
65 |
68 |
40 |
1.4 |
2.2 |
S.D. |
0.3 |
0.9 |
0.6 |
5 |
3 |
2 |
0.1 |
0.4 |
|
250 ppm |
Mean |
6.1 |
6.7 |
5.7*** |
65 |
68 |
39 |
1.4 |
2.1 |
S.D. |
0.6 |
1.1 |
1.1 |
2 |
5 |
1 |
0.2 |
0.4 |
* p<0.05 ** p<0.01*** p<0.001
Table 7: Group mean clinical chemistry, Occasion: Week 13
Group |
ALT(GPT) |
ALK PHOS |
T BILI |
|
Sex |
Iu/l |
Iu/l |
µmol/l |
|
Males |
||||
0 ppm |
Mean |
48 |
282 |
2.0 |
S.D. |
5 |
45 |
1.0 |
|
10 ppm |
Mean |
61 |
345 |
2.5 |
S.D. |
16 |
112 |
0.6 |
|
50 ppm |
Mean |
72* |
375 |
2.2 |
S.D. |
35 |
101 |
0.6 |
|
Females |
||||
0 ppm |
Mean |
46 |
218 |
1.2 |
S.D. |
8 |
59 |
0.5 |
|
10 ppm |
Mean |
75 |
264 |
1.3 |
S.D. |
42 |
47 |
0.5 |
|
50 ppm |
Mean |
57* |
320 |
1.4 |
S.D. |
10 |
128 |
0.9 |
* p<0.05 ** p<0.01*** p<0.001
Applicant's summary and conclusion
- Conclusions:
- Clear treatment-related effects were seen at 50 and 250 ppm and were present to a marginal degree at 10 ppm. It was concluded that the effect level was 50 ppm. The no-effect level was in the region of, but less than, 10 ppm due to the reversible changes in the nasal mucosa
- Executive summary:
In an OECD 413 study, groups of 10 rats/sex were exposed by inhalation to DMDS 6 h/day, 5 d/week for 90 days to concentrations of 0, 10, 50, 150, 250 ppm (Collins, 1992). The exposure of the 150 ppm group was terminated after 6 weeks and its treatment-free subgroup necropsied 2 weeks later. The remaining groups received a 13 week exposure period followed by 4 weeks for the treatment-free subgroups. The only clinical signs attributable to treatment were salivation, lacrimation or reduced activity during exposures 1 and 2 of the 150 and 250 ppm groups and a low incidence of dyspnea or wheezing in the early part of the study, particularly in the 250 ppm animals at week 1. Functional observation tests indicated no evidence of neurotoxicity. Body weight gains and food consumption were decreased in all treatment groups; this effect was reversible during the recovery period. Hematological profiles suggested a possible small reduction in Hb, RBC and PCV in the 250 ppm female group only. Blood chemistry examinations showed treatment-related changes in ALT, alkaline phosphatase and bilirubin. The changes did not include the 10 ppm group except for elevated ALT in occasional animals at week 13 and after the treatment-free period. There were no changes in organ weights that were considered to be treatment-related and no treatment-related macroscopic abnormalities. Microscopic evaluations indicated a dose-related effect on nasal mucosa characterised by squamous metaplasia of the respiratory epithelium accompanied by atrophy and microcavitation in the anterior olfactory epithelium. In the 10 ppm group the effects were limited to a local, minor degree of squamous metaplasia of the anterior nasal cavity. The changes were still present in the 50 and 250 ppm groups after the treatment-free period but the 10 ppm group was generally unremarkable. Clear treatment-related effects were seen at 50 and 250 ppm and were present to a marginal degree at 10 ppm.
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