1-chloro-2,3-epoxypropane

Endpoint summary

Description of key information

In carcinogenicity studies and subchronic studies, histopathologic changes were noted at the site of entry following oral or inhalation administration, thus histopathologic changes were observed in the stomach following oral administration and nasal turbinates following inhalation exposure to vapors. In addition, some slight histologic changes were observed in the liver and kidneys following both oral and inhalation exposure for 90 days; these occured at the same or higher doses than the portal of entry effects.

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not stated

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was not conducted according to guideline/s and GLP but the report contains sufficient data for interpretation of study results

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Deviations:

yes

Remarks:

selected clinical chemistry tests not performed

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Male and female cesarean-derived Sprague-Dawley rats (Crl: CD BR), confirmed free of viral antibodies, bacteria, and parasites, were obtained from Charles River Laboratories (Portage, MI). For the 90-day study, 30-31 day old animals were procured, acclimatized for 2 weeks, and started at 45 days of age. At the initiation of treatment, the males ranged from 210.8 - 215.7 g and the females 157.1 to 160.0 g. The test animals were housed in a temperature (70-72F) and humidity (40 - 60%) controlled room on a 12 hour light-dark cycle in elevated wire mesh cages abd individually for the 90-day study. The rats were provided Purina-certified Chow 5002 (Ralston-Purina Co., St. Louis, Missouri) and tap water ad libitum. Animal identification was via ear tags with the rats assigned to vehicle and treatment groups according to a computerized randomization process. All aspects of this study were conducted under guidelines of the American Association for Accreditation of Laboratory Animal Care.

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

Epichlorohydrin was administered (in distilled water) by daily gavage for either 10 or 90 consecutive days. Four treatment levels of epichlorohydrin were employed in the 10-day study (3, 7, 19, and 46 mg/kg-day), and three levels (1, 5 and 25 mg/kg-day) in the 90-day study. The controls were intubated with distilled water. All treatments were administered at a constant volume (1 ml/kg) and dosages were based on the weekly individual body weight measurements in order to assure delivery of the precise levels.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Stability tests confirmed that epichlorohydrin was stable in the aqueous dosing preparations for at least 10 days. However, dosing solutions were prepared daily for the 10-day study and weekly for the 90-day study. These preparations were stored at room temperature in amber colored bottles fitted with a teflon-lined, crimp-top cap.

Duration of treatment / exposure:

Four treatment levels of epichlorohydrin were employed in the 10-day study (3, 7, 19, and 46 mg/kg/day), and three levels (1, 5 and 25 mg/kg/day) in the 90-day study.

Frequency of treatment:

Daily for 7 days/week for 10 or 90 consecutive days.

Remarks:

Doses / Concentrations:
10-day study (3, 7, 19, and 46 mg/kg/day) and 90-day study (1, 5 and 25 mg/kg/day).
Basis:
other: actual oral gavage

No. of animals per sex per dose:

Each study group consisted of 10 males and 10 females with epichlorohydrin being administered (in distilled water) by daily gavage for either 10 or 90 consecutive days.

Control animals:

yes, concurrent vehicle

Details on study design:

Cage-side observations; for behavioral changes and for mortality and morbidity were made twice daily. Body weights were recorded prior to randomization, at initiation of dosing, and weekly, thereafter. At each weighing, examinations were made to detect any changes of the skin, eyes, or appearance. Water consumptioll was determined three times per week and food consumption weekly in both studies. Ophthalmoscopic examination of dilated pupils was performed twice in the 90-day study, prior to treatment and during the last week of the study.

The animals were fasted overnight prior to the terminal salcrifice at which time the animals were anesthetized, weighed, and two blood samples were collected via the orbital sinus for hematological and serum clinical chemistry evaluations. Hematological analysis was conducted using a Coulter Counter, Model ZBI (Hileah, FL) for red blood cell count (RBC), white blood cell count [(WBC), hemoglobin, hematocrit, reticulocyte count, platelet count (90-day study only), and mean corpuscular volume (MCV) (10-day study only). A differential WBC analysis was done to obtain the percentage of segmented neutrophils, lymphocytes, monocytes, and eosinophils.

Serum chemistry determinations, perforrned in both the 10- and 90-day studies using diagnostic bits and a Baker Encore Chemistry Analyzer (Allentown, PA), were: blood urea nitrogen (BUN), calcium, creatinine, lactate dehydrogenase (LDH), alkaline phosphatase (ALK-P), aspartate aminotransaminase (AST), and alanine aminotransaminase (ALT). For the 90-day study, additional analysis was conducted for: sodium, potassium, albumin, total protein, and total bilirubin; whereas, cholesterol and glucose were measured only In the 10-day study. Urinalysis was perforedm at the end of the 90-day study using multiple testlng sticks (Ames Division, Elkhart, IN) and consisted of measurements for; pH, glucose, proteln, bilirubin, occult blood, and urobilinogen.

Euthanasia was vla exsanguination, during necropsy, after the animals had been anesthetized using 60 mg/kg of sodlum pentobarbital. The necropsy included gross examination of the total anlmal surface, all orifices, the carcass, the external surface of the brain, cervical tissues, all organs, and the cranial, thoracic, abdominal, and pelvic cavities.

The adrenal glands, brain (including the brain stem), gonads, heart, kidneys, liver, lungs, spleen, and thymus were removed and weighed. In addition, tissues from 35 additional organs as well as any gross lesions, were collected and preserved in 10% neutral buffered formalin. The harvested tissues (and all gross lesions) were trimmed, processed, embedded in paraffin, and sectioned. Slides were prepared, stained with hematoxylin and eosin, and examlned microscopically. During microscopic examination the inflammatory and degenerative leslons were graded according to severity using a scale of one to four (mlnimal, mild, moderate, or marked). In both studies, data were tabulated according to individual anlmal and summarized by group.

Positive control:

No positive control.

Observations and examinations performed and frequency:

Cage-side observations; for behavioral changes and for mortality and morbidity were made twice daily. Body weights were recorded prior to randomization, at initiation of dosing, and weekly, thereafter. At each weighing, examinations were made to detect any changes of the skin, eyes, or appearance. Water consumptioll was determined three times per week and food consumption weekly in both studies. Ophthalmoscopic examination of dilated pupils was performed twice in the 90-day study, prior to treatment and during the last week of the study.

Sacrifice and pathology:

Euthanasia was vla exsanguination, during necropsy, after the animals had been anesthetized using 60 mg/kg of sodlum pentobarbital. The necropsy included gross examination of the total anlmal surface, all orifices, the carcass, the external surface of the brain, cervical tissues, all organs, and the cranial, thoracic, abdominal, and pelvic cavities.

The adrenal glands, brain (including the brain stem), gonads, heart, kidneys, liver, lungs, spleen, and thymus were removed and weighed. In addition, tissues from 35 additional organs as well as any gross lesions, were collected and preserved in 10% neutral buffered formalin. The harvested tissues (and all gross lesions) were trimmed, processed, embedded in paraffin, and sectioned. Slides were prepared, stained with hematoxylin and eosin, and examlned microscopically. During microscopic examination the inflammatory and degenerative leslons were graded according to severity using a scale of one to four (mlnimal, mild, moderate, or marked). In both studies, data were tabulated according to individual anlmal and summarized by group.

Other examinations:

The animals were fasted overnight prior to the terminal salcrifice at which time the animals were anesthetized, weighed, and two blood samples were collected via the orbital sinus for hematological and serum clinical chemistry evaluations. Hematological analysis was conducted using a Coulter Counter, Model ZBI (Hileah, FL) for red blood cell count (RBC), white blood cell count [(WBC), hemoglobin, hematocrit, reticulocyte count, platelet count (90-day study only), and mean corpuscular volume (MCV) (10-day study only). A differential WBC analysis was done to obtain the percentage of segmented neutrophils, lymphocytes, monocytes, and eosinophils.

Serum chemistry determinations, perforrned in both the 10- and 90-day studies using diagnostic bits and a Baker Encore Chemistry Analyzer (Allentown, PA), were: blood urea nitrogen (BUN), calcium, creatinine, lactate dehydrogenase (LDH), alkaline phosphatase (ALK-P), aspartate aminotransaminase (AST), and alanine aminotransaminase (ALT). For the 90-day study, additional analysis was conducted for: sodium, potassium, albumin, total protein, and total bilirubin; whereas, cholesterol and glucose were measured only In the 10-day study. Urinalysis was perforedm at the end of the 90-day study using multiple testlng sticks (Ames Division, Elkhart, IN) and consisted of measurements for; pH, glucose, proteln, bilirubin, occult blood, and urobilinogen.

Statistics:

For both studies, a one-factor analysis of variance (ANOVA) was used to test for a dose-related effect of normally-distributed measure. Males and females were considered separately In all statistical analyses and the parameters analyzed were: body weights, absolute organ weights, organ-to-body weight ratlos, water and food consumption, hematology, and serum chemistry measurements. When a treatment effect was observed (p< or = 0.05), the difference between the control and treatment groups was further probed, using a multiple comparison procedure for individual differences (10-
day study-Tukey's, 90-day study-Dunnett's). Due to the high variability of some of the clinical chemistry measures, a nonparametric analysis of variance, the Kruskal-Wallis test, and associated mulltiple comparison tests were employed in the 10-day study to determine differences amongst the dose groups. For the 90-day study, the data transformations (e.g., log, square root, rank) performed were sufficient to meet the assumptions required for validity of the ANOVA procedure.

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

no effects observed

Ophthalmological findings:

not specified

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

effects observed, treatment-related

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Details on results:

10-Dav Toxicity Study
Mortality: No animals died during the study.

Food and Water Consumption: Water consumption was significantly increased, relative to controls, whereas food consumption was significantly decreased in both males and females receiving 46 mg/kg/day. These differences were also significant when the consumption data was calculated on a per gram body weight basis (data not shown).

Body and Organ Weights. Significant decreases in both final mean body weights and total body weight gain were observed for both sexes at the high-dose level. Minimal differences in brain, heart, liver, lung, spleen, thymus and adrenal weights were observed, although a significant (15%) increase in kidney weights was seen in females at the highest dose.

Relative Organ Weights. Significant increases (22-25%) were seen in the relative weights of the kidneys for both sexes at the two highest doses and in the relative weight of the liver at the highest dose in females and at the two highest doses for males. In addition, relative testes weights were increased in males at the highest dose. All other relative organ weights were unchanged relative to controls.

Hematology. Other than slight but significant decreases in RBC's (6.8 +/- 0.2 v. 6.4 +/- 0.3 x 10(6)/ul males and reticulocyte counts (3.6 +/- 0.1 v. 1.7 +/- 0.7 females) in the high-dose groups, the clinical hematological parameters were comparable for treated and control groups.

Serum Chemistry. In males, some statistically significant changes form the control group were seen in several serurn parameters: slight decreases (not dose-related) in creatinine at the three highest doses; decreases in LDH at 7 and 46 mg/kg/day (1 399 +/- 440 vs. 785 +/- 547 & 218 +/- 252 U/L); and a decrease in calcium at 7 and 19 mg/kg/day, but not at the high dose. An apparent dose-related increase in glucose occurred in males with the change reaching significance at the highest dose compared to the control (113.2 +/- 19.4 vs. 154.3 +/- 32.5 mg/dl). No significant changes were seen in serum chemistries of the females.

Histopathology. The nonglandular stomach (forestomach) was clearly affected by the 10- day intubation with epichlorohydrin. The changes consisted of a range of inflammatory and epithelial alterations in both sexes. The most pronounced occurrence was of hyperplasia (acanthosis) and hyperkeratosis of the forestomach mucosa; with the exception of one male, all rats in the two highest dose group had these changes. The incidence of these changes was significantly elevated at all dose levels in the females and at doses greater than 3 mg/kg-day for males. Hyperplasia was characterized by increased thickness of the mucosa; whereas, hyperkeratosis consisted of an increased thickness of the keratin overlying the mucosa. Degeneration of the mucosa (excessive vacuolization) also occurred at the two highest dose level in both sexes. Each lesion was scored on a scale of normal to severe (1 to 4 respectively) and for both sexes the severity closely paralleled the incidence. The forestomach also exhibited inflammatory responses as evident from the infiltration of macrophages, eosinophils, lymphocytes, and plasrna cells at the two highest doses in males and the highest dose in females. These inflammatory changes appeared to be reactions to the cellular damage occurring in conjunction with the mucosal hyperplasia and hyperkeratosis. Five of the ten female rats exposed to 3 mg/kg-day exhibited at least one of these inflammatory changes. All other histopathological changes occurred with no apparent treatment relationship and were present in both treated and control groups in about equal frequency and severity.


90-Day Toxicity Study
Mortality and Clinical Signs. Dosages for the 90-day study were based on the results of the 10-day study. No animals died during the study. Clinical signs, including ophthalmoscopic diagnoses were essentially normal except for excessive salivation which was frequently observed in the high-dose group, beginning at week 2.

Food and Water Consumption. No significant differences between the treated and control groups were found for food or water consumption.

Body and Organ Weights. No significant differences were observed in total body weights; however, kidney and liver weights were increased for both sexes at 5 and 25 mg/kg/day (significant at 25 mg/kg/day). The absolute weights of the other organs in treated animals were not changed relative to those of controls.

Relative Organ Weight::. The organ-to-body (relative) weight ratios were based on the terminal body weights recorded at necropsy. A dose-related increase was seen in two organs, the kidney and liver, in both males and females at 5 and 25 mg/kg/day and these increases had statistical significance at the higher dose. The relative liver weight was increased significantly at 5 mg/kg/day only in the males. The increases in relative liver weights were comparable between the sexes, but the relative kidney weights were increased 43% in males but only 23% in females.

Hermatology. Treatment with 25 mg/kg/day epichlorohydrin for 90-days caused a significant decrease in the RBC count in both sexes. In addition, males at this dose level also presented with decreased hemoglobin and hematocrit levels. No other dose-related effects were observed in the hematological parameters.

Serum Chemistry. Epichlorohydrin treatment produced minimal changes in the measured clinical chemistry parameters. Creatinine levels in females at the 25 mg/kg/day dose were significantly decreased and significant decreases rn serum LDH levels were observed in females at all dose levels.

Urinalvsis. An increase in severity of urine protein grading was observed in high dose males at the termination of the study. Several animals (6/10) registered +2 (100 mg/dL) and +3 (300 mg/dL) while the controls were generally +1 (50 mg/dL) or less.

Gross Pathology. The main treatment-related changes observed at necropsy were marked thickening of the mucosal lining of the forestomach in 5 male and 3 female rats intubated with 25 mg/kg/day epichlorohydrin.

Histopathology. The only treatment-related microscopic changes observed were in the forestomach where hyperkeratosis and hyperplasia (acanthosis) were observed in both sexes receiving 5 and 25 mg/kg/day but not in the 1 mg/kg/day dose group. The incidences of these lesions were comparable between the two sexes and were clearly dose-related. The stomach lesions were characterized by a varying severity of hyperplasia with a down-growth of the mucosa and increased production of the keratin layer. The cells of the germinal layer of the mucosa were hyperchromatic and contained occasional mitotic figures. histopathologic changes observed in other tissues were considered incidental and unrelated to treatment. A variety of commonly observed spontaneous changes were present in the kidneys of male rats in both treated and control groups.

Dose descriptor:

NOAEL

Remarks:

10 day study

Effect level:

>= 3 mg/kg bw/day (actual dose received)

Sex:

female

Basis for effect level:

other: Forestomach pathologic changes noted in the 10 day study.

Remarks on result:

not determinable

Remarks:

no NOAEL identified

Dose descriptor:

LOAEL

Remarks:

10 day

Effect level:

3 mg/kg bw/day (actual dose received)

Sex:

female

Basis for effect level:

other: Forestomach pathologic changes noted in the 10 day study.

Dose descriptor:

NOAEL

Remarks:

10 day study

Effect level:

<= 3 mg/kg bw/day (actual dose received)

Sex:

male

Basis for effect level:

other: Forestomach pathologic changes noted in the 10 day study at higher dose levels

Dose descriptor:

LOAEL

Remarks:

10 day study

Effect level:

>= 7 mg/kg bw/day (actual dose received)

Sex:

male

Basis for effect level:

other: Forestomach pathologic changes noted in the 10 day study.

Dose descriptor:

NOAEL

Remarks:

90-day study

Effect level:

1 mg/kg bw/day (actual dose received)

Sex:

male/female

Basis for effect level:

other: Forestomach pathological effects noted at higher doses.

Critical effects observed:

not specified

10-Dav Toxicity Study

Mortality: No animals died during the study.

Food and Water Consumption: Water consumption was significantly increased, relative to controls, whereas food consumption was significantly decreased in both males and females receiving 46 mg/kg/day. These differences were also significant when the consumption data was calculated on a per gram body weight basis (data not shown).

Body and Organ Weights. Significant decreases in both final mean body weights and total body weight gain were observed for both sexes at the high-dose level. Minimal differences in brain, heart, liver, lung, spleen, thymus and adrenal weights were observed, although a significant (15%) increase in kidney weights was seen in females at the highest dose.

Relative Organ Weights. Significant increases (22-25%) were seen in the relative weights of the kidneys for both sexes at the two highest doses and in the relative weight of the liver at the highest dose in females and at the two highest doses for males. In addition, relative testes weights were increased in males at the highest dose. All other relative organ weights were unchanged relative to controls.

Hematology. Other than slight but significant decreases in RBC's (6.8 + 0.2 v. 6.4 + 0.3 x 10⁶/ul; malesj and reticulocyte counts (3.6 + 0.1 v. 1.7 + 0.7; females) in the high-dose groups, the clinical hematological parameters were comparable for treated and control groups.

Serum Chemistry. In males, some statistically significant changes form the control group were seen in several serurn parameters: slight decreases (not dose-related) in creatinine at the three highest doses; decreases in LDH at 7 and 46 mg/kg/day (1 399 + 440 vs. 785 + 547 & 218 + 252 U/L); and a decrease in calcium at 7 and 19 mg/kg/day, but not at the high dose. An apparent dose-related increase in glucose occurred in males with the change reaching significance at the highest dose compared to the control (113.2 + 19.4 vs. 154.3 + 32.5 mg/dl). No significant changes were seen in serum chemistries of the females.

Histopathology. The nonglandular stomach (forestomach) was clearly affected by the 10- day intubation with epichlorohydrin. The changes consisted of a range of inflammatory and epithelial alterations in both sexes. The most pronounced occurrence was of hyperplasia (acanthosis) and hyperkeratosis of the forestomach mucosa; with the exception of one male, all rats in the two highest dose group had these changes. The incidence of these changes was significantly elevated at all dose levels in the females and at doses greater than 3 mg/kg-day for males. Hyperplasia was characterized by increased thickness of the mucosa; whereas, hyperkeratosis consisted of an increased thickness of the keratin overlying the mucosa. Degeneration of the mucosa (excessive vacuolization) also occurred at the two highest dose level in both sexes. Each lesion was scored on a scale of normal to severe (1 to 4 respectively) and for both sexes the severity closely paralleled the incidence. The forestomach also exhibited inflammatory responses as evident from the infiltration of macrophages, eosinophils, lymphocytes, and plasrna cells at the two highest doses in males and the highest dose in females. These inflammatory changes appeared to be reactions to the cellular damage occurring in conjunction with the mucosal hyperplasia and hyperkeratosis. Five of the ten female rats exposed to 3 mg/kg-day exhibited at least one of these inflammatory changes. All other histopathological changes occurred with no apparent treatment relationship and were present in both treated and control groups in about equal frequency and severity.

90-Day Toxicity Study

Mortality and Clinical Signs. Dosages for the 90-day study were based on the results of the 10-day study. No animals died during the study. Clinical signs, including ophthalmoscopic diagnoses were essentially normal except for excessive salivation which was frequently observed in the high-dose group, beginning at week 2.

Food and Water Consumption. No significant differences between the treated and control groups were found for food or water consumption.

Body and Organ Weights. No significant differences were observed in total body weights; however, kidney and liver weights were increased for both sexes at 5 and 25 mg/kg/day (significant at 25 mg/kg/day). The absolute weights of the other organs in treated animals were not changed relative to those of controls.

Relative Organ Weight::. The organ-to-body (relative) weight ratios were based on the terminal body weights recorded at necropsy. A dose-related increase was seen in two organs, the kidney and liver, in both males and females at 5 and 25 mg/kg/day and these increases had statistical significance at the higher dose. The relative liver weight was increased significantly at 5 mg/kg/day only in the males. The increases in relative liver weights were comparable between the sexes, but the relative kidney weights were increased 43% in males but only 23% in females.

Hermatology. Treatment with 25 mg/kg/day epichlorohydrin for 90-days caused a significant decrease in the RBC count in both sexes. In addition, males at this dose level also presented with decreased hemoglobin and hematocrit levels. No other dose-related effects were observed in the hematological parameters.

Serum Chemistry. Epichlorohydrin treatment produced minimal changes in the measured clinical chemistry parameters. Creatinine levels in females at the 25 mg/kg/day dose were significantly decreased and significant decreases rn serum LDH levels were observed in females at all dose levels.

Urinalvsis. An increase in severity of urine protein grading was observed in high dose males at the termination of the study. Several animals (6/10) registered +2 (100 mg/dL) and +3 (300 mg/dL) while the controls were generally +1 (50 rng/dL) or less.

Gross Pathology. The main treatment-related changes observed at necropsy were marked thickening of the mucosal lining of the forestomach in 5 male and 3 female rats intubated with 25 mg/kg/day epichlorohydrin.

Histopathology. The only treatment-related microscopic changes observed were in the forestomach where hyperkeratosis and hyperplasia (acanthosis) were observed in both sexes receiving 5 and 25 mg/kg/day but not in the 1 mg/kg/day dose group. The incidences of these lesions were comparable between the two sexes and were clearly dose-related. The stomach lesions were characterized by a varying severity of hyperplasia with a down-growth of the mucosa and increased production of the keratin layer. The cells of the germinal layer of the mucosa were hyperchromatic and contained occasional mitotic figures. histopathologic changes observed in other tissues were considered incidental and unrelated to treatment. A variety of commonly observed spontaneous changes were present in the kidneys of male rats in both treated and control groups.

Conclusions:

Based on the data presented, a lowest observable adverse effect level (LOAEL) for oral exposure of Sprague-Dawley rats to epichlorohydrin is 3 mg/kg/day for 10 days and 1 mg/kg/day is the no observed adverse effect level (NOAEL) for a 90 day oral exposure. These conclusions were the same whether the lesions were analyzed for each sex individually or whether the data in each study was pooled.

Executive summary:

Adult male and female Spragile-Dawley rats received epichlorohydrin via gavage in distilled water for 10 consecutive days at dose levels of 3, 7, 19, and 46 mg/kg/day, and for 90 days at dose levels of 1, 5, and 25 mg/kg/day. Epichlorohydrin did not adversely effect mortality, but toxicity, at the higher doses, was evident by: 1) losses in body weight gain and organ weights, 2) reductions in food and water consumption, and 3) in the hematological and microscopic examinations in both study periods. Significant decreases in erythrocyte count, hemoglobin, and hematocrit levels were found in the high dose level in males after 10 and 90 days. Dose-related increases in kidney and liver weights were observed in both sexes at 25 mg/kg/day in the 90-day study and in various organs for both 19 and 46 mg/kg/day in the 10-day study. Histopathological examination identified the forestomach as the primary target organ for both sexes and in both studies with significant dose-related increases in mucosal hyperplasla (acanthosis) and hyperkeratosis. Based on the data presented, a lowest observable adverse effect level (LOAEL) for oral exposure of Sprague-Dawley rats to epichlorohydrin is 3 mg/kg/day for 10 days and 1 mg/kg/day is the no observed adverse effect level (NOAEL) for a 90 day oral exposure. These conclusions were the same whether the lesions were analyzed for each sex individually or whether the data in each study was pooled.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

1 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not specified

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study was conducted prior to advent of GLP.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

GLP compliance:

no

Limit test:

no

Species:

other: rat and mice

Strain:

other: rats- Fischer 344 and Sprague-Dawley; mice- B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

Fischer 344 rat: 9-11 weeks old from Charles River Laboratories, Wilmington, Massachusetts, males 205-219 g, females 125-139 g.
Sprague-Dawley rat: 9-11 weeks old from Spartan Research Animals, Haslett, Michigan, males 357-376 g, females 236-245 g.
B6C3F1 mouse: 7-9 weeks old from Charles River Laboratories, Wilmington, Massachusetts, males 20-27 g, females 20-22 g.
(age of the animals is age at time of initial exposure to epichlorohydrin)

Upon receipt, all animals were randomized from a single lot for each sex, species and/or strain, using a statistical randomization procedure generated from a digital computer program (GRAND. CLIST, Computations Research Laboratory, Dow Chemical U.S.A.). For each species and strain, twenty males and twenty females were assigned to each of three exposure groups and a control group. All animals were acclimated to the laboratory environment for approximately three weeks prior to exposure.

Mice were individually housed in suspended wire mesh cages. Rats were housed in groups of 3 or 4 per cage in suspended wire mesh cages. All animals were housed in the exposure, chambers during nonexposure periods. Solid food (Laboratory Animal Chow, Ralston Purina) was not available during exposure but was otherwise available ad libitum. Water was available at all times from an automatic watering system. All exposure chambers were maintained on a twelve-hour light and dark cycle.

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: not applicable

Details on inhalation exposure:

Whole-body vapor exposures were carried out in 14.5 cubic meter chambers. Atmospheres were generated by metering liquid through a pump into a warmed vaporization flask (120C), then sweeping the vapors into the chamber with compressed air. Total airflow through the chambers was approximately 3000 liters/minute.

The chambers are designed to operate under dynamic airflow conditions with temperature maintained at approximately 70-75°F and relative humidity maintained at approximately 40-60%. The exposures were carried out between the hours of 8 a.m. and 5 p.m. on Monday through Friday except during holidays.

The nominal concentrations of epichlorohydrin vapor in the exposure chambers were determined daily from the ratio of the rate at which the liquid was dispensed to the rate of airflow through the chambers.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Chamber air was assayed for vapor concentration at least 3 times during each 6-hour exposure period. Epichlorohydrin in all chambers was assayed by gas chromatography.

One-milliliter air samples were injected onto a 6'x1/8" O.D. stainless steel column packed with 10% UCW-98 on 80/100 Mesh Chromosorb P. The column and gas sample loops were housed in a Model 2440 gas chromatograph (Varian Associates, Palo Alto, California) equipped with hydrogen flame ionization detectors. The gas sample loops and column were maintained at 115°C, while the detector temperature was 230°C. Standards for the analysis were prepared by injecting a known volume of liquid epichlorohydrin into a Saran bag filled with a measured amount of filtered compressed air. Standard curves bracketing the entire range of exposure concentrations were prepared weekly. A single calibration standard (25 ppm) was run each exposure day.

Duration of treatment / exposure:

6 hours/day

Frequency of treatment:

5 days/week for 87 days (males) or 88 days (females)

Remarks:

Doses / Concentrations:
0, 5, 25, 50 ppm (0, 18.9, 94.5, 189 mg/m3)
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
0, 5.01 +/- 0.42, 24.90 +/- 0.94, 50.10 +/- 1.60 ppm
Basis:
analytical conc.

No. of animals per sex per dose:

20/sex/dose of each species and or strain

Control animals:

yes, concurrent no treatment

Details on study design:

For each species and strain, groups of 20 animals per sex per dose level were exposed to 0, 5, 25, or 50 ppm six hours daily, five days per week, for approximately 12 weeks (87 days, males; 88 days, females).

Additional male and female Fischer 344 rats were simultaneously exposed and used for supplementary studies. Ten rats/sex/exposure level and
control were used for bone marrow cytogenetic evaluation (Dow Chemical Co., 1979a). An additional five male Fischer 344 rats and B6C3F1 male mice/exposure level and control were added for pharmacokinetic/metabolism studies following repeated exposure (Dow Chemical Co., 1979b). These rats and mice were removed from the study at various time intervals during the 90-day portion of the study.

Dow Chemical Co., (1979a). Epichlorohydrin - Subchronic Studies. III. Cytogenetic evaluation of bone marrow cells from rats exposed to epichlorohydrin for four weeks. Sponsored by Manufacturing Chemists Association.

Dow Chemical Co., (1979b). Pharmacokinetics of epichlorohydrin (EPI) administered to rats by gavage or inhalation. Toxicology Research Laboratory,
Sponsored by Manufacturing Chemists Association.

Positive control:

No

Observations and examinations performed and frequency:

Animals were observed daily for signs of toxicity and morbidity/mortality. Body weights were collected twice weekly for the first two weeks of exposure, weekly for weeks three and four, and every two weeks thereafter.

Feed/water consumption were not monitored during the study. Ophthalmoscopic examinations were not performed during the study.

Sacrifice and pathology:

One to two weeks prior to necropsy (rats) or at necropsy (mice), blood samples were collected for hematologic analysis. Parameters examined were packed cell volume, red blood cell count, hemoglobin concentration, and white blood cell count. Urinalysis samples from rats were collected when blood samples were collected; parameters examined were specific gravity, pH, sugar, protein, ketones, bilirubin, occult blood, urobilinogen.

At necropsy, blood samples were collected for analysis of clinical chemistry parameters: blood urea nitrogen, glutamic pyruvic transaminase activity, alkaline phosphatase activity, glutamic oxaloacetic transaminase activity, and glucose concentration.

A complete necropsy examination was conducted on each animal, during which organ weights for brain, heart, liver, kidneys, testes, spleen, and thymus were recorded. With the exception of testes and epididymides of all male rats and mice which were in Bouin's solution and eyes from 5 rats and 5 mice/sex/groupat each necropsy which were preserved in Zenker's fixative, all tissues were fixed in buffered 10% formalin. Approximately 40 organs/tissues (esophagus, stomach, small intestine, pancreas, mediastinal lymphoid tissue (thymus, mediastinal lymph nodes), urinary bladder, heart, testes, ovaries, uterus, gall bladder, pituitary gland, salivary glands, lungs, vertebral bone and bone marrow, spinal cord, spleen, kidneys, prostate, epididymides, skeletal tissue, oviducts, parathyroid gland, brain, skin, eyes, trachea, nasal turbinates, large intestine, liver, lymph nodes, seminal vesicles, aorta, adrenal gland, thyroid gland, mammary gland, adipose tissue, peripheral nerve) from each animal were examined histologically for the control and high dose groups; possible target organs were examined for low and middle dose groups. For the nasal turbinates, the nasal turbinates and vertebral bone were decalcified and three to four transverse sections were obtained from the nasal turbinate region. Sections of regions lined primarily by respiratory epithelium, transitional epithelial region and olfactory epithelium were examined.

After thirty days on test, an interim sacrifice was conducted on 10 animals per sex per dose level. Parameters evaluated were hematology, urinalysis (rats only), clinical chemistry, gross pathology, organ weights, and histopathology. Histopathology was conducted on five animals per sex per dose level from the control and high dose groups.

Other examinations:

not applicable

Statistics:

Body weights, hematology, urinalysis, clinical chemistries, and organ weights were analyzed via ANOVA with Dunnetts Test, p< 0.05.

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

Terminal white blood cell counts in male Fischer 344 rats were statistically decreased from controls only at 5 ppm. At 5 ppm, interim and terminal kill white blood cell counts in female Sprague Dawley rats were statistically identified as different from controls. Terminal SGOT values for male Fischer 344 rats at 5 ppm only were statistically lower than controls. Interim kill BUN values in male B6C3F1 mice and AP values in female B6C3F1 mice were statistically different from controls at 5 ppm, but were not different from controls at the terminal kill. Urine specific gravity was statistically decreased in female Fischer 344 rats at 5 ppm on test day 73, but not at study termination. Interim (day 30) absolute kidney and testes weights in male Fischer 344 rats at 5 ppm were statistically increased, but relative kidney and testes weights were unaffected. Terminal absolute kidney weights in male Sprague-Dawley rats at 5 ppm were statistically increased, but relative kidney weights were unaffected. Interim (day 30) absolute and relative liver weights in male and female B6C3F1 mice at 5 ppm were statistically decreased; this effect was not seen at study termination. Terminal spleen weights in female B6C3F1 mice at 5 ppm were statistically increased; this effect was not seen at higher exposure concentrations. Since neither dose-response nor temporal patterns were consistently present, all of the differences described above were not considered treatment-related.

ACTUAL DOSE RECEIVED:
Analysis of chamber air for epichlorohydrin found the concentrations (mean +/- SD) to be 5.01 +/- 0.42, 24.90 +/- 0.94, 50.10 +/- 1.60 ppm.
No treatment-related deaths were observed at any dose level.

TOXIC RESPONSE/EFFECTS:
Clinical Observations (Fischer 344 and Sprague-Dawley rats, B6C3F1 mice): During the hours of exposure, the rats appeared to show conjunctival redness and palpebral closure without subsequent evidence of ocular involvement. These effects appeared to be transient, with recovery occurring overnight. Slight decreases in cage movements were observed in rats exposed to 25 or 50 ppm primarily during the first ten days of exposure and intermittently thereafter. These effects were not observed in mice.

FISCHER 344 RATS
Body Weights: Female Fischer 344 rats exposed to 50 ppm showed statistically decreased body weights on day zero which tended to remain lower throughout the study. Female Fischer 344 rats exposed to 25 ppm occasionally showed decreased body weights during the first month of exposure, but not at study termination.

Clinical Chemistry: No treatment-related changes in clinical chemistries were found in Fischer 344 rats.

Hematology: No treatment-related changes in hematology were found in Fischer 344 rats.

Urinalysis: No treatment-related changes in urinalysis parameters were found in Fischer 344 rats.

Organ Weights: Absolute and/or relative kidney weights were increased in male and female Fischer 344 rats at 25 and 50 ppm at interim and terminal examinations. Various other changes in organ weights were judged to be unrelated to treatment.

Gross Pathology: No lesions were observed which were considered treatment-related.

SPRAGUE-DAWLEY RATS
Body Weight: Male Sprague-Dawley rats exposed to 50 ppm showed statistically decreased body weights during the first month which tended to remain lower throughout the study. There were no treatment-related changes in body weights for female rats.

Clinical Chemistry: No treatment-related changes in clinical chemistries were found in Sprague-Dawley rats.

Hematology: No treatment-related changes in hematology were found in Sprague-Dawley rats.

Urinalysis: No treatment-related changes in urinalysis parameters were found in Sprague-Dawley rats.

Organ Weights: Absolute and/or relative kidney weights were increased in male and female Sprague-Dawley rats at either 25 or 50 ppm at interim and terminal examinations. Various other changes in organ weights were judged to be unrelated to treatment.

Gross Pathology: Kidneys in male Sprague-Dawley rats exposed to 25 or 50 ppm were slightly pale in color and increased in size at study termination. Livers in male Sprague-Dawley rats exposed to 50 ppm exhibited a slight accentuated lobular pattern with a pale color at study termination. No other lesions were observed which were considered treatment-related in either male or female Sprague-Dawley rats.

B6C3F1 MICE
Body Weight: Male and female B6C3F1 mice exposed to 50 ppm showed a trend toward decreased weight during the last few weeks of the study, occasionally identified as statistically significant.

Clinical Chemistry: No treatment-related changes in clinical chemistries were found in B6C3F1 mice.

Hematology: No treatment-related changes in hematology were found in B6C3F1 mice.

Organ Weights: Interim (day 30) absolute and relative liver weights in male mice at 5 and 50 ppm were statistically decreased; this effect was not seen at study termination. Male mice at 50 ppm had statistically significantly increased relative brain weights at study termination. Interim (day 30) absolute and/or relative liver weights in female mice at 5, 25, and 50 ppm were statistically decreased; this effect was not seen at study termination. Absolute heart weight was also decreased in female mice at 50 ppm; this effect was not seen at study termination.

Gross Pathology: At study termination, male mice (and one female mouse) at 50 ppm had decreased intraabdominal fat, consistent with decreased body weight. No other lesions were observed which were considered treatment-related in either male or female mice.

Histopathology (Fischer 344 and Sprague-Dawley rats, B6C3F1 mice): Histopathological examinations showed that the nose was the most sensitive organ to exposure. At the higher concentrations microscopic examination revealed hyperplasia, metaplasia and inflamed cell infiltration in the nasal turbinates. In addition, exposure at 25 or 50 ppm caused slight non-progressive kidney effects in rats but not mice, as evidenced by increased kidney weights (relative and/or absolute). Slight non-degenerative liver effects were noted in rats of both strains as well as the mice exposed to 50 ppm. Male rats of both strains at 50 ppm had slight effects on the adrenal glands, possibly mediated by stress. In male Sprague-Dawley rats at 50 ppm, there were minimal changes in the contents of the epididymides.

Dose descriptor:

NOAEL

Effect level:

5 ppm

Sex:

male/female

Basis for effect level:

other: For all species and strains.

Dose descriptor:

LOAEL

Effect level:

25 ppm

Sex:

male/female

Basis for effect level:

other: For all species and strains pathological changes were noted in the nasal epithelium.

Critical effects observed:

not specified

FISCHER 344 RATS The most consistent and readily recognized treatment-related effect observed in both male and female Fischer 344 rats was in the nasal turbinates. There were inflammatory, degenerative, and reactive changes in the epithelium in rats exposed to 25 or 50 ppm epichlorohydrin. The lesions within the nasal turbinates were exposure concentration related in severity in both male and female rats. However, the changes in the nasal turbinates of males were generally more severely involved than the females, at both the interim and the terminal kill. These changes were interpreted to be a result of irritation caused by inhaling the test material. There were no treatment-related changes detected in the nasal turbinates of rats exposed to 5 ppm epichlorohydrin.

There were slight decreases in body weight gain noted in the 50 ppm males and the 25 ppm females. The 50 ppm females frequently showed a statistically significantly decreased body weight compared to the controls. However, this difference was present from day 0 onward, and the relative difference in weight between the controls and 50 ppm group did not change during the course of the study. These minimal effects upon the weight gain of the male and female rats may be a result of the irritation in the nasal turbinates resulting in decreased food consumption. These observations were noted to be accentuated when rats and mice were exposed to 100 ppm epichlorohydrin by the inhalation route.

Treatment-related effects were observed in the liver and kidneys of male and female rats from the 25 or 50 ppm groups at either the interim or terminal kill. These were observed as either minimal changes in organ weight or organ to body weight ratios. Based upon gross pathology and histopathology there were treatment-related effects detected in these organs only at the 50 ppm level. The changes observed in these organs were of a minimal degree and did not result in alterations of hematology, clinical chemistry or urinalysis parameters which were considered treatment related. In addition, the changes affecting these organs did not increase in severity from the 30 to 90-day kill which suggests a lack of progression of the effects upon repeated exposure. Clinical observations which would suggest treatment-related toxicity were not detected during the course of the study.

The adrenal glands of some 50 ppm male rats from the terminal kill showed slight microvacuolation of cells in the zona fasciculata, a possible stress response.

There were no toxicologically significant treatment-related effects detected in the 5 ppm group of male or female Fischer 344 rats. The following parameters were evaluated in this study and were interpreted to be unaffected at the 5 ppm level of exposure: clinical observations, body weight, hematology, urinalysis, clinical chemistry, fasted body, weight, organ weights, organlbody weight ratios, gross pathology, and histopathology.

SPRAGUE-DAWLEY RATS The most consistent and readily recognized treatment-related effect in both male and female Sprague-Dawley rats was in the nasal turbinates. There were inflammatory, degenerative, and reactive changes in the epithleium in rats exposed to 25 or 50 ppm epichlorohydrin. The lesions within the nasal turbinates were exposure concentration related in severity in both male and female rats. However, the nasal turbinates of males were generally more severely involved than the females, at both the interim and terminal kill. These changes were interpreted to be a result of irritation caused by inhaling the test material. In general, the inflammatory and degenerative changes noted in the turbinates of the Sprague-Dawley rats appeared more severe than in the Fischer 344 rats. There were no treatment-related changes detected in the nasal turbinates of rats exposed to 5 ppm epichlorohydrin.

There was a slight decrease in body weight gain in the 50 ppm male rats during the first month of the study. No other groups of male or female rats showed any significant changes in weight gain. These minimal effects upon weight gain of 50 ppm males may be a result of irritation in the nasal turbinates resulting in decreased food consumption. These observations were noted to be accentuated when rats and mice were exposed to 100 ppm epichlorohydrin by the inhalation route.

Treatment-related effects were observed in the liver and kidneys of male and female rats from the 25 or 50 ppm groups at either the interim or terminal kill. These were observed as either minimal changes in organ weight, prgan to body weight ratios, or gross pathology. Based upon histopathology there were treatment-related effects detected in these organs only at the 50 ppm level. The changes observed in these organs were of a minimal degree and did not result in alterations of hematology, clinical chemistry or urinalysis parameters which were considered treatment related. In addition, the changes in these organs were less remarkable at the terminal kill than at the interim kill which suggests a lack of progression of the effects upon repeated exposure. Clinical observations which would suggest treatment-related toxicity were not detected during the course of the study.

The adrenal glands of some 50 ppm male rats from the terminal kill showed slight microvacuolation of cells in the zona fasciculata, a possible stress response. In addition, in the epididymides of several male rats from the 50 ppm group there was normal sperm content present with either increased numbers of nucleated cells and/or amorphous eosinophilic staining material within the lumen.

There were no toxicologically significant treatment-related effects detected in the 5 ppm, group of male or female Sprague-Dawley rats. The following parameters were evaluated in this study and were interpreted to be unaffected at the 5 ppm level of exposure: clinical observations, body weight, hematology, urinalysis, clinical chemistry, fasted body weight, organ weiglits, organ/body weight ratios, gross pathology, and histopathology.

B6C3F1 MICE The most consistent and readily recognized treatment-related effect in both male and female B6C3F1 mice was in the nasal turbinates. There were inflammatory, degenerative, and reactive changes in the epithelium in mice exposed to 25 or 50 ppm epichlorohydrin. The lesions within the nasal turbinates were exposure concentration related in severity in both male and female mice.

Both male and female mice from the 50 ppm group showed a trend towards decreased weight gain. These minimal effects upon weight gain noted may be a result of irritation in the nasal turbinates resulting in decreased food consumption. These observations were noted to be accentuated when rats and mice were exposed to 100 ppm epichlorohydrin by the inhalation route. Evaluation of gross pathology, histopathology, hematology, and clinical chemistry data from the interim and terminal kills do not reveal any treatment-related changes suggestive of liver or kidney toxicity. A slight decrease in liver weight was observed in all groups from the interim kill; however, the liver weight was normal at the terminal kill. The decreased liver weight observed at the interim kill was not associated with histopathology suggestive of hepatotoxicity, but rather it was suggestive of a decreased food intake. These observations for the liver weight were consistent with the.slightly lighter body weight of the exposed mice at the interim kill compared to the controls. One very significant species difference was noted in the kidneys of mice when compared to rats exposed to epichlorohydrin. The mice did not show any kidney weight changes or histopathology compared to the changes noted in both Fischer 344 and Sprague-Dawley rats. There were no toxicologically significant treatment-related effects detected in the 5 ppm group of male or female B6C3F1 mice. The following parameters were evaluated in this study and were interpreted to be unaffected at the 5 ppm level of exposure: clinical observations, body weight, hematology, clinical chemistry, absolute organ weights, organ/body weight ratios, gross pathology, and histopathology.

Conclusions:

The results of this sub chronic study indicate that both strains of rats as well as mice exposed to 25 or 50 ppm of epichlorohydrin consistantatly had substantial changes in the epithelium nasal turbinates. Lesser effects in the other tissues also occurred at these exposure levels, but with some variation in response. Rats of both strains as well as the mice exposed to 5 ppm of epichlorohydrin had no adverse effects in any of the parameters monitored in these studies.

Executive summary:

The subchronic toxicity of epichlorohydrin was studied in 2 strains of rats (Fischer 344 and Sprague-Dawley) and 1 strain of mouse (B6C3F1). Inhalation exposures of 0, 5, 25, and 50 ppm of epichlorohydrin were conducted 6 hours/day, 5 days/week for 3 months, with an interim kill after 1 month.

Inhalation of 5 ppm of epichlorohydrin did not result in toxicologically significant effects in the rats or mice as measured by clinical observations, body weights, hematology, urinalysis, clinical chemistry, organ weights, gross pathology and histopathology examination of tissues.

However, in both strains of rats and in the mice, inhalation of 25 or 50 ppm of epichlorohydrin caused multiple treatment-related effects; the most consistent and readily detectable of which were degenerative, inflammatory and reactive histopathologic changes in the epithelium of the nasal turbinates. These changes were observed with some degree of species and strain variability. The lesions in the nasal turbinates were most severe in the Sprague-Dawley rats and least severe in the B6C3F1 mice with Fischer 344 rats being intermediate in severity.

Additional treatment-related effects at both these exposure levels included slight nonprogressive kidney effects observed in rats of both strains, but not mice. Slight nondegenerative liver effects were noted in rats of both strains as well as the mice exposed to 50 ppm of epichlorohydrin. Male rats of both strains exposed to 50 ppm of epichlorohydrin also had slight effects in the adrenal gland, possibly mediated via stress. In male Sprague-Dawley rats exposed to 50 ppm of epichlorohydrin there were minimal changes in the content of the epididymides. These toxic effects were accompanied by some slight indications of decreased body weight gain in rats of both strains and the mice exposed to 50 ppm of epichlorohydrin as well as the female Fischer 344 rats exposed to 25 ppm of epichlorohydrin.

In summary, the results of this subchronic study indicate that both strains of rats as well as mice exposed to 25 or 50 ppm of epichlorohydrin consistently had substantial changes in the epithelium of the nasal turbinates. Lesser effects in other tissues also occurred at these exposure levels, but with some variation in response. Rats of both strains as well as the mice exposed to 5 ppm of epichlorohydrin had no adverse effects in any of the parameters monitored in these studies.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEC

95 mg/m³

Study duration:

subchronic

Species:

rat

System:

respiratory system: upper respiratory tract

Organ:

other: nasal epithelium

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The lowest observable adverse effect level (LOAEL) for oral exposure of Sprague-Dawley rats to epichlorohydrin was 3 mg/kg/day for 10 days and 1 mg/kg/day was the no observed adverse effect level (NOAEL) for a 90 day oral exposure. These conclusions were the same whether the lesions were analyzed for each sex individually or whether the data in each study was pooled.

The NOAEC was 19 mg/m³ in the 90 day inhalation study in mice and two strains of rats. At higher concentrations, histopathologic changes were noted in the nasal epithelium and, to a lesser degree, in livers and kidneys.

In both the oral and inhalation studies, effects were mainly observed at the portal of entry; this constitutes a local effect. Slight histologic changes to the liver and kidneys constitute systemic effects.

 

Repeated dose toxicity via oral route

Adult male and female Spragile-Dawley rats received epichlorohydrin via gavage in distilled water for 10 consecutive days at dose levels of 3, 7, 19, and 46 mg/kg/day, and for 90 days at dose levels of 1, 5, and 25 mg/kg/day. Epichlorohydrin did not adversely effect mortality, but toxicity, at the higher doses, was evident by: 1) losses in body weight gain and organ weights, 2) reductions in food and water consumption, and 3) in the hematological and microscopic examinations in both study periods. Significant decreases in erythrocyte count, hemoglobin, and hematocrit levels were found in the high dose level in males after 10 and 90 days. Dose-related increases in kidney and liver weights were observed in both sexes at 25 mg/kg/day in the 90-day study and in various organs for both 19 and 46 mg/kg/day in the 10-day study. Histopathological examination identified the forestomach as the primary target organ for both sexes and in both studies with significant dose-related increases in mucosal hyperplasia (acanthosis) and hyperkeratosis. Based on the data presented, a lowest observable adverse effect level (LOAEL) for oral exposure of Sprague-Dawley rats to epichlorohydrin is 3 mg/kg/day for 10 days and 1 mg/kg/day is the no observed adverse effect level (NOAEL) for a 90 day oral exposure. These conclusions were the same whether the lesions were analyzed for each sex individually or whether the data in each study was pooled.

Epichlorohydrin is a direct-acting alkylating agent and an irritant, and, therefore, the target organ is dependent upon the route of exposure. The tissue distribution of epichlorohydrin closely follows that expected of a reactive chemic. For example, Smith et al., observed high local concentrations in the nasal turbinates after inhalation exposure and in the gastrointestinal tract upon ingestion. Thus, the forestomach pathology observed in this study is consistent with the known site-directed reactivity/toxicity of epichlorohydrin.

 

Repeated dose toxicity via inhalation

The short term toxicity of epichlorohydrin was studied in 2 strains of rats (Fischer 344 and Sprague-Dawley) and 1 strain of mouse (B6C3Fl). Inhalation exposure to 0 or 100 ppm of epichlorohydrin was conducted 7 hours/day, 5 days/week for a total of 9 exposures in 12 days. The objectives of this study were (1) to more definitively characterize the possible target-tissue effects following repeated exposure to a higher concentration of epichlorohydrin than previously studied and (2) to evaluate early changes in the nasal turbinates at the level of exposure reported previously by another laboratory to result in tumors of the nasal turbinates.

Multiple effects were associated with repeated exposure to 100 ppm of epichlorohydrin. These included clinical evidence of nasal irritation, decreased body weight gain, leukocytosis secondary to nasal inflammation, decreased specific gravity of urine (hematologic and urinary examination conducted only on rats), and increased kidney weights in rats, but not mice.

Upon histopathologic examination of tissues, the most consistent and readily detectable changes were present in the nasal turbinates, with degeneration, inflammation, hyperplasia and squamous metaplasia present to some degree in all exposed rats and mice. These changes were more severe than noted in the rats and mice used in a 90-day subchronic study previously conducted in this laboratory. Slight degenerative changes were noted in the kidneys of both strains of rats, but not the mice. Slight nondegenerative liver effects and thymic atrophy, both secondary to stress, were noted in rats and mice. Male rats of both strains (but not the mice) had slight changes in the contents of the epididymides. Male Sprague-Dawley rats had slight changes in the adrenal glands, possibly secondary to stress. In general, there was a decreasing order of toxicity observed as follows: Sprague-Dawley rats, Fischer 344 rats, and B6C3F1 mice.

In summary, the results of this short-term study indicate that subsequent to an exposure (concentration of 100 ppm epichlorohydrin, the most consistent target tissue for both rats and mice was the nasal turbinates, which showed substantial changes in the epithelium. Additional effects included kidney toxicity in rats, but not mice, as well as effects in other tissues considered stress related. These data are interpreted to indicate that repeated exposure to 100 ppm epichlorohydrin exceeds the maximal tolerated dose for conducting long-term chronic toxicity studies in these species.

 

The subchronic toxicity of epichlorohydrin was studied in 2 strains of rats (Fischer 344 and Sprague-Dawley) and 1 strain of mouse (B6C3F1). Inhalation exposures of 0, 5, 25, and 50 ppm of epichlorohydrin were conducted 6 hours/day, 5 days/week for 3 months, with an interim kill after 1 month.

Inhalation of 5 ppm of epichlorohydrin did not result in toxicologically significant effects in the rats or mice as measured by clinical observations, body weights, hematology, urinalysis, clinical chemistry, organ weights, gross pathology and histopathology examination of tissues.

However, in both strains of rats and in the mice, inhalation of 25 or 50 ppm of epichlorohydrin caused multiple treatment-related effects; the most consistent and readily detectable of which were degenerative, inflammatory and reactive histopathologic changes in the epithelium of the nasal turbinates. These changes were observed with some degree of species and strain variability. The lesions in the nasal turbinates were most severe in the Sprague-Dawley rats and least severe in the B6C3F1 mice with Fischer 344 rats being intermediate in severity.

Additional treatment-related effects at both these exposure levels included slight nonprogressive kidney effects observed in rats of both strains, but not mice. Slight nondegenerative liver effects were noted in rats of both strains as well as the mice exposed to 50 ppm of epichlorohydrin. Male rats of both strains exposed to 50 ppm of epichlorohydrin also had slight effects in the adrenal gland, possibly mediated via stress. In male Sprague-Dawley rats exposed to 50 ppm of epichlorohydrin there were minimal changes in the content of the epididymides. These toxic effects were accompanied by some slight indications of decreased body weight gain in rats of both strains and the mice exposed to 50 ppm of epichlorohydrin as well as the female Fischer 344 rats exposed to 25 ppm of epichlorohydrin.

In summary, the results of this subchronic study indicate that both strains of rats as well as mice exposed to 25 or 50 ppm of epichlorohydrin consistently had substantial changes in the epithelium of the nasal turbinates. Lesser effects in other tissues also occurred at these exposure levels, but with some variation in response. Rats of both strains as well as the mice exposed to 5 ppm of epichlorohydrin had no adverse effects in any of the parameters monitored in these studies.

 

 

 

 

Justification for classification or non-classification

Because effects noted in studies constituted portal of entry effects, and irritancy is already documented in acute classification, no additional classification is proposed.