Registration Dossier

Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
fertility, other
Remarks:
based on test type (migrated information)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
not specified
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No data on GLP but the report meets generally accepted scientific standards and contains sufficient data for interpretation of study results.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1989

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Male fertility was assessed by examining mating behavior, fertility tests, ejaculated and epididymal sperm parameters

Female fertility was assessed by dosing females with ECH for 2 weeks prior to mating with unexposed males. Dams were allowed to deliver their young and the young were raised to postnatal day 21 (with one male and one female pup sacrificed on postnatal day 42).
GLP compliance:
not specified
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
1-chloro-2,3-epoxypropane
EC Number:
203-439-8
EC Name:
1-chloro-2,3-epoxypropane
Cas Number:
106-89-8
Molecular formula:
C3H5ClO
IUPAC Name:
2-(chloromethyl)oxirane
Details on test material:
99+% purity, Aldrich Chemical

Test animals

Species:
rat
Strain:
Long-Evans
Sex:
male/female
Details on test animals or test system and environmental conditions:
Long-Evans hooded rats were received from Charles River Breeding Laboratories (Portage, MI). On arrival, males (80-90 days old) and females (70-80 days old) were maintained on Purina Lab Chow 5001 and tap wa ter ad libitum. Animal rooms were maintained at approximately 25°C and 55% humidity. Males were singly housed in stainless-steel hanging cages. Females were housed three to a cage until pregnant, when they were transferred to individual shoebox cages. All animals were allowed to adapt for 2 to 3 weeks before beginning treatment. They were assigned to treatment groups such that mean body weights were the same across groups. The animals were weighed on alternate days (except pregnant females which were weighed daily).

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
Concentrations were adjusted so that animals received 1 ml solution per kilogram of body weight. Dosing solutions were made fresh weekly and stored in the refrigerator. Chemical analyses showed that these solutions were stable for this period (Weiss, 1970).

Male Reproductive Protocol
Treated males and the females mated to these males were kept on a 14: 10 reverse light-dark cycle with lights on at 2000 hr. This schedule facilitated evaluation of mating behavior (see below).

The results of pilot studies indicated that 100 mg/kg epichlorohydrin given for 15 days resulted in severe toxicity in male rats (weight loss, nephrosis, testicular edema, epididymal granulomas, decreased testicular and epididymal sperm counts). Treatment levels for the expanded study were, therefore, set at 0, 12.5.25, and 50 mg/kg body wt (n = 20/group). Animals were treated beginning at 0900 hr for 21 consecutive days to evaluate the effects of epichlorohydrin on epididymal spermatozoa and late-stage spermatids. Following the treatment regimen, mating behavior was studied, fertility tests were conducted, necropsy data were obtained, and ejaculated and epididymal sperm parameters were evaluated.

Males received five or six mating experiences in their home cages over a 3-week period preceding the initiation of treatment. At these times, an ovariectomized, hormonally primed female was placed with the male for approximately 3 hr. Males received additional mating experience with ovariectomized females throughout treatment to ensure mating proficiency. Males were also allowed to acclimate in Plexiglas observation cages severa1 times prior to the conduct of the actual behavioral at the end of the third week of treatment. At that time, males were placed in Plexiglas cages and 15 min later a hormonally primed female was introduced. Observations took place during the dark cycle (1300-1600 hr) using a red light for illumination. Mount latency period, number of mounts and intromissions, and ejaculation latency period were recorded (Zenick et a[.. 1984). Ten minutes after the single ejaculation, the mated female was sacrificed and the semen recovered from the reproductive tract. The ejaculated semen sample was for sperm motility and morphology and sperm count. Copulatory plug weight, an indicator of androgen status, was also recorded. The protocol followed pre-reported methods (Zenick et al., 1984).

Two days after copulatory and semen assessments, an intact female in proestrus was placed in the male's cage and allowed to cohabit overnight (0 and 50 mg/kg groups only). Day 1 of pregnancy was established by presence of a copulatory plug or sperm in the vagina. Males were allowed 5 days to mate, with a different proestrous female introduced each day until each male had copulated successfully with one female. Females were sacrificed on Day 15 of pregnancy and corpora lutea, implantations, and resorptions were counted.

Males were sacrificed 48 hr after successful mating. This 2-day lapse allowed replenishment of epididymal reserves that may have been depleted in the mating trial. At sacrifice the following organs were excised and weighed: liver, kidney, adrenals, spleen, heart, testes, accessory organs (prostate and seminal vesicles), vas deferens, and epididymis. One testis was homogenized in a Triton-X-100 solution (0.01% Triton-X-100 in 0.9% saline) to obtain spermatid counts. The cauda of one epididymis w as minced, filtered, and processed for sperm counts and sperm morphology (Zenick el al., 1984).

For the measurement of cauda epididymal sperm motion, an additional group of animals was used at each dose level. Conditions for dosing of the males were identical to those listed above, except that all animals were sacrificed 2 days after the last day of dosing (sacrifice on Day 23). a time corresponding to the first mating for the group of males from the initial portion of this study. Testis and epididymis weights and manually determined cauda epididymal sperm counts (using a hemocytometer) were also measured. Sperm motion parameters were measured with the CellSoft (CRY0 Resources, Ltd., New York) computer-assisted sperm motion analysis system. Percentages of motile sperm were determined both visually from playback of videotapes and with the CellSoft system and were found not to differ significantly at the settings used (unpublished data). The cauda epididymis was nicked and subsequently incubated for 3 min at 37°C in 10 ml Dulbecco's phosphate-buffered saline (+ Ca2+ and Mg2+), pH 7.2, plus 10 mg/ml bovine serum albumin (Sigma, Fraction V). An aliquot of this mixture was then diluted 10-fotct and I0 pl was placed in a Petroff-Hausser chamber (Hausser Scientific, Philadelphia, PA; (20-umdepth). Sperm motion, as viewed on an Olympus BH-2 microscope ( 12.5 power, phase contrast), equipped with a "Fryer" (Fryer Co. Inc., Carpentersville, IL) stage wanner (37"C), was videotaped and analyzed using the CellSoft instrument.

Characteristics of the motion of sperm, generated by analysis of videotapes with CellSoft computer software, included percentage motile sperm (number of sperm exceeding threshold minimum velocity/total number of sperm); curvilinear velocity (mean frame-to-frame velocity); straight-line velocity [velocity between centroids (computer-calculated centers of sperm mass) in first and last frame tracked]; linearity [(straight-line velocity/curvilinear velocity) X 101; amplitude of lateral head displacement (ALH: displacement of the centroid from a computer-calculated mean trajectory); and beat/cross frequency (frequency centroid crosses this mean trajectory). Detailed system settings are available from the author (G.P.T.). Briefly, they were frames analyzed = 15; framing rate = 30 frameslsec; maximum velocity = 1500 um/sec; threshold velocity = 20 um/sec; minimum sampling for motility = 2 frames; minimum sampling for velocity = 3 frames; minimum sampling for straight-line velocity, linearity, ALH, and beat/cross frequency = [1 frames (determined with an auxiliary computer program); minimum linearity for ALH = 3.5; pixel scale = 3.26 um/pixel; 20 fields/sample; at least 200 cells analyzed/sample. Maximum number cells/field = 40. (Pixel scale was determined empirically with an optical micrometer.)

Female Reproductive Protocol
Treated females and the males mated to these females were maintained on a 12: 12 light-dark cycle with light commencing at 0600 hr. Dosing was performed at 1300 hr.

The results of pilot studies indicated that 200 mg/kg epichlorohydrin was lethal, causing death in 10/10 animals within 48 hr of initiation of treatment. Administering epichlorohydrin for 15 days at levels of 50 and 100 mg/kg caused dose-dependent increases in liver, kidney, adrenal, and spleen organ-to-body weight ratios. In the 100 mg/kg group, 5/10 animaIs were so moribund as to warrant their sacrifice after 7-9 days treatment. The remaining 5 animals did not show weight loss or other overt toxic signs, but on sacrifice after 15 days treatment they displayed pale.and enlarged kidneys. Since half of the females treated with 100 mgfkgjday survived, this was selected as the high dose, while 25 and 50 mg/kg/day were chosen as the low and middoses, respectively. Females were dosed 5 days per week for 2 weeks prior to mating. This ensured some exposure prior to pregnancy
and permitted examination of the effects of ECH on cyclicity and copulatory behavior. During the third week of treatment, an untreated male was placed in each female cage to cohabit overnight. Presence of a plug or in the vagina established Day 1 of pregnancy, and these females were dosed daily until delivery. After one week of mating opportunities, females showing no positive signs of mating were monitored and dosed as if pregnant. Animals not delivering by Day 23 were sacrificed and examined for signs of pregnancy.

Litters were sexed and weighed on Postnatal Day 1 (day of delivery). Dams and pups were weighed weekly thereafter. At Day 4, litters were culled to 8 pups (approximately 4 male and 4 female). At Postnatal Day 2 1, dams were sacrificed and litters reduced to 1 male and I female. Weanlings were weighed weekly until sacrifice at Postnatal Day 42.



WEISS, F. T. (1970). In Determination of Organic Cormpounds: Methods and Procedures (P. J . Elving and I. M. Kolthof, Eds.), Vol. 32, pp. 200-214. Wiley-Interscience, New York.

ZENICKH, ., BLACKBURNK,., HOPE,E ., OUDIZD, ., AND GOEDENH, . (1984). Evaluating male reproductive toxicity in rodents: A new animal model. Teratogen. Carcinogen. Mutagen. 41, 109-128.
Details on mating procedure:
Male Reproductive Protocol.
Two days after copulatory and semen assessments, an intact female in proestrus was placed in the male's cage and allowed to cohabit overnight (0 and 50 mg/kggroups only). Day 1 of pregnancy was established by presence of a copulatory plug or sperm in the vagina. Males were allowed 5 days to mate, with a different proestrous female introduced each day until each male had copulated successfully with one female. Females were sacrificed on Day 15 of pregnancy and corpora lutea, implantations, and resorptions were counted.

Female Reproductive Protocol
Females were dosed 5 days per week for 2 weeks prior to mating. This ensured some exposure prior to pregnancy and permitted examination of the effects of ECH on cyclicity and copulatory behavior. During the third week of treatment, an untreated male was placed in each female cage to cohabit overnight. Presence of a plug or in the vagina established Day 1 of pregnancy, and these females were dosed daily until delivery. After one week of mating opportunities, females showing no positive signs of mating were monitored and dosed as if pregnant. Animals not delivering by Day 23 were sacrificed and examined for signs of pregnancy.
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
no information available
Duration of treatment / exposure:
daily
Frequency of treatment:
5 days/week for 14 days (females) or 21 days (males) prior to mating trials with untreated animals
Treated females were further dosed until delivery.
Details on study schedule:
Fertility was assayed only in high dose males.
Doses / concentrations
Remarks:
Doses / Concentrations:
Males: 0, 12.5, 25, 50 mg/kg/day; Females: 0, 25, 50, and 100 mg/kg/day
Basis:
nominal conc.
No. of animals per sex per dose:
20 males and 10-12 females /dose
Control animals:
yes, concurrent vehicle
Details on study design:
In a well-conducted and well-reported study, groups of 20 (m) and 10-12 (f) rats received ECH by oral gavage. Males received ECH daily prior to mating to evaluate effects on late-stage spermatids and epididymal spermatozoa only. At the end of the treatment, ejaculatory sperm was assessed by mating each (m) with hormonally primed untreated (f). Two days later, (m) in the 0 and 50 mg/kg groups only were allowed to mate for up to 5 days with a different prooestrus (f) each day until each (m) had copulated successfully with one female. The (f) were sacrificed on day 15 of pregnancy and corpora lutea, implantations and resorptions were counted. (m) were sacrificed 48 h. after successful mating to assess testicular and epididymal sperm.
For the measurement of cauda epididymal motion, an additional group of animals was used at each dose level and treated with ECH using an identical protocol to the one described above. These groups were mated 2 days after the last day of dosing (day 23) corresponding to the matings used for ejaculatory sperm assessment described above.
Positive control:
no data

Examinations

Parental animals: Observations and examinations:
No information provided.
Oestrous cyclicity (parental animals):
No information provided.
Sperm parameters (parental animals):
After dosed males mated with undosed females, pregnant females were sacrificed on Day 15 of pregnancy and corpora lutea, implantations, and resorptions were counted. Males were sacrificed 48 hr after successful mating. This 2-day lapse allowed replenishment of epididymal reserves that may have been depleted in the mating trial. At sacrifice the following organs were excised and weighed: liver, kidney, adrenals, spleen, heart, testes, accessory organs (prostate and seminal vesicles), vas deferens, and epididymis. One testis was homogenized in a Triton-X-100 solution (0.01% Triton-X-100 in 0.9% saline) to obtain spermatid counts. The cauda of one epididymis w as minced, filtered, and processed for sperm counts and sperm morphology.

For the measurement of cauda epididymal sperm motion, an additional group of animals was used at each dose level. Conditions for dosing of the males were identical to those listed above, except that all animals were sacrificed 2 days after the last day of dosing (sacrifice on Day 23). a time corresponding to the first mating for the group of males from the initial portion of this study. Testis and epididymis weights and manually determined cauda epididymal sperm counts (using a hemocytometer) were also measured. Sperm motion parametes were measured with the CellSoft (CRY0 Resources, Ltd., New York) computer-assisted sperm motion analysis system.
Litter observations:

Litters were sexed and weighed on Postnatal Day 1 (day of delivery). Dams and pups were weighed weekly thereafter. At Day 4, litters were culled to 8 pups (approximately 4 male and 4 female). At Postnatal Day 2 1, dams were sacrificed and litters reduced to 1 male and I female. Weanlings were weighed weekly until sacrifice at Postnatal Day 42.
Postmortem examinations (parental animals):
Males dosed with ECH were allowed to mate with untreated females. These untreated females were sacrificed on Day 15 of pregnancy and corpora lutea, implantations, and resorptions were counted.

Males were sacrificed 48 hr after successful mating. At sacrifice the following organs were excised and weighed: liver, kidney, adrenals, spleen, heart, testes, accessory organs (prostate and seminal vesicles), vas deferens, and epididymis. One testis was homogenized in a Triton-X-100 solution (0.01% Triton-X-100 in 0.9% saline) to obtain spermatid counts. The cauda of one epididymis w as minced, filtered, and processed for sperm counts and sperm morphology.

For the measurement of cauda epididymal sperm motion, an additional group of animals was used at each dose level. Conditions for dosing of the males were identical to those listed above, except that all animals were sacrificed 2 days after the last day of dosing (sacrifice on Day 23). a time corresponding to the first mating for the group of males from the initial portion of this study. Testis and epididymis weights and manually determined cauda epididymal sperm counts (using a hemocytometer) were also measured. Sperm motion parameters were measured with the CellSoft (CRY0 Resources, Ltd., New York) computer-assisted sperm motion analysis system.

Females that were dosed with ECH were mated with untreated males and allowed to deliver. They were sacrificed on Postpartum Day 21. No further information was provided.
Postmortem examinations (offspring):
Offspring were culled to 8 pups on Postpartum Day 4 and all but one male and one female were sacrificed on Postpartum Day 21. The surviving pups were sacrificed on Postpartum Day 42. No further information was provided.
Statistics:
Body weights for all animals were analyzed using a repeated-measures analysis of variance (BMDP, Los Anglles, CA). Fertility and pregnancy rates were analyzed by X2 methods (Snedecor and Cochran, 1980). All other data were analyzed by one-way analysis of variance followed by Tukey's multiple comparison procedure (SAS, Cary, NC), with the following parameters being transformed before analysis: mount latency period and ejaculation latency period (logarithmic); numbers of mounts and intromissions (square root); and percentage normal sperm morphology; and percentage motile sperm (arc-sin). Cellsoft-generated sperm motion parameters were analyzed using t tests (control vs treated groups) with a modified Bonferroni correction (Simes, 1986). Dose dependence was determined by linear regression for trend.
Reproductive indices:
Fertility rate = (No. pregnant/No. mated) x 100
Offspring viability indices:
No offspring viability indices were reported.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
effects observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
not specified
Other effects:
not specified

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
no effects observed
Reproductive function: sperm measures:
effects observed, treatment-related
Reproductive performance:
effects observed, treatment-related

Details on results (P0)

Complete sterility (no viable litters produced) in the highest dose group in the mating trials but there were no effects on mating performance, or selected sperm measurements (sperm morphology and percentage mobile sperm). Sperm velocity parameters were decreased at all treatment levels. In the same study, females dosed by gavage with 25 and 50 mg/kg body weight/day for 14 days prior to mating showed no effects on reproduction or fertility (a high dose group of 100 mg/kg body weight/day was terminated due to excessive toxicity). In the same study, females dosed by gavage with 25 and 50 mg/kg body weight/day for 14 days prior to mating showed no effects on reproduction or fertility (a high dose group of 100 mg/kg body weight/day was terminated due to excessive toxicity). The NOAELs for reproduction/fertility in this study were 25 mg/kg body weight/day for males and 50 mg/kg body weight/day for females.

Effect levels (P0)

open allclose all
Dose descriptor:
NOAEL
Effect level:
25 mg/kg bw/day
Sex:
male
Basis for effect level:
other: Based on reproductive endpoints such as fertility and litter size.
Dose descriptor:
NOAEL
Effect level:
> 100 mg/kg bw/day (actual dose received)
Sex:
female
Basis for effect level:
other: No effect was observed in reproductive parameters in female rabbits administered 100 mg/kg/day bw.
Dose descriptor:
other: Sperm motion parameters LOAEL
Effect level:
12.5 mg/kg bw/day
Sex:
male
Basis for effect level:
other: Based on spermatic function, specifically circular and linear movement.

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Mortality / viability:
no mortality observed
Body weight and weight changes:
no effects observed
Sexual maturation:
not specified
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
not specified
Histopathological findings:
not specified

Details on results (F1)

Litter size and mean pup birth weight were not significantly different. One dam in the 25 mg/kg group neglected her pups, which all died by Postnatal
Day 4 (On Postnatal Day 4, survival for the control, 25 and 50 mg/kg/day group was 97, 90 and 99%, respectively). This accounts for the slightly decreased percentage survival seen in the 25 mg/kg group. Male and female pup weights, measured weekly, did not significantly differ during lactation or in the 3 weeks postweaning.

Effect levels (F1)

Dose descriptor:
NOAEL
Generation:
F1
Effect level:
50 mg/kg bw/day (actual dose received)
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
other: no adverse effects at highest administered dose level

Overall reproductive toxicity

Reproductive effects observed:
yes
Lowest effective dose / conc.:
12.5 mg/kg bw/day (actual dose received)
Treatment related:
yes
Relation to other toxic effects:
reproductive effects in the absence of other toxic effects
Dose response relationship:
yes
Relevant for humans:
not specified

Any other information on results incl. tables

Confirming previous reports in the literature, epichlorohydrin in these studies brought about severely reduced fertility in exposed male rats at a dose of 50 mg/kg body weight/day for 21 days (a period covering development of the late-stage spermatids and their transit through the cauda epididymis). Fertility was not evaluated at lower doses. Jones et. al. (1969) and Hahn (1970) observed varying degrees of infertility in rats with oral doses of 50 mg ECH/kg for 1 day or of 15 mg ECH/kg/day for 12 days, respectively. John et al. (1983b) also reported ECH-induced infertility following inhalation of 50 ppm ECH for 10 weeks.

Several male reproductive endpoints were measured in our studies to determine the origin of this infertility. Changes in organ-to-body weight ratios were unremarkable, except for slight increases in the liver and kidney, which are known targets for epichlorohydrin toxicity. Epididymis-to-body weight ratios were slightly increased at the 50 mg/kg dose, possibly as a result of inflammation and swelling from spermatocoeles and sperm granulomas. These are phenomena reported previously for ECH-treated male rats by Kluwe et al. (1983), although, in these studies, no evidence of granulomas was found on gross examination of epididymides. All measures of male copulatory behavior were normal. The number, morphologyy and percentage motility of ejaculated sperm recovered from sacrificed females were comparable to control values. Testicular sperrnatid count, cauda epididymal sperm count, and cauda epididymal sperm morphology were not significantly different from controls.

These trends were essentially borne out in the second group of males studied with two exceptions: (1) a significant decrease (22%) in epididymal sperm counts was evident at the 50 mg/kg dose level, and (2) no significant change was seen in epididymis-to-body weight ratios, although a trend toward higher ratios was evident. Epididymal sperm counts were also decreased in animals dosed with 100 mg/kg in the pilot study. The 22% depletion in sperm concentration reported here is unlikely to be responsible for the observed infertility.

Sperm Motion Parameters (Means + SD)

Dose (mg/kg)

 

0

 12.5  25  50
   (n=18)  (n=16)  (n=18)  (n=15)
 % Motile Sperm  58.7 +14.8  57.5 +13.1  55.6  + 9.8  51.8  + 10.8
 Curvilinear velocity (um/sec)  148.7  + 14.5  137.6  + 14.8a  116.9  + 10.1a  103.3  + 11.7a
 Straight-line velocity (um/sec)  59.01  + 8.77  53.95  + 7.17a  44.00  + 5.75a  33.31  + 5.62a
 Linearity  4.04 + 0.35  4.03  + 0.34  3.89  + 0.34  3.34  + 0.38a
 Amplitude of lateral head displacements (um)  6.95  + 0.75  6.35  + 0.87a  5.02  + 0.56a  4.05  + 0.44a
 Beat/cross frequency (Hz)  10.2  + 0.8  10.7 + 0.4a  10.8  + 0.5a  11.0  + 0.5a
 % Circular cells  17.3  + 4.3  18.1  + 3.9  17.9  + 4.7  18.0 + 3.9

a Groups differed significantly from controls (p < 0.05).

The infertility in ECH-treated males may in part be a result of the effects of ECH on the vigor and swimming pattern of cauda epididymal sperm. The measures of sperm vigor-curvilinear and straight-line velocity- were significantly depressed at all doses and in a dose-dependent manner. Three measures of sperm swimming pattern (ALH, linearity and flagellar beat frequency) were also significantly changed in ECH-treated animals and showed dose-dependent trends. Since the percentage of motile sperm was not changed in either epididymal or ejaculated sperm, these changes in relative sperm motion suggest a steadily decreasing energy store and/or an impairment in energy transduction in the sperm of the ECH-treated animals.

HAHN, J. D. (1970). Post-testicular antifertility effects of epichlorohydrin and 2,3-epoxypropanol. Nature(London) 26: 87.

JOHN, J. A., QUAST, J. F., MURRAY, F. J., CALHOUN, L. G., AND STAPLES, R. E. (1983b). Inhalation toxicity of epichlorohydrin: Effects on fertility in rats and rabbits. Toxicol. Appl. Phannacol. 68:415-423.

JONES, A . R., DAVIES, P,., EDWARDS, K., AND JACKSON, H. (1969). Antifertility effects and metabolism of alpha- and epichlorohydrin in the rat. Nature (London) 224:83.

KLUWE, W. M., GUPTA, B. N., AND LAMB, J. C. (1983). The comparative effects of 1,2-dibromo-3-chloropropane (DBCP) and its metabolites, 3-chloro-1,2-propanediol (alpha-chlorohydrin), and oxalic acid, on the urogenital system of male rats. Toxicol. Appl. Pharmacol. 70:67-86.

Applicant's summary and conclusion

Conclusions:
The parental NOAEL is 25 mg/kg/day and the sperm motion parameters LOAEL is 12.5 mg/kg/day.
Executive summary:

Male and female Long-Evans rats were treated with epichlorohydrin (ECH) by oral gavage (males: 12.5, 25, and 50 mg/kg/day; females: 25, 50, and 100 mg/kg/day) for 21 and 14 days, respectively, prior to mating trials with untreated animals. Treated females were further dosed until delivery. Fertility was assayed in the high-dose males only and was found to be totally impaired. No measured parameters of female reproduction were changed relative to controls. Treated males showed normal copulatory behavior. Sperm morphology and percentage motile sperm were not statistically different from control values in both ejaculated and cauda epididymal samples from ECH-treated animals. The number of sperm in ejaculates was normal while cauda epididymal sperm count was slightly decreased in males at the 50 mg ECH/kg dose level. Mean curvilinear velocity, straight-line velocity, and amplitude of lateral head displacement of cauda epididymal sperm were significantly reduced by ECH at 12.5 mg/kg/day and above. Sperm track linearity was also reduced, but only at 50 mg/kg/day. Beat/cross frequency of sperm was significantly increased at 12.5 mg/kg/day and above. All of the above sperm motion parameters showed dose dependent trends. These effects are consistent with the spermatozoa1 metabolic lesions reported for a-chlorohydrin, a metabolite of ECH.