Sodium hypochlorite

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Link to relevant study records

Reference

Endpoint:

one-generation reproductive toxicity

Remarks:

based on test guideline (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: No deficiencies.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 415 [One-Generation Reproduction Toxicity Study (before 9 October 2017)]

Deviations:

yes

Remarks:

dose administration to males only 8 weeks instead of 10 as recommended by the guideline

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

Long-Evans

Sex:

male/female

Details on test animals or test system and environmental conditions:

Source: Charles River Breeding Laboratories, Portage, USA
4-6 weeks old, weight not stated

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

Total volume applied: 10 mL/kg

Details on mating procedure:

One male housed with two females throughout breeding period.
Duration of mating: 10 days

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Duration of exposure before mating
Males: 56 days; Females: 14 days

Duration of exposure in general P, F1
Males: 56 days prior to breeding and throughout the 10-day breeding period.
Females: 14 days prior to breeding and throughout breeding, gestation and lactation until pups were weaned on day 21.

Frequency of treatment:

daily

Details on study schedule:

Male were dosed 56 days prior and throuout breeding, females were dosed 14 days prior to breeding, throughout breeding, gestation and lactation until day 21 of lactation.

Remarks:

Doses / Concentrations:
1, 2, or 5 mg/kg bw/day
Basis:
nominal conc.

No. of animals per sex per dose:

12 males, 24 females

Control animals:

yes, concurrent vehicle

Parental animals: Observations and examinations:

Clinical signs Yes
Body weight Yes

Oestrous cyclicity (parental animals):

Not stated

Sperm parameters (parental animals):

Testis weight
Epididymides weight
Sperm motility
Sperm morphology
Sperm concentration in epididymides

Litter observations:

Number of pups
Stillbirths
Litter size
Live births
Presence of gross anomalies
Weight gain
Weight of reproductive organs
Day of eye opening
Complete blood counts
Hormone analysis
Vaginal patency

Postmortem examinations (parental animals):

Organ weights P and F1:
Female reproductive tract
Testes
Epididymides (total and cauda)
Prostate
Seminal vesicles

Histopathology P and F1
Organs of the reproductive tract

Postmortem examinations (offspring):

Organ weights P and F1:
Female reproductive tract
Testes
Epididymides (total and cauda)
Prostate
Seminal vesicles

Histopathology P and F1
Organs of the reproductive tract

Statistics:

not stated

Clinical signs:

no effects observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Other effects:

not examined

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

Dose descriptor:

LOAEL

Effect level:

> 5 mg/kg bw/day (nominal)

Sex:

male/female

Dose descriptor:

NOAEL

Effect level:

>= 5 mg/kg bw/day (nominal)

Sex:

male/female

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Dose descriptor:

LOAEL

Generation:

F1

Effect level:

> 5 mg/kg bw/day (nominal)

Sex:

male/female

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

>= 5 mg/kg bw/day (nominal)

Sex:

male/female

Reproductive effects observed:

not specified

Conclusions:

LO(A)EL
Parent males > 5.0 mg/kg bw/day
Parent females > 5.0 mg/kg bw/day
F1 males > 5.0 mg/kg bw/day
F1 females > 5.0 mg/kg bw/day

NO(A)EL
Parent males ≥ 5.0 mg/kg bw/day
Parent females ≥ 5.0 mg/kg bw/day
F1 males ≥ 5.0 mg/kg bw/day
F1 females ≥ 5.0 mg/kg bw/day

Executive summary:

No differences were observed between control rats and those rats exposed to up to 5 mg/kg bw/day of the test material when fertility, viability, litter size, day of eye opening or day of vaginal patency were evaluated. No alterations in sperm count, sperm direct progressive movement, percent motility or sperm morphology were observed among adult male rats. In addition, male and female reproductive organ weights were comparable to the control groups and no significant histopathological changes were observed among treated male female rats.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

5 mg/kg bw/day

Additional information

The reproductive effects of chlorinated water have been examined in a one-generation gavage study in rats (Carlton et al. 1986). 12 males were treated with 0, 1, 2 and 5 mg av Cl/kg bw/d for 56 days and 24 females for 14 days prior to breeding and throughout the 10-day breeding period. Additionally, females received the hypochlorite solutions throughout gestation and lactation. Following breeding, the males were necropsied and evaluated for sperm parameters and reproductive tract histopathology. Adult females and some pups were necropsied at weaning on postnatal day 21. Other pups were treated post weaning until 28 or 40 days of age. These pups were evaluated for the day of vaginal patency and for thyroid hormone levels. No differences were observed between control rats and those rats exposed to up to 5 mg av Cl/kg bw/d of the test material when fertility, viability, litter size, day of eye opening or day of vaginal patency were evaluated. No alterations in sperm count, sperm direct progressive movement, percent motility or sperm morphology were observed among adult male rats. In addition, male and female reproductive organ weights were comparable to the control groups and no significant histopathological changes were observed among treated male and female rats.

In a multi-generation study highly chlorinated water, containing available chlorine at a level of 100 mg/L (corresponding to 5 mg/kg bw/d), was administered daily as drinking water to 236 BD II rats over seven consecutive generations (Duckrey 1968). The first generation received the treated drinking water from an age of 100 days on, subsequent generations were treated throughout the lifetime with the exception of F3 and F4, which were treated only until weaning of their pups. Effects on the lifespan, fertility, growth, blood, organ weights and histopathology were recorded. There were no significant differences between control (2 groups of BD II rats, a total of 56 animals) and treated animals with respect to lifetime, fertility, breeding outcome, clinical signs, organ weights, haematological parameters, histopathology, neoplastic lesions. Based on this finding the parental, reproductive and developmental NOAEL is considered to be greater than 5 mg av Cl/kg bw/d.

To examine the effects on the reproductive performance groups of C3H/HeJ and C57BL/6J mice were treated with chlorinated water (10 ppm; corresponding to 1.7 mg/kg bw/d (males) and 2 mg/kg bw/d (females) acidified with hydrochloric acid (pH 2.5) over a period of 6 months (Les 1968). Males and females were housed in pairs or trios and the number of pups born and weanlings were recorded. There were no adverse effects on the reproductive performance observed. Treated C3H/HeJ mice showed increased numbers of pups born and weaned in total and per dam compared to control. The percentage weaned of those born was practically identical. Treated C57BL/6J mice showed a higher reproductive performance in all evaluated parameters if the type of mating (pairs or trios) is disregarded. The number of mice weaned in the C3H/HeJ treatment group was 5.7 % greater than in the control group. In treated C57BL/6J mice the number of weaned pups was 17.5 % greater than in the respective control. There is no detrimental effect on the reproduction of mice treated with chlorinated and acidified water (10 ppm, pH 2.5); on the contrary, reproductive performance in treated animals was statistically significantly increased when compared to control. The parental, reproductive and developmental NOAEL is considered to be greater than 1.7 mg av Cl/kg bw/d (males) and 2 mg av Cl/kg bw/d (females).

Short description of key information:
There are no relevant studies of sodium hypochlorite per se looking at its reproductive toxicity potential in animals. No significant effects were seen in a well conducted one generation reproductive toxicity study in rats up to a concentration of 5 mg/kg bw of aqueous chlorine as well as in teratogenicity studies in rats and mice.
This value is further supported by another multi-generation study, in which also no effects were noted at doses of 5 mg/kg bw/day. Long-term toxicity studies provide also additional assurance that the substance is not a reproductive toxicant as they did not identify the testes or ovaries as target organs. Thus, the NOAEL derived by the author was set to > 5.7 mg available Cl/kg bw/day.

Effects on developmental toxicity

Description of key information

One study with clorine is available. There were no treatment-related changes in viability, foetal weights and external appearance of all foetuses in all dose groups. Skeletal and soft-tissue defects were in the normal range for all dose groups. The NOAEL was set to > 5.7 mg available Cl/kg bw/day.

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Deficiency: Yes. Maternal toxicity not evaluated.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

maternal effects not stated, treatment period longer than required (2 ½ months plus gestation)

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

Age/weight at study initiation: Mature, 225-250 g

Route of administration:

oral: drinking water

Vehicle:

water

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

not stated

Duration of treatment / exposure:

2 1/2 months, prior to and throughout gestation

Frequency of treatment:

ad libitum

Duration of test:

2 1/2 months, prior to and throughout gestation

Remarks:

Doses / Concentrations:
0, 1, 10, 100 ppm corresponding to approximately 0, 0.08, 0.8, 8.0 mg/kg bw/day (assuming a water intake of 25 mL/rat/day and a body weight of 320 g)
Basis:
nominal conc.

No. of animals per sex per dose:

6

Control animals:

yes, concurrent vehicle

Details on study design:

Sex: female

Maternal examinations:

not determined

Ovaries and uterine content:

Examination of uterine content: Number of resorptions

Fetal examinations:

No. of dead Foetuses, Foetal Weight
Skeletal Yes
Soft tissue Yes

Statistics:

Chi-square analysis

Details on maternal toxic effects:

Maternal toxic effects:not examined

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
There was no treatment related effect on viability, external appearance and foetal weight. The percentage of skeletal, soft-tissue and total defects (combined skeletal and soft-tissue) was calculated and presented in the table. The foetuses from the 10 and 100 mg/L groups had a higher percentage of skeletal defects compared with control. However, these did not achieve statistical significance. The highest dose group also showed a higher rate of soft-tissue defects, again without achieving statistical significance when compared to control by chi-square analysis. These defects consisted of three cases of adrenal agenesis, one right-sided heart, one case of improper orientation of the apex of the heart, and one atrio-ventricular valve enlargement. Total defects were statistically higher in the high dose group than in control, whereas the lowest dose produced a lower percentage of defects than control.

Dose descriptor:

NOAEL

Effect level:

>= 5.7 mg/kg bw/day

Basis for effect level:

other: teratogenicity

Dose descriptor:

LOAEL

Effect level:

> 5.7 mg/kg bw/day

Basis for effect level:

other: teratogenicity

Abnormalities:

not specified

Developmental effects observed:

not specified

Effect of chlorine in drinking water on the formation of skeletal and soft-tissue defects in rat foetuses.

Concentration [ppm]	Skeletal defects [%]^a	Soft-tissue defects [%]^a	Total defects [%]^a
0	34.5	7.1	21.1
1	23.8	0.0	12.2
10	59.1	0.0	27.1
100	57.7	19.2	38.5^b

a            Values represent % of defects for all foetuses in each treatment

b            Statistically different from control (p < 0.05), chi-square analysis

Conclusions:

A NO(A)EL for embryotoxic / teratogenic effects of >= 100 ppm corresponding to 5.7 mg/kg bw/day and a LO(A)EL for embryotoxic / teratogenic effects of > 100 ppm corresponding to 5.7 mg/kg bw/day were found.

Executive summary:

There were no treatment-related changes in viability, foetal weights and external appearance of all foetuses in all dose groups. Skeletal and soft-tissue defects were in the normal range for all dose groups. If skeletal and soft-tissue defects were combined a statistically significant increase was observed in the highest dose group. In the absence of a clear dose response and a relatively high incidence of defects in control animals, these findings were not considered to be of relevance. The authors conclude that chlorinated drinking water at the tested concentrations is relatively harmless to the rat when fed to pregnant dams. Unfortunately maternal toxicity was not evaluated. However, subchronic studies show that the NOAEL is 50 mg/kg bw/day.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

5.7 mg/kg bw/day

Additional information

In a teratogenicity study (Abdel-Rahman et al. 1982), groups of 6 female Sprague-Dawley rats were exposed to concentrations of 0, 1, 10 and 100 mg/L hypochlorite in drinking water (corresponding to 0.057, 0.57 and 5.7 mg av Cl/kg bw/d) for 2 ½ months prior to and throughout gestation. Rats were sacrificed on day 20 of gestation and foetuses were preserved for soft-tissue and skeletal examination. There were no treatment-related changes in viability, foetal weights and external appearance of all foetuses in all dose groups. Skeletal and soft-tissue defects were in the normal range for all dose groups. If skeletal and soft-tissue defects were combined a statistically significant increase was observed in the highest dose group. In the absence of a clear dose response and a relatively high incidence of defects in control animals, these findings were not considered to be of relevance. It was concluded that chlorinated drinking water at the tested concentrations is relatively harmless to the rat when fed to pregnant dams. The NOAEL for embryotoxic and teratogenic effects was considered to be greater than 5.7 mg av Cl/kg bw/d. Toxic effects on dams were not reported in this study. However, in subchronic studies which were performed at even higher dose levels than those administered in the rat teratogenicity study demonstrate an NOAEL of 57.2 mg av Cl/kg bw/d.

Justification for classification or non-classification

Although limited data are available in animals, the available studies are sufficient in their design and quality to draw the conclusion that there is no evidence to suggest that sodium hypochlorite would present adverse effects on development or fertility. Similarly, no such evidence is forthcoming from epidemiological studies on populations consuming chlorinated drinking water. Thus, sodium hypochlorite is not classified reprotoxic according to 67/548/EEC and CLP.