Nitric acid

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Link to relevant study records

Reference

Endpoint:

screening for reproductive / developmental toxicity

Remarks:

based on test type

Type of information:

other: Experimental study of a supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

From 2002-01-07 to 2002-10-14

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Well documented GLP study. Study performed according to OECD guideline 422 (Combined Repeated Dose Toxicity study with the Reproduction / Developmental Toxicity Screening Test) with minor deviations (only 5 animals per sex tested instead of 10). The read-across rationale can be found in the category approach document attached in Section 13.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

yes

Remarks:

5 animals of each sex instead of 10 animlas of each sex tested

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, NC
- Age at study initiation: males were 64 days of age on day of arrival; females were 61 days of age on day of arrival
- Weight at study initiation: 225 - 325 grams for male rats; 161-219 for female rats
- Fasting period before study: no data
- Housing: Animals were individually housed except for during the cohabitation and lactation period in wire mesh suspended stainless steel cages which conformed with GLP requirements. During cohabitation each pair of rats were housed in the male rat's cage. Beginning no later than Day 20 of gestation, female rats were individually housed in polyethylene shoebox cages containing nesting material with wire mesh lids. Each dam and litter was housed in a common nesting box during the lactation/postnatal period
- Use of restrainers for preventing ingestion (if dermal): not applicable
- Diet (e.g. ad libitum): Purina Certified Rodent Diet #5002; ad libitum
- Water (e.g. ad libitum): automatic dispenser; ad libitum and when females and litters were housed in shoebox cages via water bottle; ad libitum
- Acclimation period: 12 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 - 22 °C
- Humidity (%): 43-66%
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12 hours dark/12 hours light

IN-LIFE DATES: From: 2002-01-08 To: 2002-02-23

Route of administration:

oral: gavage

Vehicle:

other: distilled water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Dose calculations: For female rats in the Reproduction groups, individual doses were calculated based on the most recent body weights and were adjusted to maintain the targeted dose level (i.e., mg/kg/day). All doses were administered by volume of 10 mL/kg after correcting for concentration of the test mixture. Control animals received the vehicle only at the same volume as the test groups.

Dose preparations: The test substance (011101-3D) was ground in a Krups coffee mill (Model 203) prior to use and again upon receipt of additional test substance (020122-1D). A quantity sufficient to cover the grinding blade was added to the coffee mill and ground to a fine powder. Appropriate amounts of ground test material were accurately weighed into a 100 mL volumetric flask and diluted to volume with distilled water for each of the low, mid and high concentrations. Given that there was visual evidence (i.e. settling of test substance to bottom of cup) of a small amount of precipitate, the dosing mixtures were constantly stirred on a magnetic stir plate while being sampled to dose the test animals during the study.

DIET PREPARATION
- Rate of preparation of diet (frequency): Not applicable, route of administration of test substance is via gavage
- Mixing appropriate amounts with (Type of food):Not applicable
- Storage temperature of food: No data

VEHICLE
- Justification for use and choice of vehicle (if other than water): not applicable
- Concentration in vehicle: no data
- Amount of vehicle (if gavage): no data
- Lot/batch no. (if required): no data
- Purity: 100% (distilled water)

Details on mating procedure:

No data

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The test substance was assumed to be homogenous and stable at the time drawn by syringe to dose the test animals. Analysis of dosing mixtures, therefore, were limited to concentration verification of representative preparations intended for the control, low, intermediate and high dose levels in the study. Representative dosing mixtures of each concentration during the study were provided to the analytical department at three time points during the study prior to animal exposure, near the middle (test days 24 and 28) and near the end of the study (test day 45). Vehicle control samples were inadvertently not submitted for analysis. Each dose preparation was evaluated by flame atomic absorption spectroscopy for total potassium (SOAC Official Method 975.03) (1988). A reference standard of potassium (999 µg/mL), supplied by EM Science, was used for calibration.

Duration of treatment / exposure:

The exposure period for males and females in the toxicity subgroup was 28 days. The exposure period for reproductive subgroup males was at most 28 days. The exposure period for reproductive subgroup females was at most 53 days (14 days pre-mating, 14 days mating, and gestational and lactational periods up to lactation day 4).

Frequency of treatment:

daily
Dose frequency: Each animal was dosed by oral intubation using a stainless steel ball-tipped gavage needle attached to an appropriate syringe. Dose administration was daily (7 days/week for all adult animals as follows):
Male rats: reproduction groups: during two-week premating and two-week mating periods for at least 28 days of exposure
Female rats: reproduction groups: during two-week premating, two-week mating, gestational and lactational periods

Remarks:

Doses / Concentrations:
0, 270, 750 and 1500 mg/kg/day
Basis:
other: Doses were selected based on parameters assessed in a range-finding study at concentrations up to 1000 mg/kg/day

No. of animals per sex per dose:

5 males and 5 females

Control animals:

other: yes, but no data mentioned

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily for viability and cage-side observations were performed daily during acclimation, premating and mating, gestation, and lactation periods, except when scheduled detailed observations were conducted. All observations were recorded.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Observations were performed and recorded at least once during the acclimation period for all male and female rats. Observations were performed and recorded approximately once per week during the premating and mating periods for females of the reproduction groups during the gestational days (GD7, GD14 and GD20) and lactational (LD4 only) periods. Female rats were evaluated for adverse clinical signs during parturition. Maternal behaviour was checked on LD0 and LD4 and recorded. The date and clock time of all observations and/or mortality checks was recorded.

BODY WEIGHT: Yes
- Time schedule for examinations: Individual body weights were recorded at least twice during the acclimation period (including the day after receipt) before pairing and mating. All male rats were weighted weekly during the premating and mating periods and at the time of sacrifice. Mated females were weighted on GD0, 7, 14 and 20, and on the day of delivery (LD0) and LD4 (prior to terminal sacrifice). Females showing no evidence of mating were assigned a GD0 after cessation of cohabitation and body weighs were measured accordingly. Body weight gains were calculated for males and females during each appropriate interval.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
Although not a feeding study, food consumption was determined weekly during the premating period (no mating period) for all males and females. Individual food consumption was measured during the gestational period for the females in the reproductive groups. Food consumption was also recorded on LD0 and LD4. The data were then used to calculate food efficiency for the associated intervals.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data
- Time schedule for examinations: no data

Litter observations:

Offspring bodyweight, sex ration, litter size

Postmortem examinations (parental animals):

Necropsy: Gross necropsy of all males and females included an initial examination of external surfaces and orifices, as well as the cranial, thoracic and abdominal cavities and their contents. Rats were examined for gross lesions. Gross lesions were retained in neutral bueffered 10% formalin (NBF).

Reproductive Groups: Special attention was paied to the organs of the reproductive system. For male rats, the testes and epididymides, seminal vesicles with coagulating gland and prostate were retained. The testes and epididymides were weighed. The testes were fxed in Bouin's solution for 4-12 hours (depending on size) before being retained in 70% alcohol. For females, special care was taken to examine the uterus for the presence of conceptuses. For each female, the ovaries were weighed; the ovaries, uterus and accompanying structures, and a mammary gland were retained in NBF. Subsequently, the fixed uteruses from all adult female rats (including those that did not deliver litters and those that delivered pups) were stained with potassium ferricyanide to confirm pregnancy status and to determine post-implantation loss.

Rats were evaluated for gross lesions. Pregnancy status and uterine contents of female rats were recorded. Aborted fetuses and/or delivered pups were examined to the extent possible. Organs and tissues were excised, weighed, preserved and/or stained and implantation sites counted as described for those animals sacrificed by design.

Histology for reproductive subgroup animals was restricted to retained reproductive organs (and andy other abnormalities observed at necropsy). Histopathologic examination was performed on the preserved organs and tissues of the Reproductive and General Toxicity Group animals from the control (Groups I and II) and high dose (Groups VII and

Postmortem examinations (offspring):

SACRIFICE
- no data

GROSS NECROPSY
- Gross necropsy was performed, no further details

HISTOPATHOLOGY / ORGAN WEIGTHS: no data

Statistics:

Mean and standard deviations were calculated for all quantitative data. Except for clinical pathology data were the contract laboratory, Huntingdon Life Sciences, elected to use statistics to aid in the data interpretation; no further statistical treatment of the study was conducted due to small group sizes.

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:

not examined

Reproductive performance:

not examined

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS): there were no treatment-related deaths and no signs of overt clinical toxiicty

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS): There were no effects on body weight, food consumption, or food efficiency. There were no effects of test-substance treatment on food consumption in males. There were no effects of food consumption on females gestation and lactation. Food consumption was not measured during the mating period. Food efficiency was also unaffected by treatment.

TEST SUBSTANCE INTAKE (PARENTAL ANIMALS): not examined

REPRODUCTIVE FUNCTION: ESTROUS CYCLE (PARENTAL ANIMALS): not examined

REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS): not examined

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS): not examined

ORGAN WEIGHTS (PARENTAL ANIMALS): Mean organ weights and organ-to-body weight ratios for the Reproduction groups, in general, were considered comparable to their respective control groups. Any slight increases or decreases from the control were incidental, not dose-related and judged not to be of toxicological importance.

GROSS PATHOLOGY (PARENTAL ANIMALS): No gross observations were reported.

HISTOPATHOLOGY (PARENTAL ANIMALS): No treatment-related histopathological changes were reported.

Dose descriptor:

NOAEL

Effect level:

>= 1 500 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No effects at the highest dose tested

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

no effects observed

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

no effects observed

Histopathological findings:

not specified

There were no treatment-related effects on litter size, offspring survival indices, sex ration, offspring bodyweight, or macropathology for offspring.

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

>= 1 500 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no effects observed up to the highest dose tested

Reproductive effects observed:

not specified

NOAEL: 1500 mg/kg/day (reproduction/developmental toxicity)

LOAEL: No adverse effects were seen on reproduction/developmental toxicity endpoints.

Reproductive subgroup:: There were no treatment-related deaths and no signs of overt clinical toxicity. There were no effects on body weight, food consumption, or food efficiency. Mating performance and fertility were unaffected by treatment. All animals mated within 4 days. There were no treatment-related effects on gestation length, gestation index, litter size, offspring survival indices, sex ration, offspring bodyweight, or macropathology for offspring.

Conclusions:

There were no treatment-related deaths and no signs of overt clinical toxicity after exposure to potassium nitrate. There were no effects on body weight, food consumption, or food efficiency. Mating performance and fertility were unaffected by treatment. All animals mated within 4 days. There were no treatment-related effects on gestation length, gestation index, litter size, offspring survival indices, sex ration, offspring bodyweight, or macropathology for offspring. A NOAEL value of 1500 mg/kg/day was derived for reproduction/developmental toxicity in this study.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 500 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The study has a klimisch code 2.

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Read accross with nitrates for nitric acid, as defined in the read-accross sodium and potassium nitrates are the nitrates with most structural similarities with nitric acid.

An OECD 422 study with rats shows no effects at all up to doses of 1500 mg/kg bw/day of potassium nitrate. No effects were found on reproduction parameters, neither embryotoxic or developmental effects were seen. Although in several other less reliable studies, this is not always suppoted, these studies show a very limited description of methods and results. In repeated dose toxicity studies no effects on reproduction organs were found. No further studies are considered necessary. Therefore, an additional 2 -generation reproduction study is not considered necessary.

Short description of key information:
As nitric acid will not be bioavailable as such in the body but in form of H+ and NO3-, studies on nitrates are used for read-accross.
In a reliable OECD screening study in rats with potassium nitrate no effects were found up to the highest dose tested (1500 mg/kg bw/d). In addition, in repeated dose studies with potassium nitrate no effects on reproduction organs were found. Together with the available data showing no effects, an additional study is not considered necessary. The overall conclusion for nitrate and by extension nitric acid is that the substance may present a hazard to fertility but only at parentally toxic doses.

Justification for selection of Effect on fertility via oral route:
One study on the read-across substance potassium nitrate is available. The read-across rationale can be found in the category approach document attached in Section 13.

Effects on developmental toxicity

Description of key information

In a reliable OECD screening study in rats with potassium nitrate no effects were found up to the highest dose tested (1500 mg/kg bw/d). This is supported by less reliable studies with potassium nitrate also showing no developmental effects up to 400 mg/kg bw/day.  The overall conclusion for potassium nitrate and thus nitric acid is that there is no evidence that the substance may present a risk for developmental toxicity.

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

other: Experimental study of a supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: According to OECD 422 and GLP procedures. The read-across rationale can be found in the category approach document attached in Section 13.

Qualifier:

according to guideline

Guideline:

other: OECD 422

Deviations:

not specified

GLP compliance:

yes

Species:

rat

Strain:

Sprague-Dawley

Route of administration:

oral: gavage

Vehicle:

not specified

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

no data

Duration of treatment / exposure:

Animals on the study were divided between two subgroups (toxicity and reproductive subgroups). The exposure period for males and females in the toxicity subgroup was 28 days. The exposure period for reproductive subgroup males was at most 28 days. The exposure period for reproductive subgroup females was at most 53 days (14 days pre-mating, 14 days mating, and gestational and lactational periods up to lactation day 4).

Frequency of treatment:

daily

Duration of test:

tox group: 28 days
repro group: 53 days

No. of animals per sex per dose:

5 males/group
10 females/group

Dose descriptor:

NOAEL

Effect level:

>= 1 500 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: no effects observed up to the highest dose tested

Dose descriptor:

NOAEL

Effect level:

>= 1 500 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no effects observed up to the highest dose tested

Abnormalities:

not specified

Developmental effects observed:

not specified

NOAEL:

1,500 mg/kg/day (general toxicity)

1,500 mg/kg/day (reproduction/developmental toxicity)

LOAEL:                                  

No adverse effects were seen on general toxicity endpoints. 

No adverse effects were seen on reproduction/developmental toxicity endpoints

Toxicity subgroup: There were no treatment-related deaths and no signs of overt clinical toxicity. There were no effects on body weight, food consumption, or food efficiency. Functional observational battery (FOB) and motor activity tests identified no treatment-related changes in behavior, function, or motor activity. A slight increase in blood urea nitrogen was observed in male and female rats at 1,500 mg/kg/day and in female rats at 750 mg/kg/day. Although outside the range of the historical control, the absence of other indicators of renal dysfunction (e.g., creatinine) discounted the clinical significance of this endpoint. Minimal changes in electrolyte levels in male rats (e.g., 10% decrease in potassium, 4% decrease in calcium, and 22% increase in phosphorus) and female rats (3% decrease in chloride, 4% decrease in magnesium) were observed at 1,500 mg/kg/day. These changes were within the range of historical control and were not considered to be of biological significance. No treatment-related histopathological changes were reported.   

Reproductive subgroup: There were no treatment-related deaths and no signs of overt clinical toxicity. There were no effects on body weight, food consumption, or food efficiency. Mating performance and fertility were unaffected by treatment. All animals mated within 4 days. There were no treatment-related effects on gestation length, gestation index, litter size, offspring survival indices, sex ration, offspring bodyweight, or macropathology for offspring.

Conclusions:

NOAEL:
1,500 mg/kg/day (general toxicity)
1,500 mg/kg/day (reproduction/developmental toxicity)

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 500 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The study has a klimisch code 2.

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

An OECD 422 study with rats shows no effects at all up to doses of 1500 mg/kg bw/day of potassium nitratee. No effects were found on reproduction parameters, neither embryotoxic or developmental effects were seen. This is supported by less reliable studies with potassium nitrate. No further studies are considered necessary. Together with the available data showing no effects, a developmental toxicity is not considered necessary.

Justification for selection of Effect on developmental toxicity: via oral route:
One study on the read-across substance potassium nitrate is available. The read-across rationale can be found in the category approach document attached in Section 13.

Justification for classification or non-classification

The results of the OECD screening study (a very high NOAEL) on the read-across substance potassium nitrate do indicate that no classification is required for nitric acid according to the CLP Regulation.