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Effects on fertility

Description of key information

In two 13-week whole-body inhalation studies using Formic Acid in rats and mice (OECD 413) no effects on sperm motility, density, and testes and epididymal weight, or estrous cycle length were observed in animals exposed to 0, 8, 16, 32, 64, or 128 ppm formic acid vapours for 6 hours/day, 5 days/week.

Sperm motility and morphology was examined at termination in all males. Estrous cycle of all females was examined during the last two weeks of exposure. Male and female reproductive organs were weighed and subjected to histopathological examination. There were no findings that would indicate adverse effects on male and female reproductive organs at any dose

Link to relevant study records

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Endpoint:
screening for reproductive / developmental toxicity
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1992
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Justification for type of information:
GLP guideline study, according to the requirements of the OECD TG 413 with extended consideration of male and female reproductive parameters.
Qualifier:
equivalent or similar to guideline
Guideline:
other: OECD Guideline 413 - Subchronic Inhalation Toxicity: 90-Day
Version / remarks:
Male and Female reprodcutive parameters examined
Deviations:
yes
Remarks:
Reproductive parameters included: Sperm motility and density; vaginal cytology; histopathology of male and female reproductive organs (epididymis/seminal vesicles/ prostate/testes or ovaries/uterus)
Principles of method if other than guideline:
Reproductive parameters included: Sperm motility and density; vaginal cytology; histopathology of male and female reproductive organs (epididymis/seminal vesicles/ prostate/testes or ovaries/uterus)
GLP compliance:
yes
Limit test:
no
Specific details on test material used for the study:
- 95 % formic acid in water
- Physical state: liquid
- Analytical purity: 95%
- Impurities (identity and concentrations): water. Formaldehyde: <0.1%
Species:
rat
Strain:
Fischer 344
Details on species / strain selection:
- Source: Taconic Farms, Inc., Germantown, NY
- Age at study initiation: 6 wks (7 weeks for mice in 13-week studies)
- Housing: individually
- Diet: standard NIH-07 diet ad libitum
- Water: tab water ad libitum
- Acclimation period: 12 days
Sex:
male/female
Details on test animals or test system and environmental conditions:
- Temperature (°C): temperature 75°F
- Humidity (%): rel. humidity 55+/-15%,
- air changes per hour: 15
- Photoperiod (hrs dark / hrs light): 12/12
Route of administration:
inhalation
Type of inhalation exposure (if applicable):
whole body
Vehicle:
unchanged (no vehicle)
Remarks:
Air
Details on exposure:
- Exposure apparatus: commercial 1.7 m³ inhalation chambers
- Temperature, humidity, pressure in air chamber: temperature 75°F, rel. humidity 55+/-15%
- Vapor generation: liquid formic acid was pumped by a micrometer pump to a vaporizer heated to 97.5°C. The vapor entered a distribution line where a constant 2300 ppm atmosphere was maintained. Dilution air (HEPA filtered, rel. humidity 50%) carried a metered amount to the individual exposure chambers.

Details on mating procedure:
No mating
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
A Foxboro Mitran 980 infrared spectrometer at 9.050 microns was used to monitor the exposure chambers, control chamber, exposure room, an online standard of formic acid vapor, and a pure nitrogen source. All locations were monitored every 40 min. In addition, formaldehyde concentrations were monitored in the 8 ppm and 128 ppm exposure chambers, and in the formic acid distribution line. Corrections were made for absorbance of water and for instrument drift.
The online monitor was calibrated with GC analyses of grab samples taken from the exposure chambers at the time of the readings.

The limit of detection and limit of quantification for the on-line monitor were determined at an average chamber relative humidity of 33-51%.
The practical detection limit was 0.36 ± 0.10 ppm, with a practical quantification limit of 0.68 ± 0.10 ppm.
Duration of treatment / exposure:
13 weeks (90 days)
Frequency of treatment:
5 days per week, 6 hour per day
Details on study schedule:
Sperm morphology and vaginal cytology examinations were performed for rats and mice administered formic acid at 0, 8, 32, and 128 ppm in the 13-week study. males were examned at necropsy, females were subjected to vaginal lavage during the last 2 weeks, followed by vaginal cytology evaluation
Dose / conc.:
0 ppm
Remarks:
vapour
Dose / conc.:
8 ppm
Remarks:
vapour
Dose / conc.:
32 ppm
Remarks:
vapour
Dose / conc.:
64 ppm
Remarks:
vapour
Dose / conc.:
128 ppm
Remarks:
vapour
No. of animals per sex per dose:
10 Males, 10 Females
Control animals:
yes, concurrent vehicle
Parental animals: Observations and examinations:
Daily:
Bahavioural & Clinical Observations, Body Weights,
Haematology on additional rats on days 3 and 23, core study animals at termination in week 13
Clinical Chemistry on blood collection

- sperm morphology and vaginal cytology were evaluated in rats and mice exposed to 0, 8, 32, and 128 ppm.
Oestrous cyclicity (parental animals):
Epididymal sperm motility was evaluated at necropsy, and vaginal cytology was evaluated on animals during the 2 weeks just preceding necropsy, using procedures outlined by Morrissey et al. (1988). For the 12 days prior to sacrifice, females were subject to vaginal lavage with saline. The aspirated cells were air-dried onto slides, stained with Toluidine Blue O, and cover slipped. The relative preponderance of leukocytes, nucleated epithelial cells, and large squamous epithelial cells were used to identify the stages of the estrual cycle.
Sperm parameters (parental animals):
Testis weight, epididymis weight, sperm count in testes, sperm motility, sperm morphology
Litter observations:
N/A
Postmortem examinations (parental animals):
At Sacrifice:
- Gross pathology, Histopathology
- Tissues examined: adrenal glands, brain, bronchial lymph nodes, cecum, colon, duodenum, epididymis/seminal vesicles/ prostate/testes or ovaries/uterus, esophagus, eyes (if grossly abnormal), femur (including marrow), gallbladder (mice), gross lesions and tissue masses with regional lymph nodes, heart, ileum, jejunum, kidneys, larynx, liver, lungs with mainstem bronchi, mammary gland and adjacent skin, mandibular and mesenteric lymph nodes, mediastinal lymph nodes, nasal cavity and turbinates, pancreas, parathyroid glands, pharynx (if grossly abnormal), pituitary gland, preputial /clitoral glands (rats), rectum, salivary glands, spinal cord and sciatic nerve (if neurologic signs present), spleen, stomach (including forestomach and glandular stomach), thigh muscle, thymus, thyroid gland, trachea, and urinary bladder. In addition to all gross lesions, the following tissues were examined in all other dose groups:
rats--nose (three transverse sections), lung, larynx, trachea, bronchial and mediastinal lymph nodes;
mice--nose (three transverse sections).
Organ weights (to the nearest mg) were obtained from all core study animals and include: liver, thymus, right kidney, right testis, heart
and lungs.
Postmortem examinations (offspring):
N/A
Statistics:
Data were presented as mean +/- standard error, n=10 Differences from the control group for reproductive tissue weights and spermatozoal
measurements were evaluated by Dunn's test or Shirley's test.
Reproductive indices:
Sperm morphology and vaginal cytology were evaluated in rats and mice exposed to 0, 8, 32, and 128 ppm.
Offspring viability indices:
N/A
Clinical signs:
no effects observed
Dermal irritation (if dermal study):
not examined
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Body weight gains were significantly greater in male rats exposed to 16, 32, and 64 ppm formic acid compared to control animals
Food efficiency:
effects observed, treatment-related
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
effects observed, non-treatment-related
Description (incidence and severity):
Changes in hematologic variables were few and generally minimal to mild in magnitude.
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
There were mild, significant decreases in concentrations of serum albumin in female rats at day 3 (32, 64, and 128 ppm exposure groups) and increases in male rats at 13 weeks (8, 16, and 32 ppm exposure groups). Concentrations of total serum protein were decreased in female rats in all exposure groups at day 3. Male and female rats exposed to 16, 32 (female only), 64, and 128 ppm formic acid had significant increases in serum AP at 13 weeks. Additional changes in serum biochemical variables in rats exposed to formic acid included decreases in activities of amylase (female rats, days 3 and 23) and CK (male rats, day 3; female rats, day 23), increases in activities of SDH (male rats, day 3), and decreases in concentrations of UN and creatinine (male and female rats, day 3).
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Microscopic lesions following exposure to 125 ppm formic acid for 2 weeks were limited to the nasal respiratory and olfactory epithelium. At the end of the 13-week studies there was little evidence for progression (in severity or incidence) of the respiratory or olfactory lesions.
Histopathological findings: neoplastic:
not examined
Other effects:
effects observed, treatment-related
Description (incidence and severity):
Site-specific and morphological effects of formic acid on the upper respiratory tract in rats and mice are consistent with those produced by exposure to irritant chemicals administered by the inhalation route.
Reproductive function: oestrous cycle:
no effects observed
Reproductive function: sperm measures:
no effects observed
Reproductive performance:
not examined
Organ Weights (Male Reproductive Organs): No Effect
Gross Pathology (Parental Animals): No Effect
Histopathology (Parental Animals): No Effect
Reproductive Function: Estrous Cycle: No Effect
Reproductive Function: Sperm Measures: No Effect
Key result
Dose descriptor:
NOEC
Effect level:
128 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
organ weights and organ / body weight ratios
gross pathology
histopathology: non-neoplastic
reproductive function (oestrous cycle)
reproductive function (sperm measures)
Not examined
Remarks on result:
not measured/tested
Key result
Reproductive effects observed:
no

Parameter          Exposure concentration (ppm)    
                    0         8         32          128 
----------------------------------------------------------- 
Males 
Weight (g) 
right testis      1.40      1.45       1.47       1.41 
left epididymis   0.449     0.461      0.469      0.460    
left epididymal   0.167     0.171      0.174      0.169 
tail 

Spermatozoal measurements 
Motility (%)     91+/-1     91+/-1     91+/-1     88+/-1 
Concentration   658+/-21   706+/-21   580+/-60   651+/-29   
(10E06/g) 

Females 
Estrous cycle    4.80       4.75       4.95        4.95 
length (d)        

Conclusions:
In a 13-week whole-body inhaltion study in rats (OECD 413) no effects on sperm motility, density, and testes and epididymal weight, or estrous cycle length were observed in animals exposed to 0, 8, 16, 32, 64, or 128 ppm formic acid vapours for 6 hours/day, 5 days/week.

Sperm motility and morphology was examined at termination in all males.
Estrous cycle of all females was examined during the last two weeks of exposure.
Male and female reproductive organs were weighed and subjected to histopathological examination.

There were no findings that would indicate adverse effects on male and female reproductive organs at any dose.
Endpoint:
screening for reproductive / developmental toxicity
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1992
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Justification for type of information:
GLP guideline study, according to the requirements of the OECD TG 413 with extended consideration of male and female reproductive parameters.
Qualifier:
equivalent or similar to guideline
Guideline:
other: OECD Guideline 413 - Subchronic Inhalation Toxicity: 90-Day
Version / remarks:
Male and Female reprodcutive parameters examined
Deviations:
yes
Remarks:
Reproductive parameters included: Sperm motility and density; vaginal cytology; histopathology of male and female reproductive organs (epididymis/seminal vesicles/ prostate/testes or ovaries/uterus)
Principles of method if other than guideline:
Reproductive parameters included: Sperm motility and density; vaginal cytology; histopathology of male and female reproductive organs (epididymis/seminal vesicles/ prostate/testes or ovaries/uterus)
GLP compliance:
yes
Limit test:
no
Specific details on test material used for the study:
- 95 % formic acid in water
- Physical state: liquid
- Analytical purity: 95%
- Impurities (identity and concentrations): water. Formaldehyde: <0.1%
Species:
mouse
Strain:
B6C3F1
Details on species / strain selection:
- Source: Taconic Farms, Inc., Germantown, NY
- Age at study initiation: 7 weeks for mice in 13-week studies
- Housing: individually
- Diet: standard NIH-07 diet ad libitum
- Water: tab water ad libitum
- Acclimation period: 12 days
Sex:
male/female
Details on test animals or test system and environmental conditions:
- Temperature (°C): temperature 75°F
- Humidity (%): rel. humidity 55+/-15%,
- air changes per hour: 15
- Photoperiod (hrs dark / hrs light): 12/12
Route of administration:
inhalation
Type of inhalation exposure (if applicable):
whole body
Vehicle:
unchanged (no vehicle)
Remarks:
Air
Details on exposure:
- Exposure apparatus: commercial 1.7 m³ inhalation chambers
- Temperature, humidity, pressure in air chamber: temperature 75°F, rel. humidity 55+/-15%
- Vapor generation: liquid formic acid was pumped by a micrometer pump to a vaporizer heated to 97.5°C. The vapor entered a distribution line where a constant 2300 ppm atmosphere was maintained. Dilution air (HEPA filtered, rel. humidity 50%) carried a metered amount to the individual exposure chambers.

Details on mating procedure:
No mating
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
A Foxboro Mitran 980 infrared spectrometer at 9.050 microns was used to monitor the exposure chambers, control chamber, exposure room, an online standard of formic acid vapor, and a pure nitrogen source. All locations were monitored every 40 min. In addition, formaldehyde concentrations were monitored in the 8 ppm and 128 ppm exposure chambers, and in the formic acid distribution line. Corrections were made for absorbance of water and for instrument drift.
The online monitor was calibrated with GC analyses of grab samples taken from the exposure chambers at the time of the readings.

The limit of detection and limit of quantification for the on-line monitor were determined at an average chamber relative humidity of 33-51%.
The practical detection limit was 0.36 ± 0.10 ppm, with a practical quantification limit of 0.68 ± 0.10 ppm.
Duration of treatment / exposure:
13 weeks (90 days)
Frequency of treatment:
5 days per week, 6 hour per day
Details on study schedule:
Sperm morphology and vaginal cytology examinations were performed for rats and mice administered formic acid at 0, 8, 32, and 128 ppm in the 13-week study. males were examned at necropsy, females were subjected to vaginal lavage during the last 2 weeks, followed by vaginal cytology evaluation
Dose / conc.:
0 ppm
Remarks:
vapour
Dose / conc.:
8 ppm
Remarks:
vapour
Dose / conc.:
32 ppm
Remarks:
vapour
Dose / conc.:
64 ppm
Remarks:
vapour
Dose / conc.:
128 ppm
Remarks:
vapour
No. of animals per sex per dose:
10 Males, 10 Females
Control animals:
yes, concurrent vehicle
Parental animals: Observations and examinations:
Daily:
Bahavioural & Clinical Observations, Body Weights,
Haematology on additional rats on days 3 and 23, core study animals at termination in week 13
Clinical Chemistry on blood collection

- sperm morphology and vaginal cytology were evaluated in rats and mice exposed to 0, 8, 32, and 128 ppm.
Oestrous cyclicity (parental animals):
Epididymal sperm motility was evaluated at necropsy, and vaginal cytology was evaluated on animals during the 2 weeks just preceding necropsy, using procedures outlined by Morrissey et al. (1988). For the 12 days prior to sacrifice, females were subject to vaginal lavage with saline. The aspirated cells were air-dried onto slides, stained with Toluidine Blue O, and cover slipped. The relative preponderance of leukocytes, nucleated epithelial cells, and large squamous epithelial cells were used to identify the stages of the estrual cycle.
Sperm parameters (parental animals):
Testis weight, epididymis weight, sperm count in testes, sperm motility, sperm morphology
Litter observations:
N/A
Postmortem examinations (parental animals):
At Sacrifice:
- Gross pathology, Histopathology
- Tissues examined: adrenal glands, brain, bronchial lymph nodes, cecum, colon, duodenum, epididymis/seminal vesicles/ prostate/testes or ovaries/uterus, esophagus, eyes (if grossly abnormal), femur (including marrow), gallbladder (mice), gross lesions and tissue masses with regional lymph nodes, heart, ileum, jejunum, kidneys, larynx, liver, lungs with mainstem bronchi, mammary gland and adjacent skin, mandibular and mesenteric lymph nodes, mediastinal lymph nodes, nasal cavity and turbinates, pancreas, parathyroid glands, pharynx (if grossly abnormal), pituitary gland, preputial /clitoral glands (rats), rectum, salivary glands, spinal cord and sciatic nerve (if neurologic signs present), spleen, stomach (including forestomach and glandular stomach), thigh muscle, thymus, thyroid gland, trachea, and urinary bladder. In addition to all gross lesions, the following tissues were examined in all other dose groups:
rats--nose (three transverse sections), lung, larynx, trachea, bronchial and mediastinal lymph nodes;
mice--nose (three transverse sections).
Organ weights (to the nearest mg) were obtained from all core study animals and include: liver, thymus, right kidney, right testis, heart
and lungs.
Postmortem examinations (offspring):
N/A
Statistics:
Data were presented as mean +/- standard error, n=10 Differences from the control group for reproductive tissue weights and spermatozoal
measurements were evaluated by Dunn's test or Shirley's test.
Reproductive indices:
Sperm morphology and vaginal cytology were evaluated in rats and mice exposed to 0, 8, 32, and 128 ppm.
Offspring viability indices:
N/A
Clinical signs:
no effects observed
Description (incidence and severity):
There were no clinical signs associated with exposure of male or female mice to formic acid concentrations up to 128 ppm.
Dermal irritation (if dermal study):
not examined
Mortality:
no mortality observed
Description (incidence):
There was no mortality observed male or female mice to formic acid concentrations up to 128 ppm.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Body weight gains were significantly less than controls in the 128 ppm exposure groups of both sexes and in female mice exposed to 64 ppm formic acid.
Food efficiency:
effects observed, treatment-related
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
effects observed, non-treatment-related
Description (incidence and severity):
Changes in hematologic variables were few and generally minimal to mild in magnitude.
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
There were mild, significant decreases in concentrations of serum albumin in female rats at day 3 (32, 64, and 128 ppm exposure groups) and increases in male rats at 13 weeks (8, 16, and 32 ppm exposure groups). Concentrations of total serum protein were decreased in female rats in all exposure groups at day 3. Male and female rats exposed to 16, 32 (female only), 64, and 128 ppm formic acid had significant increases in serum AP at 13 weeks. Additional changes in serum biochemical variables in rats exposed to formic acid included decreases in activities of amylase (female rats, days 3 and 23) and CK (male rats, day 3; female rats, day 23), increases in activities of SDH (male rats, day 3), and decreases in concentrations of UN and creatinine (male and female rats, day 3).
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Microscopic changes attributed to toxicity of formic acid were limited to degeneration of the olfactory epithelium of the nose in a few mice from the 64 and 128 ppm exposure groups
Histopathological findings: neoplastic:
not examined
Other effects:
no effects observed
Description (incidence and severity):
There were no adverse effects of formic acid exposure on reproductive parameters evaluated in male or female mice. Sperm motility was somewhat lower in the exposed groups compared to controls, but the values for controls were rather high, and the values for exposed mice
fall well within the historical range for control mice.
Reproductive function: oestrous cycle:
no effects observed
Reproductive function: sperm measures:
no effects observed
Reproductive performance:
not examined
Organ Weights (Male Reproductive Organs): No Effect
Gross Pathology (Parental Animals): No Effect
Histopathology (Parental Animals): No Effect
Reproductive Function: Estrous Cycle: No Effect
Reproductive Function: Sperm Measures: No Effect
Key result
Dose descriptor:
NOEC
Effect level:
128 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
organ weights and organ / body weight ratios
gross pathology
histopathology: non-neoplastic
reproductive function (oestrous cycle)
reproductive function (sperm measures)
Not examined
Remarks on result:
not measured/tested
Key result
Reproductive effects observed:
no

Parameter                 Exposure concentration (ppm)    
                    0         8         32          128 
----------------------------------------------------------- 
Males 
Weight (g) 
right testis      0.122     0.121      0.122      0.120 
left epididymis   0.042     0.045      0.042      0.041    
left epididymal   0.017     0.017      0.015      0.015 
tail 

Spermatozoal meausurements 
Motility (%)     94+/-0     91+/-1**   86+/-1**   90+/-1** 
Concentration     1060       1114     1337**      1406**   
(10E06/g) 

Females 
Estrous cycle    4.00       4.17       4.00        4.40 
length (d)        

Conclusions:
In a 13-week whole-body inhaltion study in mice (OECD 413) no effects on sperm motility, density, and testes and epididymal weight, or estrous cycle length were observed in animals exposed to 0, 8, 16, 32, 64, or 128 ppm formic acid vapours for 6 hours/day, 5 days/week.

Sperm motility and morphology was examined at termination in all males.
Estrous cycle of all females was examined during the last two weeks of exposure.
Male and female reproductive organs were weighed and subjected to histopathological examination.

There were no findings that would indicate adverse effects on male and female reproductive organs at any dose.
Effect on fertility: via inhalation route
Endpoint conclusion:
no adverse effect observed

Justification for classification or non-classification

In two 13 -week whole-body inhalation studies in rats and mice (OECD 413) no effects on sperm motility, density, and testes and epididymal weight, or estrous cycle length were observed in animals exposed to 0, 8, 16, 32, 64, or 128 ppm formic acid vapours for 6 hours/day, 5 days/week.

Sperm motility and morphology was examined at termination in all males. Estrous cycle of all females was examined during the last two weeks of exposure. Male and female reproductive organs were weighed and subjected to histopathological examination. There were no findings that would indicate adverse effects on male and female reproductive organs at any dose

Additional information