resorcinol; 1,3-benzenediol

Endpoint summary

Description of key information

The following information is taken into account for any hazard / risk assessment:

 

• Repeated dose toxicity (oral): In multiple repeat dose studies, the lowest no adverse effect level (NOAEL) associated with a reproducible effect (body weight changes) is 80 mg/kg bw/day. NOAELs associated with the NTP studies are based on CNS effects as requested under the Organization of Economic Cooperation and Development (OECD) Screening Information Data Set (SIDS) Program, whilst the NTP review panel regarded these effects as acute effects and were considered a result of bolus dosing.
  
  
  


• Repeated dose toxicity (inhalation): In a 14-day range finding study, no adverse effect concentration (NOAEC) is 991 mg/m3. There are no findings suggestive of local effects on respiratory tract.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline Study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

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

Principles of method if other than guideline:

The study was designed to comply with OECD Guideline No. 408, 21 September 1998.

GLP compliance:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Route of administration:

oral: gavage

Vehicle:

other: purified water

Duration of treatment / exposure:

Three treated groups of 10 male and 10 female Sprague-Dawley rats received the test item, Resorcinol (A011), (batch No. 706030517), daily by
gavage at 40, 80 or 250 mg/kg/day for 13 weeks. An additional group of 10 males and 10 females received only the vehicle (purified water) and actedas a control group. At 0 and 250 mg/kg/day (groups 1 and 4), six animals of each sex were treated for 13 weeks and then kept for a 4-week
treatment-free period. Six animals of each sex in groups 2, 3 and 4 were used for toxicokinetic investigations.

Frequency of treatment:

Daily for 13 weeks

Remarks:

Doses / Concentrations:
0, 40, 80 and 250 mg/kg/day
Basis:
other:

No. of animals per sex per dose:

Three treated groups of 10 male and 10 female Sprague-Dawley rats received the test item. An additional group of 10 males and 10 females
received only the vehicle (purified water) and acted as a control group.

Observations and examinations performed and frequency:

The animals were checked daily for mortality and clinical signs. Detailed clinical observations were carried out weekly, and a Functional Observation
Battery (including motor activity) was performed at the end of the treatment period. Detailed observations included (but were not limited to) changes
in the skin, fur, eyes, mucous membranes, occurrence of secretions and excretions and autonomic activity (e.g. lachrymation, piloerection, pupil size,
unusual respiratory pattern). Changes in gait, posture and response to handling as well as the presence of clonic or tonic movements, stereotypes
(e.g. excessive grooming, repetitive circling) or bizarre behavior (e.g. self-mutilation, walking backwards) were also recorded. In the functional
observation battery the following parameters were assessed and graded: "touch escape" or ease of removal from the cage, in the hand: fur
appearance, salivation, lachrymation, piloerection, exophthalmia, reactivity to handling, pupil size (presence of myosis or mydriasis), in the standard arena (two-minute recording): grooming, palpebral closure, defecation, and urination counts, tremors, twitches, convulsions, gait, arousal (hypo-
and hyper-activity), posture, stereotypic behaviour and breathing, ataxia, hypotonia. In addition, the following parameters, reflexes and responses
were recorded: touch response, forelimb grip strength, pupil reflex, visual stimulus, auditory startle reflex, tail pinch response, righting reflex,
landing foot splay, at the end of observation: rectal temperature.

The motor activity of each animal was also measured by automated infra-red sensor equipment over a 1-hour period.

Sacrifice and pathology:

On completion of the treatment period and after the treatment-free period, the animals were sacrificed and submitted to a complete macroscopic
post-mortem examination. Designated organs (see list below) were weighed and selected tissue specimens were preserved. A microscopic
examination was performed on selected tissues.

The following organs and/or tissues were evaluated: Adrenals, Aorta, Brain (including medulla/pons cerebellar and cerebral cortex), Cecum, Colon, Duodenum, Epididymides, Esophagus, Eyes with Harderian glands, Femoral bone with articulation, Heart, Ileum (with Peyer patches),Jejunum,
Kidneys, Liver, Lungs with bronchi, Lymph nodes (mandibular and mesenteric), Mammary glands/area, Ovaries (including oviducts), Pancreas,
Pituitary gland, Prostate, Rectum, Salivary glands (sublingual and submandibular), Sciatic nerve, Seminal vesicles (including coagulation gland),
Skeletal muscle, Skin, Spinal cord (cervical, thoracic and lumbar), Spleen, Sternum with bone marrow, Stomach with forestomach, Testes, Thymus,
Thyroids with parathyroids, Tongue, Trachea, Ureters, Urinary bladder, Uterus (horns and cervix) and Vagina. Macroscopic and microscopic
evaluations were perfomed on all above organs/tissues with the following above organs/tissues not receiving a microscopic evaluation:
skeletal muscle, tongue and ureters.

Other examinations:

Body weight and food consumption were recorded weekly. Ophthalmological examinations were performed before the beginning of the treatment
period on all animals and at the end of the treatment period for control and high dose-group animals. Hematological and blood biochemical
investigations were performed at the end of the treatment period and at the end of the treatment-free period. Urine parameters were investigated at
the end of the treatment period.

Venous blood (approximately 0.5 mL) was taken from the orbital sinus of the animals under light isoflurane anesthesia into a tube containing lithium heparin. The blood was centrifuged, and the plasma was kept frozen in individual tubes at -20°C until analysis after the development and validation ofthe analytical method.

Satellite animals were checked for clinical signs and mortality. Body weight was recorded for dosing purposes only. The data were filed and are
presented separately from those of the principal animals in the study report. No necrospy was performed.

Statistics:

Statistical analysis were peformed using the followng tests when appropriate: Kolmogorov-Lilliefors test, Dunn test, Mann-Whitney/Wilcoxon test,
Student test, Bartlet test and Fischer test.

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

Under the experimental conditions of the study, the No Observed Adverse Effect Level (NOAEL) was 80 mg/kg/day in both sexes.

FOB: Examination of the animals during the Functional Observation Battery did not reveal any treatment-related effect.

Mortalities and clinical observations:
Two males out of 20 total animals receiving 80 mg/kg/day were found dead, one on day 48 and another on day 85. Both males experienced
convulsions before death and one male also had excessive salivation. One female out of 20 total animals receiving 250 mg/kg/day was found dead onday 35 (week 5) of treatment. No clinical observations were recorded for this animal prior to death. At necropsy, foamy content was noted in the lungs in one animal and in the lungs and trachea of two animals. At microscopy, the major findings were alveolar hemorrhage in the lungs of one animal;
moderate alveolar emphysema in the lungs of one animal; and slight alveolar edema in the lungs of one animal. The lung lesions might be a
contributing factor to these mortalities, in relation with highly probable misdosings. Taking into consideration that there were no mortalities in the
male rats given the higher dose-level (250 mg/kg/day) and that observed deaths were probably caused by gavage errors, the above mentioned
mortalities were considered to be accidental and not to be treatment-related. Therefore, no treatment-related deaths were noted during the study
and the animals found dead died as a consequence of misdosing.

The majority of animals given 250 mg/kg/day experienced intermittent convulsive movements and excessive salivation from around week 7 until the end of the dosing period. Two males had loud breathing, one during week 6 and the other between weeks 11 and 13. No clinical observations
considered to be related to treatment were noted after the cessation of treatment. With the exception of the two males which had convulsions and
died (probable misdosings), no clinical observations were recorded at 80 mg/kg/day.

One male receiving 40 mg/kg/day had a round back, partially closed eyes and an emaciated appearance during weeks 11 and 12, a piloerection
during weeks 11 and 13, associated with a marked body weight loss and a slightly lower food consumption. As these clinical signs were observed in
isolated animals and not noted at higher doses (80 or 250 mg/kg/day), they were considered to be incidental and not test item-related. One satellite male given 40 mg/kg/day had dyspnea and loud breathing during weeks 11 and 12, associated with a marked body weight loss, an emaciated
appearance and regurgitation during week 12 of treatment. These events were considered to be related to an abnormal growth of teeth noted in this
animal, and were not considered to be treatment-related. Body weight and body weight gain: There were no effects on group mean male body weight during either the treatment or treatment-free periods. Females receiving 250 mg/kg/day gained slightly less weight than the controls in weeks 4 to
8 of treatment. During week 11, mean body weight decreased (-3g) in males receiving 40 mg/kg/day. This was mainly due to one animal
(E27368, -93 g during this period) having abnormal teeth growth and therefore was not considered to be treatment-related.

The female group receiving 250 mg/kg/day gained only 37g versus 43g in controls (ie 86% of the weight gained by the controls) from week 4 to week 8. With this exception, body weight changes of females were similar in treated and control groups. The recovery group of males receiving
250 mg/kg/day consistently weighed statistically and significantly more than the recovery control males during the last third of the dosing period
and during the post-treatment period. However, generally the control recovery males weighed slightly less than the principal control males so this
was considered not to be related to treatment.

The recovery group of females receiving 250 mg/kg/day also weighed significantly more than the recovery control females over weeks 1 to 13 of
dosing. There was no difference in body weight between the recovery group of females treated at 250 mg/kg/day and the principal control females,
so the statistically significant increase in body weight was not considered to be toxicologically significant. The recovery group of females treated at
250 mg/kg/day continued to weight more than the recovery control females for the duration of the treatment and post-treatment periods, although body weight gains were comparable between the two groups.

Food consumption: There were no effects of treatment on group mean male or female food consumption. During the treatment-free period, males and female at 250 mg/kg/day consumed slightly more food than the controls.

Functional Observation Battery and motor activity: There were no effects of treatment on forelimb grip strength, landing foot splay, rectal
temperature, pupil size, reactivity to handling, defecation or urination. Motor activity was not affected by the treatment either.

Hematology and blood biochemistry: No differences of toxicological importance were noted between treated and control animals in any of the
parameters examined.

Urinalysis: No treatment-related effects on the qualitative or quantitative urine parameters investigated were noted.

Organ weight: No treatment-related effects on organ weights were noted.

Necropsy findings and histopathological examination: No treatment-related necropsy findings were noted and no changes that were considered to
be related to treatment were seen at microscopic examination.

Dose descriptor:

NOAEL

Effect level:

80 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

Critical effects observed:

not specified

Conclusions:

Under the experimental conditions of the study, the No Observed Adverse Effect Level (NOAEL) was 80 mg/kg/day in both sexes.

FOB: Examination of the animals during the Functional Observation Battery did not reveal any treatment-related effect.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

80 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

The oral database is of a good/standard quality.

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Provides basic data for initial dose selection in the 90 day study.

Qualifier:

according to guideline

Guideline:

other: standard repeated dose

Principles of method if other than guideline:

Method: other

GLP compliance:

not specified

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Route of administration:

inhalation

Type of inhalation exposure:

not specified

Duration of treatment / exposure:

14 days

Frequency of treatment:

8 hrs/day

Remarks:

Doses / Concentrations:
220 ppm
Basis:

Details on study design:

A preliminary 14 day inhalation exposure was conducted on 10 rats, five males and five females, to detemine the feasibility of the 220 ppm  concentration for the 90 day study.  At the end of the exposure, all animals were sacrificed and examined grossly.

Details on results:

Except for slight hemorrhagic spotting on the lungs of one male rat, all tissues appeared essentially normal.  No tissues of animals in this group were examined histopathologically.  On the basis of this pilot study, it was concluded that the 220 ppm concentration was appropriate for the 90 day study

Dose descriptor:

other: Determination of definitive study concentration

Effect level:

220 ppm

Based on:

test mat.

Sex:

male/female

Critical effects observed:

not specified

Conclusions:

A 14 day range finding study in 5 male and female Wistar rats (exposed to 220 ppm for 8 hrs/day) was conducted to determine appropriate concentrations for a subsequent 90 day study. At 220 ppm only one male rat had slight hemorrhagic spotting on the lungs while the remaining tissues appeared normal. No tissues of animals in this group were examined histopathologically. The subsequent 90 day study was considered invalid as it does not meet the requirements of current guidelines.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

991 mg/m³

Study duration:

subacute

Species:

rat

Quality of whole database:

Range-finding study.

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Oral: A 13 week OECD TG 408 study was conducted with groups of 10 male and female Sprague-Dawley rats (CIT, 2004).  Rats received doses of 0, 40, 80 or 250 mg/kg/day (groups 1, 2, 3, and 4, respectively) via the oral bolus dosing (gavage) route 5 days/week. At 0 and 250 mg/kg/day, six animals (groups 1 and 4) of each sex were treated for 13 weeks and held for a 4 week recovery period.  Six animals of each sex in groups 2, 3, and 4 were used for toxicokinetic investigations.  In addition, a functional observation battery was performed at the end of the treatment period.  The NOAEL was 80 mg/kg/day in both sexes.  The majority of animals given 250 mg/kg/day experienced intermittent convulsive movements and excessive salivation from around week 7 until the end of the dosing period.  Two males had loud breathing, one during week 6 and the other between weeks 11 and 13.  No clinical observations considered to be treatment-related were noted after the cessation of treatment.  There were no effects on body weight and gains in males.  Female animals receiving 250 mg/kg/day from week 4 to 8 showed reduced body weight gain.  Examination of the animals during the study did not reveal any treatment related effects.

 

In a 17 day range finding study, male and female Fischer 344 rats were administered 0, 27.5, 55, 110, 225 and 450 mg/kg bw resorcinol in water by gavage, 5 days/week for a total of 12 doses (NTP, 1992).  The female NOAEL is 27.5 mg/kg bw based on hyperexcitability at doses at and greater than 55 mg/kg bw along with tachypnea at 110 and 450 mg/kg bw decreased absolute and relative thymus weights were observed at 450 mg/kg bw and not repeated at similar doses in the 13 week study. As a result, the significance of these findings remains unclear. In males the NOAEL is 110 mg/kg bw based on hyperexcitability and tachypnea at 225 and 450 mg/kg bw.  These effects appeared within half an hour of dosing and lasted 1 to 2 hours. In a 13 week study male and female Fischer 344 rats were administered 0, 32, 65, 130, 260 and 520 mg/kg bw resorcinol in water by gavage 5 days/week (NTP, 1992). All female rats and all but 2 males receiving 520 mg/kg died from compound related toxicity during first 4 weeks of the study.  On day 2 rats receiving 260 mg/kg were given 520 mg/kg in error.  Within 5 days 2 males and 5 females died from this group. These deaths were attributed to error in dosing since no further deaths occurred from rats receiving this dose. Absolute and relative adrenal gland weights were significantly increased in all surviving male dosed groups.  (See below text regarding the NTP’s conclusions on this effect.)  The female NOAEL is 32 mg/kg bw based on increased absolute and relative liver weight at 65 mg/kg bw.  Tremors were observed at 520 mg/kg bw.  The male NOAEL is 65 mg/kg bw based on increased absolute and relative liver weights at 130 and 260 mg/kg bw.  Tremors were observed at 520 mg/kg bw. In a 104 week study, male Fischer 344 rats were administered 0, 112, 225 mg/kg and female rats were administered 0, 50, 100 and 150 mg/kg bw resorcinol in water by gavage 5 days/week (NTP, 1992).  The female NOAEL is  50 mg/kg bw based on ataxia, prostration, salivation and tremors at 100 mg/kg bw.  Body weight changes (decreased) and increased mortality were seen at the highest dose of 150 mg/kg bw; in males a NOAEL was not achieved.  The LOAEL is 112 mg/kg bw based on ataxia, prostration, salivation and tremors at all doses.  Body weight changes (decreased) and increased mortality were seen at the highest dose of 225 mg/kg bw.   

 

In a 17 day range finding study, male and female B6C3F1 mice were administered 0, 37.5, 75, 150, 300 and 600 mg/kg bw resorcinol in water by gavage 5 days/week for a total of 12 doses (NTP, 1992). The female NOAEL is 150 mg/kg bw based on prostration and tremors at 300 mg/kg bw.  Complete mortality occurred at 600 mg/kg bw.  The male NOAEL is 75 mg/kg bw based on prostration and tremors at 150 mg/kg bw with 80% mortality at 600 mg/kg bw and 20% mortality at 300 mg/kg bw.  In a 13 week study male and female B6C3F1 mice were administered 0, 28, 56, 112, 225 and 420 mg/kg bw of resorcinol in water by gavage 5 days/week (NTP, 1992).  Eight mice of each sex receiving 420 mg/kg died by week 4 of the studies from compound-related toxicity.  All except two of these deaths occurred during the first week.  The death of one male receiving 112 mg/kg was due to improper gavage.  In male mice, decreases in absolute and relative adrenal gland weights were noted at 28, 56, 112 and 225 mg/kg bw. (See below text regarding the NTP’s conclusions on this effect.)  The NOAEL in male and females is 225 mg/kg bw based on dyspnea, prostration, tremors and mortality occurring at 420 mg/kg bw.  In a 104 week study, male and female B6C3F1 mice were administered 0, 112, 225 mg/kg bw resorcinol in water by gavage 5 days/week (NTP, 1992).  A NOAEL for male and females was not achieved. The LOAEL in males and females is 112 mg/kg bw based on ataxia, recumbency and tremors occurring at both doses. In females body weight changes (decreased) occurred at 225 mg/kg bw.

 

The NTP commissioned a review panel to investigate the CNS effects observed in each of the NTP studies along with the changes in adrenal weights in the 13 week study (NTP, 1992).  It was determined by the NTP panel that the CNS effects occurred shortly after dosing and subsided within approximately one hour of dosing. This timing also coincided with the rapid clearance of the test substance.  In addition, these effects were exaggerated by day 5 of the weekly dosing cycle but a dose response relationship was not determined. As a result, the NTP review panel concluded these effects to be considered an acute response even though they were observed within the repeated dose studies.  In addition, the significance of the adrenal weight changes remains unclear.  In the 13 week studies the findings were inconsistent between species, as rats showed an increase and mice showed a decrease in adrenal weights.  Furthermore, the adrenal weight changes are not repeated in subsequent studies (see WIL, 2005).  In the 17 day study in rats, the high dose female rats had significantly decreased absolute and relative thymus weights that were not repeated at similar doses in the 13 week study.  As a result, the significance of these findings remains unclear even though the NOAEL is determined based on these findings. 

 

Inhalation:

 

A 14-day range finding study in 5 male and female Wistar rats (exposed to 220 ppm (991 mg/m3) for 8 hrs/day) was conducted to determine appropriate concentrations for a subsequent 90 day study (Industrial Health Foundation Inc., 1977).  While only one male rat had slight hemorrhagic spotting on the lungs, there are no findings suggestive of local effects on respiratory tract. The subsequent 90 day study was considered invalid as it does not meet the requirements of current guidelines. Moreover, due to high mortality possibly caused by an infection, the exposure was temporarily terminated at 64 days in the study.

 

Justification for classification or non-classification

Repeated dose toxicity (oral): In multiple repeat dose studies, the lowest no adverse effect level (NOAEL) associated with a reproducible effect (body weight changes) is 80 mg/kg bw/day.

Repeated dose toxicity (inhalation): In a 14 -day range finding study, no adverse effect concentration (NOAEC) is 991 mg/m³.