1,6-Hexanediamine, N1,N1,N6,N6-tetramethyl-, propoxylated (>1 < 4,5 mol PO)

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

March, 1996

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: OPPTS 870.3650 (Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test)

Version / remarks:

July, 2000

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: OECD 421 (Reproduction/Developmental Toxicity Screening Test)

Version / remarks:

July, 1995

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: OPPTS 870.3550 (Reproduction/Developmental Toxicity Screening Test)

Version / remarks:

July, 2000

Test guideline 5

Qualifier:

according to guideline

Guideline:

EU Method B.7 (Repeated Dose (28 Days) Toxicity (Oral))

Version / remarks:

May, 2008

Test guideline 6

Qualifier:

according to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Version / remarks:

October, 2008

Test guideline 7

Qualifier:

according to guideline

Guideline:

other: OPPTS 870.3050 (Repeated dose 28-day oral toxicity study in rodents)

Version / remarks:

July, 2000

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

1,6-Hexanediamine, N1,N1,N6,N6-tetramethyl-, propoxylated (>1 < 4,5 mol PO)

EC Number:

605-146-4

Cas Number:

158451-78-6

Molecular formula:

C16H38N2O2

IUPAC Name:

1,6-Hexanediamine, N1,N1,N6,N6-tetramethyl-, propoxylated (>1 < 4,5 mol PO)

Specific details on test material used for the study:

- Name of test material (as cited in study report): 1,6-Hexanediamine, N1,N1,N6,N6-tetramethyl-, propoxylated
- Appearance: clear yellowish liquid
- Batch: 0011784570
- Purity/composition: Water: 13.9% 1,6-Hexanediamine, N1,N1,N6,N6-tetramethyl-,propoxylated, 3.4% Propylene glycol, 82.7% Water
- Test substance storage: at room temperature
- Expiry date: 31 October 2015
- Specific gravity/density: 1.02 - 1.03 g/cm3 (20 *C)
- pH: 14

Test animals

Species:

rat

Strain:

Wistar

Remarks:

Crl:WI(Han)

Details on species / strain selection:

outbred, SPF-Quality

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany.
- Females nulliparous and non-pregnant: yes
- Age at study initiation: approximately 12 weeks
- Weight at study initiation: Males: 330 - 332 g; Females: 209 - 213 g
- Housing:
Pre-mating: Animals were housed in groups of 5 animals of the same sex in Macrolon plastic cages (MIV type, height 18 cm).
Mating: Females were caged together with males on a one-to-one-basis in Macrolon plastic cages (MIII type, height 18 cm).
Post-mating: Males were housed in their home cage (Macrolon plastic cages, MIV type, height 18 cm) with a maximum of 5 animals/cage. Females were individually housed in Macrolon plastic cages (MIII type, height 18 cm).
General: Sterilized sawdust as bedding material (Lignocel S 8-15, JRS - J.Rettenmaier & Söhne GmbH + CO. KG, Rosenberg, Germany) and paper as cage-enrichment/nesting material (Enviro-dri, Wm. Lillico & Son (Wonham Mill Ltd), Surrey, United Kingdom) were supplied. During locomotor activity monitoring, animals were housed individually in a Hitemp polycarbonate cage (Ancare corp., USA; dimensions: 48.3 x 26.7 x 20.3 cm) without cage-enrichment, bedding material, food and water.
- Diet: pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany), ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days

DETAILS OF FOOD AND WATER QUALITY: Diet, water, bedding and cage enrichment evaluation for contaminants and/or nutrients was performed according to facility standard procedures. There were no findings that could interfere with the study.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-24
- Humidity (%): 40-70
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Remarks:

(Elix, Millipore S.A.S., Molsheim, France)

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: Formulations (w/w) were prepared daily within 5 hours prior to dosing and were homogenized to a visually acceptable level. Adjustment was made for specific gravity of the test substance (using a value of 1.025 g/cm3). No adjustment was made for specific gravity/density of the vehicle. No correction was made for the purity/composition of the test substance.

VEHICLE
- Amount of vehicle: 10 mL/kg

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples of dose preparations were taken at the test facility on a single occasion during the treatment period (formulations were prepared and sampled on 10 March 2015). The samples were dispatched on dry ice to the test facility where they were analysed to assess accuracy of preparation, homogeneity and stability in vehicle over 5 hours at room temperature under normal laboratory light conditions.

Duration of treatment / exposure:

Males were exposed for 29 days, i.e. 2 weeks prior to mating, during mating, and up to the day prior to scheduled necropsy. Females were exposed for 41-55 days, i.e. during 2 weeks prior to mating, during mating, during post-coitum, and during at least 4 days of lactation (up to the day prior to scheduled necropsy). Some of the femaleswere not dosed on post-coitum Day 22 or Day 23 as these females were littering at the time of dosing. The omission of one day of dosing over a period of several weeks was not considered to affect the toxicological evaluation.

Frequency of treatment:

Once daily for 7 days per week

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

63 mg/kg bw/day (actual dose received)

Doses / concentrations 2

Dose / conc.:

250 mg/kg bw/day (actual dose received)

Doses / concentrations 3

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

10

Details on study design:

- Dose selection rationale: Dose levels were based on a 14-day dose range finding study in which dose levels of 300 and 1000 mg/kg bw/day were tested. Animals given 1000 mg/kg bw/day had reduced body weight gain, most markedly at the start and end of the study, and slightly lower food consumption at the end of the study. They had no clinical signs of toxicity, macroscopic findings or organ weight changes. Some differences in clinical pathology values were noted, most of which were minor. No adverse findings were seen at 300 mg/kg bw/day.

Positive control:

No

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS:
- Time schedule: at least twice daily

DETAILED CLINICAL OBSERVATIONS:
- Time schedule: At least once daily from start of treatment onwards up to the day prior to necropsy, detailed clinical observations were made for all animals. Once prior to start of treatment and at weekly intervals during the treatment period this was also performed outside the home cage in a standard arena. These clinical observations were made after dosing (at no specific time point as there was no peak occurrence of clinical signs after dosing in the dose range finding study.
- The time of onset, grade and duration of any observed sign were recorded. Signs were graded for severity and the maximum grade was predefined at 3 or 4. Grades were coded as slight (grade 1), moderate (grade 2), severe (grade 3) and very severe (grade 4). For certain signs, only its presence (grade 1) or absence (grade 0) was scored.

BODY WEIGHT:
- Time schedule for examinations: Males and females were weighed on the first day of exposure and weekly thereafter. Mated females were weighed on Days 0, 4, 7, 11, 14, 17 and 20 post-coitum and during lactation on Days 1 and 4.

FOOD CONSUMPTION AND COMPOUND INTAKE:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day.
- Time schedule for examinations: weekly, except for males and females which were housed together for mating and for females without evidence of mating. Food consumption of mated females was measured on Days 0, 4, 7, 11, 14, 17 and 20 postcoitum and on Days 1 and 4 of lactation.

WATER CONSUMPTION AND COMPOUND INTAKE:
Subjective appraisal was maintained during the study, but no quantitative investigation was introduced as no treatment related effect was suspected.

HAEMATOLOGY:
- Time schedule for collection of blood: at the end of the treatment period on the day of scheduled necropsy between 7.00 and 10.30 a.m.
- Anaesthetic used for blood collection: Yes, isoflurane
- Animals fasted: Yes, overnight (maximum of 24 hours)
- How many animals: 5 animals/sex/group
- Parameters examined: White blood cells, Differential leukocyte count (neutrophils, lymphocytes, monocytes, eosinophils, basophils), Red blood cells, Reticulocytes, Red blood cell distribution width, Haemoglobin, Haematocrit, Mean corpuscular volume, Mean corpuscular haemoglobin, Mean corpuscular haemoglobin concentration, Platelets, Prothrombin time, Activated Partial thromboplastin time

CLINICAL CHEMISTRY:
- Time schedule for collection of blood: at the end of the treatment period on the day of scheduled necropsy between 7.00 and 10.30 a.m.
- Animals fasted: Yes, overnight (maximum of 24 hours)
- How many animals: 5 animals/sex/group
- Parameters examined: Alanine aminotransferase, Aspartate aminotransferase, Alkaline phosphatase, Total Protein, Albumin, Total Bilirubin, Bile acids, Urea, Creatinine, Glucose, Cholesterol, Sodium, Potassium, Chloride, Calcium, Inorganic Phosphate

NEUROBEHAVIOURAL EXAMINATION:
-The following functional observation tests were performed on each individual animal of the selected 5 animals/sex/group:
- hearing ability, pupillary reflex and static righting reflex (Score 0 = normal/present, score 1 = abnormal/absent).
- fore- and hind-limb grip strength were recorded as the mean of three measurements (Series M4-10, Mark-10 Corporation, J.J. Bos, Gouda, The Netherlands).
- locomotor activity (recording period: 1-hour under normal laboratory light conditions, using a computerized monitoring system, Kinder Scientific LLC, Poway, USA). Total movements and ambulations were reported. Ambulations represent movements characterized by a relocation of the entire body position like walking, whereas total movements represent all movements made by the animals, including ambulations but also smaller or more fine movements like grooming, weaving or movements of the head.
- The selected males were tested during Week 4 of treatment and the selected females were tested towards the end of the scheduled lactation period from lactation Day 4 onwards (all before blood sampling). These tests were performed after observation for clinical signs (incl. arena observation, if applicable) at no specific time point, but within a similar time period after dosing for the respective animals.

Sacrifice and pathology:

SACRIFICE
- Male animals: All surviving animals. Following completion of the mating period (a minimum of 28 days of dose administration)
- Maternal animals: All surviving animals. Females which delivered: lactation day 5-6; females which failed to deliver: post-coitum day 27 (female with evidence of mating); females with total litter loss: withiin 24 hours of litter loss

GROSS NECROPSY
After the animals were exsanguinated they were subjected to a full post mortem examination, with special attention being paid to the reproductive organs. Samples of the following tissues and organs were collected from all animals and fixed in 10% buffered formalin and examined: Adrenal glands, Peyer's patches [jejunum, ileum] if detectable, Brain (cerebellum, mid-brain, cortex), Pituitary gland, Caecum Preputial gland, Cervix Prostate gland, Clitoral gland Rectum, Colon, Coagulation gland, Ovaries, Sciatic nerve, Duodenum, Seminal vesicles, Epididymides, Skeletal muscle, Eyes (with optic nerve (if detectable) and Harderian gland), Spinal cord (-cervical, midthoracic, lumbar), Female (and male) mammary gland area, Spleen, Femur including joint, Sternum with bone marrow, Heart, Stomach (forestomach and glandular stomach), Ileum, Testes, Jejunum, Thymus, Kidneys, Thyroid including parathyroid if detectable, Trachea, Liver, Urinary bladder, Lung (infused with formalin Uterus), Lymph nodes (- mandibular, mesenteric), Vagina, All gross lesions. The numbers of former implantation sites and corpora lutea were recorded for all paired females.

ORGAN WEIGHTS:
Terminal body weight was recorded from all surviving animals. The following organ weights were
recorded from the following surviving animals on the scheduled day of necropsy (from 5 animals/sex/group): Adrenal glands, Brain, Epididymides, Heart, Kidnesy, Liver, Ovaries, Spleen, Testes, Thymus, Uterus (including cervix), Prostate, Seminal vesicles including coagulating glands (Weighed when fixed for at least 24 hours), Thyroid including parathyroid

HISTOPATHOLOGY: tissues examined:
- From groups 1 and 4 (dose levels of 0 and 1000 mg/kg bw/day): Adrenal glands, Pancreas, Aorta, Peyer's patches [jejunum, ileum] if detectable, Brain (cerebellum, mid-brain, cortex), Pituitary gland, Caecum Preputial gland, Cervix Prostate gland, Clitoral gland Rectum, Colon (Salivary glands - mandibular, sublingual), Coagulation gland, Ovaries, Sciatic nerve, Duodenum, Seminal vesicles, Epididymides, Skeletal muscle, Eyes (with optic nerve (if detectable) and Harderian gland), Skin, Spinal cord (-cervical, midthoracic, lumbar), Female (and male) mammary gland area, Spleen, Femur including joint, Sternum with bone marrow, Heart, Stomach (forestomach and glandular stomach), Ileum, Testes, Jejunum, Thymus, Kidneys, Thyroid including parathyroid if detectable, Lacrimal gland (exorbital), Tongue, Larynx, Trachea, Liver, Urinary bladder, Lung (infused with formalin Uterus), Lymph nodes (- mandibular, mesenteric), Vagina, Nasopharynx, Esophagus, All gross lesions
- The additional slides of the testes of all males of Groups 1 and 4 and all males that failed to sire to examine staging of spermatogenesis.
- All gross lesions of all animals (all dose groups).
- The stomach of the selected males and females of Groups 2 and 3 (dose levels of 63 and 250 mg/kg bw/day), the heart, adrenal glands and mesenteric lymph nodes of the selected males of Groups 2 and 3, and the thymus, ileum, spleen
and caecum of the selected females of Groups 2 and 3, based on suspected treatment-related microscopic findings in these organs.
- The reproductive organs of all animals of Groups 1 and 4 and all males that failed to sire and all females that failed to deliver healthy pups and the mammary glands of females with total litter loss

Statistics:

- If the variables could be assumed to follow a normal distribution, the Dunnett-test (many-to-one t-test) based on a pooled variance estimate was applied for the comparison of the treated groups and the control groups for each sex.
- The Steel-test (many-to-one rank test) was applied if the data could not be assumed to follow a normal distribution.
- The Fisher Exact-test was applied to frequency data.
- The Kruskal-Wallis nonparametric ANOVA test was applied to motor activity data to determine intergroup differences. In case intergroup differences were seen, the Wilcoxon test was applied to compare the treated groups to the control group.

All tests were two-sided and in all cases p < 0.05 was accepted as the lowest level of significance. Group means were calculated for continuous data and medians were calculated for discrete data (scores) in the summary tables. Test statistics were calculated on the basis of exact values for means and pooled variances.

Results and discussion

Results of examinations

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

- No clinical signs of toxicity were noted up to 1000 mg/kg bw/day.
- Incidental findings that were noted included alopecia and salivation. These findings occurred within the range of background findings to be expected for rats of this age and strain which are housed and treated under the conditions in this study. At the incidence observed, these were considered signs of no toxicological relevance.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

No mortality occurred during the study period that was considered to be related to treatment with the test substance. Two females were sacrificed on Day 2 or 3 of lactation because of total litter loss (one from Group 1, one from Group 4).

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

- Males at 1000 mg/kg bw/day had lower body weights and lower body weight gain from Day 1 of the mating period onwards. The differences from control values were statistically significant except for the lower mean body weight on Day 1 of the mating period. Towards the end of the study (Day 15 of the mating period), mean body weight of males at 1000 mg/kg bw/day was 7% lower than that of controls).
- Males at 250 mg/kg bw/day showed a statistically significantly lower body weight gain on Day 8 of the mating period. The difference from controls was slight and mean body weights of these males did not differ significantly from those of controls. Therefore, this finding was considered not to be toxicologically relevant.
- Females showed no treatment-related changes in body weight or body weight gain up to 1000 mg/kg bw/day. Statistically significantly higher body weight gain values were noted in females at 250 mg/kg bw/day on post-coitum Days 17 and 20. These findings were not attributed to treatment because there was no dose-related response.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

- Males at 1000 mg/kg bw/day had lower food consumption before allowance for body weight between Days 8-15 of the pre-mating and mating periods.
- Food consumption of these males after allowance for body weight was slightly lower between Days 8-15 of the pre-mating period. Food consumption of females before or after allowance for body weight was similar between treated and control animals throughout the study.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not examined

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

- Haematological parameters of treated rats were not affected by treatment. Statistically significantly higher numbers of platelets were noted in males at 250 and 1000 mg/kg bw/day. These differences were not attributed to treatment because there was no dose-related response. Moreover, the concurrent control value was at the lower end of the normal range.
- A statistically significantly lower percentage of reticulocytes was noted in males at 250 mg/kg bw/day. In the absence of a dose-related response this finding was not attributed to treatment.
- Further it was noted that males at 1000 mg/kg bw/day had a higher mean value for neutrophils and lower mean values for lymphocytes and WBC. This was due to abnormal values of one male coming from Group 4. The other males treated at 1000 mg/kg bw/day had normal white blood cell values. Therefore, it was concluded that no toxicologically relevant changes occurred in haematology values of treated rats.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

- Clinical biochemistry parameters of treated rats were not affected by treatment. Males at 1000 mg/kg bw/day had a lower mean value for total protein and a higher mean value for bile acids. The differences from controls were not statistically significant and were particlularly due to a low (total protein) or high (bile acids) value in a single male animal. Therefore, these findings were considered not to be related to treatment.
- Further it was noted that the mean value for ALP was lower in males at 1000 mg/kg bw/day and that the mean glucose value was higher in females at this dose level. These findings were not attributed to treatment because the differences from controls were not statistically significant and in the normal range.
- A statistically significantly lower plasma level of inorganic phosphate noted in males treated at 250 mg/kg bw/day was not attributed to treatment because there was no dose-related response.

Urinalysis findings:

not examined

Behaviour (functional findings):

effects observed, non-treatment-related

Description (incidence and severity):

- Hearing ability, pupillary reflex, static righting reflex and grip strength were not adversely affected by treatment. Mean forelimb grip strength and, to a lesser extent, mean hind limb grip strength values were lower in males at 1000 mg/kg bw/day. The differences from controls were not statistically significant and remained in the normal range for male rats of this age and strain. Therefore, these findings were considered not to be toxicologically relevant.
- The variation in motor activity did not indicate a relation with treatment. All groups showed a similar habituation profile with high activity in the first interval that decreased over the duration of the test period. The mean value for amubulations was statistically significantly higher in males at 250 mg/kg bw/day. As there was no dose-related response, this finding was not attributed to treatment.

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

- Mean terminal body weight of males at 1000 mg/kg bw/day was statistically significantly lower than that of controls (relative difference 7%).
- It was noted that the mean prostate weight (absolute and relative to body weight) in males at 1000 mg/kg bw/day was lower than that in controls (relative difference from control value: about 20%). The lower prostate weight was not associated with any histological changes and within the historical control range. Moreover, the difference from controls was not statistically significant. Therefore, this finding was not attributed to treatment.
- Males at 250 mg/kg bw/day had a statistically significantly higher mean testes weight (absolute and relative to body weight). In the absence of a dose-related response, this slight difference was considered not to be related to treatment.
- The other organ weights and organ to body weight ratios of treated animals were similar to those of control animals.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

- Treatment-related macroscopic findings were noted in the stomach of males and females treated at 1000 mg/kg bw/day, namely: thickened forestomach in 4/10 males and 1/10 females, and irregular surface and grown together with the diaphragm in 1/10 females.
- Other incidental findings among control and treated animals were within the background range of findings that are encountered among rats of this age and strain, and did not show a dose-related trend. These necropsy findings were therefore considered to be unrelated to treatment.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Treatment-related microscopic findings were noted in forestomach (both sexes) and cecum (females).

Test item-related forestomach lesions were noted at 1000 mg/kg bw/day and consisted of:
- Erosion/ulceration in 3/8 males (moderate) and 2/6 females (marked). The erosion/ulceration was in all cases accompanied by the presence of significant submucosal granulation tissue.
- Lymphogranulocytic inflammation in 4/8 males (3 slight, 1 moderate) and 2/6 females (1 moderate, 1 marked).
- Edema in 4/8 males (1 minimal, 2 slight, 1 moderate) and 1/6 female (1 slight).
- Squamous cell hyperplasia in 5/8 males (2 minimal, 2 slight, 1 moderate) and 5/6 females (4 minimal, 1 slight).
- Hyperkeratosis at increased severity in 3/6 females (slight).

Test item-related findings were noted in the cecum of females at 1000 mg/kg bw/day and consisted of:
- Increased incidence of mucosal hypertrophy in 3/5 females (3 minimal) at 1000 mg/kg bw/day compared to 1/5 females at 250 mg/kg bw/day (1 minimal) and 0/5 at 63 and 0 mg/kg bw/day.

Findings of note were recorded in the thymus of females at 250 and 1000 mg/kg bw/day and consisted of:
- Increase in incidence of increased lymphocytolysis in 2/6 females at 1000 mg/kg bw/day compared to 1/5 females at 250 mg/kg bw/day and 0/5 at 63 and 0 mg/kg bw/day.

The remainder of the histologic changes were considered to be incidental findings. There was no test item-related alteration in the prevalence, severity, or histologic character of those incidental tissue alterations.

Histopathological findings: neoplastic:

not examined

Effect levels

1

Key result

Dose descriptor:

NOAEL

Effect level:

>= 139 mg/kg bw/day (nominal)

Based on:

act. ingr.

Sex:

male/female

Basis for effect level:

other: no systemic treatment-related effects

2

Key result

Dose descriptor:

NOAEL

Remarks:

local effects

Effect level:

250 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

histopathology: non-neoplastic

3

Key result

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: overall systemic toxicity

Target system / organ toxicity

Key result

Critical effects observed:

no

Any other information on results incl. tables

ANALYSIS OF DOSE PREPARATIONS

- No test substance was detected in the Group 1 formulations.

- The concentrations analysed in the formulations of Groups 2, 3 and 4 were in agreement with the target concentrations (i.e. mean accuracies between 90% and 110%).

- The formulations of Group 2 and Group 4 were homogeneous (i.e. coefficient of variation ≤ 10%).

- Formulations at the entire range were stable when stored at room temperature under normal Laboratory light conditions for at least 5 hours (i.e. relative difference ≤ 10%).