Terephthalic acid

Endpoint summary

Description of key information

The toxicity of TPA has been investigated in studies using repeated dose dietary exposure and repeated inhalation exposure in studies in the rat. No adverse effects were noted in the key inhalation study in the rat. The critical effect of oral exposure is urolithiasis, the formation of urinary calculi and secondary effects on the urinary system including inflammation, hyperplasia, haematuria and increased kidney weights. Effects at high dose levels result in mortality.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: oral

Remarks:

combined repeated dose and reproduction / developmental screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 October 1979 to May 17 1980

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Older proprietary study, scientifically acceptable methods, specifically investigation urolithiasis

Qualifier:

no guideline followed

Principles of method if other than guideline:

The study was a combined repeated dose toxicity / reproduction study. Rats were exposed to the test substance in the diet for 90 days. A satellite group of rats were selected for mating at the end of the 90 days (test substance administration continued during the reproductive study). Non-reproductive study rats were sacrificed and necropsied at 30, 60 or 90 days. Pathology was limited to the urinary tract, as the study was specifically investigating TPA-induced urolithiasis.

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

other: Wistar and CD

Sex:

male/female

Details on test animals or test system and environmental conditions:

Male and female Wistar and CD rats were obtained from Charles River Breeding Laboratories, aged 10-12 weeks. Fischer 344 rats were obtained from Microbiological Associates, however this strain showed serious health problems (abnormal clinical signs, weight loss) during the quarantine period thought to be indicative of Mycoplasma pulmonis infection, and were therefore not included in the study.The rats underwent a 35 day quarantine period, and were housed in separate rooms according to strain. Rats were housed in same sex groups of 3 in suspended stainless steel cages equipped with automatic waterers. Individuals were identified by metal ear tags. The rats were fed non-autoclaved NIH-31 diet (Ziegler Brothers) ad libitum, new feed was supplied weekly. Temperature was maintained at 70±2°F and relative humidity was 20-80%. Light was provided on a 12 hour light:dark cycle. Polycarbonate cages were supplied during the mating period (see section 7.8.1 for more detail).Rats were 15-17 weeks of age at the start of the study.

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

NNIH-31 diet containing 0, 0.03, 0.125, 0.5, 2.0 and 5.0% TPA was prepared by Zeigler Brothers.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Each week 100 g feed samples were collected in glass bottles for each dietary level of TPA, purged with nitrogen for 1 minute then stored at -20°C. 2-10 g sized samples were placed in 6-ounce narrow mouth bottles and a measured amount of the internal standard (phthalic acid PA) in 2% NH4OH in methanol was added to each sample. The samples were extracted using 2% NH4OH in methanol (200 ml) by shaking vigorously in a mechanical for 1 hr at room temperature. After most of the feed particles had settled, 2 ml aliquots of the extracts were filtered through 4 µm Nucelopore membrane filters.. Aliquots of these filtered solutions were analysed using HPLC.Weekly feed samples were analysed for the first 12 weeks of the study. The 0.125% diet was found to contain consistently higher values than the nominal, and this was thought to be an error during diet formulation. Overall, the analyses indicated reasonable agreement between nominal and measured values.

Duration of treatment / exposure:

90 days

Frequency of treatment:

Continuous - ad libitum in feed

Remarks:

Doses / Concentrations:0, 0.03, 0.125, 0.5, 2.0 and 5.0% Basis:nominal in diet

Remarks:

Doses / Concentrations:0, 30, 125, 500, 2000 and 5000 mg/kg bw/dBasis:other: approximate mean achieved intake

No. of animals per sex per dose:

30 rats/sex of each strain per dietary level

Control animals:

yes, plain diet

Details on study design:

The study was designed as a randomised complete block design. Interim necropsies were conducted on 5 rats/sex/strain/dose at 30 days and 60 days on study. At 90 days 10 rats/sex/strain/dose were necropsied. Rats were not fasted prior to necropsy. Remaining animals were then used for the one-generation reproduction study (section 7.8.1).

Positive control:

Not required.

Observations and examinations performed and frequency:

Cageside observations were conducted twice a day 7 days a week for clinical signs, morbidity and mortality. Feed consumption and body weights were determined weekly. Physical examinations were performed at least weekly for each rat at the time time body weights were taken.

Sacrifice and pathology:

At sacrifice rats were anaesthetised with Metofane, the thoracic cavity opened, and the animals exsanguinated by cardiac puncture. The bladder was exposed and urine collected by sterile puncture. Urinary pH was determined immediately, followed by concentrations of Ca2+, Mg2+, phosphate (90 day sacrifice only), TPA and specific gravity. Various tissues were collected at necropsy for histopahtology. Any animals dying during the study were necropsied if they had not undergone significant autolysis. Necropsies were performed by Experimental Pathology Laboratories (EPL). Major internal organs were examined grossly for lesions. Both kidneys, lower urinary tract structures and tissues with gross abnormalities were fixed in 10% neutral buffered formalin. The kidneys were weighed prior to fixation. Fixed tissues were sectioned and stained with haematoxylin and eosin.

Other examinations:

Reproductive toxicity - see section 7.8.1

Statistics:

ANOVA, ANCOVA, Dunnett's t-test.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

5 deaths, diarrhoea/urogenital discharge in rats fed 5% during first 4 weeks

Mortality:

mortality observed, treatment-related

Description (incidence):

5 deaths, diarrhoea/urogenital discharge in rats fed 5% during first 4 weeks

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

decreases in treated rats; lower terminal bodyweights and weight gains at 0.5% and above.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

decreased in females at 5% level in both strains, decreased in CD females at 4 and 13 weeks at 2% level, decreased in Wistar males at 4 and 8 weeks at 5% level

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

acidic urine in treated rats, strain differences in urinary TPA levels and specific gravity

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

only kidney weights determined

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

urinary calculi, hepatic cysts containing parasitic larvae

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

inflammatory lesions in the bladder and urethra

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITYWeight loss, diarrhoea or urogenital discharge were observed more frequently in rats ingesting 5% TPA during the first four weeks. No deaths occurred during the first 4 weeks. One death (1 male Wistar; 5% TPA) occurred in the 4-8 week period, and four deaths (1 male and 1 female Wistar, 3 female CD; all 5% TPA) occurred in the 8-13 week period. Trichobezoars (hairballs) were found in the gastrointestinal tract of one CD female that died. BODY WEIGHT AND WEIGHT GAINThe animals demonstrated a progressive decline in mean body weight relative to controls weeks 4, 8 and 13, with increasing concentration of TPA from 0.5 to 5.0%. The decrease in body weight (relative to controls) was significant in males and females of boths strains fed the 5% diet. The only exception was a lack of significance for the CD males at 8 weeks, however the mean weights were still lower than those of the respective controls. Body weights were also significantly reduced in the male and female CD rats fed the 2% diet at weeks 4 and 13. CD males fed the 0.5% diet had significantly lower body weights at week 4, and those fed 0.03% had significantly lower weights at week 13.Average body weight gain was calculated for intervals of 0-4 weeks, 4-8 weeks and 8-13 weeks. The average weight gain slowed or remained stable for all rats after the fourth week. Rats of both strains and sex fed the 5% diet had significantly reduced body weight gains throughout the 13 week study period. Average weight gain in CD rats fed 2.0% and 0.5% diets was also significantly reduced at 13 weeks. CD males fed 0.03% also had a sigificantly decreased average weight gain. More marked weight gain (or weight loss) was seen during the early phase of the study, consistent with an adverse effect on palatability. FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)Total food consumption was significantly decreased in females of both strains fed the 5% diet at weeks 4, 8 and 13. The CD females fed the 2% diet showed significantly decreased food consumption at 4 and 13 weeks. Males showed a tendency to decreased food consumption with increasing TPA concentration, the decrease was significant at the 5% level for Wistar males at weeks 4 and 8. URINALYSISA tendency towards decreased urinary pH at higher doses of TPA was observed at each sacrifice. Significantly increased acidity, compared to controls, was observed at the 90 day sacrifice in both strains and sexes at dietary concentrations 0.5% TPA and greater. Significantly lower pH values were noted in male CD rats fed 0.125% TPA. There was no statistically significant effect of TPA on Ca2+ at any sacrifice time-point, however a trend towards increased Ca2+ was noted in rats fed 2% and 5% TPA. No statistically significant effect of TPA on Mg2+ was noted, although there was an apparent trend toward greater Mg2+ concentrations at 5% TPA.Phosphate levels were determined at the 90 day sacrifice; there were no statistically significant differences. A tendency towards higher phosphate levels was noted at the 2% and 5% TPA levels.Lower urinary TPA levels were detected at the 30 day sacrifice compared to the 60 and 90 day sacrifices. A possible explanation offered with loss of TPA from the diluted urine due to precipitation whilst in storage. Consistent and statistically significant effects of strain on urinary TPA concentration was noted at the 90 day sacrifice at the 2% and 5% TPA dietary level in males, and at the 0.5%, 2% and 5% levels in females. The concentration of TPA in the urine of Wistar rats was 2- to 6-fold higher than that of CD rats (within treatment groups). Statistically significant effects of dose on specific gravity were observed at the 90 day sacrifice in CD males. Strain differences were observed at the higher doses, with Wistar rats generally excreting higher specific gravity urine than CD rats.ORGAN WEIGHTSThere were no differences in kidney weights between treatment groups.GROSS PATHOLOGYDistention or enlargement of the urinary bladder, calculi in the urinary bladder and distention of the cecum and colon with water contents were the most frequent gross observations that occurred in rats fed TPA. Calculi in the urinary bladder were noted in 1 male Wistar rat sacrificed at 30 days, 4 male Wistar rats sacrificed at 90 days, and 1 female CD rat sacrificed at 90 days; all rats were fed the 5% diet except 1 male Wistar (90 day sacrifice) fed 0.03% . Additional calculi were observed in the bladder during gross trimming of 1 female Wistar sacrificed at 90 days. The calculi were frequently observed in enlarged/distended bladders. Distention of the cecum and colon with watery intestinal contents was observed in male and female rats of both strains given 5.0% TPA at the 30, 60 and 90 day sacrifices. Similar changes were present in CD females fed 2% at the 60 and 90 day sacrifice, and in Wistar males fed 2% at 90 days.Tan nodules and cysts in the liver were observed in several rats in all treatment groups. The incidence of these lesions increased with length of exposure. The nodules and cysts were characterised by thick-walled cysts containing parasitic larvae, characteristic of Cysticercus fasciolaris (the larval stage of Taenia taeniaeformis). HISTOPATHOLOGY: NON-NEOPLASTICThe right kidney and right ureter were examined: Several lesions were noted, however there was no correlation between microscopic lesions and grossly observed bladder calculi. There were no other lesions that could be definitively attributed to TPA. Inflammatory and proliferative lesions of the ureter were observed only in rats given 5% TPA, however the lesions were observed in low incidence and therefore could not be definitively atrributed to treatment.The urinary bladder and urethra were examined: Inflammatory lesions were observed in the urinary bladder and urethra of several rats. Chronic cystitis and urethritis were characterised by a submucosal infiltration of mononuclear inflammatory cells. In most instances, the chronic inflammatory changes in the submucosa were associated with minimal to moderate hyperplasia of the transitional epithelium lining the bladder or urethra. Most of the rats with bladder lesions noted during necropsy had chronic cystitis and/or transitional cell hyperplasia. The incidence and severity of chronic cystitis and urethritis was greatest in rats fed 5% TPA, and lesions were more frequently observed in females than males.

Dose descriptor:

LOEL

Effect level:

300 ppm

Based on:

test mat.

Sex:

male

Basis for effect level:

other: Decreased urinary pH in CD males fed diet containing 0.03% TPA

Dose descriptor:

NOAEL

Effect level:

1 250 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Reduced terminal body weights / weight gains at higher dose levels

Critical effects observed:

not specified

Calculated Mean TPA consumed

Strain	Sex	% TPA in diet	Total TPA consumed (mean ± SE)
Wistar	F	0	--
		0.03	0.48 ± 0.003
		0.125	2.06 ± 0.023
		0.5	7.90 ± 0.096
		2.0	31.92 ± 0.402
		5.0	75.50 ± 0.565
	M	0	--
		0.03	0.68 ± 0.005
		0.125	2.80 ± 0.016
		0.5	11.18 ± 0.127
		2.0	43.72 ± 0.526
		5.0	107.37 ± 0.900
CD	F	0	--
		0.03	0.54 ± 0.004
		0.125	2.14 ± 0.021
		0.5	8.54 ± 0.054
		2.0	33.66 ± 0.310
		5.0	78.90 ± 0.615
	M	0	--
		0.03	0.65 ± 0.005
		0.125	2.71 ± 0.024
		0.5	10.94 ± 0.128
		2.0	43.02 ± 0.452
		5.0	109.52 ± 0.630

Values calculated from mean food consumption; n = 30 weeks 0-4,

n = 25 weeks 4-8, n = 20 weeks 8-13.

Terminal bodyweights (g)

Strain	Sex	Dose level (%)
		0	0.03	0.125	0.5	2.0	5.0
Wistar	M	524.8	550.5	547.9	517.0	517.3	494.3
	F	307.4	292.2	308.7	300.9	294.2	285.7
CD	M	572.5	541.2	537.8	547.9	537.2	515.4
	F	374.9	376.3	362.3	361.6	340.3	314.0

Adjusted mean bodyweights at Week 13 (g)

Strain	Sex	Dose level (%)
		0	0.03	0.125	0.5	2.0	5.0
Wistar	M	471.6	468.0	483.0	464.1	448.9	431.6**
	F	404.7	379.7	404.7	400.8	394.6	383.9**
CD	M	485.8	447.9*	458.7	458.6	450.2*	440.5**
	F	426.8	427.1	411.4	409.6	390.6**	362.6**

*significantly different to controls (p<0.05); **p<0.01 [Dunnett's test]

Overall weight gain (g)

Strain	Sex	Dose level (%)
		0	0.03	0.125	0.5	2.0	5.0
Wistar	M	126.2	122.6	133.1	127.4	109.1	87.6
	F	46.1	41.4	45.0	42.9	38.3	22.3
CD	M	139.9	110.9	119.4	111.6	105.4	92.1
	F	70.1	70.4	59.7	50.5	41.2	14.3

Adjusted weight gains at Week 13 (g)

Strain	Sex	Dose level (%)
		0	0.03	0.125	0.5	2.0	5.0
Wistar	M	97.5	93..4	102.2	97.8	82.2	58.5**
	F	57.3	55.1	55.9	54.1	50.5	36.7**
CD	M	97.5	80.4*	88.4	76.7**	76.0**	64.2**
	F	69.9	66.9	63.0	51.3**	43.8**	19.8**

*significantly different to controls (p<0.05); **p<0.01 [Dunnett's test]

Bladder histopathology

Timepoint	Finding	Strain	Sex	Dose level (%)
				0	0.03	0.125	0.5	2.0	2.0
Day 30 (n=5)	Chronic cystitis	Wistar	M	-	-	-	-	-	1
			F	-	-	-	-	-	2
		CD	M	-	-	-	-	1	-
			F	-	-	-	-	-	-
	Transitional hyperplasia	Wistar	M	-	-	-	-	-	1
			F	-	-	-	-	-	2
		CD	M	-	-	-	-	1	-
			F	-	-	-	-	-	-
	Calculus	Wistar	M	-	-	-	-	-	-
			F	-	-	-	-	-	-
		CD	M	-	-	-	-	-	-
			F	-	-	-	-	-	-
Day 60 (n=5)	Chronic cystitis	Wistar	M	-	-	-	-	-	2
			F	-	-	-	-	-	-
		CD	M	-	-	-	-	-	-
			F	-	-	-	-	-	1
	Transitional hyperplasia	Wistar	M	-	-	-	-	-	1
			F	-	-	-	-	-	1
		CD	M	-	-	-	-	-	-
			F	-	-	-	-	-	2
	Calculus	Wistar	M	-	-	-	-	-	-
			F	-	-	-	-	-	-
		CD	M	-	-	-	-	-	-
			F	-	-	-	-	-	-
Day 90 (n=10)	Chronic cystitis	Wistar	M	-	2	-	-	-	3
			F	-	-	-	-	-	4
		CD	M	-	-	-	-	-	1
			F	1	-	-	-	-	4
	Transitional hyperplasia	Wistar	M	-	-	-	-	-	3
			F	-	-	1	-	-	5
		CD	M	-	-	-	-	-	1
			F	1	-	-	-	-	4
	Calculus	Wistar	M	-	-	-	-	-	1
			F	-	-	-	-	-	-
		CD	M	-	-	-	-	-	-
			F	-	-	-	-	-	-

Conclusions:

TPA administration resulted in increased acidity of the urine, decreased body weights, urinary calculi and chronic inflammatory lesions on the bladder and urethra. Some small strain differences were present, but it was concluded that there is no substantial difference in TPA toxicity between CD and Wistar rats.

Executive summary:

Terephthalic acid (TPA) was fed to groups of male and female Wistar and CD rats for 90 days, to investigate TPA-induced urolithiasis. Nominal dietary concentrations were 0, 0.03, 0.125, 0.5, 2.0 and 5.0%. Sacrifices were carried out at 30, 60 and 90 days for gross pathology and histopathological examination of the urinary tract. Urine was collected at the time of sacrifice. Ten rats/sex/strain/group were not sacrificed, and instead continued onto a reproductive toxicity study (reported seperately). Toxicity was evident in rats fed diets containing 0.5% TPA and above; these rats exhibited reduced weight gain compared to controls. CD males fed 0.03% also exhibited significantly reduced weight gain. Five deaths occurred between 4 and 13 weeks in the rats fed 5% TPA; these rats did not have bladder calculi. Diarrhoea was observed in some of the rats exposed to high TPA concentrations. A small number of bladder calculi were found in rats fed the 5% TPA-diet for 90 days; calculi were more frequently observed in Wistar rats (6/20) than CD rats (1/20). TPA-administration resulted in a decrease in urinary pH. Chronic inflammatory lesions of the bladder and urethra were observed in treated rats, with the highest incidence occurring in rats fed 5% TPA. Nodules and cysts containing parasitic larvae were discovered in the liver of a number of treated rats. Some small strain differences were present, but it was concluded that there is no substantial difference in TPA toxicity between CD and Wistar rats. Based on body weight reductions, the NOAEL can be considered to be 0.125% TPA in the diet; equivalent to 1250 ppm or 125 mg/kg bw/d.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

125 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

A number of sub-chronic rat studies of variable quality are available.

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 October 2006 to 7 March 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Proprietary, guideline and GLP compliant study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

The animals were male and female Sprague-Dawley rats (Crl:CD(SD)), approximately 4 weeks of age at delivery. They were purchased from Charles River Deutschland. The rats underwent a 5 week acclimatisation period. Starting in the first week of the acclimatisation period, a training programme was performed to familiarise the animals with the exposure tubes for increasing period of time. The rats were observed daily. Body weight and food and water consumption were measured in the last week of the acclimatisation period.Rats were housed two per cage in Makrolon Type III cages with absorbent softwood as bedding material. Tap water was offered fresh weekly, ad libitum. Food (Sniff R/M-Z, sniff GmbH, Germany) was offered ad libitum. The temperature was maintained at 22±2°C and the relative humidity at 30-70%. Light was provided on a 12 hour light/dark cycle. Rats were uniquely identified by ID numbers held on the cages. They were placed into groups by weight using a computer-generated randomisation program. The weight variation per sex within or between groups did not exceed ±20% of the mean weight at randomisation.

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: The MMAD was 3.25, 2.87 and 2.94 μm for the low, mid and high dose group.

Details on inhalation exposure:

The rats were placed around the exposure cylinder in tapered acrylic glass tubes with adjustable backstops. The animal's snout protruded in the anterior end of the tube, which was connected to the exposure cylinder by way of a push fit. The aerosol entered the nasal region of the animal through a small tube. The exposure cylinder was operated at slightly positive pressure with respect to the surrounding air. This ensured that a continuous air flow was passing through the animal's breathing zone. The exposure units were placed in separate chambers in the animal room to avoid cross contamination between the groups.The exposure air was supplied by the animal house air conditioning system. The test substance was aerosolized using a microfeeding system and a dispersion nozzle operated with pressurised air. A pre-classifier removing bigger particles was tested and used to adjust the size distribution of the aerosols to MMAD’s about 3 μm. The aerosol concentration was monitored continuously using aerosol photometers developed by Fraunhofer ITEM. The signal was used to control the feed rate of the micro feeder used in order to keep the aerosol concentration in the inhalation unit constant.Mean temperature in the exposure chamber ranged from 22.4 to 23.4°C. Mean relative humidity ranged from 45.8 to 50.9%.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Actual concentrations were measured in the breathing zone of the animals. For calibration of the photometers the aerosol concentration in each exposure chamber was determined gravimetrically two times per week using filter samples. Additionally the exposure concentration of terephthalic acid was determined two times per week by chemical analysis of these filter samples. The mass median aerodynamic diameter (MMAD) of the aerosol was determined twice during the exposure period for each exposure concentration using a cascade impactor. The mass of each size fraction was determined gravimetrically. All samples were taken through a special sampling port of the inhalation chamber.

Duration of treatment / exposure:

6 hours/day, 5 days/week for 4 weeks

Frequency of treatment:

5 days/week for 4 weeks

Remarks:

Doses / Concentrations:0, 1, 3 and 10 mg/m3Basis:nominal conc.

Remarks:

Doses / Concentrations:0, 1.03, 2.93 and 10.05 mg/m3Basis:analytical conc.

No. of animals per sex per dose:

There were 10 males and 10 females per dose, with an additional 5 per sex in the control and high dose groups.

Control animals:

yes, concurrent vehicle

Details on study design:

Four groups were exposed to the substance (or air alone) for 28 days. Two additional groups (one control and one high dose) were allowed a 14 day recovery period after the 28 day exposure period.

Positive control:

Not examined: not required

Observations and examinations performed and frequency:

All animals were observed daily before, during and after exposure. In addition, all animals were removed from their cages once a week and carefully examined for abnormalities. Individual body weight, food and water consumption were recorded throughout the study starting 1 week prior to exposures.Ophthalmologic evaluations were performed with a slit lamp for all groups predose and during the fourth week of exposure for the non-recovery groups, and during week 6 for the recovery groups.Spontaneous locomotor activity was assessed during the last week of treatment, over 90 minutes using a computerised light-beam system. The total values for distance, time in rest, time in movement, rearing time and number of rearings were determined.A functional observational battery (FOB) was carried out during the last week of treatment. The following endpoints were determined: forelimb grip strength, righting reflex, body temperature, salivation, startle response, respiration, urination, mouth breathing, convulsions, pineal response, piloerection, diarrhea, pupil response, lacrimation, impaired gait, stereotypy, toe pinch, tail pinch, wire maneuver, hind-leg splay, tremors, extensor thrust, positive geotropism, activity and limb rotation.Hematological, clinical chemistry analyses (hematology and serum chemistry), and urinalysis were performed before final sacrifice for all animals (see below).

Sacrifice and pathology:

Animals were anaesthetised with CO2, exsanguinated and necropsied. The physical condition of the animal prior to euthanasia and the examination of the internal organs was described in detail on individual necropsy protocol sheets. In addition to the terminal body weight, selected organs (lung including 2/3 of trachea, heaert, liver, spleen, brain, adrenals, kidneys, testes and ovaries) were weighed (paired organs separately). Relative organ weight data was also computed.The following organs and tissues were collected and fixed in 10% neutral buffered formalin: adrenals, aorta, bone, brain, cecum, colon, duodenum, epididymides (fixed in modified Davidson's fixative), oesophagus, eyes with optic nerve, forestomach, femur including joint, glandular stomach, harderian glands, heart, ileum, jejunum, submandibular lymph nodes (unilateral), lacrimal glands, larynx, liver, lungs, lung associated lymph nodes (tracheobronchial), mammary glands, mandibular lymph nodes, mesentery and lymph nodes, nasal and paranasal cavities, ovaries (fixed in modified Davidson's fixative), pancreas, parathyroids, peripheral nerve (Sciatic nerve), pharynx, pituitary, prostate, rectum, salivary glands, seminal vesicles, skeletal muscle, skin, spinal cord, spleen, stomach, testes (fixed in modified Davidson's fixative), thymus, thyroid, tongue, trachea, urinary bladder, uterus, vagina and ureters.Tissues were fixed, embedded in paraffin, sectioned and stained with haematoxylin and eosin. Slides were examined by light microscopy.

Other examinations:

None reported.

Statistics:

All evaluations were done separately for males and females. Differences between groups were considered case by case as statistically significant for p < 0.05. Data were analysed using analysis of variance. If the group means differed significantly according to the analysis of variance, the means of the treatment groups were compared with the means of the control group, using DUNNETT's modification of the t-test. Kruskal-Wallis ANOVA and Mann-Whitney U-test were applied in the case of non - homogeneous data. The statistical evaluation of the histopathological findings was done with the two-tailed FISHER test using the P.L.A.C.E.S system. For comparisons of semi-quantitative data, the chi-square test was used.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

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

effects observed, treatment-related

Description (incidence and severity):

Total water consumption was significantly lower in the female mid and high dose groups compared to the control group. This effect was not seen in males and is not considered to be of toxicological significance

Ophthalmological findings:

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:

MortalityNo deaths occurred.Signs of toxicityNo adverse clinical signs were observed in the rats during the course of the study.Bodyweights, food and water consumptionBody weight development was not affected by exposure. There were no compound-related effects on food consumption throughout the course of the study. Total water consumption was significantly lower in the female mid and high dose groups compared to the control group. This effect was not seen in males. The male and female high dose recovery groups showed a higher (not significant) total water consumption compared to the recovery control group. The effect was considered to be of low toxicological relevance.OphthalmoscopyThere were no compound-related ophthalmologic findings.FOBThere were some (mainly transient) effects in some of the locomotor activity parameters of all treated groups, without any dose-response relationship and differently directed in males and females. They were considered to be of low toxicological relevance. Functional Observational Battery: In females, body temperature was significantly lower in the low dose group compared to the control group. In males, forelimb grip strength was significantly increased in the low dose group and the righting reflex score was significantly increased in the high dose group compared to the control group. A similar, but statistically nonsignificant effect was observed for the righting reflex in females of the high dose group. No other treatment induced effects were observed in any of the investigated endpoints. Since only one parameter was affected in the high dose group, this finding may be considered of low toxicological relevance. Clinical investigationsRelevant differences in the total and differential blood counts were not observed. After the recovery period, the partial thromboplastin time was significantly elongated in the high dose group in both sexes. Male rats in the high dose group showed decreased cholinesterase levels, which can be indicative for decreased synthesis in the liver. Bilirubin levels were significantly decreased in the low dose group in males and females but slightly increased in female rats in the high dose group. In male rats, plasma glucose levels were slightly increased in the low dose group whereas glucose was mildly decreased in the mid and high dose groups. The same trend was seen in female rats, with the decrease in the male and female high dose groups being statistically significant. The changes listed were all reversed in the recovery group and were considered to be of limited toxicological relevance. All other changes were considered to be secondary to biological variance. Furthermore, all values were in the range expected for this species, strain, sex and age. Relevant changes were not observed in the urinalysis parameters. All values were in the range expected for this species, strain, sex and age.NecropsyNo compound-related effects were observed during necropsy. Statistical significant differences observed in organ weights and relative organ weights are declared as incidental and therefore of no toxicological relevance.Statistically significant test substance related histopathological findings were not observed.Some histopathological lesions were detected in the nasal and paranasal cavities but they were regarded as incidental as they were also seen in some control rats. Inflammatory cell infiltration in the larynx was distributed equally over control and treated groups, and may be mild irritation due to the route of exposure (nose-only inhalation). There were some pulmonary findings such as a relatively high incidence of alveolar macrophage accumulations (alveolar histiocytosis), however the findings were within the limits of normal variation for this strain. Lesions observed in other organs, such as retrobulbar haemorrhage of the eyes, necrosis and inflammation in the Harderian glands or tubular mineralisation in the kidneys were either related to the blood sampling procedure or spontaneous in origin and not unusual for rats of this strain and age.

Dose descriptor:

NOAEL

Effect level:

10.05 mg/m³ air (analytical)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No effects were seen at the highest concentration in this study

Critical effects observed:

not specified

The 28 day NOAEL was 10.05 mg/m³

Conclusions:

No significant inflammatory or other lesions were observed in the terephthalic acid treatment groups under the present experimental conditions.The 28 day NOAEL was >10.05 mg/m3

Executive summary:

The objective of this study was to evaluate the possible toxicity of terephthalic acid after inhalation in rats for 28 days. In addition the effect (degeneration of the tracheal lining epithelium) observed in the previous 28-day study performed by the IIT Research Institute (Leach & Hatoum, 1987) was investigated. Fifty male and fifty female Sprague Dawley rats (Crl:CD(SD)) , approximately 8 weeks of age at study start were exposed for 6 hrs/day, 5 days/week over a period of 4 weeks to clean air or terephthalic acid at concentrations of 1.03 mg/m³, 2.93 mg/³ and 10.05 mg/m³ for the low, mediu, and high dose group. The mass aerodynamic diameter (MMAD) was 3..25, 2.87, and 2.94 μm for the low, medium, and high dose group. Additionally the study included a control and high dose group with a 14 day recovery period. No adverse compound-related effects were observed in clinical observations, body weight, food consumption, water consumption, organ weights, and gross pathology findings. Male rats in the high dose group showed decreased cholinesterase levels, which can be indicative for decreased synthesis in the liver. Bilirubin levels were significantly decreased in the low dose group in males and females but slightly increased in females rats in the high dose group. In male rats, plasma glucose levels were slightly increased in the low dose group whereas glucose was mildly decreased in the medium and high dose groups. The same trend was seen in female rats, with the decrease in the high dose group being statistically significant. The changes listed above were all reversed in the recovery group and are thus considered to be of limited toxicological relevance. Statistically significant treatment-related histopathological lesions were not observed in the main or recovery groups, either in the target organs or in any other organ. All findings in the nasal and paranasal cavities were regarded as incidental. The incidence of inflammatory/mononuclear cell infiltration in the larynx was distributed equally over control and treatment groups. The relatively high incidence of this change might be attributed to mild local irritation due to the experimental setting (nose only inhalation), as the lesion was also frequently observed in the control groups. In almost all cases the cellular infiltrates were located at level 1 of the larynx, i.e. in close vicinity to the nasal and oral cavities. The assumption, that this change might be caused by the experimental setting is also supported by the fact that the incidences of this lesion decreased in the recovery groups as compared to the main groups. The observed changes in the trachea were minimal and all considered to be unrelated to inhalation of TPA. The degenerative lesions observed in a previous inhalation study (LEach & Hatoum, 1987) could consistently not be reproduced in the this study. The pulmonary findings, especially the relatively high incidence of alveolar macrophage accumulations (alveolar histiocytosis) were still within the limits of normal variation in Sprague Dawley (SD) rats, which are known to develop an age-related high incidence of spontaneous alveolar histiocytosis. Lesions observed in other organs, such as retrobulbar haemorrhage of the eyes, necrosis and inflammation in the Harderian glands or tubular mineralization in the kidneys were either related to the blood sampling procedure or spontaneous in origin and not unusual for rats of this strain and age. In summary, no significant inflammatory or other lesions were observed in the terephthalic acid treatment groups under the experimental conditions.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

10 mg/m³

Study duration:

subacute

Species:

rat

Quality of whole database:

A recent, guideline-compliant study is supported by an older study

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:

key study

Study period:

23 October 2006 to 7 March 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Proprietary, guideline and GLP compliant study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

The animals were male and female Sprague-Dawley rats (Crl:CD(SD)), approximately 4 weeks of age at delivery. They were purchased from Charles River Deutschland. The rats underwent a 5 week acclimatisation period. Starting in the first week of the acclimatisation period, a training programme was performed to familiarise the animals with the exposure tubes for increasing period of time. The rats were observed daily. Body weight and food and water consumption were measured in the last week of the acclimatisation period.Rats were housed two per cage in Makrolon Type III cages with absorbent softwood as bedding material. Tap water was offered fresh weekly, ad libitum. Food (Sniff R/M-Z, sniff GmbH, Germany) was offered ad libitum. The temperature was maintained at 22±2°C and the relative humidity at 30-70%. Light was provided on a 12 hour light/dark cycle. Rats were uniquely identified by ID numbers held on the cages. They were placed into groups by weight using a computer-generated randomisation program. The weight variation per sex within or between groups did not exceed ±20% of the mean weight at randomisation.

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: The MMAD was 3.25, 2.87 and 2.94 μm for the low, mid and high dose group.

Details on inhalation exposure:

The rats were placed around the exposure cylinder in tapered acrylic glass tubes with adjustable backstops. The animal's snout protruded in the anterior end of the tube, which was connected to the exposure cylinder by way of a push fit. The aerosol entered the nasal region of the animal through a small tube. The exposure cylinder was operated at slightly positive pressure with respect to the surrounding air. This ensured that a continuous air flow was passing through the animal's breathing zone. The exposure units were placed in separate chambers in the animal room to avoid cross contamination between the groups.The exposure air was supplied by the animal house air conditioning system. The test substance was aerosolized using a microfeeding system and a dispersion nozzle operated with pressurised air. A pre-classifier removing bigger particles was tested and used to adjust the size distribution of the aerosols to MMAD’s about 3 μm. The aerosol concentration was monitored continuously using aerosol photometers developed by Fraunhofer ITEM. The signal was used to control the feed rate of the micro feeder used in order to keep the aerosol concentration in the inhalation unit constant.Mean temperature in the exposure chamber ranged from 22.4 to 23.4°C. Mean relative humidity ranged from 45.8 to 50.9%.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Actual concentrations were measured in the breathing zone of the animals. For calibration of the photometers the aerosol concentration in each exposure chamber was determined gravimetrically two times per week using filter samples. Additionally the exposure concentration of terephthalic acid was determined two times per week by chemical analysis of these filter samples. The mass median aerodynamic diameter (MMAD) of the aerosol was determined twice during the exposure period for each exposure concentration using a cascade impactor. The mass of each size fraction was determined gravimetrically. All samples were taken through a special sampling port of the inhalation chamber.

Duration of treatment / exposure:

6 hours/day, 5 days/week for 4 weeks

Frequency of treatment:

5 days/week for 4 weeks

Remarks:

Doses / Concentrations:0, 1, 3 and 10 mg/m3Basis:nominal conc.

Remarks:

Doses / Concentrations:0, 1.03, 2.93 and 10.05 mg/m3Basis:analytical conc.

No. of animals per sex per dose:

There were 10 males and 10 females per dose, with an additional 5 per sex in the control and high dose groups.

Control animals:

yes, concurrent vehicle

Details on study design:

Four groups were exposed to the substance (or air alone) for 28 days. Two additional groups (one control and one high dose) were allowed a 14 day recovery period after the 28 day exposure period.

Positive control:

Not examined: not required

Observations and examinations performed and frequency:

All animals were observed daily before, during and after exposure. In addition, all animals were removed from their cages once a week and carefully examined for abnormalities. Individual body weight, food and water consumption were recorded throughout the study starting 1 week prior to exposures.Ophthalmologic evaluations were performed with a slit lamp for all groups predose and during the fourth week of exposure for the non-recovery groups, and during week 6 for the recovery groups.Spontaneous locomotor activity was assessed during the last week of treatment, over 90 minutes using a computerised light-beam system. The total values for distance, time in rest, time in movement, rearing time and number of rearings were determined.A functional observational battery (FOB) was carried out during the last week of treatment. The following endpoints were determined: forelimb grip strength, righting reflex, body temperature, salivation, startle response, respiration, urination, mouth breathing, convulsions, pineal response, piloerection, diarrhea, pupil response, lacrimation, impaired gait, stereotypy, toe pinch, tail pinch, wire maneuver, hind-leg splay, tremors, extensor thrust, positive geotropism, activity and limb rotation.Hematological, clinical chemistry analyses (hematology and serum chemistry), and urinalysis were performed before final sacrifice for all animals (see below).

Sacrifice and pathology:

Animals were anaesthetised with CO2, exsanguinated and necropsied. The physical condition of the animal prior to euthanasia and the examination of the internal organs was described in detail on individual necropsy protocol sheets. In addition to the terminal body weight, selected organs (lung including 2/3 of trachea, heaert, liver, spleen, brain, adrenals, kidneys, testes and ovaries) were weighed (paired organs separately). Relative organ weight data was also computed.The following organs and tissues were collected and fixed in 10% neutral buffered formalin: adrenals, aorta, bone, brain, cecum, colon, duodenum, epididymides (fixed in modified Davidson's fixative), oesophagus, eyes with optic nerve, forestomach, femur including joint, glandular stomach, harderian glands, heart, ileum, jejunum, submandibular lymph nodes (unilateral), lacrimal glands, larynx, liver, lungs, lung associated lymph nodes (tracheobronchial), mammary glands, mandibular lymph nodes, mesentery and lymph nodes, nasal and paranasal cavities, ovaries (fixed in modified Davidson's fixative), pancreas, parathyroids, peripheral nerve (Sciatic nerve), pharynx, pituitary, prostate, rectum, salivary glands, seminal vesicles, skeletal muscle, skin, spinal cord, spleen, stomach, testes (fixed in modified Davidson's fixative), thymus, thyroid, tongue, trachea, urinary bladder, uterus, vagina and ureters.Tissues were fixed, embedded in paraffin, sectioned and stained with haematoxylin and eosin. Slides were examined by light microscopy.

Other examinations:

None reported.

Statistics:

All evaluations were done separately for males and females. Differences between groups were considered case by case as statistically significant for p < 0.05. Data were analysed using analysis of variance. If the group means differed significantly according to the analysis of variance, the means of the treatment groups were compared with the means of the control group, using DUNNETT's modification of the t-test. Kruskal-Wallis ANOVA and Mann-Whitney U-test were applied in the case of non - homogeneous data. The statistical evaluation of the histopathological findings was done with the two-tailed FISHER test using the P.L.A.C.E.S system. For comparisons of semi-quantitative data, the chi-square test was used.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

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

effects observed, treatment-related

Description (incidence and severity):

Total water consumption was significantly lower in the female mid and high dose groups compared to the control group. This effect was not seen in males and is not considered to be of toxicological significance

Ophthalmological findings:

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:

MortalityNo deaths occurred.Signs of toxicityNo adverse clinical signs were observed in the rats during the course of the study.Bodyweights, food and water consumptionBody weight development was not affected by exposure. There were no compound-related effects on food consumption throughout the course of the study. Total water consumption was significantly lower in the female mid and high dose groups compared to the control group. This effect was not seen in males. The male and female high dose recovery groups showed a higher (not significant) total water consumption compared to the recovery control group. The effect was considered to be of low toxicological relevance.OphthalmoscopyThere were no compound-related ophthalmologic findings.FOBThere were some (mainly transient) effects in some of the locomotor activity parameters of all treated groups, without any dose-response relationship and differently directed in males and females. They were considered to be of low toxicological relevance. Functional Observational Battery: In females, body temperature was significantly lower in the low dose group compared to the control group. In males, forelimb grip strength was significantly increased in the low dose group and the righting reflex score was significantly increased in the high dose group compared to the control group. A similar, but statistically nonsignificant effect was observed for the righting reflex in females of the high dose group. No other treatment induced effects were observed in any of the investigated endpoints. Since only one parameter was affected in the high dose group, this finding may be considered of low toxicological relevance. Clinical investigationsRelevant differences in the total and differential blood counts were not observed. After the recovery period, the partial thromboplastin time was significantly elongated in the high dose group in both sexes. Male rats in the high dose group showed decreased cholinesterase levels, which can be indicative for decreased synthesis in the liver. Bilirubin levels were significantly decreased in the low dose group in males and females but slightly increased in female rats in the high dose group. In male rats, plasma glucose levels were slightly increased in the low dose group whereas glucose was mildly decreased in the mid and high dose groups. The same trend was seen in female rats, with the decrease in the male and female high dose groups being statistically significant. The changes listed were all reversed in the recovery group and were considered to be of limited toxicological relevance. All other changes were considered to be secondary to biological variance. Furthermore, all values were in the range expected for this species, strain, sex and age. Relevant changes were not observed in the urinalysis parameters. All values were in the range expected for this species, strain, sex and age.NecropsyNo compound-related effects were observed during necropsy. Statistical significant differences observed in organ weights and relative organ weights are declared as incidental and therefore of no toxicological relevance.Statistically significant test substance related histopathological findings were not observed.Some histopathological lesions were detected in the nasal and paranasal cavities but they were regarded as incidental as they were also seen in some control rats. Inflammatory cell infiltration in the larynx was distributed equally over control and treated groups, and may be mild irritation due to the route of exposure (nose-only inhalation). There were some pulmonary findings such as a relatively high incidence of alveolar macrophage accumulations (alveolar histiocytosis), however the findings were within the limits of normal variation for this strain. Lesions observed in other organs, such as retrobulbar haemorrhage of the eyes, necrosis and inflammation in the Harderian glands or tubular mineralisation in the kidneys were either related to the blood sampling procedure or spontaneous in origin and not unusual for rats of this strain and age.

Dose descriptor:

NOAEL

Effect level:

10.05 mg/m³ air (analytical)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No effects were seen at the highest concentration in this study

Critical effects observed:

not specified

The 28 day NOAEL was 10.05 mg/m³

Conclusions:

No significant inflammatory or other lesions were observed in the terephthalic acid treatment groups under the present experimental conditions.The 28 day NOAEL was >10.05 mg/m3

Executive summary:

The objective of this study was to evaluate the possible toxicity of terephthalic acid after inhalation in rats for 28 days. In addition the effect (degeneration of the tracheal lining epithelium) observed in the previous 28-day study performed by the IIT Research Institute (Leach & Hatoum, 1987) was investigated. Fifty male and fifty female Sprague Dawley rats (Crl:CD(SD)) , approximately 8 weeks of age at study start were exposed for 6 hrs/day, 5 days/week over a period of 4 weeks to clean air or terephthalic acid at concentrations of 1.03 mg/m³, 2.93 mg/³ and 10.05 mg/m³ for the low, mediu, and high dose group. The mass aerodynamic diameter (MMAD) was 3..25, 2.87, and 2.94 μm for the low, medium, and high dose group. Additionally the study included a control and high dose group with a 14 day recovery period. No adverse compound-related effects were observed in clinical observations, body weight, food consumption, water consumption, organ weights, and gross pathology findings. Male rats in the high dose group showed decreased cholinesterase levels, which can be indicative for decreased synthesis in the liver. Bilirubin levels were significantly decreased in the low dose group in males and females but slightly increased in females rats in the high dose group. In male rats, plasma glucose levels were slightly increased in the low dose group whereas glucose was mildly decreased in the medium and high dose groups. The same trend was seen in female rats, with the decrease in the high dose group being statistically significant. The changes listed above were all reversed in the recovery group and are thus considered to be of limited toxicological relevance. Statistically significant treatment-related histopathological lesions were not observed in the main or recovery groups, either in the target organs or in any other organ. All findings in the nasal and paranasal cavities were regarded as incidental. The incidence of inflammatory/mononuclear cell infiltration in the larynx was distributed equally over control and treatment groups. The relatively high incidence of this change might be attributed to mild local irritation due to the experimental setting (nose only inhalation), as the lesion was also frequently observed in the control groups. In almost all cases the cellular infiltrates were located at level 1 of the larynx, i.e. in close vicinity to the nasal and oral cavities. The assumption, that this change might be caused by the experimental setting is also supported by the fact that the incidences of this lesion decreased in the recovery groups as compared to the main groups. The observed changes in the trachea were minimal and all considered to be unrelated to inhalation of TPA. The degenerative lesions observed in a previous inhalation study (LEach & Hatoum, 1987) could consistently not be reproduced in the this study. The pulmonary findings, especially the relatively high incidence of alveolar macrophage accumulations (alveolar histiocytosis) were still within the limits of normal variation in Sprague Dawley (SD) rats, which are known to develop an age-related high incidence of spontaneous alveolar histiocytosis. Lesions observed in other organs, such as retrobulbar haemorrhage of the eyes, necrosis and inflammation in the Harderian glands or tubular mineralization in the kidneys were either related to the blood sampling procedure or spontaneous in origin and not unusual for rats of this strain and age. In summary, no significant inflammatory or other lesions were observed in the terephthalic acid treatment groups under the experimental conditions.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

10 mg/m³

Study duration:

subacute

Species:

rat

Quality of whole database:

A recent, guideline-compliant study is supported by an older study

Repeated dose toxicity: dermal - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: dermal

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: dermal

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Repeated dose oral toxicity

Studies with TPA

In an older study (Williams, 1955), male and female albino rats were fed terephthalic acid in the diet for 90 days, at levels of 0, 1, 3.2 and 10%. All groups showed a tendency towards anaemia. Pathological examination of the 3.2% group revealed mild injury to the urinary tract in 2 of 12 rats. Rats fed 10% showed decreased food consumption and growth rate, and exhibited recurring haematuria. Males were more affected than females. Pathological examination revealed the presence of calculi in the urinary tract. A NOAEL of 1% (approximately equivalent to 1000 mg/kg bw/d) can be determined for this study, however it is noted that the investigations in this study were limited.

In a further study, a single dose level of terephthalic acid was fed to rats in the diet for 90 days (Vogin, 1972). The initial dose level was 5%, but this was reduced to 3% one week into the study because the rats showed decreased body weight gain. There were no substance related mortalities. Occult blood was found in the urine, and crystalluria was seen after 90 days. There was an increase in kidney weights, but as no other organs were affected this was not thought to be biologically significant. Bladder and kidney calculi formed, with a higher incidence in males than females. The only effect noted at necropsy was a mild to moderate epithelial hyperlasia of the bladder and evidence of chronic cystitis. The dose level in this study is estimated to be equivalent to 3000 mg/kg bw/d (using default conversion factors); 2070 and 2490 mg/kg bw/d in males and females respectively using food consumption and terminal bodyweight values.

In a further study (Kohn, 1970), terephthalic acid was fed to male and female albino rats for 15 weeks to determine the oral toxicity of the substance. Dietary dose levels were 0.05, 0.16, 0.5, 1.6 and 5% (w/w). Two additional groups were fed plain diet to serve as controls. Interim sacrifices were conducted following 30, 60 and 90 days of testing on 3 males and 3 females from each group. The remaining 10 rats/sex/group were necropsied at the end of the 15 week feeding period. Blood and urine samples were obtained immediately prior to the start of the test and at 1, 2 and ~3 months later. Males and females in the high dose group exhibited a small reduction in body weight gain, but food consumption and utilisation were apparently unaffected. Haematuria was observed on a sporadic basis amongst the high dose males during the second and third months of the study, haematuria was not seen in females. However, urinalysis revealed occult blood was present at various time points in males in the 0.16, 0.5, 1.6 and 5% groups, and in females in all dose groups. It appeared that the majority of terephthalic acid was exrected in the urine. Gross pathology revealed significant effects of treatment on the urinary bladder of high dose males. A high incidence of bladder stones were found in this group, and microscopic examination revealed proliferative changes characterised by a thickening of the epithelium, and in some cases a narrowing of the lumen of the bladder was observed. It appears that males were more affected by treatment than females.

Dose levels based on default conversion factors are calculated to be equivalent to 0, 50, 160, 500, 1600 and 5000 mg/kg bw/d. Using figures for bodyweight and food consumption for the final week of the study, actual intakes of 0, 31, 96, 313, 980 and 2820 mg/kg bw/d are calculcated for males; values of 0, 39, 121, 372, 1186 and 3922 mg/kg bw/d are calculated for females.

The isolated findings of urinary occult blood seen at all dose levels in this study are difficult to interpret. Findings are reported semi-quantitatively (classed as 'negative', 'small', 'moderate' and 'large' for pooled urine samples taken from 2 rats/sex/group pre-test and after treatment for 1, 2 and 3 months. It is notable that the results of uirnalysis from the chronic toxicity and carcinogenicity study of Preache et al (1983) do not report any effects on the incidence of urinary occult blood (measured in 5 rats/sex at 6 and 12 months and in 20 rats /sex at 18 and 24 hours) with the exception of both sexes at the highest dose level of 1000 mg/kg bw/day at 18 months. The effects seen at lower dose levels in the Kohn study are therefore not considered to be reliable due to the small sample size and the potential for cross-contamination.

In a further 90 -day study (Ledoux et al, 1982), terephthalic acid was fed to groups of male and female Wistar and CD rats for 90 days, to investigate TPA-induced urolithiasis. Nominal dietary concentrations were 0, 0.03, 0.125, 0.5, 2.0 and 5.0%. Sacrifices were carried out at 30, 60 and 90 days for gross pathology and histopathological examination of the urinary tract. Urine was collected at the time of sacrifice. Ten rats/sex/strain/group were not sacrificed, and instead continued onto a reproductive toxicity study. Toxicity was evident in rats fed diets containing 0.5% TPA and above; these rats exhibited reduced weight gain compared to controls. CD males fed 0.03% also exhibited significanty reduced weight gain. Five deaths occurred between 4 and 13 weeks in the rats fed 5% TPA; these rats did not have bladder calculi. Diarrhoea was observed in some of the rats exposed to high TPA concentrations. A small number of bladder calculi were found in rats fed the 5% TPA-diet for 90 days; calculi were more frequently observed in Wistar rats (6/20) than CD rats (1/20). TPA-administration resulted in a decrease in urinary pH. Chronic inflammatory lesions of the bladder and urethra were observed in treated rats, with the highest incidence occurring in rats fed 5% TPA. Nodules and cysts contaiing parasitic larvae were discovered in the liver of a number of treated rats. Some small strain differences were present, but it was concluded that there is no substantial difference in TPA toxicity between CD and Wistar rats. Based on body weight reductions, the NOAEL can be considered to be 0.125% TPA in the diet.

Study with DEHT/DOTP

In a 90 -day rat study performed with the read-across substance DEHT, effects of treatment were limited to reduced erythrocyte parameters at 0.5% and 1.0% and increased relative liver wieght at 1.0%. Effects on haematological parameters at 0.5% (reduced MCV in males; reduced MCV and MCH in females) are not considered to be of toxicological significance in the absence of effects on erythrocyte count or haematocrit. A NOAEL of 0.5% is therefore determined for this study, equivalent to mean achieved intakes of 277 and 309 mg/kg bw/d in males and females, respectively. Based on the hydrolysis of DEHT to form TPA in the gastrointestinal tract, mean intakes of TPA at the NOAEL are calculated to be 118 and 131 mg/kg bw/d in males and females, respectively. The NOAEL is therefore comparable with TPA studies.

Repeated inhalation toxicity

In one inhalation study (Leach & Hatoum, 1987), terephthalic acid was administered as an aerosol by inhalation at target concentrations of 0, 0.5, 1.0 and 3.0 mg/m³ to four groups of 10 male and 10 female Sprague-Dawley rats each. The rats were exposed 6 hours per day, 5 days per week, for 4 weeks. In addition, 6 rats per sex, designated for pulmonary function assessment, were included in the control and high exposure groups. The analytical time weighted average concentrations were 0, 0.52, 1.19 and 3.31 mg/m³ for the filtered air control, low, medium and high exposure groups, respectively. No deaths occurred during the study. The minimal adverse clinical signs noted were of comparable incidences among all groups including controls, and there were no effects of test article exposure on observations noted at necropsy. Histopathological findings consisted of minimal tracheal epithelial lining degeneration, occurring at an incidence of 5%, 30%, 65% and 95% in the control, 0.5, 1.0 and 3.0 mg/m³ groups, respectively. A slight increase of small areas of haemorrhage at the respiratory lymph nodes was also noted in test article exposed females. There were no statistically significant effects of treatment on body weights, organ weights, haematology or clinical chemistry parameters. Pulmonary function assessments did not reveal any significant differences between the control and high exposure groups. A NOEC could not be identified due to histopathological evidence of tracheal irritation in all exposure groups. The lowest exposure concentration of 0.5 mg/m3 can be considered a minimal LOEC, however the toxicological significance of these findings is unclear.

In order to further characterise the inhalation toxicity of TPA and specifcally to elucidate the local tracheal effects seen in the previous study, a further 28 -day inhalation toxicity study was performed. In this study (Fuhst, 2008), male and female Sprague-Dawley rats 10/sex/group) were exposed for 6 hrs/day, 5days/week for 4 weeks to clean air or terephthalic acid at analytical concentrations of 1.03, 2.93 and 10.05 mg/m³. The study included an additional control and high dose group of 5/sex that were permitted a 14-day recovery period prior to sacrifice. No adverse compound-related effects were observed in clinical observations, body weight, food consumption, water consumption, organ weights, and gross pathology findings. There were no ophthalmological findings, or any effects on locomotion and a functional observation battery. There were some effects of exposure on clinical chemistry parameters (cholinesterase, bilirubin and plasma glucose), however the changes were reversed in the recovery group and therefore considered to be of limited toxicological relevance. Statistically significant treatment-related histopathological lesions were not observed in the main or recovery groups, either in the target organs or in any other organ. Specifically, the tracheal effects reporetd in all treated groups in the previous study were not reproduced. The 28 day inhalation NOAEL of terephthalic acid in Sprague Dawley rats was therefore >10.05 mg/m³.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
Most recent study, specificaly investigating the most sensitive endpoint

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:
Most recent study

Justification for selection of repeated dose toxicity inhalation - local effects endpoint:
Most recent study

Justification for selection of repeated dose toxicity dermal - local effects endpoint:
No local effects identified in dermal irritation or dermal toxicity studies.

Repeated dose toxicity: via oral route - systemic effects (target organ) urogenital: urinary bladder

Justification for classification or non-classification

No classification for specific target organ toxicity is proposed.

Although specific organ toxicity has been identified in repeated dose oral toxicity studies with TPA, findings (effects on the urinary bladder secondary to urolithiasis) were not seen at relevant dose levels (i.e. <10 mg/kg bw/d or <100 mg/kg bw/d). NOAELs for the available studies are consistently approximately 1000 mg/kg bw/d with evidence of urolith formation in more sensitive weanling rats at dose levels of above 250 mg/kg bw/d. Additionally, the relevance of these effects to humans is questionable since, for anatomical reasons, rodents are more susceptible to urolithiasis than humans. Although an initital inhalation study (Leach & Hatoum, 1987) reported local microscopic effects on the tracheal lining (minimal degradation) at all exposure levels, these were not reproduced in a more recent study performed at higher exposure concentrations (Fuhst, 2008). As the Fuhst 2008 study was carried out at a specialist inhalation toxicology laboratory with special attention to respiratory tract pathology and a higher exposure concentration the results of this study are concluded to take precedence over those reported by Leach & Hatoum, (1987 .