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Testing Status of Agents at NTP
Testing Status of Agents at NTP
Home » Testing Information » Testing Status of Agents at NTP » Pentaerythritol Triacrylate » Executive Summary Pentaerythritol Triacrylate
V. TOXICOLOGICAL EFFECTS
1. Human Data
No data were found on the chemical disposition of pentaerythritol
triacrylate in humans.
2. Animal Data
No data were found on the chemical disposition of pentaerythritol
triacrylate in animals
B. Acute
1. Human Data
No data were found on the acute toxicity of pentaerythritol triacrylate
in humans.
2. Animal Data
Data on the acute toxicity of pentaerythritol triacrylate in animals
are presented in Table 1. Additional data are described below.
Route | Species (sex/strain) | Number of Animals | Dose (Confidence Limits)* | Reference |
---|---|---|---|---|
Oral | Rat (NR/NR) | NR | LD50=1350 mg/kg | AIHA, 1981 |
Oral | Rat (m or f/ Carworth-Wistar) | NR | LD50=2.46 ml/kg (1.79-3.39) | Carpenter et al., 1974 |
Oral | Rat (NR/NR) | NR | LD50>500-5000 mg/kg | Andrews and Clary, 1986; Celanese, date unspecified |
Inhalation | Rat(NR/NR) | NR | No deaths | Celanese, date unspecified |
Intraperitoneal | Rat (m and f/ Sprague-Dawley) | 5m/5f | LD50=25 mg/kg (12.5-37.5) | Celanese, 1982c |
Intraperitoneal | Rat (m/Sprague- Dawley) | 5 | LD50=18.5 mg/kg (not calculated) | Celanese, 1982c |
Intraperitoneal | Rat (f/Sprague- Dawley) | 5 | LD50=27 mg/kg (2- 53 mg/kg) | Celanese, 1982c |
Dermal | Rabbit (NR/NR) | NR | LD50>2000 mg/kg | AIHA, 1981 |
Dermal | Rabbit (m/New Zealand) | NR | LD50=4.00 ml/kg (1.50-10.6) | Carpenter et al., 1974 |
Dermal | Rabbit (NR/NR) | NR | LD50>200-2000 mg/kg | Andrews and Clary, 1986; Celanese, date unspecified |
NR=not reported
m=male
f=female
*=if not listed in the table, the limits were not provided in the study
For each concentration and control, ten rats (5 males and 5 females) were injected with the chemical and then observed for viability twice daily for two weeks. Each animal was weighed prior to dosing, on the day of dosing, and days 7 and 14 following dosing. In addition, the animals were observed for pharmacologic and toxicologic signs 1, 2, and 4 hours after dosing and daily thereafter for fourteen days. Neurological examinations were conducted 1, 2, 4, and 24 hours after dosing in all animals and then daily through day 14 for animals in the 30 mg/kg dose group. Animals in the 10 mg/kg group that exhibited neurological abnormalities at 24 hours were observed daily thereafter through day 7, and animals that continued to exhibit abnormalities at day 7 were observed through day 14. Animals that succumbed were weighed and necropsied at the time of death, and survivors were weighed, sacrificed, and necropsied at the end of the 14 day observation period.
From the mortality data of all test
animals, the intraperitoneal LD50 value for pentaerythritol triacrylate
was determined to be 25 mg/kg with confidence limits of 12.5
-37.5 mg/kg. For male rats, the value was found to be 18.5 mg/kg
(confidence limits not calculated) and for female rats the LD50
value was 27 mg/kg (confidence limits of 2-53 mg/kg). Six of
the eight animals that died after receiving 30 mg/kg showed substantial
(P value not reported) weight loss at the time of death. Also,
weight gains in survivors (2/10) at the 30 mg/kg dose level and
in males survivors (5/5) at the 10 mg/kg dose level were lower
than those in control animals (P value not reported). Two of
the 5 females in the 10 mg/kg group exhibited weight loss at 7
or 14 days. Weight gain in the remaining three animals of this
group were comparable to controls.
Signs of neurological toxicity, including
ataxia, flaccid limb and body tone, and abnormal righting and
visual placing reflexes, were seen in all or most animals at the
30 and 100 mg/kg dose levels, and in 5/10 animals at the 10 mg/kg
dose level. No abnormalities were observed in animals that received
3 mg/kg of pentaerythritol triacrylate. More specific data on
neurotoxicity are presented in section G.2. Signs of acute toxicity
(decreased activity, decreased respiration rates, and abdominal
writhing) were seen in the animals at the 10, 30, and 100 mg/kg
dose levels on the day of treatment and throughout the post-dose
period. The two female survivors in the 30 mg/kg dose group,
and 2/5 survivors in the 10 mg/kg group, exhibited decreased activity
and respiration rates and decreased food consumption. These animals
also exhibited urinary and fecal staining and unthrifty coat.
Animals treated with 3 mg/kg of pentaerythritol triacrylate were
free of abnormalities except for the presence of swollen eyelids
and/or ocular discharge in two animals between days 8 and 14.
The authors, however, concluded for unstated reasons, that these
symptoms did not represent effects of the test material.
Necropsy observations of all animals that were killed after 14 days revealed abnormalities exclusive to test groups as well as abnormalities that were seen in both test and control groups. Survivors from the control group and groups treated with pentaerythritol triacrylate (3, 10 and 30 mg/kg) showed dark red foci (all test and control animals) and mottled dark red areas on the lungs (5/10 controls, 5/10 in the 3 mg/kg group, 1/10 in the 10 mg/kg group, 1/2 in the 30 mg/kg group). The survivors in the 3 mg/kg dose group did not have any abnormalities that were considered by the authors to represent an effect of pentaerythritol triacrylate. Survivors in the 10 mg/kg group exhibited rounded edges of the liver (3/5 males, 1/5 females), swollen eyes (2/5 males), and pale red adrenals (2/5 females). These symptoms were not seen in control animals, except for one female control that had rounded edges of the liver. In the 30 mg/kg dose group, the two female survivors exhibited swollen eyes, urinary staining alopecia, distended abdomen, rounded edges of the liver, adherence of the liver to the diaphragm, a distended large intestine containing green fluid, and pale red adrenals. Again, these abnormalities were not seen in control groups. No P values were reported for these results.
Necropsy performed on animals that died during the study also showed several abnormalities that were not present in control animals, most of which appeared in the abdominal viscera. For conciseness, Table 2 summarizes the abnormalities found in male and female rats that were treated with 30 or 100 mg/kg pentaerythritol triacrylate and that had expired during the study. Since no P values were provided, only those observations that were seen in three or more animals at either dose have been reported [Celanese, 1982c].
Necropsy Obserrvation |
30 mg/kg* | 100 mg/ks** | ||
males | females | males | females | |
Lungs | ||||
pale red | 2/5 | 1/3 | 4/5 | 3/5 |
bright red | 3/5 | 2/3 | 1/5 | 4/5 |
Stomach | ||||
red walls | --- | --- | 5/5 | 4/5 |
brown/yellow/green fluid or substance | 4/5 | 2/3 | --- | --- |
Small Intestine | ||||
red walls | 2/5 | 1/3 | 0/5 | 4/5 |
distended | 1/5 | 1/3 | --- | --- |
mottled red | 1/5 | 2/3 | --- | --- |
orange/yellow/green fluid | 2/5 | 2/3 | 0/5 | 4/5 |
brown fluid | 2/5 | 1/3 | --- | --- |
Large Intestine | ||||
mottled red | 1/5 | 2/3 | --- | --- |
brown fluid | 4/5 | 1/3 | --- | --- |
Adrenals | ||||
dark red/red | 4/5 | 3/3 | 5/5 | 2/5 |
Body Cavity | ||||
yellow fluid | --- | --- | 5/5 | 3/5 |
red fluid | 1/5 | 2/3 | --- | --- |
Miscellaneous | ||||
ocular discharge | 4/5 | 0/3 | --- | --- |
urinary staining | 1/5 | 2/3 | --- | --- |
--- = did not occur in three or more animals
* = five males and three females examined
** = five males and five females examined
After receiving the undiluted dose of the chemical, all mice appeared lethargic and inactive. Some (unspecified number) were salivating. After the first day of treatment, 3 of the 5 mice had died and 4 had died after the second day. When the mice were treated with 50 mg of the 10% solution of pentaerythritol triacrylate in acetone (5 mg/mouse), the skin became epilated, crusted and severely burned. Finally, the investigators observed that 50 mg of a 5% solution of pentaerythritol triacrylate in mineral oil (2.5 mg/mouse of the test chemical) did not result in any toxic effects. No signs of toxicity were seen after five weeks. From this data, it was recommended that future long-term skin paint studies (see section V.D.) use pentaerythritol triacrylate as a 5% solution in mineral oil, at doses of 50 mg twice per week, for a final concentration of 2.5 mg/mouse pentaerythritol triacrylate [Celanese, 1982d].
C. Prechronic
1. Human Data/Case Reports
A summary of the following case reports concerning
potential exposure to acrylates and the subsequent patch tests
conducted with pentaerythritol triacrylate is presented in Table
3.
All subjects were patch tested with each component
of the printing ink, as well as the ink itself. They were also
patch tested with pentaerythritol triacrylate, a multifunctional
acrylate, also reported to be used in this type of ink. The duration
of the tests was not reported. Although six patients tested positive
to patch tests with 0.5% and 0.1% trimethylolpropane triacrylate
(TMPTA) in acetone, the multifunctional acrylate present in this
ink formulation, only 4 out of 6 subjects tested positive to 0.1%
pentaerythritol triacrylate in acetone. The four workers positive
to pentaerythritol triacrylate reported previous exposure to similar
ultraviolet printing inks. However, since no information was
available on the composition of these inks, it was impossible
to determine whether a cross-reaction between pentaerythritol
and trimethylolpropane triacrylate occurred. None of the 30 control
subjects reacted to the ink. Four additional control workers,
however, showed slight brown-red outlined erythema without infiltration
with pentaerythritol triacrylate and TMPTA. These were considered
to be weak irritant reactions. [Bjorkner et al. , 1980].
Patch tests on the patient were done with 0.2% pentaerythritol
triacrylate, full strength primer (without cross-linker), and
the full strength cross-linker, all in petrolatum. The pentaerythritol
triacrylate was applied to the upper portion of the back and kept
in place for 48 hours. The primer and the cross-linker were
applied as open patch tests to the anterior upper portion of the
patient's arm and kept in place for 48 hours. The results were
read 15 minutes after the patches were removed, and at one week.
Positive reactions were seen to both the pentaerythritol triacrylate
and the full strength cross-linker at 48 hours and one week.
The reaction to the cross-linker persisted for weeks. To rule
out an irritant reaction, the patient was tested with the cross-linker
at concentrations of 1.0%, 0.5%, and 0.1% in petrolatum and
ethyl alcohol. Positive reactions were seen to all concentrations
in both solvents; the reactions to the petrolatum mixtures were
more severe. Normal volunteers (n=7) serving as controls had
no reaction to the above test doses of the cross-linker in petrolatum.
Also, 50 additional subjects showed no reactions to 0.1% cross-linker
in petrolatum. The study also noted that since the patient had
been exposed only to a cross-linker composed of trimethylolpropane
triacrylate, his reaction to pentaerythritol triacrylate could
be attributed to cross-sensitization [Cofield et al. ,
1985].
All four patients tested positive to patch tests
(duration unspecified) with 0.1% (v/v) hardener in acetone, and
to a 0.1% (v/v) solution in acetone of the polyfunctional acrylate
found in the hardener (trimethylolpropane triacrylate). Two patients
also reacted to 0.1% pentaerythritol triacrylate in acetone.
Patch tests done with the polyurethane dispersion and the other
components of the top coat were negative. Patch tests with the
hardener at 1% in acetone were given to 12 control subjects, while
tests with the hardener at 0.1% in acetone were given to 33 subjects.
All control tests were negative. In addition, the batch formulation
(specifications not reported) that had produced the original positive
allergic reactions in the four patients did not result in any
reactions in 10 controls. The authors concluded that the hardener
(TMPTA), and not the other products used in the flooring material,
caused the dermatitis. The reactions to pentaerythritol triacrylate
may be attributed to cross-sensitization [Dahlquist, et al.,
1983].
A 51-year-old male lye tank operator who cleaned
the containers for ink ingredients developed vesicular dermatitis
on his trunk, back, hands, and forearms. A 45-year-old male maintenance
operator, who also cleaned containers, developed eczematous eruptions
on his eyelids, wrists, hands, and fingers. This subject reportedly
rubbed his eyes when his hands were contaminated with ink ingredients.
A 53-year-old male, who weighed radiation-dried ink ingredients,
developed eczematous dermatitis on his ears, forearms, and fingers.
A 63-year-old male mill hand developed eczematous dermatitis
on his forearms, hands, fingers, and loin area. Finally, a 37-year-old
male production manager developed erythema and isolated papules
on his left wrist, which appeared related to his habit of holding
his watch over an ink mill to observe the condensation of vapors
on the metal watch case.
Patch testing was done individually with each component
of the ultraviolet inks used in the plant, including a 0.2% solution
of pentaerythritol triacrylate in petrolatum. All dilutions were
previously determined to be non-irritating. Tests were also performed
with three ink varnish formulations containing 0.2% of the pentaerythritol
triacrylate in petrolatum. Results were recorded after 48 hours.
Four of the five patients reacted positively to pentaerythritol
triacrylate and the three varnish formulations containing pentaerythritol
triacrylate. Although the fifth patient did not have significant
reactions at 48 or 72 hours, he did exhibit an irritant dermatitis
following patch testing with pentaerythritol triacrylate. No reactions
were seen to the other components of these varnish formulations.
All subjects sensitized to pentaerythritol triacrylate also reacted
to trimethylolpropane triacrylate, a similar polyfunctional acrylate
monomer. However, since all subjects had potential exposure
to both compounds, it could not be determined whether the multiple
reactivity was a result of cross-sensitization or concomitant
sensitization. No data were provided on control group testing
[Emmett, 1977].
For all patch tests, the test materials were applied
to the upper back on 3.8 square centimeter patch test plasters
and occluded with surgical tape. Patches were removed after 48
hours and the sites were examined one hour later. In cases of
mild or questionable readings, additional data were recorded 72
hours after application. All compounds were tested at concentrations
found to be non-irritating in patch tests on normal, unaffected
volunteers. For pentaerythritol triacrylate, all patients were
tested with a 0.2% solution in petrolatum. Other acrylates tested
included trimethylolpropane triacrylate and 1,6-hexanediol diacrylate.
The results of the patch test show 4 of the tested subjects had
positive reactions to pentaerythritol triacrylate, and in three
cases, the results were categorized as strong edematous or vesicular
reactions. The fourth case showed a weak (nonvesicular) reaction
and the fifth patient had a doubtful reaction. From this data,
the authors concluded that the multifunctional acrylic monomer,
pentaerythritol triacrylate, is a strong allergen capable of sensitizing
a significant percentage of the work force exposed to the compound.
The authors noted that some of the observed reactions represent
cross-reactions, but since the employees were potentially exposed
to each of the materials, cross-sensitization could not be evaluated
[Emmett and Kominsky, 1975; Emmett and Kominsky, 1977].
All seven patients were patch tested with several
potential allergens, including pentaerythritol triacrylate, urethane
acrylate, and several epoxy acrylate resins. Each substance was
tested at a concentration of 0.1% in petrolatum. This dose had
been shown to be non-irritating in 20 healthy volunteers. Patches
were applied to the upper back of each subject on "A1-Test-Strips"
secured with Dermicel tape and then removed after 48 hours.
Once the pressure effect of the patches had resolved (30 minutes),
the sites were examined and scored. Reexamination was done at
72 and 96 hours. The scoring system used was recommended by the
International Contact Dermatitis Group.
Although 5 out of 7 workers tested positive to urethane
acrylate, only one patient also showed a positive reaction to
pentaerythritol triacrylate. This machine operator exhibited
a spreading, ulcerative reaction (3+ score) at both 48 and 96
hours. Since the chemical structures of these two compounds differ,
and no contamination of urethane acrylate with pentaerythritol
triacrylate was shown by chemical analysis and the individual
had been exposed to both substances, the investigators concluded
that these reactions did not represent cross-sensitization, but
rather concurrent sensitization [Nethercott, et al., 1983].
Each man was patch tested with the three colored
inks (red, black, and gold) diluted to 10% in methyl ethyl ketone
and with the reducer (pentaerythritol triacrylate). Positive reactions
were seen with pentaerythritol triacrylate and the black and gold
inks that contained pentaerythritol triacrylate. No reaction
was seen with red ink, which did not contain pentaerythritol triacrylate.
To clarify the results, a second series of patch tests were run.
This time the men were patch tested with pentaerythritol triacrylate
at 1.0% and 0.1% in methyl ethyl ketone, the other components
of the inks, and two alternative acrylates, trimethylolpropane
triacrylate and tripropylene glycol triacrylate. The length of
the patch tests was not reported. Both patients had positive
patch tests with pentaerythritol triacrylate and the two alternative
acrylates, but not with any other component of the inks. No data
were provided on control subjects. The investigators concluded
that pentaerythritol triacrylate is a strong allergen capable
of producing sensitization in a significant percentage of the
work force. Positive reactions observed with the two alternative
acrylates were believed to be due to cross-sensitization [Smith,
1977].
Number of Workers Potentially Exposed | Number of Workers with Irritation/ Sensitization Reactions | Concentration (%) in Skin Patch Tests (Time) | Number Positive in Patch Test | Reference |
---|---|---|---|---|
unspecified | 6 | 0.1 in ace (NR) | 4 | Björkner et al., 1980 |
unspecified | 1 | 0.2 in pet (48 hrs) | 1 | Cofield et al., 1985 |
10-30 | 4 | 0.1 in ace (NR) 0.01 in ace (NR) | 1 1 | Dahlquist et al., 1983 |
26 | 5 | 0.2 in pet (48 hrs.) | 4 | Emmett, 1977 |
58 | 8 | 0.2 in pet (48 hrs.) | 4 | Emmett and Kominsky, 1975 |
unspecified | 19* | 0.1 in pet (48 hrs.) | 7/18 | Nethercott, 1978 |
10 | 7 | 0.1 in pet (48 hrs.) | 1 | Nethercott et al., 1983 |
unspecified | 2 | 1.0 in mek (NR) 0.1 in mek (NR) | 2 2 | Smith, 1977 |
unspecified | 59 | 0.2 in alcohol 0.1 in vaseline® | NR** 5 | Kalensky, 1987 |
pet=petrolatum
ace=acetone
mek=methyl ethyl ketone
NR=not reported
NR**=not reported in abstract
* = only 18 workers were patch tested
3. Animal Data
Induction was performed in two stages. First, each animal was injected intradermally on either side of the shoulder region with the following formulations (3 pairs of injections per animal): (1) 0.1 ml of 0.001% pentaerythritol triacrylate (5 animals), 0.01% pentaerythritol triacrylate (15 animals), 0.05% pentaerythritol triacrylate (5 animals) or 0.5% pentaerythritol triacrylate (10 animals) in propylene glycol; (2) 0.05 ml of FCA mixed with 0.05 ml of the appropriate concentration (0.001, 0.01, 0.05 or 0.5%) of pentaerythritol triacrylate in propylene glycol; (3) 0.1 ml of Freund's complete adjuvant (FCA). After one week, the shoulder region was clipped and pentaerythritol triacrylate in petrolatum at the appropriate concentration (0.001, 0.01, 0.05, or 0.5%) was applied to the injection site on Whatman filter paper. The patch was kept in place for 48 hours. Two weeks after this topical exposure, the animals were subjected to challenge patch tests. Pentaerythritol triacrylate was applied at a non-irritating concentration (unreported) to a shaved area of the flank as described in the induction procedure. After 24 hours, the patch was removed. At 48 hours, the sites were examined for evidence of a reaction.
Using probit analysis, the percentage of animals
sensitized at each concentration was calculated. At 0.001%,
only 15.4% (2/5) of the animals were sensitized to pentaerythritol
triacrylate. This percentage increased to 55.6% (8/15) for animals
induced with 0.01% pentaerythritol triacrylate, 93.3% (4/5) for
animals induced with 0.05% pentaerythritol triacrylate, and 100%
(10/10) for the 0.5% pentaerythritol triacrylate induced group.
The intradermal concentration required to sensitize half the guinea
pigs (IDSC50) was calculated to be 0.005%. This value indicates
that pentaerythritol triacrylate possesses a high potential to
induce cutaneous allergy in guinea pigs [Nethercott et al.,
1983].
Polak method: On the
first day of this procedure, the test animals received 4 footpad
injections of a 0.1 ml emulsion containing 2 mg/ml pentaerythritol
triacrylate in ethanol:saline (1:4), in Freund's complete adjuvant
(FCA). Another injection of 0.1 ml of the emulsion was given
into the nape of the neck, resulting in a total dose of 1 mg pentaerythritol
triacrylate per animal. On day 7, open skin testing was done
by dropping 0.02 ml of a solution of pentaerythritol triacrylate
in acetone:olive oil (4:1) onto a shaved flank of the animal.
Pentaerythritol triacrylate was used at concentrations of 0.1
and 0.25%, which were described as the maximum concentrations
that did not result in non-specific irritation. The skin tests
were repeated weekly at different sites on the flank for up to
12 weeks.
Split adjuvant method:
On day zero, 0.05 ml of FCA was injected into 5 sites on the
dorsal shaved flank of the guinea pig. One day later, 0.1 ml (100
µg) of pentaerythritol triacrylate in ethanol:saline (1:100)
was injected intradermally into the same five sites. Finally,
on day 14, skin tests were begun, as described in the Polak method,
and continued for 12 weeks.
Maximization method:
On day zero, guinea pigs received intradermal injections onto
shaved sites on the back of the neck. Each animal received two
injections of 0.1 ml FCA, 0.1 ml of 1% pentaerythritol triacrylate
in saline, and 0.1 ml of 1% pentaerythritol triacrylate in FCA.
At day 14, skin tests (as described above) were done for up to
12 weeks.
Epicutaneous method (A): On day zero, 0.1 ml of a 0.3 Msolution of pentaerythritol triacrylate in 95% ethanol:2-methoxyethanol :Tween 80 (9:9:2) was dropped onto a marked area of the animal's shaved flank. This procedure was repeated on days 2, 4, 7, 9, and 11. On day 28, the weekly skin testing was begun (as described above) and continued for up to 12 weeks.
Epicutaneous method (B): On
day zero, 0.1 ml of 0.25% pentaerythritol triacrylate in acetone:olive
oil (1:1) was applied to a marked and shaved area of the back
of the neck on six test animals. This was repeated on days 1,
2, 3, 4, 7, 8, 9, 10, and 11. On day 21, the skin test procedures
began (as described above) and continued for up to 12 weeks.
All skin test sites were observed at 24, 48, and
72 hours. The data reported show that both the Polak method and
the epicutaneous (B) method were able to induce contact sensitivity
to pentaerythritol triacrylate. With the Polak method, six guinea
pigs exhibited positive skin reactions on the 14th day of the
skin test studies. The reactions were scored using a 0-3 scale
(0= no reaction, 3 = a red and elevated reaction). Scores of
1.1 using 0.1% pentaerythritol triacrylate and 1.4 using 0.25%
pentaerythritol triacrylate were determined. When immunized using
the epicutaneous method (B), 5 out of 6 animals were sensitized
to the compound. The severity of the reactions was not specified.
Results concerning the other methods of induction were not reported.
However, it can be assumed that pentaerythritol triacrylate did
not induce sensitization reactions using these protocols. Information
concerning control groups was not reported [Parker and Turk, 1983].
For induction, an unreported number of test animals
were given three intradermal injections into each side of the
shoulder region. The formulations were: (1) 0.1 ml of Freund's
complete adjuvant (FCA) mixed with an equal amount of water; (2)
0.1 ml of 1.0% trimethylolpropane triacrylate in olive oil and;
(3) 0.1 ml of 1.0% trimethylolpropane triacrylate in olive oil
with an equal amount of FCA. One week after the injections, a
topical patch consisting of 25% trimethylolpropane triacrylate
in petrolatum was applied to the reshaved injection sites on Whatman
paper. The patch was held in place for 48 hours. Two weeks after
this induction procedure, 24 animals were challenged with patch
tests of 0.5 and 0.1% pentaerythritol triacrylate in petrolatum.
For these tests, an occluded patch was applied to a clipped and
shaved area of the flank for 24 hours and then removed. Each site
was examined for evidence of a positive reaction. During induction,
control groups (unspecified number of animals) were intradermally
injected with FCA and olive oil, and treated topically with only
olive oil. In challenge tests, 24 control animals were also patch
tested with pentaerythritol triacrylate at the same concentrations.
The results of the challenge tests show that 18/24 guinea pigs (75%) sensitized to trimethylolpropane triacrylate gave positive reactions when challenged with 0.5% pentaerythritol triacrylate. Twelve of 24 animals (50%) reacted to pentaerythritol triacrylate in a 0.1% test concentration. Control animals, tested simultaneously, did not react to challenge with pentaerythritol triacrylate. In this study, trimethylolpropane triacrylate sensitized 67% of the guinea pigs and is consequently considered a strong allergen. Since 75% of the trimethylolpropane triacrylate-sensitized animals also reacted to pentaerythritol triacrylate, cross-sensitivity between the two compounds is suggested [Björkner, 1980].
Guinea pigs were given challenge patch tests with
the commercial forms of PETA-3 and PETA-4, the "purified"
forms of PETA-3 and PETA-4, pentaerythritol, and two structurally
similar acrylates, all in petrolatum. In two separate tests,
one week apart, approximately 0.015 g of each chemical was applied
to test sites on a shaved area of the animal's flank. The duration
of exposure was not reported in this study. The control animals
were challenged with the same chemicals at the same doses. Forty-eight
hours after the first challenge, test animals received a booster
dose consisting of a 1% solution of the sensitizing chemical (PETA-3
or PETA-4) in olive oil:acetone (9:1) injected intradermally into
the neck. For control animals, the booster injections consisted
of only olive oil.
Of the animals sensitized to commercial PETA-3, 10/15
(67%) reacted to commercial pentaerythritol triacrylate in challenge
tests. Six of these animals also reacted to purified PETA-3,
seven to commercial PETA-4, 3 to purified PETA-4, 3 to pentaerythritol,
and 7 to trimethylolpropane triacrylate (TMPTA). Only one animal
of the 15 sensitized to commercial PETA-4 reacted to this compound
in challenge tests. The same animal reacted to purified PETA-4,
purified PETA-3, and TMPTA. Two other animals that did not react
to PETA-4 reacted to PETA-3 (commercial form only). None of the
control animals reacted positively to any of the compounds tested.
According to the manufacturer, the PETA-3 used in
this investigation consisted mostly of pentaerythritol triacrylate.
HPLC analysis indicated that the compound contained a high degree
of impurities, including PETA-4. Complete purification of this
product was impossible and the "purified" form used
in testing contained 1% PETA-4. Commercial PETA-4 had a higher
degree of purity than PETA-3. Analysis of the "purified"
PETA-4 shows two small peaks, the smaller of which was identified
as PETA-3 (15% of main peak). From this study, the authors
concluded that PETA-3 is a stronger sensitizer than PETA-4. In
addition, the possibility of cross-reactivity between pentaerythritol
triacrylate and TMPTA was supported by the results of this study
[Björkner, 1984].
Immunization with pentaerythritol triacrylate by the Polak method resulted in positive skin reactions in the guinea pigs, whereas sensitization was not induced by epicutaneous application. The reported skin test scores, recorded one and two days after skin test patches were removed, are presented below in Table 4 [Bull et al., 1985].
Induction Method |
7 Days | 14 Days | |||||||
24 hours | 48 hours | 24 hours | 48 hours | ||||||
0.1% | 0.25% | 0.1% | 0.25% | 0.1% | 0.25% | 0.1% | 0.25% | ||
______________________________________________________ | |||||||||
Polak | 0.2 | 0.5 | 0.8 | 1.5 | 0.8 | 1.3 | 1.2 | 2.1 | |
Epicutaneous | 0.1 | 0.1 | 0.1 | 0.2 | 0.1 | 0.2 | 0.2 | 0.2 | |
______________________________________________________ |
For tolerance and cross-reactivity
tests, outbred Hartley guinea pigs of either sex were used.
To assess cross-reactivity, groups of five test animals were immunized
with pentaerythritol triacrylate and skin tested with pentaerythritol
triacrylate, as well as additional acrylates of similar structure
(concentrations unspecified). The procedure for all patch tests
is described in detail in the study above. In an attempt to induce
tolerance epicutaneously, 0.1 ml of a solution of 10% pentaerythritol
triacrylate in acetone was applied to the dorsum of the animals
ear 14 and 7 days before immunization with methyl acrylate
or trimethylol propane triacrylate (concentrations unspecified).
The control group was not pretreated with pentaerythritol triacrylate.
Skin tests on the test animals and the control animals were
conducted with the immunizing compound on day 7 after induction.
Methyl acrylate was skin tested at 1% and 5%, while trimethylol
propane triacrylate was tested at 0.25% and 0.5%. Again, for
skin tests at each concentration, the mean reactivity score of
5 animals was reported 24 and 48 hours after the patches were
removed.
Animals sensitized to pentaerythritol
triacrylate also reacted to trimethylolpropane triacrylate (TMPTA),
4-vinyl pyridine (4VP), methyl acrylate (MeA), and methyl vinyl
ketone (MVK). The relative degree of cross-reactivity was assessed
as a percentage of the contact reaction induced by the immunizing
chemical. In the case of TMPTA, greater than 80% of the reaction
was induced by pentaerythritol triacrylate, while 60-80% of the
reaction to 4VP was induced by this compound. For MeA and MVK,
only 20-60% of the contact reactions seen were induced by pentaerythritol
triacrylate. These numbers indicate that pentaerythritol triacrylate
does have the potential to cross-react with several other chemicals.
The results of the tolerance study show that treatment with pentaerythritol triacrylate prior to immunization does not suppress the contact reactions to methyl acrylate or trimethylolpropane triacrylate. For example, without pretreatment, immunization with 5% MeA produced a skin test reaction of 0.9±0.6 and 1.7±0.4 at 24 and 48 hours, respectively. With a pretreatment application of pentaerythritol triacrylate, skin test scores were 1.3±0.6 and 1.4±0.9 at 24 and 48 hours, respectively. Immunization with 0.5% TMPTA without epicutaneous application of pentaerythritol triacrylate resulted in skin test scores of 0.4±0.4 and 1.5±0.9 for the two time points. With application of pentaerythritol triacrylate, the scores were 0.2±0.2 and 1.2±1.0 for 24 and 48 hours, respectively. According to these results, pentaerythritol triacrylate was determined not to induce epicutaneous tolerance to these compounds. The authors also concluded that strong cross-reactivity between compounds is not alone sufficient to produce epicutaneous tolerance [Parker et al., 1985].
For the first stage of induction (day
0), three pairs of intradermal injections were given to the animal
in a shaved area of the shoulder. The injections were as follows:
(1) 2 x 50 µl of Freund's complete adjuvant (FCA) in sterile
water (1:1); (2) 2 x 50 µl of a 5% solution of the test
chemical in soy bean oil; and (3) 2 x 50 µl of a 5% solution
of the test chemical in FCA and water (1:1). The control animals
received the same treatment without the test substance. On day
7, the same area of the neck was clipped and 250 mg of 10% sodium
dodecyl sulfate in petrolatum was applied to the site and left
uncovered for 24 hours. On day 8, 400 µl of the test compound
(100%) were applied to the test area on a piece of Whatman filter
paper which was left in place for 48 hours. The control group
received the same treatment, substituting the test substance
with petrolatum. Challenge patch tests were conducted on day
21 on a shaved area of the animal's flank. Up to six patches,
containing 25 µl of 2% pentaerythritol triacrylate, were
applied and secured for 24 hours. Readings were made 48 and 72
hours after the application of the patches and the sites were
scored on a scale of 0-3 (0=no reaction, 3=intense erythema and
marked edema). Controls received identical treatment.
Seven out of twenty animals induced
with TEDMA and 9/19 animals induced with TMPTMA also reacted to
pentaerythritol triacrylate in challenge patch tests. No cross-reaction
with pentaerythritol triacrylate was seen in animals induced with
either MMA or EDMA. No reactions were seen in the control animals.
The author concluded that pentaerythritol triacrylate is a potent
sensitizer that can cross-react [Clemmensen, 1985].
From the results, it was found that
the weight gain in test animals was comparable to the weight gain
in the control group, with the exception of one male and one female
that exhibited slight weight losses (-0.2 kg). Motor activity
decrease and nasal discharge also occurred in several animals,
primarily during the treatment period. Gross dermal observations
revealed that all test animals treated with pentaerythritol triacrylate
exhibited severe erythema with necrosis and eschar formation,
fissuring, desquamation, and slight to moderate edema and atonia.
While edema, atonia and fissuring subsided during the post-treatment
period, the other signs persisted through termination of the study.
Exfoliation of eschar tissue occurred during the last week of
the post-treatment period. Other than a few rabbits with slight
erythema and desquamation, control animals were free of abnormalities.
Gross post-mortem observations of selected tissues revealed discolorations
of the lungs and kidneys in animals after two weeks of treatment
with pentaerythritol triacrylate. In rabbits held for 2 weeks
post-treatment, mottled, dark red foci were observed on the surface
of the lungs. However, since similar abnormalities were seen in
organs of control animals, the authors concluded that they were
probably due to infectious etiology and were not treatment related.
Microscopic examinations of treated
or exposed skin from rabbits sacrificed following two weeks of
treatment (2 males/4 females) revealed severe necrosis of the
epithelium and subepithelium (2 males/3 females and 2 males/1
female, respectively) and congestion of the dermis (2 males/3
females). These effects were not observed in control animals.
In addition, inflammatory cell infiltrates were seen in the subepithelial
connective tissue of all animals treated with pentaerythritol
triacrylate. Such infiltrates were only seen in one control animal
(female). Other abnormalities seen in treated skin, but not in
controls, include subcutaneous edema (1 male/3 females), epithelial
hyperplasia (2 females), and hyperkeratosis (2 females). Pathological
examination of animals sacrificed at four weeks revealed that
the epithelium was intact, but evidence of prior moderate to severe
irritation was present. For example, healing of the skin with
re-epithelization (hyperplasia), was observed in 2/2 males treated
with pentaerythritol triacrylate. These animals also had regions
of dense subepithelial fibrosis and regions where normal follicular
structures had been destroyed. Control animals examined at four
weeks did not show any abnormalities related to treatment with
pentaerythritol triacrylate
Microscopic examination of other selected
tissues from animals sacrificed after two and four weeks revealed
various inflammatory changes in the liver, kidneys, brain, and
lungs. However, these lesions were also seen in control rabbits
and were not considered by the pathologist to be treatment related.
No evidence of systemic toxicity resulting from administration
of pentaerythritol triacrylate was observed [Celanese, 1979].
All animals treated with pentaerythritol
triacrylate exhibited weight loss (0.1 to 0.7 kg) during the first
week of study. Rabbits that survived beyond day 7 continued to
lose weight until death or sacrifice. Overall, weight loss ranged
from 0.3 to 1.0 kg. All control animals exhibited normal weight
gain or no change (one female) during the first two weeks and
continued to gain weight during the two-week recovery period.
Dermal observations revealed that at day 7, all animals in the
test group exhibited moderate to severe erythema and edema, which
persisted until death or sacrifice (day 15). At the time of death
(spontaneous or sacrifice) most animals also exhibited necrosis
and eschar formation (9/10 and 8/10, respectively) and atonia
(8/10). A few also showed slight desquamation (4/10) and/or fissuring
(2/10). Most animals exhibited hypoactivity, hypopnea, nasal
discharge, and food consumption decrease. Some also exhibited
soft stool, fecal staining, emaciation, piloerection, hypothermia,
and respiratory arrhythmia. Individual animals exhibited ataxia,
dry rales, and prostration. Other signs which, according to the
authors, probably represent irritation from the test material
include hair loss and irritation of the eyes and scrotum. Toxicological
signs were generally similar in animals that died spontaneously
and those that survived through day 15. Control animals treated
with mineral oil showed little or no evidence of dermal irritation
or toxicity throughout the study, with the exception of ocular
irritation and decreased food consumption in a few animals.
Gross observations from the post-mortem
examination of the four test animals sacrificed after two weeks
(1 male/3 females) revealed morphological abnormalities of the
skin, which were recorded as a slight dark red coloring with red
areas accompanied by thickened, hairless scabs. Similar abnormalities
were seen on the skin of the six animals (4 males/2 females) that
died during the study. Numerous black foci were observed on the
stomach of 2 of the 6 animals that died during the study. These
foci were not seen in any control animals. Other gross abnormalities
seen in animals that were sacrificed, animals that spontaneously
expired, and control animals were sporadic and inconsistent.
The pathologist concluded that they did not appear related to
administration of the test compound.
Histological examination of rabbits treated with pentaerythritol triacrylate and sacrificed at two weeks revealed extensive degeneration of the subcutis and severe epidermal necrosis and ulceration in all 4 animals. Other abnormalities seen in these animals included dermal and subcutis edema (1 male/1 female), dermal hemorrhage and inflammation (2 females), and subcutis inflammation (3 females). The authors report that the absence of epidermal hyperplasia, epidermal hyperkeratosis, and dermal fibrosis or granular tissue reactions suggests marked toxicity and a suppression of tissue repair attempts. All animals that died during the study exhibited degeneration and edema of the dermis and degeneration and inflammation of the subcutis. Microscopic evaluation of these animals also revealed epidermal necrosis (3 males/2 females), epidermal atrophy (2 males), and dermal hemorrhage (2 males, 1 female). A variety of inflammatory changes were also observed in the kidneys, lungs, brain, and other organs of treated and control animals. These changes were random and without predilection to treatment groups and were interpreted by the pathologist as spontaneous. Other changes were too few or mild to demonstrate definite systemic effect. The pathology report concluded that the evaluation of the animals failed to conclusively demonstrate the presence or absence of systemic toxicity with pentaerythritol triacrylate [Celanese, 1981].
1. Human Data
No data were found on the chronic/carcinogenic
effects of pentaerythritol triacrylate in humans.
2. Animal Data
Mice treated with the test mixture
of pentaerythritol triacrylate showed no incidence of skin tumors,
in contrast to the positive control group in which 36/40 mice
treated with methylcholanthrene developed skin tumors. No clinical
or histological signs of chronic toxicity were observed in the
animals treated with the test material. The survival rate of
test material-treated mice (25 after one year, 16 after 1.5 years,
and 5 after 2 years) was not unusual when compared to the acetone
controls (P values not reported). According to the results of
this study, the authors concluded that the test material is not
oncogenic [DePass, 1982; DePass et al., 1985].
No skin tumors were found in mice treated
with pentaerythritol acrylate-HF. Only one mouse in the negative
control group developed a squamous cell carcinoma of the skin,
which may or may not have been related to acetone treatment.
Mice in the test group, however, did exhibit an increase in gross
hepatic tumors when compared to the acetone-treated group (13/39
v. 4/34, respectively). In those mice examined histologically,
the incidences of hepatic tumors in test and control groups were
13/14 and 4/5, respectively. The authors reported that in this
study, histological examination was only carried out to confirm
gross findings or if unusual lesions were discovered during gross
observation. Consequently, there are histology data only for
selected tissues of several mice.
Historic control data for the same
test species indicate that the incidence of gross hepatic tumors
in other negative control groups was not numerically or statistically
different (P value not reported) than the incidence seen in the
animals of this study treated with pentaerythritol acrylate-HF.
The number of hepatic tumors observed in previous studies was
higher (13/36) than those observed in the concurrent negative
control group of this experiment (4/34). The gross observations
of mouse liver tumors, while statistically significant (P value
not reported) in this study, would be equivocal when compared
to historic controls. Based on this data, Union Carbide Corporation
believes that the results of this study do not contain substantial
risk information under TSCA Section 8(e) [Union Carbide, 1979;
Union Carbide, 1988].
Gross observations of the skin sites
indicate that pentaerythritol triacrylate applied repeatedly in
non-irritating doses to the same area results in slightly epilated
and crusted skin. Similar irritant reactions were not seen in
mice treated with mineral oil. Pathological results show that
of the 43 test compound-treated mice examined, all developed acanthosis
of the epidermis and 39/43 had fibrosis of the dermis. These
responses were also found in the negative control and vehicle
control groups, and are most likely due to the repeated shavings.
Hyperkeratosis was noted in 11 of the test animals and in none
of the vehicle or negative control animals.
Only one mouse treated with pentaerythritol triacrylate developed a neoplasm during the skin painting study. By histological examination, this tumor was determined to be a squamous cell carcinoma. The incidence of tumors in mice treated with pentaerythritol triacrylate was much lower that the incidence seen in the positive control group (44/48) (P values not reported). One mouse in the negative control group developed a squamous cell carcinoma, while none of the mice in the vehicle control group developed any type of neoplasm. Mice treated with pentaerythritol triacrylate also exhibited atropy of the gonads, prostatitis, prostatic hyperplasia, and mononuclear infiltrates in the adrenals. In addition, there was an increased incidence of lymphomas in animals treated with pentaerythritol triacrylate (P value not reported). Six mice treated with pentaerythritol triacrylate had lymphomas with spleen or lymph node involvement, while the incidence of lymphomas was 1/49 and 0/48 in the vehicle and negative control groups, respectively. From these data, the investigators concluded that although pentaerythritol triacrylate does not seem to be tumorigenic to mouse skin, it may be absorbed and act as an internal carcinogen to the lymphoid systems [Celanese, 1982d].
This review was submitted to the United States Environmental Protection Agency (EPA) and evaluated by a Senior Science Advisor for the Health and Environmental Review Division. After scrutinizing the DuPont report, the advisor concluded that the EPA should not overturn the "limited positive evidence of carcinogenicity" of pentaerythritol triacrylate supported by the study conducted by Celanese Chemical Company for several reasons. First, due to missing material (histology slides), there is no way to determine if the sections available to the DuPont review pathologists were the same sections on which the original conclusion was made. Second, the EPA cannot choose to believe the conclusions of one laboratory over the conclusions of another. A third review would be equally uninformative due to the missing slides. Finally, a pilot experiment for the Celanese study found the acrylates, including pentaerythritol triacrylate, to be systemically toxic, which prompted the complete histological examination. The EPA has recommended that the current categorization of pentaerythritol triacrylate be maintained until a similar long-term dermal exposure study can be completed [USEPA, 1988].
E. Reproductive Effects and Teratogenicity
1. Case Reports
No data were found on the reproductive
effects or teratogenicity of pentaerythritol triacrylate in humans.
2. Animal Data
The results from exposure to pentaerythritol triacrylate present equivocal findings at a clearly maternally toxic (unspecified) dose level. At 100 mg/kg, the test chemical caused uncommon malformations in a small number of fetuses/litter. However, in a second study in which pentaerythritol triacrylate was given at a level (dose not reported) that caused minimal maternal toxicity, teratogenic effects were not noted. From these results, the authors concluded that pentaerythritol triacrylate was not a teratogen [Andrews and Clary, 1986].
1. Human Data
No data were found on the genetic toxicology
of pentaerythritol triacrylate in humans.
2. Prokaryotic Data
3. Eukaryotic Data
In the three experiments, pentaerythritol
triacrylate induced a dose-responsive increase in mutant frequency.
The highest increase in mutant frequency observed was 416 x 10-6
at a pentaerythritol triacrylate concentration of 0.37 µg/ml
(15% survival). Increases in mutant frequency were primarily
due to the induction of small-colony TFT-resistant mutants. Pentaerythritol
triacrylate also induced a dose-responsive increase in the number
of aberrations and micronuclei observed. The highest frequency
observed was 50 aberrations per 100 cells scored and 38 micronuclei
per 1000 cells scored at a concentration of 0.350 µg/ml pentaerythritol
triacrylate (15% survival).
The authors concluded that the genotoxicity of pentaerythritol triacrylate is elicited via a direct-acting clastogenic mechanism because no metabolic activation is required. The induced level of micronuclei paralleled the increased aberration frequency and small-colony formation, adding further support that small-colony formation may correlate with clastogenic activity and that pentaerythritol triacrylate is indeed clastogenic [Dearfield, et al. 1989].
G. Other Toxicological Effects
1. Immunotoxicity
Four days after the epicutaneous application, a significant increase in weight in the homolateral auricular, homolateral cervical, and contralateral cervical lymph nodes was observed in animals treated with pentaerythritol triacrylate (numbers not reported). There was also evidence of increased T-lymphocyte proliferation, as measured by an increase in LPC, in the paracortical areas of these lymph nodes when compared to the control values (P<0.001). For example, in the homolateral auricular lymph nodes, 39 cells (per microscopic field of 270 µm diameter) were found in test animals as compared to 15 LPC in the control animals. These results were consistent after 6 days for the homolateral auricular nodes. From this study, the authors concluded that a positive correlation exists between skin sensitization reactions, increases in lymph node weight, and T-lymphocyte proliferation [Bull, et al., 1985]
2. Neurotoxicity
Table 5 summarizes the principal signs
of neurological toxicity seen in animals who were found dead after
treatment with 30 or 100 mg/kg of pentaerythritol triacrylate
(5 males/3 females and 5 males/5 females, respectively) at some
point prior to death. The two survivors (females) in the 30 mg/kg
group continued to exhibit ataxia, body and limb flaccidity, and/or
abnormal righting and visual placing reflexes throughout most
or all of the 14-day post-dose observation period. One female
also exhibited compulsive biting between days 7 and 14. In both
dose groups (30 and 100 mg/kg), a few animals that died also exhibited
convulsions, toe pinch, abnormal startle reflexes, abnormal pupil
or corneal reflexes, and uncoordinated eye movements prior to
death.
Neurological abnormalities were noted in 5 of the 10 animals in the 10 mg/kg group (3 males, 2 females) and consisted of ataxia (1 male, 2 females), flaccid limb and body tone (2 males, 2 females), and abnormal righting and visual placing reflexes (2 females). The males were free of neurological abnormalities by day 5. One of the females was free of abnormalities by day 10, but the second continued to exhibit an abnormal righting reflex through the termination of the study (day 14). No neurological abnormalities were observed in animals that received 3 mg/kg of pentaerythritol triacrylate or in control animals receiving only mineral oil [Celanese, 1982b].
Sign | Dose | ||||||||
30 mg/kg | 100 mg/kg | ||||||||
male/female | male/female | ||||||||
___________________________________________________ | |||||||||
Ataxia | 5/3 | 5/5 | |||||||
Body tone flaccidity | 4/2 | 4/4 | |||||||
Limb tone flaccidity | 4/1 | 3/3 | |||||||
Abnormal righting reflex | 5/3 | 5/5 | |||||||
Anormal visual-placing reflex | 4/1 | 4/3 | |||||||
___________________________________________________ |
3. Biochemical Toxicology
No data were found on the biochemical toxicology
of pentaerythritol triacrylate in humans or animals.
Web page last updated on August 15, 2005
The National Institute of Environmental Health Sciences is one of the National Institutes of Health within the U.S. Department of Health and Human Services. The National Toxicology Program is headquartered on the NIEHS campus in Research Triangle Park, NC.