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Toxicological information

Basic toxicokinetics

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Administrative data

Endpoint:
basic toxicokinetics
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Test procedure described in sufficient detail and study performed according to the GLP guidelines. However, a corrosive concentration was used which resulted in a damaged skin. Furthermore 14C is used and it is not known whether this is present as peracetic acid, acetic acid or carbon dioxide.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1994
Report Date:
1994

Materials and methods

Objective of study:
toxicokinetics
Test guidelineopen allclose all
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 417 (Toxicokinetics)
Version / remarks:
incorporates OECD 427
Deviations:
not applicable
Qualifier:
according to
Guideline:
other: OECD recommendations for in vivo percutaneous absorption studies (OECD, 1993; Scott et al., 1993).
Deviations:
not applicable
Principles of method if other than guideline:
OECD recommendations for in vivo percutaneous absorption studies (OECD, 1993; Scott et al., 1993).
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Radiolabelling:
yes

Test animals

Species:
rat
Strain:
other: Ola : Sprague-Dawley
Sex:
male
Details on test animals and environmental conditions:
Source: Harlan Olac Ltd., Shaw´s Farm, Blackthorn, Bicester, Oxon, UK
Animals were about 6 weeks of age at study initiation. Males weighed between 207 and 227 g (Group A) and between 182 and 202 g (Group B)

Administration / exposure

Route of administration:
dermal
Vehicle:
water
Details on exposure:
Dosing regime:
Group A (14C-Proxitane 0510): 100 µL (~ 5.5 mg peracetic acid) to an enclosed area of 4.5 cm2 of clipped dorsal skin.

Group B (14C-acetic acid): 100 µL to an enclosed area of 4.5 cm2 of clipped dorsal skin

On the day of treatment, a perspex ring (2.5 cm inner diameter x 1 cm) was glued onto the clipped skin and a piece of lens tissue was placed in contact with the skin inside the ring and the test or control substance was applied to the tissue to ensure uniform distribution of material over exposed skin. A circle of medical gauze was glued to the top surface of the perspex ring and the animals immediately placed in the metabolism cages.

Preparation of skin:
The area of skin to be treated with test item or control substance was clipped free of hair about 24 hrs before dermal administration. On the day of treatment, a ring was glued onto the clipped skin using cyanoacrylate glue. A piece of lens tissue was placed in contact with the skin inside the ring and the test article/control substance was applied to the tissue to ensure uniform distribution of the test materials over the exposed skin.
Duration and frequency of treatment / exposure:
72 hour(s)
Doses / concentrations
Remarks:
Doses / Concentrations:
Single dermal dose of 100 microliter of a 5.02 % peracetic acid solution
Total volume applied:
Group A (14C-Proxitane 0510): 457 µL/kg bw or 25 mg/kg bw (considering 5.02 % peracetic acid in Proxitane 0510 and assuming a density of 1.1g/mL)
Group B (14C-acetic acid): 517 µL/kg bw
No. of animals per sex per dose:
4
Control animals:
other: not required for this type of study
Positive control:
yes, treated with radiolabelled acetic acid.
Details on study design:
The study was conducted according to OECD guideline 417 incorporating OECD guideline 427 in order to investigate the overall metabolic fate of acetic acid and peracetic acid following single dermal application to rats under conditions representing the maximum concentration that an individual is likely to be exposed to under normal use conditions and to determine any significant accumulation of the radiolabel present in the formulation in tissues of the treated animals.

One group of four male rats was given a single application of 14C-labelled Proxitane 0510 to an enclosed area (approx. 4.5 cm2) of clipped dorsal skin. The treated animals were placed in metabolism cages and respired air, urine and faeces analysed for radioactivity content up to 72 hours post-treatment. Animals were then killed and the radioactivity in the treated skin, major organs and remaining carcass determined.

A second group of four rats was given a single application of 14C-labelled acetic acid/hydrogen peroxide solution to act as a control group. The fate of the radioactivity was compared with that from the 14C-labelled Proxitane 0510-treated animals and the percentage of radioactivity found in treated skin, major organs, remaining carcass as well as in respired air, urine and faeces was determined up to 72 hours post-treatment.
Details on dosing and sampling:
Tissues:
Groups A and B:
Animals were sacrificed by cervical dislocation 72 hrs after single dermal application. The acrylic ring was removed and the area of skin within the ring recovered. The condition of the skin was noted.
Following organs were removed, weighed and the radioactivity determined in the organs by LSC:
- Liver, kidneys, heart, lungs, testes, brain, stomach (with contents), small intestines (with contents), caecum/large intestines (with contents),
- Samples of muscle and fat
- Residual carcass at terminal sacrifice

Volatile products:
Air was drawn through the metabolism cages from start of treatment until termination after 72 hours.
Volatilised 14C acetic acid and/or peracetic acid was trapped in a Dreschel bottle containing water followed by a second bottle with 2-ethoxyethanol : ethanolamine (4:1 v/v) to trap exhaled CO2. For distinguishing between volatile parent compounds (i.e. 14C acetic acid and 14C-peracetic acid, respectively), the 14CO2 produced was trapped in Carbosorb and counted in Permafluor E scintillation cocktail.
The trapping fluids were changed for fresh fluids at regular intervals and the radioactivity concentrations determined by LSC.

Excreta:
Urine and faeces samples were recovered at 24 hrs intervals and the radioactivity concentrations determined by LSC.
Statistics:
Body weights of animals before dosing and at necropsy: two sample t-test
Elimination/retentions in tissues/carcass of the absorbed radioactivity: two sample t-test
A probability of less than or equalto 0.05 was used to indicate statistical significance between Groups A and B.

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on absorption:
- approx. 30 – 60 % of the dose recovered as CO2 after an initial lag phase of approx. 1 hour
Details on distribution in tissues:
- 20 % of radio-activity tissue-bound with highest levels found in liver, gastro-intestinal tract and exposed skin
Details on excretion:
- about 4-5 % of given radioactivity excreted via the faeces and 17 % via urine

Metabolite characterisation studies

Metabolites identified:
yes
Details on metabolites:
No metabolite profiling was undertaken in the study. Only parent compound and expired radiolabelled CO2 were investigated in this study. However, based on the chemical nature of the materials given, acetic acid and peracetic acid (after conversion to acetic acid as well) will be introduced in the C2-pool or further metabolised via physiological pathways to carbon dioxide and water. All occurring metabolites are rapidly eliminated and do not bioaccumulate. In addition, about 50 – 60 % of the absorbed radioactivity is converted to CO2 after both dermal administration of 14C-acetic acid or 14C-Proxitane 0510

Any other information on results incl. tables

Absorption

According to the results obtained, both 14C-Proxitane 0510 and 14C-acetic acid are rapidly absorbed after dermal administration as demonstrated by the percentage of radioactivity exhaled as CO2, excreted with the urine and faeces or found in tissues, respectively. Absorption of both materials was determined to be about 54-60 % when expressed as percentage of radioactivity administered or 72-99 % when expressed as percentage of total recovered radioactivity. In contrast to 14C-Proxitanehigh portion (~ 20 % of the radioactivity topically administered) of 14C-acetic acid volatilized from treated skin. 

 

Distribution in tissues

 

Group A - Treated Group:

The recovery of radioactivity in the tissues and carcass was greater than in the positive control group (topical treatment with 14C-acetic acid) and varied from 9.1 to 13.5 % (mean 12.1 %) when expressed as a percentage of administered dose. High levels of radioactivity were found in the residual carcass as well as in the liver and in the gastrointestinal tract. High levels of radioactivity were also found in the treated skin sites. Radioactivity found in tissues was higher than in the positive control group when expressed on a % dose/gram tissue basis. However, mean % of radioactivity/gram tissue were lower in the skin of the Proxitane 0510 treated group (0.15 to 0.29% of the administered dose (mean 0.22 %) or 0.21 %/g tissue).

When recovery of activity in tissues was expressed as a percentage of total recovered activity, 15.6 to 23.4 % (mean 19.9 %) of the recovered dose were found in tissues.

Group B – Control Group:

The total activity recovered from the tissues and carcass of the positive control group (expressed as percentage of the administered dose) varied from 5.5 to 9.5 % (mean 6.9 %). Relatively high levels were found in the liver and gastrointestinal tract of all animals, however, the concentration of activity (% dose/g tissue) was similar in many of the tissues and in the remaining carcass. The total activity in exposed skin sites was relatively high as well (0.17 to 0.4 % of the administered dose (mean 0.24 %) or 0.31 %/g tissue). The mean concentration in skin sites was approx. one order of magnitude higher than in the majority of tissues and carcass.

When recovery of activity in tissues was expressed as a percentage of total recovered activity, 7.8 to 13.7 % (mean 9.5 %) of the recovered dose were found in carcass and tissues.

 

Excretion

Group A – Treated Group:

Air (water trap and CO2 trap):

Recovery of volatilized radioactivity following dermal application of radiolabelled Proxitane 0501 during the first 24 hours was 0.31 – 0.53 % (mean 0.44 %) of the administered dose in the treated group. Little radioactivity was recovered during the period from 24 – 72 hours. Expressed as a percentage of total recovered radioactivity, the activity in the water trap for trapping volatilised material varied from 0.53 % to 0.88 % (mean 0.71 %) at 24 hours.

When expressed as a percentage of dermally administered radioactivity, recovery of radiolabel from 3 of four test material treated animals in the 14CO2 trap was similar to that of control group animals (~ 33 %) while recovery of one animal was substantially greater (~ 46 %) with an overall mean of 35.68 % of administered radioactivity found in the 14CO2 trap. In contrast to control animals an initial 1 – 2 hours lag phase in the formation of 14CO2 was seen. After this lag phase, formation of 14CO2 was rapid up to 8 hours post-application and continued at a lower rate up to 72 hours thereafter. Expressed as a percentage of total recovered radioactivity, the radioactivity in the 14CO2 trap was in the range of 54 – 64 % % (mean 57.82 %) for the radiolabelled Proxitane 0510-treated animals.

Urine:

Recovery of radioactivity with the urine expressed as percentage of dermally administered dose was substantially greater on day 1 than on days 2 and 3. Recovery on day 1 was about 5 to 10 % (mean 7.24 %) of the dose given while on days 2 and 3 about 1 to 3 % (mean 1.15 – 2.1 %) of the dose was excreted. Recovery of radioactivity in the urine after 72 hours was about 7.6 to 14.5 % (mean 10.47 %) of administered dose. Recovery expressed as a percentage of total recovered activity did not alter the patterns of recovery substantially and was in the range of 13.6 to 24.8 % (mean 17.16 %) of total recovered radioactivity.

Faeces:

Radioactivity excreted with the faeces during days 1 to 3 varied and was shown to be between 0.5 to 3 % of the dermally administered dose in one individual animal while in the three remaining animals daily faecal excretion during 72 hours was in the range of 0.4 to 1 % of the dose topically applied. Recovery of radioactivity after 72 hours was between 1.6 and 4.4 % (mean 2.64 % of administered dose)of administered dose. Recovery expressed as a percentage of total recovered activity did not alter the patterns of recovery substantially and was in the range of 2.7 to 7.8 % (mean 4.40 %).

Overall recovery in air, urine and faeces:

Expressed as percentage of dermally administered radioactivity, the total cumulative recovery of radioactivity after 72 hours in air (water trap and CO2 trap), urine and faeces was about 49 % of the radioactivity topically applied with approx. 36 % in expired 14CO2, 10.5 % in the urine, 2.6 % in the faeces and negligible activity in the water trap (0.44 %) for trapping volatilised material (presumably mixture of 14C-peracetic acid and 14C-acetic acid), respectively. When total cumulative recovery is expressed as a percentage of total recovered radioactivity, approx. 80 % of the radioactivity were recovered in air, urine and faeces with 58 % % thereof recovered in expired 14CO2, 17 % in the urine, 4.4 % in the faeces and d negligible activity in the water trap (0.71 %), respectively.

 

Group B – Control group:

Air (water trap and CO2 trap):

Recovery of volatilised 14C-acetic acid y following dermal application of radiolabelled acetic acid during the first 24 hours was 20 to 30 % in three of four animals and 2.5 % of administered radioactivity in one animal (mean 18.87 % for all animals). Little radioactivity was recovered during the period from 24 – 72 hours (mean of 19 % of administered radioactivity after 72 hours). Expressed as a percentage of total recovered radioactivity, the activity in the water trap for trapping volatilised 14C-acetic acid varied from 28.38 % to 41.09 % at 24 hours for the three control animals with an overall mean of 25.68 % of the radioactivity recovered from all animals after 24 hours.

Recovery of applied radioactivity from 2 of the four test material treated animals in the 14CO2 trap was about 22 % and 30 33% of the topically administered radioactivity for the remaining two animals in this group (mean of 26.97 % of all animals after 72 hours). A substantial portion of the exhaled radioactivity was recovered during the first 3 hours. Thereafter, the rate was much lower particularly for the animals having exhaled about 22 % of the radioactivity as 14CO2 during the first 3 hours. Expressed as a percentage of total recovered radioactivity, the activity in the 14CO2 trap after 72 hours was about 33 % for three of four positive control group animals and about 48 % for the remaining positive control group animal (mean of 37.1 % after 72 hours when considering all control group animals).

Urine:

Recovery of radioactivity with the urine expressed as percentage of administered dose was similar for all animals on all study days and amounted to 5 % of the dose given on each day. Recovery of radioactivity after 72 hours was between 12 and 20 % of administered dose (mean 16.7 %) . Recovery expressed as a percentage of total recovered activity did not alter the patterns of recovery substantially and was in the range of 17 to 29 % after 72 hours (mean 22.82 %).

Faeces:

Radioactivity excreted with the faeces during days 1 to 3 varied and was shown to be between 0.2 to 2.5 % of the topically administered radioactivity to individual animals. Recovery of radioactivity after 72 hours was between 1.7 and 4.7 % of administered dose (mean 3.37 %). Recovery expressed as a percentage of total recovered activity did not alter the patterns of recovery substantially and was in the range of 2.4 to 6.7 % after 72 hours (mean 4.68 %).

Overall Recovery:

Expressed as percentage of dermally administered radioactivity, the total cumulative recovery of radioactivity after 72 hours in air (water trap and CO2 trap), urine and faeces was 66 % of the radioactivity topically applied with about 19 % excreted in the water trap (reflecting volatilised 14C-acetic acid from skin), 27 % in the 14CO2 trap, 16.7 % in the urine and 3.4 % in faeces, respectively. When total cumulative recovery is expressed as a percentage of total recovered activity, approx. 90 % of the radioactivity were recovered in air, urine and faeces with approx. 25.7 % thereof recovered in the water trap, 37.1 % % as expired 14CO2, 22.8 % in the urine and 4.7 % in the faeces, respectively.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): no bioaccumulation potential based on study results
Following topical application of radiolabelled peracetic acid (given as Proxitane 0510 containing 5 % peracetic acid), absorption was found to be rapid after an initial lag phase of approx. 1 hour.
The results of this combined dermal toxicokinetic and dermal penetration study demonstrated that due to its high reactivity, peracetic acid will not be able to enter the body and become systemically available after dermal application. The absence of a systemic bioavailability of peracetic acid is confirmed by its rapid degradation upon contact with skin resulting in the noted skin damage as well as by the observation that the kinetic behaviour and also the percentage of absorbed and excreted radioactivity as well as radioactivity found in different organs and treated skin is comparable after topical administration of peracetic acid (given as Proxitane 0510) and acetic acid, respectively. The latter observation in this study suggests that the chemical entity entering the body after dermal application will be restricted to acetic acid only.
Executive summary:

Following topical application of radiolabelled peracetic acid (given as Proxitane 0510 containing 5 % peracetic acid) and radiolabelled acetic acid onto the skin of male rats, only a small portion of the administered dose ( 1 %) was recovered as unchanged acetic acid/peracetic acid while approximately 30 – 60 % of the dose was recovered as CO2 (mean of about 58 % in the Proxitane group vs. a mean of about 37 % in the acetic acid group. In the case of radiolabelled Proxitane, formation of CO2 was associated with an initial lag phase of approx. 1 hour. It is possible that this initial lag phase is due to a lower blood flow in skin capillaries and a slower distribution due to micro-emboli resulting from oxygen formation after contact and damage to the skin.

In contrast to the Proxitane group, about 20 – 30 % of the administered dose (mean 19 %) was volatilised and recovered as unchanged acetic acid in the acetic acid group during the first 24 hours. Virtually no volatilisation from treated skin was observable in the Proxitane-treated group.

The excretion via the faeces was comparable between the two materials (about 3 ‑ 4 % of administered radioactivity), while the percentage of tissue-bound radioactivity was higher after administration of Proxitane (mean of about 20 % in the Proxitane group vs. a mean of about 10 % in the acetic acid group) and urinary radioactivity was higher after administration of acetic acid (mean of about 11 % in the Proxitane group vs. a mean of about 17 % in the acetic acid group).

In tissues, highest levels of radioactivity were found in liver, gastrointestinal tract and exposed skin. In the Proxitane group, severe skin damage was observable which was not evident in the acetic acid group. However, radioactivity found in the exposed skin was comparable between the Proxitane and the acetic acid group (approx. 0.15 – 0.4 % of the dose applied).

For both, radiolabelled Proxitane 0510 and acetic acid, a major portion of the absorbed radioactivity was converted to CO2(mean of 58 % for Proxitane 0510 and 50 % for acetic acid, respectively).

When expressed as percentage of dermally administered radioactivity, the total cumulative recovery of radioactivity after 72 hours in air (water trap and CO2 trap), urine, faeces and carcass/tissues was about 61 % of the radioactivity topically applied in the Proxitane-treated group and 73 % in the acetic acid-treated group, respectively.

In this study it could be observed that Proxitane 0510 causes damage to the skin while acetic acid does not. When Proxitane contacts the skin, the damage to the skin barrier results in degradation of peracetic acid to acetic acid. The observable initial lag phase for the formation of CO2in the Proxitane group is due to the time for the degradation of peracetic acid to acetic acid to occur upon contact with skin. After degradation of peracetic acid, formed acetic acid will be the chemical entity which subsequently penetrates skin and becomes systemically available for metabolism and excretion. This is supported by the results of the blood degradation studies with peracetic acid in rat blood (refer to Document IIIA, section 6, points 6.2/02 and 6.2/03) which demonstrate instantaneous degradation and thus, no systemic availability of peracetic acid.

The observation of a relatively high tissue distribution after administration of Proxitane 0510 can be explained by the incorporation of formed acetic acid into the C2-pool which is required to maintain the intermediary metabolism. Overall, the relative percentages of radioactivity exhaled as CO2 or found in the excreta (urine, faeces) do not differ significantly in the Proxitane- and the acetic acid-treated groups. The comparable distribution of radioactivity supports a rapid degradation of peracetic acid to acetic acid upon contact with skin followed by penetration of acetic acid through skin which suffered damage by exposure towards peracetic acid.