Mequinol

Endpoint summary

Description of key information

Three non-reliable studies are available for the oral acute toxicity. The results of two studies are consistent with the official classification in Europe: Acute Tox. Cat.4, H302.

No data are available for acute inhalation toxicity. However, such study is not required since PMP particle size is higher than 100 µm.

One reliable study by dermal route is available. Based on this study the substance is not classified.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Very few information is available about the test conditions. Only 2 doses and 2 animals/group were used.

Principles of method if other than guideline:

Method: other: no data.

GLP compliance:

no

Limit test:

yes

Species:

rat

Strain:

not specified

Sex:

not specified

Vehicle:

other: corn oil

Doses:

1000; 2000 mg/kg bw

No. of animals per sex per dose:

2 per dose

Control animals:

not specified

Statistics:

no data

Sex:

not specified

Dose descriptor:

LD50

Effect level:

> 1 000 - < 2 000 mg/kg bw

DOSE           mortality     Observations
-------------------------------------------------------------------------- ---------------------               
1000 mg/kg bw       0/2       Kidney damage observed at autopsy
2000 mg/kg bw      2/2       Convulsions in 10 mins and depression in 2  hrs. Animals dead in 2 hours.
-------------------------------------------------------------------------- ---------------------

Interpretation of results:

Category 4 based on GHS criteria

Executive summary:

As the LD50, by oral route in the rat is >1000 mg/kg bw and < 2000 mg/kg bw, PMP is harmful if swallowed, according to the EU CLP Regulation (EC) n°1272/2008 (acute toxicity category 4). This is also the official classification.

Reference 2

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

no data

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: The study is not detailed enough, but it can be considered as acceptable for a weight of evidence approach for the LD50 value

Guideline:

other: no data

GLP compliance:

no

Test type:

acute toxic class method

Limit test:

no

Species:

rat

Strain:

not specified

Sex:

not specified

Details on test animals or test system and environmental conditions:

TEST ANIMALS:

- Source: no data
- Age at study initiation: no data
- Weight at study initiation: 129 to 160 mg
- Fasting period before study: no data
- Housing: no data
- Food consumption: no data
- Water consumption: no data
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS: no data

In-life dates: no data

Route of administration:

oral: gavage

Vehicle:

not specified

Details on oral exposure:

VEHICLE : no data

Doses:

150, 200, 250, 300 and 350 mg/rat
or : 1162, 1550, 1786, 2143 and 2187 mg/kg bw

No. of animals per sex per dose:

26 total

Control animals:

no

Details on study design:

no data

Statistics:

no data

Preliminary study:

no data

Sex:

not specified

Dose descriptor:

LD50

Effect level:

ca. 1 630 mg/kg bw

Mortality:

yes, see table

Clinical signs:

other: no data

Gross pathology:

no data

Other findings:

no data

Dose        No.      Mean body      Mortality        Equiv. dose
(mg)        rats        weight (g)        (%)                (mg/kg bw)
---------------------------------------------------------------------
150         2         -                 0                 1262
200        10        129                40                1550
250        7        140                86                1786
300        6        140                83                2143
350        1        160                100                2187

The LD50 is of the order of 1630 mg/kg bw.

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

PMP is harmful based on the LD50 in rat.

Executive summary:

In an acute oral toxicity study, groups of 1-10 rats were given a single oral dose of PMP at doses of 1162, 1550, 1786, 2143 and 2187 mg/kg bw.

Oral LD50 = ca 1630 mg/kg bw.

PMP is harmful if swallowed, based on the LD50 in rat, according to the EU CLP Regulation (EC) n°1272/2008 (acute toxicity category 4). This is also the official classification.

This acute oral study is classified as not reliable ; it does not satisfy the guideline requirement for an acute oral study in the rat, but it can be considered as acceptable.

Reference 3

Endpoint:

acute toxicity: oral

Data waiving:

other justification

Justification for data waiving:

other:

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

1 630 mg/kg bw

Quality of whole database:

Methoxyphenol is officially classified harmful by ingestion, and old published data gave the same results.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 23 sept 2008 to 19 dec 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study, carried out without any deviations to the guideline

Qualifier:

according to guideline

Guideline:

EU Method B.3 (Acute Toxicity (Dermal))

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: OECD No 423 Acute Oral Toxicity – Acute Toxic Class Method

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories Ltd
- Age at study initiation: 9 weeks for males and 11 weeks for females
- Weight at study initiation: 187.3 g - 263.0 g
- Fasting period before study: no fasting period
- Housing: individually in Makrolon type-3 cages with standard softwood bedding
- Diet (e.g. ad libitum): pelleted standard Provimi Kliba 3433 rat/mouse maintenance diet
- Water (e.g. ad libitum): community tap water from Füllinsdorf
- Acclimation period: 7/8 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3°C
- Humidity (%): 30 - 70%
- Air changes (per hr): air-conditioned with 10-15 airs changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours light and 12 hours dark


IN-LIFE DATES: From: 01 oct 2008 To: 15 oct 2008

Type of coverage:

semiocclusive

Vehicle:

other: purified water

Details on dermal exposure:

TEST SITE
- Area of exposure: back of animals, skin area of 12 cm2 and 9 cm2 in the males and females
- % coverage: approximately 10% of the total body surface
- Type of wrap if used: a surgical gauze patch


TEST MATERIAL
- Concentration: 2000 mg/kg bw
- Concentration used: yes
- For solids, paste formed: yes


VEHICLE
- Amount(s) applied: 0.1 mL

Duration of exposure:

24 hours

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 15 days
- Frequency of observations: during the first 30 minutes, at approximately 1, 2, 3 and 5 hours after administration on test day 1 and twice daily for viability / Mortality and once daily for clinical signs during days 2-15
- Weighing : on test days 1 (prior to administration), 8 and 15
- Necropsy of survivors performed: no
- Other examinations performed: clinical signs, body weight, macroscopic examination

Statistics:

no statistical analysis was used

Preliminary study:

A single animal of each sex was treated first. Since no death as well as no severe local effects or severe systemic symptoms were observed after the 24-hour exposure, the test was completed using the four remaining male and female animals for an exposure period of 24-hours.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Mortality:

no deaths occured during the study

Clinical signs:

other: No clinical signs were observed in all 5 males and 5 females within the first 30 minutes following the treatment. No severe clinical signs were observed in all animals. Only slight signs were observed such as: - ruffled fur: in 4 males and 1 female at the

Gross pathology:

No macroscopic findings were recorded at necropsy.

Other findings:

Local dermal signs
Delayed local dermal reactions were observed in all males and females and consisted of erythema, oedema, scaling, focal to maculated crusts. The skin was affected from test day 3 to 5 (in most of the animals) to test day 7, 8, 11, 12 or up to the end of the observation (test day 15).

Interpretation of results:

GHS criteria not met

Conclusions:

LD 50 (rat): greater than 2000 mg/kg body weight

Executive summary:

In an acute dermal toxicity study B96175, groups of 5 Wistar male and 5 Wistar female rats were dermally exposed to Paramethoxyphenol for 24 hours to 10% of the total body surface at dose of 2000 mg/kg bw.

Animals then were observed for 15 days.

Dermal LD₅₀ > 2000 mg/kg bw

Paramethoxyphenol is not classified based on the LD₅₀. (PMP is also not officially classified)

Slight clinical signs (sedation and ruffled fur) and local signs (erythema and scaling crusts) were generally observed in almost all animals. There were no treatment related macroscopic examination or changes in body weight.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Additional information

Acute oral toxicity:

Two studies are available, but their reliability in Klimisch rating is 3.

In the first one (Hodge et al. 1949), groups of 1-10 rats (unknown sex and strain) were given a single oral dose of PMP at doses of 1162, 1550, 1786, 2143 and 2187 mg/kg bw. Except the mortality, no data concerning the toxicity effects are given.

The oral LD50 = ca 1630 mg/kg bw.

In the second one (Anonymous 1959, report of Dow Chemical Company), group of 2 rats (unknown strain and sex) were given by single oral dose of PMP at 1000 or 2000 mg/kg bw. At 1000 mg/kg bw, kidney damages were observed at necropsy. At 2000 mg/kg bw, convulsions were noted 10 min after administration and depression, 2 hours after dosing.

The oral LD50 is between these 2 values : 1000< LD50 < 2000 mg/kg bw

Based on the LD50 in rat given by these 2 studies, PMP can be considered as harmful if swallowed, according to the Directive 67/548/EEC criteria (Xn R22), and to the EU CLP Regulation (EC) n°1272/2008 (acute toxicity category 4). This is also the official classification.

Acute inhalation toxicity:

No data are available for this route of exposure. However, no data for acute inhalation toxicity is needed since particle size is higher than 100 µm (Sieving + laser granulometry + measurement of the dustiness - see section 4.5).

Acute dermal toxicity:

One study was chosen as key study, of reliability 1 (RCC report, 2008). In an acute toxic class method, group of 5 Wistar females and 5 males rats were applied a single dose of PMP at 2000 mg/kg bw. At this dose, slight clinical signs (sedation and ruffled fur) and slight local signs (erythema and scaling crusts) were generally observed in almost all animals. These effects disappeared at day 7 after treatment.

The dermal LD50 > 2000 mg/kg bw

Based on the LD50 in rat given by this study, PMP can be considered as not classified by dermal route, according to the Directive 67/548/EEC criteria, and to the EU CLP Regulation (EC) n°1272/2008. PMP is not officialy classified for this endpoint.

Two other studies are referenced (anonymous, 1959; Dow Chemical Company report and Blaszcak et al. 1987) but are of reliability 3 and 4 respectively and are not sufficiently documented to permit a conclusion.

Justification for selection of acute toxicity – dermal endpoint
GLP study, OECD 423 compliant

Justification for classification or non-classification

Oral route: PMP is officially classified as harmful if swallowed (acute oral toxicity category 4, H302: Harmful if swallowed) according to CLP Regulation (EC) n° 1272/2008 Annex VI table 3.

Inhalation: Since PMP particle size is higher than 100 µm, no study by inhalation route is required.

Dermal route: Based on the dermal LD50 in rats greater than 2000 mg/kg bw, PMP is not classified for dermal acute toxicity

according to CLP Regulation (EC) n° 1272/2008.

.