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Diss Factsheets

Administrative data

Description of key information

Based on a weight-of-evidence approach, magnesium hydroxide is not considered to be a skin sensitiser.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Referenceopen allclose all

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
For details and justification of read-across please refer to the attached report in section 13 of IUCLID.
Reason / purpose for cross-reference:
read-across source
Positive control results:
The sensitisation rate after application of the positive-control substance was 100% confirming the reliabiliy of the test system. For individual results see Table 2 in "Any other information on results incl. tables."
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
Injection site 1
No. with + reactions:
5
Total no. in group:
5
Clinical observations:
erythema grade 2 in 5/5 control
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
Injection site 1
No. with + reactions:
10
Total no. in group:
10
Clinical observations:
erythema grade 2 in 10/10 test animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: other: test group and control. Dose level: Injection site 1 . Total no. in groups: 15.0. Clinical observations: erythema grade 2 in 5/5 control and 10/10 test animals.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
Injection site 1
No. with + reactions:
10
Total no. in group:
10
Clinical observations:
oedema grade 2 in 10/10 test animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: other: test group and control. Dose level: Injection site 1. Total no. in groups: 15.0. Clinical observations: oedema grade 2 in 4/5 control and 10/10 test animals.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
Injection site 1
No. with + reactions:
1
Total no. in group:
5
Clinical observations:
oedema grade 1 in 1/5 control animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: positive control. Dose level: Injection site 1. Total no. in groups: 15.0. Clinical observations: oedema grade 1 in 1/5 control animals.
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
Injection site 2
No. with + reactions:
9
Total no. in group:
10
Clinical observations:
erythema grade 1 in 9/10 test animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: Injection site 2. Total no. in groups: 15.0. Clinical observations: erythema grade 1 in 9/10 test animals.
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
Injection site 2
No. with + reactions:
8
Total no. in group:
10
Clinical observations:
eschar in 8/10 test animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: Injection site 2. Total no. in groups: 15.0. Clinical observations: eschar in 8/10 test animals.
Reading:
1st reading
Hours after challenge:
24
Group:
other: test and control group
Dose level:
Injection site 3
No. with + reactions:
2
Total no. in group:
15
Clinical observations:
erythema grade 2 in 1/5 control and 1/10 test animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: other: test and control group. Dose level: Injection site 3. Total no. in groups: 15.0. Clinical observations: erythema grade 2 in 1/5 control and 1/10 test animals.
Reading:
1st reading
Hours after challenge:
24
Group:
other: test and control group
Dose level:
Injection site 3
No. with + reactions:
10
Total no. in group:
15
Clinical observations:
erythema grade 1 in 1/5 control and 9/10 test animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: other: test and control group. Dose level: Injection site 3. Total no. in groups: 15.0. Clinical observations: erythema grade 1 in 1/5 control and 9/10 test animals.
Reading:
1st reading
Hours after challenge:
24
Group:
other: test and control
Dose level:
Injection site 3
No. with + reactions:
2
Total no. in group:
15
Clinical observations:
oedema grade 2 in 1/5 control and 1/10 test animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: other: test and control. Dose level: Injection site 3 . Total no. in groups: 15.0. Clinical observations: oedema grade 2 in 1/5 control and 1/10 test animals.
Reading:
1st reading
Hours after challenge:
24
Group:
other: test and control group
Dose level:
Injection site 3
No. with + reactions:
2
Total no. in group:
15
Clinical observations:
oedema grade 1 in 1/5 control and 2/10 test animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: other: test and control group. Dose level: Injection site 3. Total no. in groups: 15.0. Clinical observations: oedema grade 1 in 1/5 control and 2/10 test animals.
Reading:
1st reading
Hours after challenge:
24
Group:
other: test and control group
Dose level:
Injection site 3
No. with + reactions:
7
Total no. in group:
15
Clinical observations:
eschar in 1/5 control and 6/10 test animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: other: test and control group. Dose level: Injection site 3. Total no. in groups: 15.0. Clinical observations: eschar in 1/5 control and 6/10 test animals.
Reading:
2nd reading
Hours after challenge:
48
Group:
other: test and control group
Dose level:
Injection site 1
No. with + reactions:
4
Total no. in group:
15
Clinical observations:
erythema grade 2 in 1/5 control and 3/10 test animals
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: other: test and control group. Dose level: Injection site 1. Total no. in groups: 15.0. Clinical observations: erythema grade 2 in 1/5 control and 3/10 test animals.
Reading:
2nd reading
Hours after challenge:
48
Group:
other: test and control group
Dose level:
Injection site 1
No. with + reactions:
11
Total no. in group:
15
Clinical observations:
erythema grade 1 in 4/5 control and 7/10 test animals
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: other: test and control group. Dose level: Injection site 1 . Total no. in groups: 15.0. Clinical observations: erythema grade 1 in 4/5 control and 7/10 test animals.
Reading:
2nd reading
Hours after challenge:
48
Group:
other: test and control group
Dose level:
Injection site 1
No. with + reactions:
4
Total no. in group:
15
Clinical observations:
oedema grade 2 in 1/5 control and 3/10 test animals
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: other: test and control group. Dose level: Injection site 1. Total no. in groups: 15.0. Clinical observations: oedema grade 2 in 1/5 control and 3/10 test animals.
Reading:
2nd reading
Hours after challenge:
48
Group:
other: test and control group
Dose level:
Injection site 1
No. with + reactions:
11
Total no. in group:
15
Clinical observations:
oedema grade 1 in 4/5 control and 7/10 test animals
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: other: test and control group. Dose level: Injection site 1. Total no. in groups: 15.0. Clinical observations: oedema grade 1 in 4/5 control and 7/10 test animals.
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
Injection site 1
No. with + reactions:
1
Total no. in group:
10
Clinical observations:
necrosis in 1/10 test animals
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: Injection site 1. Total no. in groups: 15.0. Clinical observations: necrosis in 1/10 test animals.
Reading:
2nd reading
Hours after challenge:
48
Group:
other: test and control group
Dose level:
Injection site 1
No. with + reactions:
2
Total no. in group:
15
Clinical observations:
eschar in 1/5 control and 1/10 test animals
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: other: test and control group. Dose level: Injection site 1. Total no. in groups: 15.0. Clinical observations: eschar in 1/5 control and 1/10 test animals.
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
Injection site 2
No. with + reactions:
4
Total no. in group:
5
Clinical observations:
erythema grade 1 in 4/5 test animals
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: Injection site 2. Total no. in groups: 15.0. Clinical observations: erythema grade 1 in 4/5 test animals.
Reading:
2nd reading
Hours after challenge:
48
Group:
other: test and control group
Dose level:
Injection site 3
No. with + reactions:
11
Total no. in group:
15
Clinical observations:
erythema grade 1 in 2/5 control and 9/10 test animals
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: other: test and control group. Dose level: Injection site 3. Total no. in groups: 15.0. Clinical observations: erythema grade 1 in 2/5 control and 9/10 test animals.
Reading:
2nd reading
Hours after challenge:
48
Group:
other: test and control group
Dose level:
Injection site 3
No. with + reactions:
2
Total no. in group:
15
Clinical observations:
oedema grade 1 in 1/5 control and 1/10 test animals
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: other: test and control group. Dose level: Injection site 3. Total no. in groups: 15.0. Clinical observations: oedema grade 1 in 1/5 control and 1/10 test animals.
Reading:
other: Immediately after removing the patch
Hours after challenge:
48
Group:
other: test and control group
No. with + reactions:
3
Total no. in group:
15
Clinical observations:
Desquamation in 1/5 control animals, erythema grade 1 in 2/10 test animals
Remarks on result:
other: Reading: other: Immediately after removing the patch. . Hours after challenge: 48.0. Group: other: test and control group. Total no. in groups: 15.0. Clinical observations: Desquamation in 1/5 control animals, erythema grade 1 in 2/10 test animals.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
Injection site 1
No. with + reactions:
4
Total no. in group:
5
Clinical observations:
Oedema grade in 4/5 control animals

Preliminary Test:

One animal was treated intradermally with concentrations of 5% and 2.5% of the test item. Two animals were treated topically with concentrations of 100% and 50% of the test item for 24 as well as 48 hours.

Based on the results of this preliminary test, a concentration of 5% was chosen for the intradermal application of the main test and a concentration of 50% was selected for the dermal induction.A concentration of 50% was found to be the highest dose suspended in vehicle which did not cause any signs of irritation after a topical treatment over 24 hours and therefore was chosen for the challenge application in the main test.

Main test:

Signs of irritation during the induction:

Intradermal Induction I (24 hours reading)

Injection site 1: erythema grade 2 in 5/5 control and 10/10 test,oedema grade 2 in 4/5 control and 10/10 test animals and oedema grade 1 in 1/5 control animals.

Injection site 2: erythema grade 1 in 9/10 test animal

eschar in 8/10 test animals.

Injection site 3: erythema grade 2 in 1/5 control and 1/10 test animals, erythema grade 1 in 1/5 control and 9/10 test animals, oedema grade 2 in 1/5 control and 1/10 test animals, oedema grade 1 in 1/5 control and 2/10 test animals and eschar in 1/5 control and 6/10 test animals.

Intradermal Induction I (48 hours reading):

Injection site 1: erythema grade 2 in 1/5 control and 3/10 test animals, erythema grade 1 in 4/5 control and 7/10 test animals, oedema grade 2 in 1/5 control and 3/10 test animals, oedema grade 1 in 4/5 control and 7/10 test animals, necrosis in 1/10 animals and eschar in 1/5 control and 1/10 test animals.

Injection site 2: erythema grade 1 in 4/5 test animals

injection site 3: erythema grade 1 in 2/5 control and 9/10 test animals, oedema grade 1 in 1/5 control and 1/10 test animals.

Dermal Induction II (48 hours exposure, occlusive):

Immediately after removing the patch: Desquamation in 1/5 control animals, erythema grade 1 in 2/10 test animasl.

24 hours after removing the patch: Eschar in 5/5 control and 10/10 test animals, erythema grade 1 in 1/10 test animals, desquamation in 1/10 test animals.

Challenge exposure:

No erythema was observed in any of the test animals at any time. Erythema grade 1 was observed after 24 hours in one animal of the control group. No oedema was observed in any animal at any time. There was no evidence of sensitisation in the test item group at the challenge and the percentageof animals sensitised was 0%.

The animals of the test group showed no reduced weight gain compared to historical data.

Table 1: Classification System:

Patch test reaction

 

Grade

No visible change

0

Discrete or patchy erythema

1

Moderate and confluent erythema

2

Intense erythema and swelling

3

Table 2: Frequency of Sensitisation in Positive-Control Animals

Hours Erythema grade 0 Erythema grade 1 Erythema grade 2 Erythema grade 3 Oedema grade 0 Oedema grade 1 Oedema grade 2 Oedema grade 3 % animals sensitised
24 0 6 4 0 4 6 0 0 100
48 0 3 7 0 10 0 0 0 100
72 0 7 3 0 10 0 0 0 100
Interpretation of results:
GHS criteria not met
Conclusions:
Under the conditions of the present study it can be stated that the test item Magnesium chloride hexahydrate caused no reactions identified as sensitisating at the tested concentration.
Executive summary:

In a dermal sensitisation study conducted according to OECD guideline 406 with magnesium chloride hexahydrate (purity 100%) in 0.9% physiological saline, 10 female young adult Crl: HA- guinea pigs were tested using the method of the guinea pig maximisation test.

At the daily clinical observation the animals did not show any visible clinical symptoms and no mortality occurred.

During the induction phase slight signs of irritation were observed. These findings confirmed the validity of the study.

In the challenge phase no erythema was observed in any of the test animals at any time. Erythema grade 1 was observed after 24 hours in one animal of the control group. No oedema was observed in any animal at any time.

There was no evidence of sensitisation at the challenge and the percentage of animals sensitised was 0%.

The positive control mercaptobenzothiazole did induce an appropriate response.

 

Under the conditions of the present study, it can be stated that the test item Magnesium chloride hexahydrate caused no reactions identified as sensitising at the tested concentration.

This information is used in a read-across approach in the assessment of the target substance. For details and justification of read-across please refer to the attached report in section 13 of IUCLID.

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
2010-04-14 to 2010-05-17
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
not specified
Qualifier:
according to guideline
Guideline:
EPA OPPTS 870.2600 (Skin Sensitisation)
Deviations:
not specified
Qualifier:
according to guideline
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
not specified
GLP compliance:
yes (incl. QA statement)
Type of study:
mouse local lymph node assay (LLNA)
Specific details on test material used for the study:
- Name of the test material used in the report: Magnesium hydroxide
- Appearance: white powder
- Batch No.: 20BR0026
- Purity: 99.90%
- Storage: at room temperature in the dark
- Expiry date: 2012-01-31
Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River France, L'Arbresle Cedex, France
- Age at study initiation: Aprrox 9 weeks old.
- Weight at study initiation: Body weight variation was within +/- 20% of the sex mean.
- Housing: Individual housing in labelled Macrolon cages containing sterilised sawdust as bedding material. Paper was supplied as cage enrichment. The paper was removed on Day 1 prior to dosing and was supplied again after scoring of the ears on Day 3.
- Diet : free access to pelleted rodent diet.
- Water: Free access to tap water
- Acclimation period: At least 5 days before the start of treatment.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.0 ± 3.0°C
- Humidity (%): A relative humidity of 40-70%
- Air changes (per hr):15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours artificial fluorescent light and 12 hours darkness per day.

IN-LIFE DATES: From: 14 April 2010 To:17May 2010
Vehicle:
propylene glycol
Concentration:
The test animals were treated with test substance concentrations of 10, 25 or 50% w/w on three consecutive days, by open application on the ears,. Five vehicle control animals were similarly treated, but with vehicle alone (propylene glycol). For allocation of the doses see Table 1.
No. of animals per dose:
3 groups of 5 female CBA/J mice were treated with one test substance concentration per group. One group of 5 female CBA/J mice were treated with vehicle.
Details on study design:
MAIN STUDY
A. INDUCTION EXPOSURE
The dorsal surface of both ears was epidermally treated (25 µL/ear) with the test substance concentration, at approximately the same time per day. The control animals were treated the same as the experimental animals,except that, instead of the test substance, the vehicle alone was administered.

B. EXCISION OF THE NODES
-All animals : Each animal was injected via the tail vein with 0.25 mL of sterile phosphate buffered saline containing 20 µCi of 3 H-methylthymidine. After approximately five hours, all animals were killed by intraperitoneal injection with Euthasol 20%. The draining lymph node of each ear was excised. The relative size of the nodes was estimated by visual examination and abnormalities of the nodes and surrounding area were recorded. The nodes were pooled for each animal in approximately 3mL PBS.

TISSUE PROCESSING FOR RADIOACTIVITY:
A single suspension of lymph node cells was prepared in PBS by gentle separation through stainless steel gauze (diameter 125 µm). LNC were washed twice with an excess of PBS by centrifugation at 200g for 10 minutes at 4°C. To precipitate the DNA, the LNC were exposed to 5% trichloroacetic acid and stored in the refrigerator until the next day.
Parameter:
SI
Value:
2
Test group / Remarks:
2 (test substance concentration 10%)
Parameter:
SI
Value:
3.6
Test group / Remarks:
3 (test substance concentration 25%)
Parameter:
SI
Value:
5.9
Test group / Remarks:
4 (test substance concentration 50%)
Parameter:
other: Mean DPM
Value:
288
Test group / Remarks:
control group
Parameter:
other: Mean DPM
Value:
564
Test group / Remarks:
2 (test substance concentration 10%)
Parameter:
other: Mean DPM
Value:
1 046
Test group / Remarks:
3 (test substance concentration 25%)
Parameter:
other: Mean DPM
Value:
1 690
Test group / Remarks:
4 (test substance concentration 50%)

Skin reactions/ Irritation (table 2):

-Very slight erythema was observed for all animals treated at 50%. No oedema was observed in any of the animals examined. White staining on the ears was observed at 10, 25 and 50%, which did not hamper the scoring of any skin reactions.

Macroscopy of the auricular lymph nodes and surrounding area:

-All auricular lymph nodes of the animals of the experimental and control groups were considered normal in size. No macroscopic abnormalities of the surrounding area were noted in any of the animals.

Body weights (table 2):

-Body weights and body weight gain of experimental animals remained in the same range as controls over the study period. The slight body weight loss, noted in some animals, was considered not toxicologically significant.

Toxicity and Mortality:

-No mortality occurred and no symptoms of systemic toxicity were observed in the animals of the main study.

Table 2: Skin reactions after epidermal exposure and body weights

 

 

 

Day 1

Day 3

Animal Number

Test substance

(% w/w)

Body weight(g)

Skin reactions dorsal surface ear

Body weight (g)

 

 

 

Left

Right

 

Erythema

Oedema

Erythema

Oedema

1

25

22

02

0

02

0

21

2

20

22

12

0

12

0

22

 

Table 3: Disintegrations Per Minute (DPM) and Stimulation Index (SI)

 

 

Group

Test Substance

(% w/w)

Mean

DPM ±SEM

 

SI± SEM

2

10%

564 ± 121

2.0 ± 0.5

3

25%

1046 ± 313

3.6 ± 1.3

4

50%

1690 ± 258

5.9 ± 1.4

 

 

 

 

1

0%

288±50

1.0±0.2
Interpretation of results:
Category 1B (indication of skin sensitising potential) based on GHS criteria
Conclusions:
According to the recommendations made in the test guidelines, Magnesium hydroxide would be regarded as a skin sensitiser.
Executive summary:

In a dermal sensitization study conducted according to OECD 429, 5 young adult female CBA/J mice per group were treated with magnesium hydroxide (purity 99.9%) in propylene glycol at concentrations of 10, 25 or 50% w/w on three consecutive days, by open application on the ears.

The SI values calculated for the substance concentrations 10, 25 and 50% were 2.0, 3.6 and 5.9 respectively. These results indicate that the test substance could elicit an SI >= 3. The data showed a dose-response and an EC3 value (the estimated test substance concentration that will give a SI=3) of 19.4% was calculated.

Based on the results of this study, magnesium hydroxide would be regarded as a skin sensitiser (Cat. 1B) based on GHS criteria.

Endpoint:
skin sensitisation, other
Type of information:
other: Skin sensitisation statement
Adequacy of study:
other information
Conclusions:
Although the results of the local lymph node assay (LLNA) test on magnesium hydroxide were apparently positive it is proposed that the positive result should be interpreted as a false positive and that magnesium hydroxide thus should not be classified as a skin sensitiser. There are a number of reasons to suggest that it is highly unlikely that magnesium hydroxide is a skin sensitiser. An expert opinion has been provided from the Informationsverbund Dermatologischer Kliniken (IVDK; Schnuch, A. 2010). The IVDK is a network of over 50 dermatological hospitals, and was formed to monitor and survey the development of contact allergies. Despite 20 years of observations in 192,421 patients they have yet to observe a case of a contact allergy with magnesium hydroxide. Furthermore, no case of contact allergy to magnesium hydroxide has been reported in the world literature, despite extensive exposure of the general population to the substance. Some reports on flame retardants address magnesium hydroxide toxicity, and no sensitising effects are reported (DFE (EPA), 2008; NAP, 2000).
Furthermore, the results of a guinea pig maximisation test (GPMT) performed with magnesium chloride were obtained from the magnesium chloride consortium. The results presented show that magnesium chloride was negative in the GPMT. As any possible skin sensitising potential of magnesium hydroxide is likely to stem from the cation rather than the hydroxide anion, the outcome of this test provides additional evidence that magnesium ions should not be regarded as a skin sensitiser. Regarding the hydroxide portion of the compound, there is ample evidence in the literature that hydroxides of other metals are not skin sensitisers (NICNAS, 2003; Banerjee et. al., 2003; DFE (EPA), 2008).
False positives in the LLNA assay are not uncommon, and indeed the LLNA was judged to be no more than 90 % accurate during its validation (Basketter et. al., 2010). On this basis, certain substances have not been classified as contact sensitisers despite giving positive responses in the LLNA test. These include copper chloride (Basketter and Scholes, 1992), sodium lauryl sulphate (Loveless et. al., 1996; Montelius et. al., 1994), benzalkonium chloride (Basketter et. al., 2004) and ethanol (Basketter et. al., 2010).
Given the combination of the epidemiological data, the negative magnesium chloride guinea pig maximisation test and the history of false positives using the LLNA test, the weight of evidence suggests that the positive results obtained in the LLNA test are inaccurate and, thus, a skin sensitising effect of magnesium hydroxide is unlikely. Therefore, magnesium hydroxide should not be classified as a skin sensitiser.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

Based on a weight of evidence approach using both animal testing and human information magnesium hydroxide is not regarded and not classified as a skin sensitiser. 

Although a guideline conform local lymph node assay showed a positive response, there are a number of reasons to suggest that it is highly unlikely that magnesium hydroxide is a skin sensitiser.

An expert opinion has been provided from the Informationsverbund Dermatologischer Kliniken (IVDK; Schnuch, A. 2010). The IVDK is a network of over 50 dermatological hospitals, and was formed to monitor and survey the development of contact allergies. Despite 20 years of observations in 192,421 patients they have yet to observe a case of a contact allergy with magnesium hydroxide. Furthermore, no case of contact allergy to magnesium hydroxide has been reported in the world literature, despite extensive exposure of the general population to the substance. Some reports on flame retardants address magnesium hydroxide toxicity, and no sensitising effects are reported (DFE (EPA), 2008; NAP, 2000).

Furthermore, the results of a guinea pig maximisation test (GPMT) performed with magnesium chloride were obtained from the magnesium chloride consortium. The results presented show that magnesium chloride was negative in the GPMT. As any possible skin sensitising potential of magnesium hydroxide is likely to stem from the cation rather than the hydroxide anion, the outcome of this test provides additional evidence that magnesium ions should not be regarded as a skin sensitiser. Regarding the hydroxide portion of the compound, there is ample evidence in the literature that hydroxides of other metals are not skin sensitisers (NICNAS, 2003; Banerjee et. al., 2003; DFE (EPA), 2008).

False positives in the LLNA assay are not uncommon, and indeed the LLNA was judged to be no more than 90 % accurate during its validation (Basketter et. al., 2010). On this basis, certain substances have not been classified as contact sensitisers despite giving positive responses in the LLNA test. These include copper chloride (Basketter and Scholes, 1992), sodium lauryl sulphate (Loveless et. al., 1996; Montelius et. al., 1994), benzalkonium chloride (Basketter et. al., 2004) and ethanol (Basketter et. al., 2010).

Given the combination of the epidemiological data, the negative magnesium chloride guinea pig maximisation test and the history of false positives using the LLNA test, the weight of evidence suggests that the positive results obtained in the LLNA test are inaccurate and, thus, a skin sensitising effect of magnesium hydroxide is unlikely. Therefore, magnesium hydroxide should not be classified as a skin sensitiser.

Given the combination of the epidemiological data, the negative magnesium chloride guinea pig maximisation test and the history of false positives using the LLNA test, the weight of evidence suggests that the positive results obtained in the LLNA test are inaccurate and, thus, a sensitising effect of magnesium hydroxide is unlikely. Therefore, magnesium hydroxide should not be classified as a skin sensitiser.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Based on a weight of evidence approach using both animal testing and human information magnesium hydroxide is not regarded and not classified as a skin sensitiser.