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EC number: 931-227-1 | CAS number: 28497-59-8
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Endpoint summary
Administrative data
Link to relevant study record(s)
- Endpoint:
- basic toxicokinetics
- Type of information:
- other: experimental result and QSAR
- Adequacy of study:
- key study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Test procedure in accordance with generally accepted scientific standards and described in sufficient detail
- Objective of study:
- absorption
- metabolism
- Qualifier:
- no guideline available
- Principles of method if other than guideline:
- A physiologically based pharmacokinetic model has been formulated to predict the pharmacokinetics and systemic disposition of alkylmethacrylate esters in rats and humans.
- GLP compliance:
- not specified
- Species:
- other: rat and human
- Strain:
- other: Wistar/Fischer F344/ not applicable
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- Epidermal membrane absorption studies
Skin was used from male rats of the Wistar-derived strain (supplied by Charles River UK Ltd, Margate, Kent, UK.) aged 28 days ± 2 days
Whole skin absorption studies
Skin was taken from male Fischer F344 (supplied by Harlan Olac) rats weighing between 200 and 250 g.
Human epidermal membrane absorption studies
Extraneous tissue was removed from human abdominal whole skin samples obtained post mortem in accordance with local ethical guidelines. - Route of administration:
- intravenous
- Details on study design:
- A series of in vitro and in vivo studies with a series of methacrylates were used to develop PBPK models that accurately predict the metabolism and fate of these monomers. The studies confirmed that alkyl-methacrylate esters are rapidly hydrolyzed by ubiquitous carboxylesterases. First pass (local) hydrolysis of the parent ester has been shown to be significant for all routes of exposure. In vivo measurements of rat liver indicated this organ has the greatest esterase activity. Similar measurements for skin microsomes indicated approximately 20-fold lower activity than for liver. However, this activity was substantial and capable of almost complete first-pass metabolism of the alkyl-methacrylates. For example, no parent ester penetrated whole rat skin in vitro for n-butyl methacrylate, octyl methacrylate or lauryl methacrylate tested experimentally with only methacrylic acid identified in the receiving fluid. In addition, model predictions indicate that esters of ethyl methacrylate or larger would be completely hydrolyzed before entering the circulation via skin absorption. This pattern is consistent with a lower rate of absorption for these esters such that the rate is within the metabolic capacity of the skin. Parent ester also was hydrolyzed by S9 fractions from nasal epithelium and was predicted to be effectively hydrolyzed following inhalation exposure.
- Type:
- metabolism
- Results:
- Half-life of MMA after i.V. injection: 4.4 min (PBPK estimate)
- Metabolites identified:
- yes
- Details on metabolites:
- Methacrylic acid
- Conclusions:
- The in vivo and in vitro investigations as well as the PBPK models developed from the data showed that alkyl-methacrylate esters are rapidly absorbed and are hydrolyzed at exceptionally high rates to methacrylic acid by high capacity, ubiquitous carboxylesterases. Further, the removal of the hydrolysis product, methacrylic acid, also is very rapid (minutes).
- Endpoint:
- basic toxicokinetics, other
- Remarks:
- (Q)SAR
- Type of information:
- (Q)SAR
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- accepted calculation method
- Justification for type of information:
- QSAR prediction
- Principles of method if other than guideline:
- Protein/GSH reactivity modelling with OECD Toolbox
- GLP compliance:
- no
- Conclusions:
- Interpretation of results (migrated information): other: low reactivity with GSH
A dataset with methacrylic acid derivatives has been assessed using the reactivity profiler in the OECD QSAR Toolbox. This profiler contains structural alerts derived from an analysis of experimental reactivity data as measured using glutathione (the Schultz assay). The profiler assigns chemicals to one of five potency classes (non-reactive, slightly reactive, moderately reactive, highly reactive and extremely reactive) based on the experimental results.
The majority of the chemicals, including HEMA, are slightly reactive. For methacrylates it is well known that the addition of an alkyl group on the alpha-carbon significantly reduces reactivity in the Michael addition reaction.
There are also a group of vinyl carboxamides (methacrylamide derivatives) that have been flagged as being moderately reactive. It should be noted, however, that in the underlying QSAR data in the TB there is no information regarding the effect of an alpha substituent for this class of chemical. In reality this means that no chemicals were tested with glutathione that contained an alpha alkyl substituent thus the prediction is being made based on the un-substituted parent (acrylamide; thus the over-cautious prediction). The investigator indicated that they are likely to be pretty unreactive in reality. - Executive summary:
A dataset with methacrylic acid derivatives has been assessed using the reactivity profiler in the OECD QSAR Toolbox. This profiler contains structural alerts derived from an analysis of experimental reactivity data as measured using glutathione (the Schultz assay). The profiler assigns chemicals to one of five potency classes (non-reactive, slightly reactive, moderately reactive, highly reactive and extremely reactive) based on the experimental results.
The majority of the chemicals, including HEMA, are slightly reactive. For methacrylates it is well known that the addition of an alkyl group on the alpha-carbon significantly reduces reactivity in the Michael addition reaction.
There are also a group of vinyl carboxamides (methacrylamide derivatives) that have been flagged as being moderately reactive. It should be noted, however, that inthe underlying QSAR data in the TB there is no information regarding the effect of an alpha substituent for this class of chemical. In reality this means that no chemicals were tested with glutathione that contained an alpha alkyl substituent thus the prediction is being made based on the un-substituted parent (acrylamide; thus the over-cautious prediction). The investigator indicated that they are likely to be pretty unreactive in reality.
- Endpoint:
- dermal absorption
- Type of information:
- (Q)SAR
- Remarks:
- Based on an established human skin model by Potts and Guy (Potts RO and Guy RH (1992). Predicting Skin Permeability. Pharm. Res. 9(5): 663-669)
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- accepted calculation method
- Principles of method if other than guideline:
- The physicochemical parameters of MW, Log P and saturated aqueous solubility have been used in the evaluation of 56 methacrylate compounds. An output of predicted steady-state flux was calculated using the principles defined in the Potts and Guy prediction model. (Potts RO and Guy RH (1992). Predicting Skin Permeability. Pharm. Res. 9(5): 663- 669)
- GLP compliance:
- no
- Species:
- other: human skin model
- Details on test animals or test system and environmental conditions:
- not applicable; in silico modelling
- Type of coverage:
- other: not applicable; in silico modelling
- No. of animals per group:
- not applicable; in silico modelling
- Absorption in different matrices:
- predicted flux 2.895 μg/cm²/h; the relative dermal absorption is low
- Conclusions:
- The dermal absorption of GDMA is predicted to be moderate; the predicted flux is 24.986 μg/cm²/h.
- Executive summary:
The dermal absorption (steady-state flux) of 1,6 -HDDMA has been estimated by calculation using the principles defined in the Potts and Guy prediction model.
Based on a molecular weight of 228.24 g/mol and ag Kow of 2.05 the predicted flux of GDMA is 24.986 μg/cm²/h; the relative dermal absorption is moderate.
Referenceopen allclose all
These studies showed that any systemically absorbed parent ester will be effectively removed during the first pass through the liver (CL as % LBF,
see table). In addition, removal of methacrylic acid from the blood also
occurs rapidly (T50%; see table).
Table 1:
Rate constants for ester hydrolysis by rat-liver microsomes and predicted
systemic fate kinetics for methacrylates following i.v. administration:
Ester Vmax Km CL T50% Cmax Tmax
----------------------------------------------------------
MAA - - 51.6% - - -
MMA 445.8 164.3 98.8% 4.4 14.7 1.7
EMA 699.2 106.2 99.5% 4.5 12.0 1.8
i-BMA 832.9 127.4 99.5% 11.6 7.4 1.6
n-BMA 875.7 77.3 99.7% 7.8 7.9 1.8
HMA 376.4 34.4 99.7% 18.5 5.9 1.2
2EHMA 393.0 17.7 99.9% 23.8 5.0 1.2
OMA 224.8 11.0 99.9% 27.2 5.0 1.2
----------------------------------------------------------
Vmax (nM/min/mg) and Km (µM) from rat-liver microsome (100 µg/ml)
determinations;
CL = clearance as % removed from liver blood flow, T50% = Body elimination time
(min) for 50% parent ester, Cmax = maximum concentration (mg/L) of MAA in
blood, Tmax = time (min) to peak MAA concentration in blood from model
predictions.
---
Table 2:
Rate constants for ester hydrolysis by human-liver microsome samples:
Ester Vmax (nM/min*mg) Km (mM) CL (µL/min*mg)
-----------------------------------------------
MMA 1721 4103 419
EMA 936 1601 584
i-BMA 80 441 181
n-BMA 211 158 1332
HMA 229 66 3465
2EHMA 53 48 1109
OMA 243 38 6403
----------------------------------------------------------
CL is calculated from the mean Vmax and Km
The algorithm of the OECD toolbox has been used to predict GSH/protein reactiviry.
Test Chemical / Compound Identity |
Acronym |
SMILES |
Molecular Weight |
Protein Binding Potency |
2-ethylhexyl methacrylate |
EHMA |
O=C(OCC(CCCC)CC)\C(=C)C |
198.3 |
Slightly reactive (GSH) >> Methacrylates (MA) |
ethyl methacrylate |
EMA |
CCOC(=O)C(=C)C |
114.14 |
Slightly reactive (GSH) >> Methacrylates (MA) |
isobutyl methacrylate |
iBMA |
CC(C)COC(=O)C(=C)C |
142.2 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Methacrylic acid |
MAA |
CC(=C)C(=O)O |
100.12 |
No alert found |
Methyl methacrylate |
MMA |
CC(=C)C(=O)OC |
100.12 |
Slightly reactive (GSH) >> Methacrylates (MA) |
n-butyl methacrylate |
nBMA |
CCCCOC(=O)C(=C)C |
142.2 |
Slightly reactive (GSH) >> Methacrylates (MA) |
n-Hexyl methacrylate |
n-HMA |
CCCCCCOC(=O)C(=C)C |
170.25 |
Slightly reactive (GSH) >> Methacrylates (MA) |
ter-Butyl Methacrylate |
tBMA |
CC(=C)C(=O)OC(C)(C)C |
142.2 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Diethylaminoethyl methacrylate |
DEAEMA |
O=C(OCCN(CC)CC)C(=C)C |
185.263 |
Slightly reactive (GSH) >> Methacrylates (MA) |
2-tert-Butylaminoethyl methacrylate |
TBAEMA |
O=C(OCCNC(C)(C)C)C(=C)C |
185.26 |
Slightly reactive (GSH) >> Methacrylates (MA) |
2-Dimethylaminoethyl methacrylate |
MADAME |
CC(=C)C(=O)OCCN(C)C |
157.22 |
Slightly reactive (GSH) >> Methacrylates (MA) |
2-(2-Butoxyethoxy) ethyl methacrylate, Butyldiglycol methacrylate |
BDGMA |
CCCCOCCOCCOC(=O)C(=C)C |
230.3 |
Slightly reactive (GSH) >> Methacrylates (MA) |
2-(2-(2-Ethoxy ethoxy)-thoxyethyl methacrylate |
ET3EGMA |
O=C(OCCOCCOCCOCC)C(=C)C |
246.3 |
Slightly reactive (GSH) >> Methacrylates (MA) |
2-Methoxyethyl methacrylate |
MTMA |
CC(=C)C(=O)OCCOC |
144.08 |
Slightly reactive (GSH) >> Methacrylates (MA) |
2-Ethoxyethyl methacrylate |
ETMA |
CCOCCOC(=O)C(=C)C |
158.09 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Phenoxyethyl Methacrylate |
PTMA |
CC(=C)C(=O)OCCOC1=CC=CC=C1 |
206.24 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Allyl methacrylate |
AMA |
CC(=C)C(=O)OCC=C |
126.15 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Benzyl methacrylate |
BNMA |
CC(=C)C(=O)OCC1=CC=CC=C1 |
176.21 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Cyclohexyl methacrylate |
c-HMA |
O=C(OC(CCCC1)C1)C(=C)C |
168.23 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Isobornyl methacrylate |
IBOMA |
CC(=C)C(=O)OC1CC2CCC1(C2(C)C)C |
222.32 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Phenyethyl methacrylate |
Phenylethyl MA |
CC(=C)C(=O)OCCC1=CC=CC=C1 |
190.24 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Phenyl methacrylate |
PHMA |
CC(=C)C(=O)OC1=CC=CC=C1 |
162.19 |
Slightly reactive (GSH) >> Methacrylates (MA) |
3,3,5-Trimethylcyclohexyl methacrylate |
TMCHMA |
CC1CC(CC(C1)(C)C)OC(=O)C(=C)C |
210.31 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Tridecyl methacrylate |
TDMA C13MA |
CCCCCCCCCCCCCOC(=O)C(=C)C |
268.43 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Isodecyl methacrylate |
IDMA |
CC(C)CCCCCCCOC(=O)C(=C)C |
226.36 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Dodecyl methacrylate |
LMA |
CCCCCCCCCCCCOC(=O)C(=C)C |
254.41 |
Slightly reactive (GSH) >> Methacrylates (MA) |
n-Octyl methacrylate |
n-OMA |
CCCCCCCCOC(=O)C(=C)C |
198.3 |
Slightly reactive (GSH) >> Methacrylates (MA) |
2-Hydroxyethyl methacrylate |
HEMA |
CC(=C)C(=O)OCCO |
130.1 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Hydroxypropyl methacrylate |
HPMA |
CC(COC(=O)C(=C)C)O |
144.17 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Hydroxypropyl methacrylate |
HPMA |
CC(CO)OC(=O)C(=C)C |
144.17 |
Slightly reactive (GSH) >> Methacrylates (MA) |
N-butoxymethyl methacrylamide |
N-BMMA |
CCCCOCNC(=O)C(=C)C |
157.21 |
Moderately reactive (GSH) >> 2-Vinyl carboxamides (MA) |
N-Methylol methacrylamide |
N-MMAA |
CC(=C)C(=O)NCO |
115.13 |
Moderately reactive (GSH) >> 2-Vinyl carboxamides (MA) |
N,N'-methylenbis(methacrylamide) |
|
O=C(NCNC(=O)\C(=C)C)\C(=C)C |
154.19 |
Moderately reactive (GSH) >> 2-Vinyl carboxamides (MA) |
N-Dimethylaminopropyl methacrylamide |
DMAPMA |
CC(=C)C(=O)NCCCN(C)C |
170.25 |
Moderately reactive (GSH) >> 2-Vinyl carboxamides (MA) |
Methacrylamide |
MAA |
CC(=C)C(=O)N |
85.1 |
Moderately reactive (GSH) >> 2-Vinyl carboxamides (MA) |
1,12-Dodecanediol dimethacrylate |
1,12 DDDMA |
O=C(OCCCCCCCCCCCCOC(=O)\C(=C)C)\C(=C)C |
338.48 |
Slightly reactive (GSH) >> Methacrylates (MA) |
1,3-Butandiol dimethacrylate |
1,3-BDDMA |
CC(CCOC(=O)C(=C)C)OC(=O)C(=C)C |
226.27 |
Slightly reactive (GSH) >> Methacrylates (MA) |
1,4-Butandiol dimethacrylate |
1,4-BDDMA |
CC(=C)C(=O)OCCCCOC(=O)C(=C)C |
226.27 |
Slightly reactive (GSH) >> Methacrylates (MA) |
1,6-Hexanediol dimethacrylate |
1,6 HDDMA |
O=C(OCCCCCCOC(=O)\C(=C)C)\C(=C)C |
254.32 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Ethylene glycol dimethacrylate |
EGDMA |
CC(=C)C(=O)OCCOC(=O)C(=C)C |
198.22 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Trimethylpropane trimethacrylate |
TMPTMA |
CCC(COC(=O)C(=C)C)(COC(=O)C(=C)C)COC(=O)C(=C)C |
338.4 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Ethoxylated bisphenol A dimethacrylate |
2EBADMA |
CC(C)(C1=CC=C(C=C1)O)C2=CC=C(C=C2)O.C=CC(=O)O.C(CO)O |
452.5394 |
Slightly reactive (GSH) >> Methacrylates (MA) |
2,2-bis-[4-(3'-methacryloyloxy-2'-hydroxy)propoxyphenyl] propane |
bis-GMA |
O=C(OCC(O)COc1ccc(cc1)C(c2ccc(OCC(O)COC(=O)\C(=C)C)cc2)(C)C)\C(=C)C |
512.61 |
Slightly reactive (GSH) >> Methacrylates (MA) |
4,4'-Isopropylidenediphenol, oligomeric reaction products with 1-chloro-2,3-epoxy propane, reaction products with methacrylic acid |
Bis-GMA NLP (DSM/Akzo/+others) |
|
n.d |
Slightly reactive (GSH) >> Methacrylates (MA) |
Diethyleneglycol dimethacrylate |
DEGDMA |
CC(=C)C(=O)OCCOCCOC(=O)C(=C)C |
242.27 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Glycerol dimethacrylate |
GDMA |
O=C(OCC(O)COC(=O)\C(=C)C)\C(=C)C |
228.24 |
Slightly reactive (GSH) >> Methacrylates (MA) |
7,7,9-(resp. 7,9,9-)trimethyl-4,13-dioxo-3,14-dioxa-5,12-diazahexadecane-1,16-diol-dimethacrylate |
HEMATMDI |
O=C(OCCOC(=O)NCCC(C)CC(C)(C)CNC(=O)OCCOC(=O)\C(=C)C)\C(=C)C |
470,57 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Triethyleneglycol dimethacrylate |
TREGDMA |
O=C(OCCOCCOCCOC(=O)\C(=C)C)\C(=C)C |
286.32 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Tetraethyleneglycol dimethacrylate |
TTEGDMA/4EDMA |
CC(=C)C(=O)OCCOCCOCCOCCOC(=O)C(=C)C |
198.22 |
Slightly reactive (GSH) >> Methacrylates (MA) |
2-hydroxyethyl methacrylate phosphate |
HEMA phosphate |
CC(=C)C(=O)OCCOP(=O)(O)O |
228.14 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Methacrylic anhydride |
MAAH |
CC(=C)C(=O)OC(=O)C(=C)C |
154.16 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Hydroxyethyl ethylene urea methacrylate |
MEEUW |
O=C1NCCN1CCOC(=O)\C(=C)C |
129.16 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Tetrahydrofurfurylmethacrylat |
THFMA |
O=C(OCC1OCCC1)\C(=C)C |
170.21 |
Slightly reactive (GSH) >> Methacrylates (MA) |
2,2-dimethyl-1,3-dioxolan-4-ylmethyl methacrylate |
|
CC(=C)C(=O)OCC1COC(O1)(C)C |
200.23 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Polyethylengeglycol-200-dimethacrylate |
PEG200DMA |
for approximation see Tetraethyleneglycol dimathacrylate |
no data |
Slightly reactive (GSH) >> Methacrylates (MA) |
2,2,2-Trifluoroethyl methacrylate |
TFMEA 3FM |
CC(=C)C(=O)OCC(F)(F)F |
336 |
Slightly reactive (GSH) >> Methacrylates (MA) |
N-Trimethylammoniumpropyl methacrylamide-chloride |
MAPTAC |
CC(=C)C(=O)NCCC[N+](C)(C)C.[Cl-] |
220.74 |
Moderately reactive (GSH) >> 2-Vinyl carboxamides (MA) |
2-Trimethylammoniummethyl methacrylate-chloride |
TMAEMC |
CC(=C)C(=O)OCC[N+](C)(C)C.[Cl-] |
207.7 |
Slightly reactive (GSH) >> Methacrylates (MA) |
Based on a molecular weight of 228.24 g/mol and a g Kow of 2.05 the predicted flux of GDMA is 24.986 μg/cm²/h; the relative dermal absorption is moderate.
Description of key information
The isomeric mixture GDMA (consisting of Glycerol 1,3-dimethacrylate (CAS 1830-78-0; main isomer) and Glycerol 1,2-dimethacrylate (CAS 101525-90-0)) is likely to be readily absorbed by all routes. Due to the low vapour pressure, the dermal route is the primary route of exposure, since inhalation is unlikely. Like other substances of the category, these isomeric esters are expected to hydrolyse rapidly by carboxylesterases to methacrylic acid (MAA) and Glycerol. MAA will be degraded through the tricarboxylic acid cycle and primarily excreted as CO2. Glycerol, which is an endogeneous metabolite in mammals, is either incorporated in the standard metabolic pathways to form glucose and glycogen or it forms triglycerides which are then distributed to the adipose tissues.
Key value for chemical safety assessment
- Bioaccumulation potential:
- no bioaccumulation potential
- Absorption rate - oral (%):
- 50
- Absorption rate - dermal (%):
- 50
- Absorption rate - inhalation (%):
- 100
Additional information
Absorption
Oral absorption
The physicochemical properties of GDMA, namely the water solubility, log Pow
and the molecular weight of 228 g/mol are in a range suggestive of absorption from the gastro-intestinal tract subsequent to oral ingestion. For chemical safety assessment an oral absorption rate of 50% is assumed as a worst case default value in the absence of other data.
Dermal absorption
Based on a QSAR Prediction of Dermal Absorption (extract from Heylings JR, 2013) GDMA is predicted on the basis of its molecular weight and lipophilicity to have a low to moderate ability to be absorbed through the skin. The predicted flux was approx. 25 μg/cm²/h. For chemical safety assessment, a dermal absorption rate of 50% is assumed.
Inhalative absorption
Due to the low vapour pressure of GDMA (0.064 Pa at 25°C), exposure via inhalation is unlikely. For chemical safety assessment an inhalative absorption rate of 100% is assumed as a worst case default value in the absence of other data.
Distribution
As a rather small molecule with a logPow >0, a wide distribution can be expected. No information on potential target organs is available.
Metabolism of Methacrylic esters
Di- and mono-ester hydrolysis
Ester hydrolysis has been established as the primary step in the metabolism of methacrylate esters.
In the case of diol di-methacrylate esters the first step would be hydrolysis of one of the ester bonds to produce the corresponding mono-ester followed by subsequent hydrolysis of the second ester bond to produce methacrylic acid (MAA) and the corresponding alcohol Glycerol.
Carboxylesterases are a group of non-specific enzymes that are widely distributed throughout the body and are known to show high activity within many tissues and organs, including the liver, blood, GI tract, nasal epithelium and skin (Satoh & Hosokawa, 1998; Junge & Krish, 1975; Bogdanffy et al., 1987; Frederick et al., 1994).Those organs and tissues that play an important role and/or contribute substantially to the primary metabolism of the short-chain, volatile, alkyl-methacrylate esters are the tissues at the primary point of exposure, namely the nasal epithelia and the skin, and systemically, the liver and blood. For multifunctional methacrylates mostly the same would be the case except that because of the lower vapour pressure and hence lower likelihood of inhalation exposure the involvement of the nasal epithelium is less likely.
Kinetics data have been reported for the hydrolysis of two multifunctional methacrylates (EGDMA and TREGDMA) by porcine liver carboxylesterase in vitro. For comparison reasons, the results from two lower alkyl methacrylates (EMA and BMA), are also presented in below table (McCarthy and Witz, 1997). The four studied substances showed comparable hydrolysis rates in vitro.
Table: Hydrolysis of Acrylate Esters by Porcine Liver Carboxylesterase in vitro (extract from McCarthy and Witz., 1997)
Ester |
Km (mM) |
Vmax (nmol/min) |
Tetraethyleneglycol dimethacrylate (TREGDMA) |
39±15* |
2.9±1.0 |
Ethyleneglycol dimethacrylate (EGDMA) |
64±24* |
6.9±2.4 |
Ethyl methacrylate (EMA) |
159±90 |
5.2±2.5 |
n-Butyl methacrylate (n-BMA) |
72±28* |
1.8±0.6 |
*Significantly different (p < 0.05) from ethyl acrylate
A recent study, designed to extend an earlier work on lower alkyl methacrylates (Jones 2002, see below) to higher and more complex methacrylate esters, studied the in vitro metabolism of higher and more complex methacrylate esters in rat blood and liver microsomes. This study included three esters of the multifunctional methacrylate category (TREGDMA, EGDMA and 1,4-BDDMA; DOW, 2013). The results of those studies are summarized in below table.
Table: Elimination Rates, Intrinsic Clearance and Half-life in Rat Liver Microsomes and Whole Rat Blood for Five Methacrylate Esters at 0.25 mM Substrate Concentration (DOW, 2013)
|
|
Liver Microsomes |
|
|
Whole Blood |
|
Molecule |
Clint (μl/min/mg) |
ke |
Half‐Life (min) |
Clint(μl/min) |
ke |
Half‐Life (min) |
TREGDMA |
116 |
0.23 |
3.01 |
219 |
0.12 |
5.68 |
EGDMA |
142 |
0.28 |
2.45 |
796 |
0.44 |
1.56 |
1,4-BDDMA |
78 |
0.16 |
4.46 |
304 |
0.17 |
4.10 |
MMA |
1192 |
2.38 |
0.29 |
19 |
0.01 |
63.00 |
HEMA |
74 |
0.15 |
4.62 |
12 |
0.01 |
99.00 |
ke: elimination rate
Clint: intrinsic clearance (ke x volume of incubation / mg/mL microsomal protein)
MMA: Methyl methacrylate (supporting substance); HEMA: Hydroxyethyl methacrylate (supporting substance)
All studied methacrylate esters were rapidly converted to MAA in whole rat blood and rat liver microsomes. Hydrolysis half-lives of the studied category members were in the order of minutes for blood and liver microsomes, respectively.
The incubations in whole rat blood and rat liver microsomes were performed on three separate days with MMA included as a positive control on each day. Rat liver microsome hydrolysis rates for the positive control (MMA) were somewhat variable between days. This was likely due to the rapidity of hydrolysis of MMA. Often, measurable levels of MAA were present even in the zero minute samples and the substrate was completely hydrolyzed by 2 minutes. This made it difficult to accurately calculate hydrolysis rates for MMA in these experiments. However, generally the calculated rates were similar to rates for hydrolysis for MMA reported previously (Jones, 2002; Mainwaring et al., 2001) and confirmed that thein vitrotest systems were enzymatically active for each day of incubation experiments. The other studied methacrylates exhibited rat liver microsome hydrolysis rates approximately 10 fold lower than MMA. From its very rapid degradation to MAA, MMA can be understood as suitable donor substance for MAA as common primary metabolite of all category members.
A second extension of the metabolism study has been performed in 2017 comparing the metabolic rates of 1,3- and 1-4-BDDMA. This study indicated that the two isomers were indeed very similar, while the metabolic rates of the linear diol ester (1,4-BDDMA) appeared to be slightly higher than those of the branched isomer (1,3-BDDMA; DOW, 2017).
Table: Elimination Rates, Intrinsic Clearance and Half-life in Rat Liver Microsomes and Whole Rat Blood; Satellite Study Comparison 1,3-BDDMA and 1,4-BDDMA (DOW, 2017)
|
|
Liver Microsomes |
|
|
Whole Blood |
|
Molecule |
Clint (μl/min/mg) |
ke |
Half‐Life (min) |
Clint(μl/min) |
ke |
Half‐Life (min) |
1,3-BDDMA |
116 |
0.195 |
3.55 |
112 |
0.0559 |
12.4 |
1,4-BDDMA |
119 |
0.199 |
3.48 |
246 |
0.123 |
5.63 |
Supporting information on Alkyl methacrylates
The above mentioned EMA and n-BMA were also studied in an elaborate series of in vitro studies on carboxylesterase activity with 7 alkyl methacrylates ranging from methyl methacrylate to octyl methacrylate (with increasing ester size; Jones, 2002). This was used to construct a PB-PK model of in vivo clearance for several tissues (blood, liver, skin and nasal epithelium) from rats and humans, which showed that methacrylate mono-esters are rapidly hydrolyzed by carboxylesterases to methacrylic acid (MAA) and the respective alcohol. Whilst there was a trend of increasing half-life of alkyl methacrylates with increasing chain length (up to octyl), clearance of the parent ester from the body was always in the order of minutes.
Although the absolute rate measurements obtained by Jones differ slightly to those determined by McCarthy and Witz, presumably due to differences in experimental conditions such as protein content etc., the rates obtained for the two lower alkyl methacrylates (EMA and BMA) can be used to draw parallels between the work of the two researchers indicating that the kinetics for the hydrolysis of EGDMA and TREGDMA fall within the range observed by Jones for lower alkyl methacrylates. On this basis the parent ester would be expected to have a short systemic half–life within the body being effectively cleared from the blood within the first or second pass through the liver. Hydrolysis of the di- and mono- ester would yield the common metabolite methacrylic acid and the respective alcohol.
Subsequent metabolism
Methacrylic acid (MAA)
From the available extensive toxicokinetic data on lower alkyl methacrylates it has been established that thecommon primary metabolite methacrylic acidis subsequently cleared predominantly via the liver (valine pathway and the TCA (TriCarboxylic Acid) cycle, respectively; ECB, 2002; OECD SIAR, 2009). Methyl methacrylate (MMA) is rapidly degraded in the body to MAA and can thus be understood as metabolite donor for MAA.
Alcohol moiety: Glycerol
Glycerol is an endogeneous metabolite in mammals. As summarized by OECD (2002) and EFSA (2017), human and animal data indicate that glycerol is rapidly absorbed in the intestine and the stomach, distributed over the extracellular space and preliminary metabolized in the liver to carbon dioxide and water. As energy substrate, it is incorporated in the standard metabolic pathways to form glucose and glycogen. Glycerol is phosphorylated to α-glycerophosphate by glycerol kinase. Relevant organs are the liver (80-90%) and the kidneys (10-20%) where the α-glycerophosphate is incorporated in the standard metabolic pathways to form glucose and glycogen. Glycerol kinase is also found in intestinal mucosa, brown adipose tissue, lymphatic tissue, lung and pancreas. Another relevant physiological pathway is the lipogenesis where glycerol can be combined with free fatty acids in the liver to form triglycerides which are then distributed to the adipose tissues. The turnover rate is directly proportional to plasma glycerol levels. In untreated rats, the mean endogenous glycerol level in whole blood was reported to be 0.254 mM (23 mg/L; Ackerman et al., 1975).
Glutathione reactivity
A QSAR model for GDMA predicted only slight reactivity with glutathione for the ester and no reactivity for the primary metabolite, methacrylic acid (Cronin, 2012).
Studies with methacrylates in vitro confirm low reactivity with GSH, in particular compared to the corresponding acrylates, and have proposed that this is due to steric hindrance of the addition of a nucleophile at the double bond by the alpha-methyl side-group (McCarthy & Witz, 1991, McCarthy et al., 1994, Tanii and Hashimoto, 1982).
Table: Apparent Second-Order Rate Constants for the Reaction of Glutathione with Methacrylate Esters (extract from McCarthy et al., 1994)
Ester |
App. 2ndorder rate const. Kapp[L/mol/min] |
Tetraethyleneglycol dimethacrylate (TREGDMA) |
1.45±1.0 (0.725±0087)* |
Ethyleneglycol dimethacrylate (EGDMA) |
0.83±0.12 (0.406±0.059)* |
Methyl methacrylate (MMA) |
0.325±0.059 |
Ethyl methacrylate (EMA) |
0.139±0.022 |
Butyl methacrylate (BMA) |
No appreciable reaction rate |
*Bifunctional esters calculated as two independent esters.
.
In conclusion, ester hydrolysis is considered to be the major metabolic pathway for alkyl and multifunctional methacrylate esters, with GSH conjugation only playing a minor role in their metabolism.
Excretion
As the ester will not survive first pass metabolism in the liver, excretion of the parent compound is of no relevance. The primary methacrylic metabolite, MAA, is cleared rapidly from blood by standard physiological pathways, with the majority of the administered dose being exhaled as CO2, while the alcohol metabolite, Glycerol is either incorporated in the standard metabolic pathways to form glucose and glycogen or it forms triglycerides which are then distributed to the adipose tissues.
In summary, the metabolism data and modelling results show that GDMA would be rapidly hydrolysed in the rat.
Conclusion
Summary and discussion on toxicokinetics
Methacrylate esters are absorbed by all routes while the dermal absorption is limited with the larger members of the category. Due to the low vapour pressure of the multifunctional methacrylates, the dermal route is the primary route of exposure, since inhalation is unlikely. The rate of dermal absorption decreases with increasing ester chain length. All esters are rapidly hydrolyzed by carboxylesterases to methacrylic acid (MAA) and the respective alcohol. In the case of di- and triesters the apparent rate of hydrolysis is highest for the parent ester, but this likely reflects the higher number of hydrolysable target sites instead as opposed to any greater specific activity. Ester hydrolysis can occur in local tissues at the site of contact as well as in blood and other organs by non-specific carboxylesterases. By far the highest enzyme activity has been shown in liver microsomes indicating that the parent ester will be fully metabolized in the liver. Clearance of the parent ester from the body is in the order of minutes. There is a trend towards increasing half-life of the ester in blood with increasing ester chain length, however, none of the esters will survive first pass metabolism in the liver to any significant extent. The primary methacrylic metabolite, MAA, is subsequently cleared rapidly from bloodby standard physiological pathways, with the majority of the administered dose being exhaled as CO2. The respective alcohol moieties will undergo further metabolism in the liver.
Glycerol dimethacrylate is expected to be hydrolyzed rapidly by unspecific carboxyl esterases in the liver into methacrylic acid and Glycerol. MAA will be degraded through the tricarboxylic acid cycle and primarily excreted as CO2.Glycerol is either incorporated in the standard metabolic pathways to form glucose and glycogen or it forms triglycerides which are then distributed to the adipose tissues.
Compliance to REACh requirements
The information requirement is covered with reliable in silico predictions on the dermal absorption and glutathione reactivity of the substance itself plus reliablein vitrodata on the primary metabolism of other category substances, reliablein vitro/ in vivostudies on the metabolism of the methacrylic metabolite MAA as well as reliable publication data on the metabolism of the alcohol metabolite Glycerol. All mentioned sources are reliable (Reliability 1 or 2) so that the category/ read across approach can be done with a high level of confidence.
References
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EFSA Panel on Food Additives and Nutrient Sources added to Food (2017). Re-evaluation of glycerol (E 422) as a food additive. EFSA Journal 2017;15(3):4720 [64 pp.]
Frederick CB, Udinsky JR, Finch L (1994). The regional hydrolysis of ethyl acrylate to acrylic acid in the rat nasal cavity. Toxicology letters, 70: 49-56.
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OECD (2002). SIDS Initial Assessment Report Glycerol
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Tanii H., Hashimoto K.(1982); Structure-Toxicity Relationship of Acrylates and Methacrylates; Toxicol. Lett. 11: 125-129
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