Mecrilate

Repeated dose toxicity: other routes

Administrative data

Endpoint:

chronic toxicity: other route

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well-documented publication which meets basic scientific principles

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1966

Materials and methods

Test guideline

Qualifier:

no guideline followed

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Mecrilate

EC Number:

205-275-2

EC Name:

Mecrilate

Cas Number:

137-05-3

Molecular formula:

C5H5NO2

IUPAC Name:

methyl 2-cyanoprop-2-enoate

Test material form:

other: liquid

Details on test material:

Methyl-2-cyanoacrylate monomer with 20 % polymer

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

ANIMALS: 141 rats, 67 females and 74 males

Administration / exposure

Route of administration:

subcutaneous

Vehicle:

unchanged (no vehicle)

Details on exposure:

Methyl 2-cyanoacrylate monomer (with 20 % polymer) in volumes of 0.1 mL and 0.4 mL were injected into the dorsal subcutis of Sprague Dawley rats.
The rats were anesthetized, and a wide, shallow pocket was prepared by blunt dissection of the dorsal subcutis, using aseptic techniques.
The methyl 2-cyanoacrylate was then introduced into the pocket in the specified amount with a 26 gauge needle, and spread by gentle massage.
The incisions were closed with skin clips. Each rat was given a single injection of test material or saline as control.

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

19.5 m

Frequency of treatment:

once

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0.1 other: mL

Remarks:

single subcutane injection

Doses / concentrations 2

Dose / conc.:

0.4 other: mL

Remarks:

single subcutane injection

No. of animals per sex per dose:

see "Any other information on materials and methods"

Control animals:

yes

Examinations

Observations and examinations performed and frequency:

Growth and mortality records were kept. The injected sites were observed frequently at the onset and at approximately monthly intervals thereafter.

Sacrifice and pathology:

Some rats in each group were killed after 6 and 12 months, and all survivors after 19.5 months.
All animals were autopsied and tissues prepared for histopathological examination.

Other examinations:

no data

Statistics:

no data

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

see "Any other information on results"

Mortality:

mortality observed, treatment-related

Description (incidence):

see "Any other information on results"

Body weight and weight changes:

not specified

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

see "Any other information on results"

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

see "Any other information on results"

Histopathological findings: neoplastic:

not examined

Effect levels

Key result

Dose descriptor:

NOAEL

Remarks on result:

not determinable

Remarks:

no NOAEL identified

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

CLINICAL RESULTS

Single injections of 0.1 mL or 0.4 mL of methyl 2 -cyanoacrylate had no untoward effect on the growth of the rats.

A firm lump of polymer was palpable underneath the skin within one minute after implantation of the adhesive. A marked inflammatory reaction was seen at the implant site within 24 hours. The gross tissue reaction subsided within 2 weeks in some rats, and persisted in others. Firm masses were found at the implant site in all rats given 0.4 mL of adhesive; smaller masses or fine, gritty granules were found in the rats given 0.1 mL of adhesive. The areas containing the polymer gradually decreased in size; palpable masses were noted in all surviving rats implanted with 0.4 mL of the adhesive after one year, and in ten of the eleven survivors at 15 months. In the rats given 0.1 mL of the adhesive, palpable masses were found in 56 % at 3 months, 42 % at 6 months, and in 14% at 12 months; and at 19.5 months a small mass was found in only one of the survivors in this group.

AUTOPSY

At autopsy, the polymer was found as small, white, opaque, brittle particles, or irregular shaped, hard, semi-crystalline, friable fragments of varying dimensions, some lesion sites measuring as much as 1.5 x 1.0 x 0.3 cm. The material was usually found in a thick-walled capsule embedded in caseous material.

After the tissue had been sectioned for histological preparation, the recoverable residue was dried and weighed. The largest amount recovered from the 0.4 mL implants was 182 mg in a rat killed after 8 months. In the ten rats given 0.4 mL of adhesive and killed after 6 months, the weights of the recovered residue ranged from 5-81 mg, with a mean of 59 mg for nine rats; the polymer in the tenth rat extruded after 3 months. Polymer was found at the implant site in seventeen of the eighteen rats injected with 0.4 mL of adhesive and killed after 12 months. The amount recovered varied from less than 1.0 mg to 78 mg; the mcan was 45 mg; extrusion had occurred in the eighteenth rat after six months.

In the group of rats given 0.1 mL of adhesive, small amounts of polymer were recovered from four of the ten rats killed after 6 months. Polymer was found grossly in two of the fourteen rats killed after 12 months (less than 1 mg in one, and 72 mg in the second rat).

Extrusion of the polymer occurred in nine rats given 0.4 mL; five within 2 months, two within 6 months, and two within 1 year. The polymer was extruded after 2, 3, and 12 months in three rats implanted with 0.1 mL of the adhesive.

A recurrence of persistent edema and hyperemia in the area containing the polymer was seen grossly in a few rats at about 5 months after implantation of the adhesive. Large abscesses developed in a few of these rats; in others, the reaction subsided gradually.

Tumors varying in size from 1.0 x 0.9 cm to 8.0 x 8.0 x 7.0 cm occurred at the irnplant site in eight rats implanted with 0.4 mL of methyl 2 -cyanoacrylate; polymer was found grossIy in two of these tumors. The first tumor arising at the implant site was detected at 11 months post-injection.

The study was set up for 2 years. However, there were frequent epizootics of pneumonia in the animal room, which caused a mortality of about 30 %; and a severe outbreak of murine pneumonia at 19.5 months caused the termination the study.

HISTOPATHOLOGY

The tissues examined for histopathological conditions from animals sacrificed or which died during the first 19 months of the study were: lung, heart, liver, kidney, adrenal, small intestine, pancreas, testis or ovary, and subcutis. The tissue examined from animals sacrificed at the end of the study (19.5 months) were: brain, thyroid, salivary gland, heart, lung, Iiver, kidney, spleen, adrenal, pancreas, stomach,small and large intestine, testis, ovary, uterus, urocyst, lymph node, pituitary, bone marrow, subcutis, and skin.

Polymer in subcutis following 0.1 mL lnjection: Of four sites examined after 4 months, three contained polymer and one contained exudate only. At 6 months, five of seven sites examined contained polymer and two only exudate. At 12 months, two sites had polymer remaining, one site showed only exudate, another site showed a small focus of inflammatory cells, and in the remaining seven rats no site or deposit was discernable on study. At termination of study (19.5 months) no deposit or site remained in the subcutis of seven rats, and the eighth rat showed a suspicious Iesion.

In the group given 0.4 mL adhesive, in nine rats examined after 6 months, injected material was present in all. In the period of 4-18 months in which rats died or were killed, of twelve sites examined, three contained deposits of polymer alone, one had exudate only, one showed graulation tissue, one consisted of a granuloma undergoing malignant transformation, one contained polymer with early sarcomatous change, four were sarcomatous, and one had neither deposit nor site change. At termination of study (19.5 months) seven areas of injection were examined. One was without deposit or tissue reaction, four contained residual polymer, one had polymer and neoplastic transformation of tissue reaction, and one had sarcoma.

Tissue response of the host to methyl 2 -cyanoacrylate was similar generally to both 0.1 and 0.4 mL injected, and it did not change its essential features during the study except for neoplastic transformation in a number of rats which were injected with 0.4 mL. The lesion, with slight variation, consisted of a cavity, and a relatively narrow wall composed of several zones. The cavity contained either polymer which was not birefringent when examined with polarizing light, and/or an eosinophilic exudate densely infiltrated with polymorphonuclear Ieucocytes, and basophilic granules were also found in the cavity. The wall surrounding the cavity had an inner zone of macrophages at the lumen, and an outer zone of fibroblasts and fibrocytes. Occasionally, the inner zone contained fibrocytes and/or giant cells, the outer zone clusters of lymphocytes and/or pigment-laden macrophages. Large and small particles of calcic material (alizarin red positive) were found within the cavity and wall.

Neoplastic transformation of the tissues surrounding the deposits of polymer developed in rats injected with 0.4 mL. The neoplasms were fibrosarcomas which varied in histomorphic configuration from poorly differentiated to well differentiated. The capsule of the implant site underwent sarcomatous change in eight of the fifty-nine rats injected with 0.4 mL of the adhesive, and in two of these animals the fibrosarcoma metastasized to the lung.

At termination (19.5 months), the injected site in one rat which recieved 0.1 mL adhesive showed areas of metaplasia and what appeared to be focal anaplastic proliferation of cells of the fibrocytic series. The metaplastic area was osteogenetic and relatively large. The anaplastic cells arose in this area and did not penetrate the mature fibrous wall of the capsule.

Spontaneous tumors were infrequent and consisted of four mammary fibro-adenomas; one in the control group, one in 0.1 mL group, and two in 0.4 mL group; a sarcoma (hair papilla) of the leg in the control group, a fibroma of the leg in the 0.1 mL group, and a plasmacytoma of the lung, a granulosa cell tumor, and a basophil adenoma of the pituitary in the 0.4 group.

The was a high incidence of fortuitous lesions, mainly murine pneumonia, in the organs and tissues of the rats in all groups, but none was unusuaI for aging rats, and none was attributable to systemic effects of the adhesive injected.

Applicant's summary and conclusion

Conclusions:

This study indicates a carcinogenetic effect of methyl 2-cyanoacrylate in rats which have a large aggregate of polymer in the subcutis that persists for more than eleven months.

Executive summary:

Single subcutaneous injections of methyl 2-cyanoacrylate were given in volumes of 0.1 mL and 0.4 mL to Sprague Dawley rats to evaluate tissue reaction and fate over a period of 19.5 months. The fluid adhesive polymerized rapidly into a palpable mass following introduction into the cutis. The rate at which polymer disappeared from the injection site varied considerably. The injected material caused no discernible systemic effects; it induced a calcifying cavitary Iesion surrounded by a wall composed of macrophages at the inner aspect and a fibrocellular capsule at the periphery.

Fibrosarcoma was found at the site of injection in eight of fifty-nine rats injected with 0.4 methyl 2-cyanoacrylate, and in two of these rats the fibrosarcoma metastasized to the lung. Onset of tissue proliferation was first observed clinically at 11 months after injection and occurred at varying periods up to termination of experiment at 19.5 months. The first of the fibrosarcomas at the injection site was found in a rat killed fourteen months after injection, and the other seven were found thereafter in animals which died or were killed up to the termination of the study at 19.5 months.

One of the fifty-six rats injected with 0.1 mL of methyl 2 -cyanoacryIate that was killed at 19.5 months (termination of study) had changes suggestive of early sarcomatous transformation but, because of an area of metaplastic osseous development in the lesion, it was not possible to determine whether the anaplasia of connective tissue developed as a result of the presence of adhesive or the presence of the osseous mass.