Short Communications

UDC 615.917:547.233-053.1

V. F. Torbin

Comparative Characterization of the Embryotoxic Effects of Certain Amines of the Polymethylene (Alicyclic) Series

Kyiv Research Institute of Occupational Health and Occupational Diseases

In recent years, reports have appeared on the toxicity and toxicodynamics of amines of the polymethylene (alicyclic) series—dicyclohexylamine nitrite and an oil-soluble salt of dicyclohexylamine (NDA and MSDA-II), which are used as inhibitors of atmospheric corrosion of metals in the national economy (N. K. Statsek; Yu. I. Kundiev et al.; G. P. Rozhkovskaya). We experimentally investigated the toxicity of a new inhibitor, an oil-soluble salt of cyclohexylamine (M-I).

Experimental studies showed that NDA is highly toxic to white rats [$\mathrm{LD}_{50}$ 325 (233–417) mg/kg], M-I is the least toxic [$\mathrm{LD}_{50}$ 3490 (2630–4640) mg/kg], and MSDA-II is moderately toxic [$\mathrm{LD}_{50}$ 940 (700–1180) mg/kg]. In terms of their effects on the animal organism, these substances are polytropic compounds. They affect the central nervous system and the endocrine—

…organs, disrupt oxidative processes in the body, alter the functional state of the liver and kidneys, and cause changes in hematopoiesis and the morphological composition of the blood.

In toxicological research, the long-term consequences of exposure to occupational poisons are of considerable importance. These include embryotropic and gonadotropic, mutagenic, and blastomogenic activity. Interest in such studies is justified by the fact that many chemical substances of organic and inorganic origin adversely affect the specific functions of the female body (I. V. Sanotsky; A. P. Dyban; I. R. Barilyak; and others).

Reports on the teratogenic properties and cytogenetic effects of polymethylene-series amines and their effects on reproductive function are contradictory. Becher and Gibson found developmental abnormalities in mouse embryos following exposure to cyclohexylamine at doses of 61, 77, and 122 mg/kg for 11 days. Khera and coauthors report that cyclohexylamine sulfate impairs the fertilizing capacity of male rats, while Legator and coauthors and Stone and coauthors experimentally established a relationship between concentration and cytogenetic effect. These findings, however, were not confirmed in studies by Brewen and coauthors or Mostardi and coauthors.

As is known, a considerable number of women, including women of childbearing age, are employed in the production of the inhibitors M-I, MSDA-II, and NDA and in their use for the preservation and interoperation protection of manufactured articles. It is therefore of theoretical and practical importance to determine the effects of these compounds on pregnancy and embryonic development.

The present study investigated whether these compounds have embryotoxic effects, whether such effects are specific, the relationship between toxicity and embryotoxicity, the threshold for embryotoxic effects, and whether these substances can cause developmental abnormalities in embryos.

To answer these questions, M-I was tested at doses of 1/100, 1/10, and 1/5 LD\(_{50}\); MSDA-II at 1/100 and 1/200 LD\(_{50}\); and NDA at 1/100, 1/200, and 1/400 LD\(_{50}\). The inhibitors were administered orally to female white rats throughout pregnancy. The day on which spermatozoa were detected in a vaginal smear after the females had been placed with males was considered the first day of pregnancy. The females were killed on day 20 of pregnancy. The number of implantation sites and the numbers of embryos lost before and after implantation and overall were counted in the uterus. Live fetuses were examined for developmental abnormalities (A. P. Dyban and coauthors). In experiments using inhibitors at a dose of 1/100 LD\(_{50}\), the presence of a general toxic effect was assessed. The investigators examined peripheral blood status (erythrocyte, reticulocyte, and leukocyte counts; hemoglobin and methemoglobin levels; and erythrocyte acid resistance), renal function (daily urine output, urine specific gravity, urinary protein, and blood and urine chlorides and urea), and nervous system function (SPP). Biochemical studies were performed, including determination of aspartate and alanine aminotransferases in blood serum and liver. The organs of the sacrificed animals were examined pathomorphologically.

All numerical experimental data were analyzed using methods of variation statistics (A. K. Mitropolsky).

The experimental results are presented in the table. As the table shows, NDA and MSDA-II at a dose of 1/100 LD\(_{50}\) increased overall embryonic mortality (37.5 ± 4.9% and 35.6 ± 5.1%, respectively, versus 12.2 ± 1.7% in controls), primarily

Effect of atmospheric corrosion inhibitors for metals on embryonic development in white rats exposed throughout pregnancy

¹ Differences from the control are statistically significant (\(P < 0.05\)).

due to an increase in postimplantation embryonic mortality (NDA, \(25\pm4.8\%\); MSDA-II, \(22.2\pm4.9\%\); control, \(7\pm1.3\%\)), whereas inhibitor M-I did not disrupt pregnancy or embryonic development.

Inhibitors M-I, MSDA-II, and NDA at a dose of \(1/100\ \mathrm{LD}_{50}\) produced no general toxic effects.

The no-effect dose for embryotoxicity was \(1/200\ \mathrm{LD}_{50}\) for MSDA-II and \(1/400\ \mathrm{LD}_{50}\) for NDA. Inhibitor M-I caused statistically significant embryonic mortality only at a dose of \(1/5\ \mathrm{LD}_{50}\) (\(53.1\pm5.2\%\), compared with \(12.2\pm1.7\%\) in controls).

Investigation of the teratogenic effect showed that, despite the embryotoxic activity of the inhibitors studied, they were incapable of inducing developmental anomalies in rat embryos. Careful examination of the internal organs of rat embryos using the modified Wilson method, and of the skeletal system using cleared whole-mount preparations, revealed no abnormalities in the morphogenesis of embryonic primordia.

Thus, the experimental data show that inhibitors M-I, MSDA-II, and NDA exert an embryotoxic effect that depends on the dose and the chemical nature of the compound. This is consistent with findings on the damaging effects of other agents on embryogenesis (A. P. Dyban; I. R. Barilyak; N. A. Chebotar; and others). In particular, inhibitor M-I showed the least pronounced activity, with an embryotoxicity threshold of \(1/5\ \mathrm{LD}_{50}\) (the embryotoxicity thresholds for MSDA-II and NDA were \(1/100\ \mathrm{LD}_{50}\) and \(1/200\ \mathrm{LD}_{50}\), respectively).

These findings suggest that inhibitors MSDA-II and NDA exert a specific effect on embryos; this correlates with their general toxicity.

Despite their embryotoxic activity, the inhibitors lack teratogenic properties, probably indicating that the two effects on intrauterine development have different mechanisms.

Our results, first, justify including an assessment of the effects of polymethylene-series amines on embryogenesis in hygiene research programs; second, they indicate the possibility of finding compounds that possess the required technical properties while having no damaging effect on intrauterine development.

In view of the foregoing, and on the basis of a comparison of the toxicity data for the inhibitors, the introduction of inhibitor M-I into the national economy is acceptable from a hygiene standpoint.

References

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Received August 4, 1975.