A study was undertaken to evaluate the effects of cypermethrin on reproduction of female albino rats. The experimental rats were fed cypermethrin at 50 mg/kg b. wt. continuously for a period of 2 and 4 weeks. Feed and water intake was also noted daily for control, vehicle treated and cypermethrin-treated rats. It was observed that there was no effect on feed and water intake in treated rats as compared to the control group. Chronic exposure to cypermethrin for 4 weeks resulted in loose fecal pellets and hyperirritability in the treated rats. Treatment related mortality also occurred at the 4th wk of treatment. Significant changes in body weight and various organ weights due to cypermethrin were observed along with disruption of estrous cycle in rats. The body weight gain in treated rats was lower at both 2 and 4 weeks as compared to the control rats. The weight of liver and spleen decreased, while that of kidneys increased as compared to the control rats. Thyroid and adrenal showed increase in weight at both 2 and 4 weeks of treatments.
Ethylenethiourea (ETU) is a specific neuroteratogen that induces communicating hydrocephalus ex vacuo at oral doses far lower than those that cause any observable toxic sign or 50% death (LD50) in the rat dam. The teratogenic activity appears to be related to ETU itself and not to its metabolites. It is dependent upon the presence of an imidazolidine ring with a specific molecular location of sulfur atom. It is unlikely that ETU-induced alterations in thyroid function or thyroxine levels in the maternal rat are involved in teratogenic activity. The initial target following maternal dosing with ETU is the primitive neuroblast that undergoes necrosis, but the subsequent changes leading to the development of hydrocephalus are not clear. Teratogenicity studies in hamsters, mice, guinea pigs, rabbits, and rats revealed that ETU either required extremely high doses to produce malformations or was ineffective. The results of various distribution studies are summarized. Further, investigations dealing with exposure to ETU in the general population and in exposed workers in the rubber industry as well as those involved in the manufacture and spraying of fungicides are discussed briefly with reference to reducing the exposure levels.
Adverse effects on human reproduction during the early stages of development a r e a common occurrence; 2% of the live born suffer from major defects and a t least 20% of all pregnancies terminate in spontaneous abortion [ 521. Not all the malformations are due to environmental chemicals. On the contrary, the role of chemicals, including drugs, in the overall induction of human congenital anomalies is estimated to be a minor one [87]. Nevertheless, teratogenic testing of chemicals intended for use in food production o r processing now is considered mandatory by most regulatory agencies. At present safety assessment is based on experimental data obtained from the hamster, mouse, rat, and rabbit, and less commonly from the guinea pig, swine, dog, and monkey. Choice of appropriate species for determining the teratogenic potential of chemicals in food is of great importance (Table 1). In the early 1960s it became evident that rodents failed to respond to thalidomide in the expected manner. The search for an animal model that would respond to known human teratogens with a sensitivity and pattern of malformations similar to those in humans then was started. Nonhuman primates, Macaca mulatta, M. irus, and baboons (Papio), had a sensitivity to thalidomide of the s a m e o r d e r of magnitude as was observed in humans. However, subsequent studies showed that subhuman primates were insensitive to other known human teratogens, such as aminopterin, methotrexate, 773 may be reproduced o r transmitted in any form or by any means, electronic or mechanical. including photocopying, microfilming, and recording, or by any information storage and retrieval system. without permission in writing from the publisher.Clinical Toxicology Downloaded from informahealthcare.com by Cornell University on 12/28/14For personal use only.
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