sodium-nitrite and ethylurea

Sprague-Dawley rats were exposed to 0, 26, or 2600 ppm lead as lead acetate in drinking water for 76 weeks. At 28 weeks of lead exposure, a portion of each group was exposed simultaneously to 6.36 g/kg ethyl urea (EU) and 2.0 g/kg sodium nitrite (NaNO2) for a duration of 20 weeks, and then continued an additional 28 weeks on standard diet free of EU and NaNO2. The animals were observed for incidence, latency, and distribution of tumors. Rats exposed to 2600 ppm lead alone had 81% renal tumors, while rats given 2600 ppm lead in combination with EU/NaNO2 had a 50% incidence. Renal tumors did not occur in the EU/NaNO2 only or EU/NaNO2-26 ppm lead groups. The major tumor type found in EU/NaNO2-exposed rats was lymphosarcoma. Lead did not appear to be syncarcinogenic to the activity of ethylnitrosourea, the carcinogen formed by oral exposure to EU and NaNO2. The lead-induced renal neoplasms were histologically similar to those which occur spontaneously in man and, therefore, may serve as an animal model to study human disease.

Topics: Animals; Disease Models, Animal; Kidney Neoplasms; Lead; Male; Neoplasms, Experimental; Nitrites; Organometallic Compounds; Rats; Rats, Inbred Strains; Sodium Nitrite; Time Factors; Urea

Ethylurea (EU) and NaNO2 fed simultaneously to female braconid wasps caused several types of changes in reproductive performance. Early effects included a decrease in (a) the number of vitellogenic oocytes developing into eggs, and in (b) the hatchability of the eggs laid. After a period of no damage to transitional cells there was a late effect expressed as a pronounced reduction in the number of eggs produced from the oogonia, although the hatchability was good. Dissection of the ovarioles revealed gaps in the oogenetic sequence. Most of the specimens showed resorption of the small oocytes and some specimens contained distal masses of undifferentiated cells resembling a tumerous condition. Neither EU nor NaNO2 alone caused the damage obtained from feeding them in combination, and EU injected along with NaNO2 was ineffective.

Topics: Animals; Biotransformation; Female; Hymenoptera; Mutagens; Nitrates; Nitrites; Oocytes; Sodium Nitrite; Urea; Wasps

Topics: Animals; Cocarcinogenesis; Female; Male; Maternal-Fetal Exchange; Methylmercury Compounds; Neoplasms, Experimental; Nervous System Neoplasms; Nitrites; Pregnancy; Rats; Sodium Nitrite; Time Factors; Urea