The Finding of N-Nitrosodimethylamine in Common Medicines.

The FDA has ordered the withdrawal of all ranitidine products from the marketplace based on recent findings of increased and unacceptable levels of N‐nitrosodimethylamine (NDMA). This commentary reviews the sources and properties of NDMA, assesses the dangers it poses, and suggests measures to mitigate contamination.

The acute lethal dose 50 (LD50) of caffeine in albino rats.

An acute LD50 is a statistically derived amount of a substance that can be expected to cause death in 50% of the animals when given by a specified route as a single dose and the animals observed for a specified time period. Although conducting routine acute toxicity testing in rodents has been criticized, it can serve useful functions and also have practical implications. Material safety data sheets (MSDS) will reflect the acute toxicity of a substance and may require workers to wear protective gear, if appropriate, based on the LD50.

Evaluation of 4-methylimidazole, in the Ames/Salmonella test using induced rodent liver and lung S9.

4-methylimidazole (4-MeI) is formed by the interaction of ammonia with reducing sugars and low levels have been identified as a by-product in coffee, soy sauce, wine, dark beers, soft drinks, and caramel colors. The 4-MeI has been reported to induce alveolar/bronchiolar tumors in mice but not rats. Its mechanism of action is unlikely to be due to genotoxicity as 4-MeI does not induce mutation in Salmonella typhimurium and does not induce micronuclei in rodent peripheral erythrocytes or bone marrow cells.

Chemical carcinogenesis studies in nonhuman primates.

This review covers chemical carcinogenesis studies in nonhuman primates performed by the National Cancer Institute, USA, to provide hitherto unavailable information on their susceptibility to compounds producing carcinogenic effects in rodents. From autopsy records of 401 breeders and untreated controls, incidences of spontaneous malignant tumors were found to be relatively low in cynomolgus (1.9%) and rhesus monkeys (3.