Residual formaldehyde contents in fresh white cheese in El Salvador: Seasonal changes associated with temperature.

Detection of residual formaldehyde (FA) in dairy products could be explained by direct addition of this preservative to extend the shelf life of raw material or final product at room temperature. FA is not authorized as a preservative by international standards and its addition to dairy products is prohibited due to its potentially harmful effects on consumers. Although the carcinogenicity of FA by oral exposure has not been proven, it is also known it cause histopathological and cytogenic changes in tissues at first contact, so its toxicity by ingestion should not be underestimated.