Embalming does not preserve the body, it merely slows the rate of decomposition, according to the Funeral Consumers Alliance. The temperature a body is stored at has a much larger affect on decomposition than embalming.
The Funeral Consumers Alliance reports that embalming provides no public health benefits and merely delays the inevitable decomposition. The rate of decomposition is dependant on the strength of the embalming chemicals used and the way the body is interred. Bodies in a sealed casket above ground decompose much faster than bodies buried in the cool earth. Embalming chemicals are highly toxic, and embalmers are required to wear protective equipment when handling the chemicals.