Original sentence: For example, numerous organochlorides are found in naturally occuring food sources.Given the ubiquity of these and other organochlorides and the absence of evidence of any harm caused by these organochlorides, chemists argue that a higher burden of proof on safety for organochlorides as a class is inappropriate.However, many chemists believe that such arguments unduly exaggerate the risk associated with organochlorides
Edited sentence: However, some chemists believe that such arguments understate the risk associated with organochlorides.Organisations such as the [US Green Building council] and others have been reviewing these materials  given the growing ubiquity of these and other organochlorides