Abstract
Frequently unwanted and dangerous surrogate contaminants may be present as reaction impurities, or are formed during synthesis of other compounds. In some instances these impurities are more toxic than the compounds they contaminate. The total environment suffers — from single‐celled living matter to man. Continued widespread use of chemicals not analytically categorized must be re‐evaluated. The chlorinated dibenzodioxins and chlorinated dibenzofurans may act as a signal warning of future chemical revelations — especially as newer innovative analytical techniques are formulated.