Contamination

Definition

The unintended introduction of foreign biological material, chemical substances, or genetic material into a sample, specimen, culture, or ecosystem, compromising scientific validity, organismal health, or ecological integrity. In biological research, contamination spans multiple scales: molecular (DNA cross-contamination between specimens), microbial (pathogens or commensals in laboratory insect colonies), chemical (pesticide residues in field-collected arthropods), and environmental (exotic species or pollutants disrupting native arthropod communities).

Etymology

Latin contaminare, to pollute or corrupt by contact

Example

A preserved spider specimen stored in ethanol with beetles may suffer DNA contamination if the beetles' genetic material leaches into the vial, confounding subsequent molecular phylogenetic analysis; similarly, mite contamination can overrun Drosophila laboratory stocks, altering behavioral phenotypes and rendering experiments irreproducible.

Synonyms

• adulteration
• pollution
• taint

Related Terms

• cross-contamination
• sterile technique
• DNA barcoding
• specimen integrity
• laboratory colony
• field contamination
• exotic species
• vector competence
• degradation
• artifact

Usage Notes

Distinguish contamination from infection (active pathogenesis) and infestation (establishment of parasites or commensals). In molecular systematics, 'contamination' specifically denotes exogenous DNA, whereas in conservation, it often implies hybridization with introduced gene pools. The term carries stronger negative connotation than 'background' or 'noise' and implies preventable error rather than unavoidable interference. Specialists may specify 'carryover contamination' for PCR artifacts, 'environmental contamination' for field-collected material, or 'biological contamination' for competing organisms in cultures.