noncoplanar

In terms of structural relationship to toxicity, PCBs fall into 2 distinct categories, referred to as coplanar or non-ortho-substituted arene substitution patterns and noncoplanar or ortho-substituted congeners.

First, these microbes tend to be highly selective in their dechlorination, with lower chlorinated biphenyls being readily transformed, and with preference to dechlorination in the para and meta positions (this is an advantage however, as ortho dechlorination would transform noncoplanar PCBs into dioxin-like coplanar ones).