Aroclor misidentification in environmental samples: how do we communicate more effectively between the laboratory and...

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Environmental Forensics

Background:

• Historical disposal of carbonless copy paper (CCP) sludge in the USA led to polychlorinated biphenyl (PCB) contamination.
• A dispute emerged regarding the source of PCBs, with analytical results indicating multiple Aroclor types (1242, 1248, 1254, 1260) at a site historically linked to Aroclor 1242 (used in CCP).
• This discrepancy highlights a conflict between regulatory analytical methods and the need for precise source identification in environmental investigations.

Purpose of the Study:

• To investigate the discrepancy between historical PCB disposal records and analytical findings of multiple Aroclors at a contaminated site.
• To examine the limitations of the USEPA 8082 method when used for PCB source identification versus total content determination.
• To advocate for better alignment between laboratory analysis requests, intended data usage, and the interpretation of analytical results.

Main Methods:

• Review of historical site records concerning carbonless copy paper (CCP) sludge disposal.
• Analysis of discrepancies between documented PCB mixtures (Aroclor 1242) and laboratory-reported Aroclors (1242, 1248, 1254, 1260).
• Evaluation of the USEPA 8082 method's applicability and limitations in differentiating PCB sources.

Main Results:

• Analytical results reported four different Aroclors (1242, 1248, 1254, 1260) at a site with documented disposal of only CCP sludge, historically associated with Aroclor 1242.
• The presence of multiple reported Aroclors challenges the assumption of multiple source inputs, suggesting potential issues with analytical interpretation or weathering processes.
• The study identified an inappropriate extension of data beyond the intended scope of the USEPA 8082 method, leading to erroneous conclusions about PCB sources.

Conclusions:

• Over-interpretation of analytical data, particularly regarding Aroclor identification, can lead to flawed conclusions about environmental contamination sources.
• Laboratory analysis requests must be carefully matched to the intended data usage to prevent misinterpretations.
• There is a need for clearer communication within the PCB analysis community regarding the limitations of Aroclor identification to avoid naive assumptions by data users.