Serum PCB levels and congener profiles among US construction workers

Abstract

Background: The presence of PCB in caulking (sealant) material found in masonry buildings has been well-documented in several countries. A recent investigation of 24 buildings in the greater Boston area found that 8 buildings had high PCB levels in caulking materials used around window frames and in joints between masonry blocks. Workers removing caulking material have been shown to have elevated serum PCB levels.

Methods: This project compared serum PCB levels among male workers who installed and/or removed PCB-containing caulking material from buildings in the greater Boston area with reference serum PCB levels from 358 men from the same area. Serum PCB levels were measured in the same laboratory by liquid-liquid extraction, column chromatography clean-up and dual capillary column GC/microECD analysis.

Results: When the congener profiles were compared between the reference population and the construction workers, the serum levels of the more volatile, lighter PCBs (di-, tri-and tetrachloro, sum of IUPAC# 6-74) were substantially higher among the construction workers. One of the youngest workers had the lowest total serum PCB levels (sum of 57 congeners) of all 6 workers, but the contribution of more volatile (less chlorinated) PCB congeners (#16, 26,28,33,74,66, and 60) was markedly higher than in other 5 workers and reference men. Only this worker was working on a job that involved removing PCB caulking at the time of the blood sampling.

Conclusion: While the results of this pilot study are based upon small numbers (6 construction workers who handled PCB caulking), the serum PCB levels among the construction workers exceed the referents. Comparison of the congener profiles suggests that there are substantial differences between the construction workers and the general population samples. These differences, and the similarities of profiles among the construction workers strongly suggest that occupational contact with caulking material can be a major source of PCB exposure for construction workers.

Figure 1

Referent and Worker Mean Serum Level 57 PCB Congeners. The contrast in the congener composition by concentration reflects the influence of worker #6, who was the oldest, and had the longest duration of work with PCB caulking.

Figure 2

Referent and Worker Percent Contribution 57 PCB Congeners. The contrast in congener composition by percent contribution is apparent as the contribution of lighter congeners (di, tri-, and tetra-chlorinated, PCB 6–74) to the total PCB level is 11.7 % for the construction workers, compared to 6.5% for the referents.

Figure 3

PCB Congener Profiles. Comparison of congener percent contribution by individual worker compared to referent mean.

Figure 4

Serum Concentration Light Congeners. Comparison of congener concentrations by individual worker compared to referent mean for PCB congeners 6–74 (di, tri-, and tetra-chlorinated)

Figure 5

Serum Concentration Heavy Congeners. Comparison of congener concentrations by individual worker compared to referent mean for PCB congeners 84–209 (penta-chlorinated and higher)

Figure 6

Light Congener % Contribution. Comparison of congener profiles for PCB 6-74 for the 20 referents exceeding the construction worker subject's median value for the sum of light congeners. These referents with the highest levels of light congeners have a very different profile of congeners compared to the construction workers, most notably for congeners 6, 8, 16, 26, 33, 37, and 41.