Towards a global historical emission inventory for selected PCB congeners - a mass balance approach. 1. Global production and consumption

Information on the historical global production and consumption of polychlorinated biphenyls (PCBs) is urgently
needed for estimating PCB fluxes to the environment and for interpreting global contamination patterns by these pollutants. This study presents the methodology, principal uncertainties and selected results from an inventory, aiming
to quantify the global production and consumption of total PCBs as well as 22 PCB congeners. The available data
on the historical production of PCBs and the chemical composition of various technical mixtures have been compiled
from the literature. For some producers with less detailed information, the production of individual PCB constituents
has been estimated to derive a global estimate for individual homologues and selected congeners. Information on
imports, exports and consumption, as well as restrictions on production and imports, has further been compiled for
individual countries. These data, along with assumptions on the trade between countries and regions, have been
utilised to derive an estimate of the global historical consumption pattern. Although there are substantial uncertainties involved in these estimates, important aspects governing the large scale temporal and spatial patterns are most likely captured in these estimates. In particular, the information on imports and exports for the principal users of PCBs around the time of peak production is considered to be fairly reliable. The estimates account for a reported historical global production of ~1.3 million t PCBs, more than 70% of which are tri-, tetra- and pentachlorinated biphenyls. The results further suggest that almost 97% of the global historical use of PCBs have occurred in the Northern Hemisphere.