The
general population is exposed to polychlorinated biphenyls
(PCBs) by consuming food from far-field contaminated agricultural
and aquatic environments, and inhalation and nondietary ingestion
in near-field indoor or residential environments. Here, we seek to
evaluate the relative importance of far- and near-field routes by
simulating the time-variant aggregate exposure of Swedish females
to PCB congeners from 1930 to 2030. We rely on a mechanistic model,
which integrates a food-chain bioaccumulation module and a human toxicokinetic
module with dynamic substance flow analysis and nested indoor-urban-rural
environmental fate modeling. Confidence in the model is established
by successfully reproducing the observed PCB concentrations in Swedish
human milk between 1972 and 2016. In general, far-field routes contribute
most to total PCB uptake. However, near-field exposure is notable
for (i) children and teenagers, who have frequent hand-to-mouth contact,
(ii) cohorts born in earlier years, e.g., in 1956, when indoor environments
were severely contaminated, and (iii) lighter chlorinated congeners.
The relative importance of far- and near-field exposure in a cross-section
of individuals of different age sampled at the same time is shown
to depend on the time of sampling. The transition from the dominance
of near- to far-field exposure that has happened for PCBs may also
occur for other chemicals used indoors