Working together, the scientific, regulatory and non-governmental communities have reduced in concentrations of legacy chemicals of concern (COCs) in the Great Lakes ecosystem since the 1970s. After controls were implemented, the reduction was characterized by an initial sharp decline followed by a slow decline, with half-lives in the order of a decade or more depending on the medium. Those trends correspond to (i) a cessation of production and new uses (rapid decline), and (ii) the inventory reduction as in-use products and materials containing the COC move into the waste stream (slow decline). For PCBs, that long tail was prolonged by the time taken in Canada to implement regulations to remove PCBs from use (mostly industrial and in infrastructure) and the incomplete, state-by-state approach in the US. For the flame retardants (FRs) polybrominated diphenyl ethers (PBDEs), the rise and initial decline of concentrations in lower Great Lakes fish corresponded well with the temporal trend in inventory of PBDEs in consumer products in the Great Lakes basin. Here, the rate of decline was coincident with our estimates of the rate of removal of in-use PBDE-containing consumer products. Since flammability standards in Canada and the US are met using FRs, the chemical industry has responded to the PBDE bans/phase-outs by providing a wide variety of PBDE alternatives. The Canadian Chemical Management Plan has recommended that controls be implemented for 3 additional FRs - TCPP, Dechlorane Plus (DP) and DBDPE. TCPP has been designated due to human health concerns, and DP and DBDPE due to environmental concerns. For TCPP, the recommended control is limiting use to 1000 mg/kg in mattresses and upholstered furniture. Recommended controls are pending for DP. The controls being considered for DPBPE are prohibiting manufacturing in Canada (no evidence of Canadian production) and importation. This paper discusses the new challenges presented if we are to reduce levels of “new” FRs of concern in the lower Great Lakes, including those designated for control in Canada. TCPP concentrations in 3 Toronto streams discharging to Lake Ontario averaged 1.1 (0.10 - 4.9) μg/L in dry and 1.7 (0.35 - 5.1) μg/L wet weather, 1.8 (0.38 - 6.7) μg/L in final WWTP effluents from three plants, and 0.12 (0.03 - 0.36) μg/L in nearshore Lake Ontario waters. Data are presented on the products from which these 3 FRs originate and the effectiveness of regulatory controls are discussed.

How do we reduce chemicals of concern in the Great Lakes after picking the low hanging fruit?

253rd National Meeting (2017)

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