Multiple Lines of Evidence Risk Assessment of Terrestrial Passerines Exposed to PCDFs and PCDDs in the Tittabawassee River Floodplain, Midland, Michigan, USA

Figures & data

Figure 1 Study site locations within the Chippewa, Tittabawassee, and Saginaw river floodplains, Michigan, USA. Reference Areas (R-1 to R-2), Tittabawassee River Study Areas (T-3 to T-6), and Saginaw River Study Areas (S-7 to to S-9) were monitored from 2004–2007. Direction of river flow is designated by arrows; suspected source of contamination is enclosed by the dashed oval.

Table 1 Toxicity reference values (TRVs) for total TEQs_WHO-Avian ^a concentrations selected for comparison to terrestrial passerines exposed to PCDD/DFs in the river systems downstream of Midland, Michigan, during 2005–2007.

Species	NOAEC	LOAEC	Reference
House wren
Dietary exposure–based ^b	14	140	Nosek et al. 1992a
Egg exposure–based ^c	710	7,940	USEPA 2003 ^d
Eastern bluebird
Dietary exposure–based ^b	14	140	Nosek et al. 1992a
Egg exposure–based ^c	1,000	10,000	Thiel et al. 1988

Figure 2 Geometric mean concentrations of ΣPCDD/DF TEQs_WHO-Avian in house wren eggs collected during 2005–2007 from the river floodplains near Midland, Michigan. Error bars show the 95% upper confidence level (UCL); Reference areas (R-1 and R-2); Tittabawassee River study areas (T-3 to T-6); and Saginaw River study areas (S-7 and S-9); sample size is indicated in parentheses under the sample site.

Figure 3 Geometric mean concentrations of ΣPCDD/DF TEQs_WHO-Avian in eastern bluebird eggs collected during 2005–2007 from the river floodplains near Midland, Michigan. Error bars show the 95% upper confidence level (UCL); Reference areas (R-1 and R-2); Tittabawassee River study areas (T-3 to T-6); and Saginaw River study areas (S-7 and S-9); sample size is indicated in parentheses under the sample site; range presented for S-7 where n = 2.

Table 2 Potential average (range) TEQ_WHO-Avian ^a daily dose (ADD_pot; ng/kg body weight/d) calculated from site-specific bolus-based and food web–based dietary exposure for adult house wrens and eastern bluebirds breeding during 2004–2006 within the river floodplains near Midland, Michigan.

	R-1 and R-2 ^b	T-3 to T-6	S-7 and S-9
House wren
Bolus	1.1 (0.73–1.7) ^c ^, ^d	150 (38–430)	— ^e
Food web	1.5 (0.54–3.0)	68 (13–140)	16 (5.9–34)
Eastern bluebird
Bolus	0.88 (0.44–1.9)	110 (13–450)	—
Food web	1.1 (0.47–2.2)	77 (24–180)	41 (6.2–110)

Figure 4 Correlation plot of percent hatching success and ΣPCDD/DF TEQs_WHO-Avian in house wren eggs for nesting attempts with data collected for both variables from the river floodplains near Midland, Michigan during 2005–2007. R- and p-values and sample size indicated; 1 = R-1; 2 = R-2; 3 = T-3; 4 = T-4; 5 = T-5; 6 = T-6; 7 = S-7; 9 = S-9.

Figure 5 Correlation plot of percent hatching success and ΣPCDD/DF TEQs_WHO-Avian in eastern bluebird eggs for nesting attempts with data collected for both variables from the river floodplains near Midland, Michigan during 2005–2007. R- and p-values and sample size indicated; 1 = R-1; 2 = R-2; 3 = T-3; 4 = T-4; 5 = T-5; 6 = T-6; 7 = S-7.

Figure 6 Modeled probabilistic distribution of expected cumulative percent frequencies for house wren egg TEQ_WHO-Avian concentrations ng/kg ww in site-specific eggs collected from the river floodplains near Midland, Michigan in 2005–2007. 10,000 simulations per site; R-1 and R-2 indicated by solid lines; T-3 to T-6 indicated by dash-dot-dash lines; S-7 and S-9 indicated by dotted lines; Y-axis offset to show R-1 and R-2; NOAEC and LOAEC indicated by vertical bars.

Figure 7 Modeled probabilistic distribution of expected cumulative percent frequencies for eastern bluebird egg TEQ_WHO-Avian concentrations ng/kg ww in site-specific eggs collected from the river floodplains near Midland, Michigan in 2005–2007. 10,000 simulations per site; R-1 and R-2 indicated by solid lines; T-3 to T-6 indicated by dash-dot-dash lines; S-7 indicated by a dotted line; Y-axis offset to show R-1 and R-2; NOAEC indicated by a vertical bar; LOAEC (not indicated) is 10,000 ng TEQs/kg ww (Thiel et al. 1988).

Figure 8 Hazard quotients (HQ) for the effects of ΣPCDD/DF TEQs_WHO-Avian for house wren eggs collected in 2005–2007 from the river floodplains near Midland, Michigan, based on the no observable adverse effect concentration (NOAEC) and the lowest observable adverse effect concentration (LOAEC). 95% confidence intervals (LCL/UCL) based on the geometric mean concentrations are presented; Left y-axis for reference areas (R-1 and R-2); Right y-axis for Tittabawassee River study areas (T-3 to T-6) and Saginaw River study areas (S-7 and S-9).

Figure 9 Hazard quotients (HQ) for the effects of ΣPCDD/DF TEQs_WHO-Avian for eastern bluebird eggs collected in 2005–2007 from the river floodplains near Midland, Michigan, based on the no observable adverse effect concentration (NOAEC) and the lowest observable adverse effect concentration (LOAEC). 95% confidence intervals (LCL/UCL) based on the geometric mean concentrations are presented; range presented for S-7 where n = 2; Left y-axis for reference areas (R-1 and R-2); Right y-axis for Tittabawassee River study areas (T-3 to T-6) and Saginaw River study areas (S-7 and S-9).

Figure 10 Hazard quotients (HQ) for the effects of potential ΣPCDD/DF TEQs_WHO-Avian daily dietary dose calculated from site-specific bolus-based (R1 to T-6) and food web–based (S-7 to S-9) dietary exposure for adult house wren and eastern bluebird collected in 2005–2007 from the river floodplains near Midland, Michigan, based on the no observable adverse effect concentration (NOAEC) and the lowest observable adverse effect concentration (LOAEC). HQs based on measured concentration ranges are presented; Left y-axis for reference areas (R-1 and R-2); Right y-axis for Tittabawassee River study areas (T-3 to T-6) and Saginaw River study areas (S-7 to S-9); food web–based dietary exposure is presented for S-7 to S-9 since no bolus samples were collected from those sites.

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