Table 3.

Explained variance of the first principal component ($R_{\text{PC1}}^2$), R² and constituent contaminants for a model predicting the first principal component

Matrix	Cluster	$R_{\text{PC1}}^2$	R 2	PCBR
Maternal blood	Low/medium chlorinated	0.97	1.00	2,3’,4,4’,5-PeCB(#118)
				3,3’,4,4’,5-PeCB(#126)
	Medium/high chlorinated	0.94	0.99	2,3,4,4’,5-PeCB(#114)
				2,3,3’,4,4’,5,5’-HpCB(#189)
Cord blood	Low/medium chlorinated	0.94	1.00	2,3’,4,4’,5-PeCB(#118)
				3,3’,4,4’,5-PeCB(#126)
	Medium/high chlorinated	0.97	0.99	2,3,4,4’,5-PeCB(#114)
				2,3,3’,4,4’,5,5’-HpCB(#189)
Cord tissue	Low/medium chlorinated	0.96	0.99	2,3’,4,4’,5-PeCB(#118)
				3,3’,4,4’,5-PeCB(#126)