To summarize, sewage workers are exposed to multiple chemicals from multiple pathways resulting in a complicated matrix of exposure to chemicals and concentrations.
We developed a checklist containing six unique sets of yes/no variables organized in a 2 × 3 matrix of exposure potential versus exposure protection at three levels corresponding to a simplified hierarchy of controls: materials, processes, and human interface.
Also urine, finger/toenails, or human milk have repeatedly been used as suitable matrices of exposure for metals.
Occupational, non-occupational, music, and home and other miscellaneous activities were each assigned noise levels derived from a matrix of mean exposures derived from peer-reviewed publications [ 26] (Additional file 1: Table S1).
The Wilks' Lambda given by the ratio det(cov X, Y))/[det(cov(X det(cov(Y))], where det(C) is the determinant of a matrix C, and (X, Y) is the data matrix of both the exposures X and the outcomes Y, is used to test the null hypothesis of no association between two data matrices X and Y.
The evaluation of infant meconium as a cumulative matrix of prenatal toxicant exposure requires comparison to established biomarkers of prenatal exposure.
Others have modeled the spread of VZV, using time-of-exposure matrices to capture the mixing between different individuals (Zagheni et al., 2008) and how they change through time (Whitaker and Farrington, 2004).
Because of missing values for the covariate maternal IQ, the available sample sizes in the regression analyses were reduced to n = 109 and n = 92, respectively, when using maternal blood or maternal milk as matrix of the prenatal exposure measures, and were downsized additionally by one female case for the masculine score.
Alternative methods and matrices of BPA exposure assessment should be considered in future studies.
The relatively weak association between administered oral gavage dose of DEP and MPB and the serum concentrations of their biomarkers exemplifies why there is growing concern about the use of the proper biologic matrix for exposure assessment (Calafat et al. 2013).
