Figure 4.

Clusters of co-occurring probable and confirmed chemicals in recycled and virgin products. This figure illustrates the occurrence patterns of chemicals within products, clustered so that chemicals with similar patterns are grouped. The black cells indicate occurrence of a chemical in a product. Chemicals and clusters vary vertically and product category vary horizontally. Twelve clusters of interest containing between 5 and 50 chemicals are pictured. Some clusters (e.g., cluster 2) identified groups of chemicals occurring in products across multiple categories, while others (e.g., clusters 5 and 9) identified chemicals concentrated in unique categories. The uses of chemicals within each cluster were investigated to provide evidence of chemical source (see Table 2).