For this application, other constituents are of concern. Organic contaminant removal is of particular concern, as well as nitrates. Although the rejection of TOC is quite high, some small organic molecules such as pharmaceuticals and carcinogenic compounds may not be as highly rejected. In many cases though, the rejection of RO membranes is sufficient to meet current requirements. However, further study on pharmaceutical compounds, hormones, and pesticides is needed. One report (Daughtery 2005) based on the GWR Phase 1 Plant at Orange County, indicates that the membranes produced permeate with halogenated compounds < 0.5 ug/l, PCB’s < 0.5 ug/l, NDMA < 5 ug/l, caffeine < 0.3 ug/l, and estrone < 10 ng/l. These results indicate that the membrane is very efficient in removing such difficult to treat compounds. Another study on these compounds was done with fresh membrane samples (Kimura 2003) and indicated that higher molecular weight species are highly rejected, as expected. However, rejection of lower molecular weight compounds is not highly rejected.