It repeatedly says things like "effects are unknown" and "we're not yet sure about its environmental effects," he said. "But it's a very nice tracer, even if it doesn't have a large effect, because in most parts of the world, you know that this is coming from a human waste source."
Just because something seems insignificant, doesn't mean that it is.
As to the caffeine sources, this summary linked to the paper's abstract. The highlights section, with bullet points, says: "► Caffeine concentrations corresponded with storm event occurrence. ► Caffeine concentrations in rivers and estuaries draining to the coast measured up to 152.2 ng/L."
This means it's not a ocean-based source of caffeine. You would need to spend US$40 to see the references for the statement that "Caffeine, a biologically active drug, is recognized as a contaminant of freshwater and marine systems." Or make an interlibrary loan request and wait a few weeks.
It repeatedly says things like "effects are unknown" and "we're not yet sure about its environmental effects," he said. "But it's a very nice tracer, even if it doesn't have a large effect, because in most parts of the world, you know that this is coming from a human waste source."
Just because something seems insignificant, doesn't mean that it is.
As to the caffeine sources, this summary linked to the paper's abstract. The highlights section, with bullet points, says: "► Caffeine concentrations corresponded with storm event occurrence. ► Caffeine concentrations in rivers and estuaries draining to the coast measured up to 152.2 ng/L."
This means it's not a ocean-based source of caffeine. You would need to spend US$40 to see the references for the statement that "Caffeine, a biologically active drug, is recognized as a contaminant of freshwater and marine systems." Or make an interlibrary loan request and wait a few weeks.