To put this in context - modern testing technology can detect levels at nanograms per liter and lower. If desired you can go as low as picograms per liter.
A nanogram is 1 billionth of a gram. 0.000,000,001 grams.
A picogram is 1 trillionth of a gram. 0.000,000,000,001 grams
For those that think this isn't correct many of you will have had a PSA test - you get your test results back in a few days. A good result is less than 2.5 nanograms per liter. The same technology is used to test horse blood!!!
A grain of white refined sugar weighs 625,000 nanograms.
A poppy seed weighs 300,000 nanograms.