Units of Measurement - Pesticide Contamination
µg/l A microgram per litre is one part per billion or a ratio of 1 part contaminant to 1,000,000,000 parts water.
ng/l A nanogram per litre is a thousand times smaller than a microgram and is 1 part per trillion. This is a ratio of 1 part contaminant to 1,000,000,000,000 parts water.