Compost tea contains a variety of ingredients, usually mature compost and water. Additives may increase bacteria in the brew, possibly increasing risk.
The USDA Agricultural Research Service recently came out with new recommendations on making compost tea. Given the recent publicity about disease carrying spinach, you may want to give this a read if you are using compost tea in your garden.
The extra additives frequently added to the tea such as soluble kelp, fish hydrolysates, humic acid, rock dust and proprietary nutrient solutions apparently increase the growth of bacteria in the mixture. This can greatly increase the level of pathogens capable of making people sick -- such as E.coli and Salmonella -- in the compost tea.
Interestingly, compost made the old fashioned way by steeping aged mature compost in plain water does not seem to increase those dangerous pathogens.
Check out the Compost Tea Task Force Report for the National Organic Standards Board.
