Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: January 5, 2004
Publication Date: August 8, 2004
Citation: INGRAM, D.T., MILLNER, P.D. FECAL BACTERIAL PATHOGENS AND INDICATORS IN COMMERCIALLY AVAILABLE COMPOST. INTERNATIONAL ASSOCIATION FOR FOOD PROTECTION. 2004.
Compost is a valuable soil amendment used by organic and conventional growers to improve the physical, chemical, and biological properties of soil. In the U.S., compost is produced from a variety of feedstocks that are sources of potentially pathogenic microbes, e.g. landscape trimmings, animal or poultry manure, food residuals, and biosolids from municipal or industrial wastewater treatment facilities. Aerobic, thermophilic compost production processes are designed to achieve significant reductions in fecal coliforms and salmonellae through timed-temperature exposures. Currently, only biosolids compost must meet time-temperature process standards according to federal statute (40 CFR Part503), and few states have pathogen or pathogen indicator standards for marketable compost. Thus, product quality could vary widely and if inadequately composted the product could introduce pathogens in systems producing fresh fruits, vegetables, and herbs that may be consumed raw. We conducted a study of the microbial quality (total heterotrophs, total and fecal coliforms, E. coli, Salmonella, and Enterococci) and seasonal variability, of commercially available compost from 11 facilities across the US. Feedstock compositions represented the wide range of materials commonly used. Results show that nearly all composts had fecal coliform counts above 1000 cfu/g and at least three contained salmonellae above 4 MPN/g (limits acceptable for distribution to the general public according to USEPA). This indicates the need for adherence to time-temperature process standards and product quality testing. Fruit and vegetable producers need to ensure that they use high quality composts, as not all currently available commercial products are disinfected.