Challenges related to compost spreading in urban green space: microbial risk assessment of accidental ingestion by children

The presence of pathogenic microorganisms in compost of solid waste can threat public health. Therefore, it is necessary to evaluate the safety of produced composts before its land application as a soil conditioner. This study was conducted to investigate the presence of pathogenic microorganisms in municipal solid waste (MSW) compost and health risks associated with accidental ingestion of compost by children.

In this study, sampling was done from compost piles at different public parks of Isfahan city during the period of compost spreading. Presence and concentration of pathogenic microorganisms including salmonella, campylobacter, cryptosporidium and adenovirus were investigated by culture or real-time PCR methods.

All pathogenic microorganisms were detected in MSW compost in a frequency from 11%-62% with the highest frequency for detection of adenovirus. The health risk assessment showed that the highest risk of daily infection was for Cryptosporidium (7.67 × 10-4 pppy) and the lowest risk was related to adenovirus (8.27 × 10-10 pppy). The annual infection risk from gastrointestinal disease was calculated above guideline infection risk (10-3 pppy).

The results showed contamination of produced compost to pathogenic microorganisms and potential health risks from applying MSW compost in urban green spaces. Therefore, the relevant organizations should pay more attention to the composting process and its microbial quality and application in public access areas.