Incorporation of probabilistic health risk assessment of heavy metals into biosolids land application guidelines

The objective of this paper was to assess the health risk for the ingestion of vegetable and rice grown on farm lands fertilized by waste activated sludge. Three heavy metals Cadmium, Copper and Zinc were chosen. After estimating the concentration of heavy metals in soil, their concentration in plants was calculated using regression uptake models. The Monte-Carlo simulation was then used to perform a probabilistic health risk assessment. The results showed that rice ingestion has more contribution to hazard index (HI) when low amount of fertilizer applied on land. It was also found that Cadmium has the most contribution to HI. The findings of this study revealed that for one-time consumption of fertilizer, the 95th percentile of HI is less than 1 even at 100 t/ha consumption rate. However, when long-term application of fertilizer was considered, only at 5 t/ha consumption rate, the HI value was less than 1.

Keywords:

Fertilizer , Heavy metals , Health risk assessment , Land application , Waste activated sludge