Arsenic and Cooper Contents in Tropical Soils and Human Health Risk Assessment.

Soil contamination by potential toxics elements (PTEs) can change the ecosystem structure, its function and can cause risk to human health. Moreover, soil is one of the main pathways to human exposure. Then, it is important to evaluate the contents of PTEs in soils in order to assess the human health risk. Our objective was to evaluate the contents of As and Cu in 15 tropical soils and to assess the human health risk.

Contents of PTEs were obtained after microwave extraction by EPA 3051a method (0.5 g soil + 9 mL HNO₃ + 3 mL HCl). Lettuce (Lactuca sativa L.), cucumber (Cucumis sativus L.), sugar beet (Beta vulgaris L.) and rocket (Eruca sativus Mill.) were cultivated under greenhouse conditions to assess the human health risk. Plants were grown until they were ready for consumption and then, the edible parts were harvested and analyzed for As and Cu. Three scenarios were evaluated, assuming that either 10, or 25 or 100% of the total consumed vegetables were taken from the contaminated area. 

Three soils had As concentration close or higher than prevention value (PV) (15 mg kg^-1) established by Sao Paulo state environmental agency, Brazil. Otherwise, only one soil presented Cu content higher than PV (60 mg kg^-1). Arsenic showed high carcinogenic risk in all scenarios. The only scenario in which As diary ingestion was lower than its Reference Dose (RfD, 0.003 mg kg^-1/day) was the 1^st one (10% of the consumed vegetables from the contaminated area.

Conversely, Cu only represented risk to human health in the most restrictive scenario (100% of the consumed vegetables taken from the contaminated area). Cu diary ingestion was higher than its RfD (0.04 mg kg^-1/day) only in this scenario and when the four vegetables were consumed together.