Behavior and fate of fungicide chlorothalonil in urban landscape soils and associated environmental concern

Degradation of four pesticides in five urban landscape soils: human and environmental health risk assessment

Pesticides are the most cost-effective means of pest control; however, the serious concern is about the non-target effects due to their extensive and intensive use in both agricultural and non-agricultural settings. The degradation rate constant (k) and half-life (DT₅₀) of four commonly used pesticides, glyphosate, 2,4-D, chlorothalonil and dimethoate were determined in five Australian urban landscape soils, with varying physicochemical characteristics, to assess their environmental and human health risks. The k values (day^-1) for the selected pesticides were inversely proportional to those of organic carbon (OC), silt, clay and Fe and Al oxides, and directly proportional to pH and sand content in soils. In contrast, the calculated values of DT₅₀ (days) of all the four pesticides in five soils positively correlated with OC, clay, silt and oxides of Fe and Al, whereas soil pH and sand content exhibited a negative correlation. The calculated values of environmental indices, GUS and LIX, for the selected pesticides indicate their potential portability into water bodies, affecting non-target organisms as well as food safety. The evaluation for human non-cancer risk of these pesticides, based on the calculated values of hazard quotient (HQ) and hazard index (HI), suggested that exposure of adults and children to soils, contaminated with 50% of initially applied concentrations, through ingestion, dermal and inhalation pathways might cause negligible to zero non-carcinogenic risks. The present data might help the stakeholders in applying recommended doses of pesticides in urban landscapes and regulatory bodies concerned in monitoring the overall environmental quality and implementing safeguard policies. Our study also clearly demonstrates the need for developing improved formulations and spraying technologies for pesticides to minimize human and environmental health risks.

Heavy Metals in Widely Consumed Vegetables Grown in Industrial Areas of Bangladesh: a Potential Human Health Hazard

The prevalence of heavy metals in frequently consumed vegetables constitutes a considerable public health hazard. This study aims to determine the quantity of heavy metals in widely consumed watercress (WC), alligator weed (AW), red amaranth (RA), spinach (SP), cauliflower (CF), and eggplant (EP) cultivated in industrial areas (e.g., Narsingdi district) of Bangladesh to assess the potential health hazards. Atomic absorption spectroscopy (AAS) served to determine the concentrations of lead (Pb), cadmium (Cd), chromium (Cr), and nickel (Ni) in vegetable samples (n = 72). The contents of Pb, Cd, Cr, and Ni were found in most of the analyzed vegetables, whereas 79.17%, 44.44%, and 1.39% samples exceeded the FAO/WHO maximum allowable concentration (MAC) for Pb, Cd, and Ni, respectively. The estimated daily intake (EDI) of single heavy metal was below the corresponding maximum tolerable daily intake (MTDI). The incremental lifetime cancer risk (ILCR) values of Cd in all samples exceeded the threshold limit (ILCR > 10^-4) for both adults and children, indicating lifetime cancer risk due to the consumption of contaminated vegetables. The target hazard quotient (THQ) of each heavy metal was THQ < 1.0 (except Ni in few samples), indicating that consumers have no non-cancer risk when exposed to a single heavy metal. However, hazard index (HI) values of heavy metals were greater than unity in contaminated WC and AW for adults and children. Meanwhile, WC, AW, and SP samples for children emerged as potential health risks of inhabitants in the studied areas. The outcomes of the present investigation might assist the regulatory bodies concerned in setting new strategies through monitoring the quality of marketed vegetables to minimize the risks to humans.