Metal (Pb, Cu, Cd, and Zn) Transfer along Food Chain and Health Risk Assessment through Raw Milk Consumption from Free-Range Cows

Abstract

Background: Metal transfer along the food chain has raised concerns about impacts on human health due to dietary exposure to low but chronic concentrations. Soil–forage–milk–consumer is a short food chain through which metals are able to reach an organism. Methods: Pb, Cu, Cd, and Zn were determined in water, soil, forage, and milk samples collected from free-range cattle farms situated near Baia Mare, Romania. The soil-to-forage (TFsf) and forage-to-milk (TFfm) transfer factors for metals and the health risk for three population groups (females, males, and children) through the consumption of milk containing low levels of metals were assessed. Results: TFsf indicated that the uptake capabilities of the metals from soil to forage were in the following order: Zn > Cd > Cu > Pb. TFfm indicated a lack of metal accumulation through forage ingestion. Estimated daily (EDI) and provisional tolerable weekly (PTWI) intake values revealed a minimal exposure of the population to those metals through milk consumption. A noncarcinogenic hazard index indicated that milk consumption from local markets does not pose any risk for human health; however, the average cancer risk showed a high potential carcinogenic risk. Conclusions: The consumption of milk produced by small local farmers does not pose noncarcinogenic risks. More extended studies should be carried out in order to identify the potential carcinogenic risk caused by the low levels of metals in the milk consumed.

Accumulation and distribution of heavy metals in soil and food crops around the ship breaking area in southern Bangladesh and associated health risk assessment

“…When the soil samples are found to be enriched with a specific metal, the plant root uptakes the metal and only a part of that metal is transferred to the edible part of green leaves, giving a plant-soil ratio of about 0.2. Therefore, the TC value of greater than 0.2 may be corroborated to the anthropogenic contribution of plant contamination [15]. From this point of view, we found that rice grain is highly contaminated with Cd, bottle gourd is contaminated mostly with Cd, Zn, and Cu, and banana is slightly contaminated with Mn, due to anthropogenic activities such as ship breaking in the study area.…”

“…The potential ability of the plant species to transfer or accumulate a specific metal from the adhered soil with respect to its concentration in the soil substrate to their edible portions is commonly expressed as the transfer coefficient (TC) or bioaccumulation ratio (BR) and can be defined as the concentration ratio of metal in the plant material to that in the respective soil [12][13][14][15]. The…”

“…Cadmium is considered as an intensively accumulated metal [14]. The high accumulation of this metal in plants is due to the fact that the ionic radii of Cd, Zn, and Cu are very close and they function almost in a similar fashion in nucleic acid metabolism [15]. Once the Cd enters into the plant cell, it interacts with the enzymes and takes the place of Zn which results in an easy transfer of this metal from soil to the edible part of the plant species compared to Zn [11,15].…”

“…The high accumulation of this metal in plants is due to the fact that the ionic radii of Cd, Zn, and Cu are very close and they function almost in a similar fashion in nucleic acid metabolism [15]. Once the Cd enters into the plant cell, it interacts with the enzymes and takes the place of Zn which results in an easy transfer of this metal from soil to the edible part of the plant species compared to Zn [11,15]. Moreover, Cd showed high accumulation in rice grain than other FSs and this might be corroborated to the vacuolar sequestration capacity in rice roots contributing to the long-distance transportation of Cd from roots to shoots and the metal hyperaccumulators showing a high accumulation of Cd in the rice grain without any visual effects [47,48].…”

“…However, the metal accumulation process in plants varies with plant species, soil properties as well as selectivity and metal permissibility [8,10]. Therefore, the enrichment of metals in the plant species is usually ascertained by the accumulation factor which expresses the metal concentrations in the soil with respect to the plants [12][13][14][15]. The uptake of metals by food crops at a level large enough to cause a potential human health risk, due to excessive metal contamination in agricultural soils around the ship breaking areas, is of great concern in recent years [9].…”