5 Health Risks Associated with Metal(loid) Accumulation
by Vegetables via Foliar Deposition
Urban agriculture (gardening) is developing globally due to its perceived health
benefits and economic conditions. However, urban agriculture may sometimes
increase human exposure to metal(loid)s through ingestion of metal contaminated
vegetables, when grown on polluted urban sites (Bi et al. 2018; Szolnoki et al. 2013;
Xiong et al. 2014a). Recently, several studies have focused on the human health
risks associated with the use of contaminated vegetables/crops (Mombo et al. 2015;
Xiong et al. 2016b; Yang et al. 2016b).
After foliar deposition of metal-enriched PM, vegetables may absorb and accumulate high levels of metals (Edelstein and Ben-Hur 2018; Li et al. 2018; Mombo
et al. 2016) (Tables 5 and 6). During the past recent years, some studies evaluated the
accumulation of heavy metal(loid)s in vegetables cultivated in areas with high
atmospheric deposition of metal-rich PM. For example, Schreck et al. (2012b)
reported 108, 107, 99, 122, and 171 mg/kg of Pb accumulation in lettuce shoot
after exposure to industrial atmospheric fallouts of a secondary lead recycling plant,
respectively for 1, 2, 3, 4, and 6 weeks. In another study, Schreck et al. (2012b)
evaluated the concentration of Pb, As, Sn, Sb, Cu, Zn, and Cd in three vegetables
(lettuce, ryegrass, and parsley) after exposure to atmospheric fallouts resulting from
the emissions of a battery recycling factory. They reported that the Pb content
reached about 100, 300, and 100 mg/kg DW in lettuce, ryegrass, and parsley,
respectively.
In another study (Schreck et al. 2014), these authors reported 700 mg/kg of Pb in
shot tissues of ryegrass, which was several times higher than the maximum allowable level set by the European Commission Regulation for leafy vegetables (0.3 mg/
kg FW). Similarly, Cd concentrations of 1.7, 0.8, and 1.6 mg/kg DW were found for
lettuce, parsley, and ryegrass, respectively, compared to limit values of 0.2 mg/kg of
fresh weight, which is about 4 mg/kg dry weight (Kabelitz and Sievers 2004). Under
foliar application of Pb-PM, 485 and 214 mg/kg of Pb were reported, respectively, in
spinach and cabbage (Xiong et al. 2014a). Similarly, Uzu et al. (2010) reported that
after 43 days of Pb-PM exposure, the thoroughly washed leaves of lettuce contained
335 Æ 50 mg/kg of Pb in shoot tissues.
Nevertheless, there exist rare data about health risk assessment due to the foliar
uptake of heavy metals. Xiong et al. (2014a) measured the gastric bioaccessibility of
metal(loid)s (Sb, Cd, Zn, and Pb) in spinach and cabbage after metal-PM atmospheric/foliar application. They reported that the gastric bioaccessibility ranged
from 13.9 to 98% of these metal(loid)s. Similarly, Schreck et al. (2012b) reported
that Pb bioaccessibility is 45% for lettuce exposed for 1 month to foliar application
of Pb-PM. Therefore, it is proposed that the leaf morphology controls both the
metal(loid) uptake by plants and metal gastric bioaccessibility once exposed to
human digestion fluids (Uzu et al. 2011b).
During the recent past, health risk assessment has emerged as a key factor to monitor
environmental pollutants and their associated health risks (Khalid et al. 2018;
84
M. Shahid et al.
by Vegetables via Foliar Deposition
Urban agriculture (gardening) is developing globally due to its perceived health
benefits and economic conditions. However, urban agriculture may sometimes
increase human exposure to metal(loid)s through ingestion of metal contaminated
vegetables, when grown on polluted urban sites (Bi et al. 2018; Szolnoki et al. 2013;
Xiong et al. 2014a). Recently, several studies have focused on the human health
risks associated with the use of contaminated vegetables/crops (Mombo et al. 2015;
Xiong et al. 2016b; Yang et al. 2016b).
After foliar deposition of metal-enriched PM, vegetables may absorb and accumulate high levels of metals (Edelstein and Ben-Hur 2018; Li et al. 2018; Mombo
et al. 2016) (Tables 5 and 6). During the past recent years, some studies evaluated the
accumulation of heavy metal(loid)s in vegetables cultivated in areas with high
atmospheric deposition of metal-rich PM. For example, Schreck et al. (2012b)
reported 108, 107, 99, 122, and 171 mg/kg of Pb accumulation in lettuce shoot
after exposure to industrial atmospheric fallouts of a secondary lead recycling plant,
respectively for 1, 2, 3, 4, and 6 weeks. In another study, Schreck et al. (2012b)
evaluated the concentration of Pb, As, Sn, Sb, Cu, Zn, and Cd in three vegetables
(lettuce, ryegrass, and parsley) after exposure to atmospheric fallouts resulting from
the emissions of a battery recycling factory. They reported that the Pb content
reached about 100, 300, and 100 mg/kg DW in lettuce, ryegrass, and parsley,
respectively.
In another study (Schreck et al. 2014), these authors reported 700 mg/kg of Pb in
shot tissues of ryegrass, which was several times higher than the maximum allowable level set by the European Commission Regulation for leafy vegetables (0.3 mg/
kg FW). Similarly, Cd concentrations of 1.7, 0.8, and 1.6 mg/kg DW were found for
lettuce, parsley, and ryegrass, respectively, compared to limit values of 0.2 mg/kg of
fresh weight, which is about 4 mg/kg dry weight (Kabelitz and Sievers 2004). Under
foliar application of Pb-PM, 485 and 214 mg/kg of Pb were reported, respectively, in
spinach and cabbage (Xiong et al. 2014a). Similarly, Uzu et al. (2010) reported that
after 43 days of Pb-PM exposure, the thoroughly washed leaves of lettuce contained
335 Æ 50 mg/kg of Pb in shoot tissues.
Nevertheless, there exist rare data about health risk assessment due to the foliar
uptake of heavy metals. Xiong et al. (2014a) measured the gastric bioaccessibility of
metal(loid)s (Sb, Cd, Zn, and Pb) in spinach and cabbage after metal-PM atmospheric/foliar application. They reported that the gastric bioaccessibility ranged
from 13.9 to 98% of these metal(loid)s. Similarly, Schreck et al. (2012b) reported
that Pb bioaccessibility is 45% for lettuce exposed for 1 month to foliar application
of Pb-PM. Therefore, it is proposed that the leaf morphology controls both the
metal(loid) uptake by plants and metal gastric bioaccessibility once exposed to
human digestion fluids (Uzu et al. 2011b).
During the recent past, health risk assessment has emerged as a key factor to monitor
environmental pollutants and their associated health risks (Khalid et al. 2018;
84
M. Shahid et al.