An assessment of heavy metal exposure risk associated with consumption of cabbage and carrot grown in a tropical Savannah region

Overview

Fonge and colleagues measured total arsenic, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead, and zinc in cabbage heads and carrot roots grown in Santa, North West Region, Cameroon. The study is occurrence evidence for edible vegetable crop concentrations and supply-chain context for soil-to-crop transfer in farms using irrigation water and agrochemical inputs. The arsenic result is total arsenic (As); the paper does not report inorganic arsenic speciation, hexavalent chromium (Cr-VI), or mercury.

Key numbers

All edible-crop values below are from Table 14, reported in mg/kg on the paper’s dry-matter basis. Soil values are supply-chain context only and should not be pooled as product concentrations.

The abstract repeats the headline exceedance pattern as total arsenic (tAs) 0.51 mg/kg in cabbage and 0.38 mg/kg in carrot, Co 1.41 mg/kg and 1.39 mg/kg, and lead (Pb) 1.36 mg/kg and 1.31 mg/kg, respectively. The Results section states that Fe had the highest vegetable concentration across sites, ranging from 3.77 mg/kg to 302.31 mg/kg, while cadmium (Cd) had the lowest range, 0.12 mg/kg to 0.19 mg/kg.

Table 10 reports paired soil context for the same production system: cabbage soils tAs 1.16 mg/kg, Cd 0.87 mg/kg, Co 2.04 mg/kg, Cu 4.61 mg/kg, chromium (Cr) 9.70 mg/kg, Fe 841.40 mg/kg, Mn 27.10 mg/kg, nickel (Ni) 2.29 mg/kg, Pb 3.03 mg/kg, and Zn 11.47 mg/kg; carrot soils tAs 1.55 mg/kg, Cd 0.91 mg/kg, Co 2.19 mg/kg, Cu 4.65 mg/kg, Cr 10.07 mg/kg, Fe 843.93 mg/kg, Mn 45.68 mg/kg, Ni 2.27 mg/kg, Pb 3.08 mg/kg, and Zn 9.16 mg/kg.

Transfer-factor context (Table 11): the mean TF across sites was highest for Co, 0.70 in cabbage and 0.64 in carrot; Fe was the lowest, 0.10 in cabbage and 0.02 in carrot. Table 15 reports Health Risk Index values greater than 1 only for Co: 2.31 in cabbage and 2.26 in carrot; all other listed metals had HRI below 1.

Methods (brief)

Samples were collected from four villages in Santa: Mbei, Akum, Moforbe, and Matazem. At each site, one cabbage farm and one carrot farm were selected; mature cabbage heads and carrot roots were collected in triplicate, washed, rinsed with distilled water, sliced, and oven-dried to constant weight at 40 °C. Soil samples were collected from 0-15 cm depth in the same production plots. Soil metals were extracted with aqua regia and measured by ContrAA 300 atomic absorption spectrometry; plant metals were digested with HNO3 in a microwave and measured with a Perkin Elmer 3000 ICP-MS. Two reagent blanks were included in each batch, and all samples were analyzed in duplicate.

Related evidence

• Leafy / Green Vegetables, Other
• Root and Tuber Vegetables
• Cabbage
• Carrot
• carrots
• Leafy Vegetables
• Root vegetables
• Vegetables
• Arsenic, Total
• Cadmium
• Cobalt
• Chromium
• Copper
• Iron
• Manganese
• Nickel
• Lead
• Zinc

Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git.