Overview
A comprehensive dietary survey in industrial northern Ningxia, China found elevated concentrations of multiple toxic metals (Al, As, Cr, Cd, Cu, Ni, Pb, Zn) in drinking water and seven food categories. Total noncarcinogenic hazard index from combined dietary metal exposure was 5.61, well above the threshold of 1, with cereals contributing the highest non-carcinogenic risk (HI = 1.21). Total carcinogenic risk was 9.98 × 10⁻⁴, above the acceptable 10⁻⁴ threshold; 87% of residents were exposed to unacceptable carcinogenic risk according to Monte Carlo simulation. Cereals had the highest lead over-standard rate (5.1% exceeding 0.2 mg/kg), beans had 60% Pb exceedance, and solanaceous vegetables had 38.2% Pb exceedance. As in drinking water exceeded the safe limit of 0.01 mg/L in 16.7% of samples; Pb exceeded 0.01 mg/L in 11.1% of drinking water samples.
Key numbers
Drinking water (n = 36, mg/L): As mean 0.0056 (max 0.0456), Pb mean 0.0037 (max 0.0121), Al mean 0.0997 (max 0.5429), Ni mean 0.0054 (max 0.1361). Over-standard rates: As 16.7%, Pb 11.1%, Al 11.1%, Ni 5.6%.
Cereals (n = 59, mg/kg): Pb mean 0.0453 (max 0.2835; safe limit 0.2; over-standard 5.1%), Cr mean 0.2564 (max 0.7701), Cd mean 0.0128 (max 0.0656), Ni mean 0.1125 (max 1.2914; over-standard 1.7%).
Beans (n = 10, mg/kg): Pb mean 0.4636 (max 1.0014; safe limit 0.2; over-standard 60%), Cr mean 0.7536 (max 2.2808; safe limit 1.0; over-standard 40%).
Potatoes (n = 4, mg/kg): As mean 0.1475 (max 0.2984; safe limit 0.2; over-standard 50%), Pb mean 0.1798 (max 0.4436; safe limit 0.2; over-standard 50%).
Solanaceous fruits (n = 34, mg/kg; peppers, eggplant, bitter gourd, cucumber): Pb mean 0.1659 (max 0.8709; safe limit 0.1; over-standard 38.2%), Cd mean 0.0185 (max 0.1096; over-standard 17.6%), Cr mean 0.2728 (max 0.9064; over-standard 26.5%).
Vegetables (n = 18, mg/kg; cabbage, cauliflower, spinach): Cr mean 0.5642 (max 1.5511; over-standard 44.4%), Ni mean 0.5560 (max 3.4651; over-standard 44.4%), Pb mean 0.1603 (max 1.8107; over-standard 11.1%).
Meat (n = 8, mg/kg; pork, beef, mutton): Cr mean 0.4719 (max 1.0140; safe limit 1.0; over-standard 12.5%); all other metals below limits.
Fruit (n = 22, mg/kg): Ni mean 0.2458 (max 1.5844; over-standard 31.8%), Pb mean 0.1496 (max 0.5846; over-standard 31.8%).
Total HI (all metals, all food categories): 5.61. Non-carcinogenic risk order: HI_cereal (1.21) > HI_solanaceous (0.91) > HI_vegetables (0.87) > HI_fruit (0.82) > HI_meat (0.73) > HI_drinking water (0.61) > HI_beans (0.30) > HI_potatoes (0.16).
Total carcinogenic risk: 9.98 × 10⁻⁴ (predominantly from As in drinking water and meat). Monte Carlo: 98.83% of population above non-carcinogenic threshold; 87.02% above unacceptable carcinogenic threshold.
Analysis: ICP-AES; acid digestion (HNO3/HClO4 4:1 for food; HNO3 for cereals). Recovery 85–110% using GBW10014 reference standard. RSD <5%. Note: analysis reports total arsenic (tAs); speciation not performed.
Methods (brief)
Samples collected September 2017 from villages and towns in industrial northern Ningxia (38°58′–39°54′N, 116°23′–106°35′E), a region hosting smelting, metal processing, electroplating, electronics, and battery manufacturing industries. Food included meat (8 portions), cereals (59), beans (10), potatoes (4), solanaceous vegetables (34), leafy vegetables (18), and fruit (22). Dietary intake data from 97 questionnaires. Deterministic risk assessment using USEPA HQ/HI framework; probabilistic using Monte Carlo simulation. Sensitivity analysis identified drinking water, cereals, vegetables, and fruit as major risk contributors.
Implications
Certification: Multi-food-category dataset showing elevated Pb, Cr, Ni, and Cd across cereals, vegetables, and beans in an industrial Chinese context. Provides supply-chain framing for certified products sourced from Chinese industrial regions; Pb in beans at 60% over-standard is especially notable given widespread use of soy-derived ingredients.
Courses: Strong case study for multi-pathway dietary exposure assessment in industrial regions; demonstrates that cereal-based diet patterns create highest HI contribution when cereals carry even modest Pb concentrations due to frequency and volume of consumption.
App: Pb in cereals (rice, flour, corn, millet) mean 0.0453 mg/kg with 5.1% exceedance; Pb in solanaceous vegetables mean 0.1659 mg/kg with 38.2% exceedance in this industrial-proximity context. Flag these as elevated-context values, not general baseline.
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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. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Change | Description |
|---|---|---|---|
| a8052bb | 2026-08-09 | major | 6 sections added; narrative text revised |