Overview
Total arsenic and total mercury concentrations in commercial hen eggs from 21 major Tehran brands were very low across both winter and summer sampling seasons: mean tAs 0.79 µg/kg and mean tHg 0.18 µg/kg across 84 samples. Neither metal approached levels of immediate toxicological concern under standard dietary exposure assumptions; target hazard quotient (THQ) for both analytes was below 1 (mean As THQ 0.00385, mean Hg THQ 0.00066 for adults). However, the International Lifetime Cancer Risk (ILCR) for arsenic in the maximum scenario exceeded 10⁻⁴, indicating a threshold carcinogenic risk under conservative assumptions. Seasonal differences were not significant for arsenic (p = 0.451) but were significant for mercury (p < 0.001), with one season reporting higher tHg.
Key numbers
Total arsenic (n = 84): mean 0.79 µg/kg (parts per billion, wet weight of whole homogenised egg). Total mercury (n = 84): mean 0.18 µg/kg wet weight. Note: tAs and tHg measured; inorganic arsenic speciation and methylmercury speciation not performed.
Estimated daily intake (EDI, Iranian adult consumption rate 25.4 g eggs/day): As 0.29 µg/day; Hg 0.06 µg/day.
Estimated weekly intake in maximum scenario: tAs 8.71 µg As/month; tHg 1.89 µg Hg/month — both well below JECFA PTWI (As 15 µg/kg BW/week; Hg 4 µg/kg BW/week).
THQ means (adults): tAs 0.00385; tHg 0.00066 (both << 1, no non-carcinogenic risk indicated).
ILCR for As by Monte Carlo simulation: 4.35 × 10⁻⁴ in the mean scenario, exceeding the 10⁻⁴ threshold under most regulatory programs, interpreted as a threshold carcinogenic risk requiring monitoring, not immediate hazard.
Seasonal difference in tHg was statistically significant (p < 0.001); tAs showed no significant seasonal variation (p = 0.451). Direction of seasonal tHg difference not specified in Marker-converted text.
Method: ICP-MS (ULTIMA2, 6100 DRC-e Perkin Elmer Elan); heat-block acid digestion per FDA Elemental Analysis Manual; analysis in triplicate; blanks and certified standards after every 10 samples.
Methods (brief)
84 fresh commercial hen eggs (two eggs per brand per season, n = 21 brands × 2 seasons = 42 per season) sampled from 30 Tehran supermarkets across five city districts (North, South, Centre, West, East) in January 2022 (winter) and August 2022 (summer). Whole eggs (yolk + white) homogenised and oven-dried at 70°C for 24 hours before 0.5 g portions digested with 10 mL 70% HNO3 and 30% H2O2. Probabilistic risk assessment using Monte Carlo simulation (SPSS; EDI, ILCR, THQ per USEPA framework). Analysis reports total arsenic and total mercury; no speciation into iAs/organoarsenic or MeHg/inorganic Hg.
Implications
Certification: Eggs show very low As and Hg contamination in this Iranian urban commercial market sample, consistent with eggs being a low-risk matrix for these two metals unless the feed source or local environment is heavily contaminated. HMT&C egg category pages can reference this data point for baseline comparison alongside other egg datasets.
Courses: Useful case study illustrating how probabilistic risk assessment (Monte Carlo) is applied to food safety monitoring and how an ILCR slightly above 10⁻⁴ threshold is interpreted as requiring monitoring attention rather than immediate regulatory action.
App: tAs 0.79 µg/kg and tHg 0.18 µg/kg WW for commercial eggs, Tehran market 2022. Speciation data absent; flag as total values only.
Related evidence
Update history
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