Abedi et al. 2023 — Arsenic and mercury in commercial hen eggs, Tehran
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.