Survey of total mercury in total diet food composites and an estimation of the dietary intake of mercury by adults and children from two Canadian cities, 1998-2000

Overview

Dabeka, McKenzie, and Bradley measured total mercury in Canadian total-diet food composites from Whitehorse and Ottawa. The paper reports total mercury occurrence by composite and food category, plus age/sex dietary-intake estimates. Mercury is not speciated in the occurrence data; comparisons to methylmercury guidance values are risk-context estimates rather than measured methylmercury (MeHg).

Key numbers

Total mercury was measured in 259 total diet food composites from two Canadian cities. 46% of composites had concentrations below the LOD, with sample LODs averaging 0.14 ng g−1 and ranging from 0.026 to 0.506 ng g−1.

The abstract states that the fish category had the highest mercury concentrations, averaging 67 ng g−1 and ranging from 24 to 148 ng g−1. All fish composites were below the Canadian guideline for total mercury in fish of 0.5 ppm.

Table 3 reports fish composite values by city in ng g−1:

Table 4 summarizes total mercury concentrations by food category in ng g−1:

Table 5 reports estimated dietary intakes of total mercury in µg kg−1 day−1:

For all age groups over 4 years, fish contributed the most to dietary mercury intake. The fish-category contribution ranged from 53% for 65+ females and 5-11 year males/females to 74% for 40-64 year-old females.

Methods (brief)

Retail foods were purchased in Whitehorse in January-February 1998 and Ottawa in October-November 2000, prepared as consumed, combined into 135 food composites per city design, homogenized, and stored at −20 °C. A 0.5-2.0 g sample was digested with nitric and hydrochloric acids plus hydrogen peroxide, diluted to 50 ml, and measured using a CETAC M6000 mercury analyser. Quality control included NIST citrus leaves, oyster tissue, and wheat flour SRMs, reagent blanks, blank spikes, sample spikes, and duplicate analysis.

Implications

This source supplies Canadian total-diet evidence for total mercury, with fish and fish products clearly dominating the occurrence and intake signal. It supports seafood, fish, freshwater-fish, canned-fish, shellfish, and broad infant-food routing for total mercury context. It should not be used as measured methylmercury occurrence; any MeHg comparison in the paper is a guidance comparison applied to total-mercury intake.

Update history

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