Mercury, lead, arsenic, and cadmium in Norwegian seafood products and consumer exposure

Overview

Naess and colleagues measured mercury, lead, arsenic, and cadmium in commercially available seafood products sold in Norway from 2015 through 2018. The study reports mg/kg concentrations for processed fish categories including fish burgers/cakes, fish au gratin, fish fingers, saithe products, fish pudding, salmon/trout spread, canned mackerel in tomato sauce, and caviar. The arsenic measurements are total/unspecified arsenic, and the mercury measurements are total/unspecified mercury; the paper’s methylmercury exposure calculations assume all measured mercury is methylmercury (MeHg) as a conservative scenario but do not measure MeHg speciation.

Key numbers

Table 3 reports mercury (Hg), arsenic (As), and cadmium (Cd) in seafood products from 2015-2018 as mg/kg; the article states that lead (Pb) was below LOQ except for one fishburger/cake sample in 2017 at 0.006 mg/kg. Each row’s N is the number of composite samples, and each composite sample comprised three different batches with four different packages included.

The text states that fish burgers had the highest mean mercury concentrations over the study years and gives two examples of within-category Hg ranges: fish au gratin in 2015 ranged from 0.005 to 0.044 mg/kg, and fish burgers in 2017 ranged from 0.019 to 0.083 mg/kg. None of the seafood products exceeded the EU maximum level for mercury in fish of 0.50 mg/kg.

The highest cadmium concentration was in a mackerel-in-tomato-sauce sample from 2017 at 0.020 mg/kg. The paper states that a 40 g portion of that product would contribute 0.5% of the TWI for cadmium for an adult weighing 70 kg and 2.1% for a child weighing 15 kg.

For mercury exposure modeling, the authors used a 150 g fish-burger/cake portion and the methylmercury TWI of 1.3 µg/kg body weight. One fish-burger/cake portion at the highest measured Hg concentration, 0.083 mg/kg, contributed 13.7% of the TWI for an adult and 63.8% for a child in Figure 1. Based on mean fish-burger/cake Hg concentrations, Figure 1 reports adult contributions of 4.8%, 5.8%, and 5.1% in 2015, 2017, and 2018, and child contributions of 22.3%, 26.9%, and 23.8% for the same years.

Method validation values in Table 2 list dry-weight LOQs of Hg 0.005 mg/kg, Pb 0.030 mg/kg, As 0.01 mg/kg, and Cd 0.005 mg/kg. Wet-weight LOQs were Hg 0.001-0.003 mg/kg, Pb 0.005-0.020 mg/kg, and Cd 0.001-0.003 mg/kg; As wet-weight LOQ was reported as NA.

Methods (brief)

Market-representative seafood products available to Norwegian consumers were collected in 2015, 2017, and 2018 using product data from Nielsen Norge and Market Trends Norway. Samples included fish burgers/cakes, fish au gratin, fish fingers, saithe products, fish pudding, salmon/trout spread, canned mackerel in tomato sauce, and caviar. Composite samples were freeze-dried and homogenized; approximately 0.2 g freeze-dried material was wet-acid digested in a microwave and diluted to 25 ml before ICP-MS analysis using accredited ISO 17025 methods. Values below LOQ were treated as the LOQ value for mean and variance calculations under an upper-bound approach. The occurrence table reports total/unspecified Hg and total/unspecified As only; MeHg and inorganic arsenic were not measured.

Implications

This source provides processed-seafood occurrence evidence for Norwegian market products on an mg/kg wet-weight basis, with total Hg, total As, Cd, and mostly non-detect Pb results. The fish-burger/cake Hg exposure section is useful as source-authored context only if the conservative assumption is preserved: total Hg was treated as MeHg for modeling, but MeHg was not analytically measured. The arsenic results should be routed as total arsenic context and not used as inorganic arsenic evidence.

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.