Abstract

In this chapter, we review the most important toxic metals in food, cadmium, lead, mercury and arsenic. In addition, aluminium, nickel, silver and tin are briefly mentioned. These metals may enter the food chain from soil, water, air, but also from packaging material and cooking utensils. They are both naturally present, for example due to local geology, and occur because of anthropogenic activity in the environment.Cadmium is taken up by the root system in plants. Cereals and vegetable products are the most important sources of exposure for non-smokers and tobacco is the main source for smokers. Many of the food items high in cadmium, i.e. edible offal crab meat and chocolate are rarely consumed, or only consumed in small quantities and contribute little to the daily intake. Whereas only a few percent of cadmium is absorbed from food, up to 40% absorption may occur in women with low iron stores. Cadmium is mainly distributed to the liver and kidney where it accumulates with a biological half-life of more than 20 years. Cadmium toxicity is characterized by proximal tubular dysfunction with low molecular proteinuria and eventual renal failure. Cadmium may also affect bone and result in osteoporosis and bone fracture. In addition it is associated with increased risk of prostate cancer and cognitive developmental impairment following exposure in utero. The dietary cadmium exposure of the European population is in the region of the tolerably weekly intake (TWI) established by the European Safety Authority (EFSA). The environmental pollution of lead and levels in food have decreased significantly in developed countries after the 1970s when the uses of lead in petrol, lead solder in cans and drinking water plumbing materials were regulated or banned. Vegetable products contribute to a high extent to the dietary intake, whereas animal products contribute less. The absorption of lead from food is low, < 10%. This figure may be higher in children. Impaired cognitive development of the foetus is considered the critical effect, but also renal toxicity and increased blood pressure in adults are important effects. Current exposures in Europe show no or only small margins to the benchmark dose lower confidence limits (BMDL) for cognitive effects, effect on blood pressure and chronic kidney disease. Mercury occurs in three chemical forms: elemental, inorganic mercury cations and organic mercury with methylmercury being the most important form in the food chain. Fish and seafood is the main dietary sources of methylmercury, which is easily absorbed in the intestine and crosses the blood brain barrier and placenta. The critical adverse effect is neurodevelopmental toxicity including motor, cognitive and auditory effects. In Europe, dietary exposure to methylmercury varies strongly dependent on amount and fish species consumed and may exceed the TWI established by EFSA in certain groups of the population. For inorganic mercury, which causes renal toxicity, no groups exceeded the TWI, established by EFSA. Arsenic is widely present in the earth's crust in oxidation states of -3, 0, +3 and +5. It occurs both as organic and inorganic species in the environment and in food and feed. Human exposure to inorganic arsenic varies strongly with geographical region and local geology. Contaminated ground water used for drinking water and irrigation of crops, in particular rice are sources of exposure, especially where rice is staple food. Fish and other seafood have the highest amounts of less toxic organic arsenic. Inorganic arsenic is readily absorbed and excreted as inorganic and methylated arsenicals in urine. Increased risk of several cancers is the critical effect of exposure to inorganic arsenic, but exposure may also cause progressive neuropathy, liver injury, cardiovascular diseases, and type II diabetes. The margin of exposure to the BMDL0.5 based on increased risk of lung cancer is small (1-30) in the European population.

Keywords

toxic metals; health; food; arsenic; cadmium; lead; mercury

Published in

Food safety assurance and veterinary public health
2019, Volume: 7, pages: 157-180
Title: ECVPH Food safety assurance, Volume 7
ISBN: 978-90-8686-326-6, eISBN: 978-90-8686-877-3
Publisher: Wageningen Academic Publishers

SLU Authors

• Oskarsson, Agneta

  • Department of Animal Biosciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Pharmacology and Toxicology
Food Science


Publication identifier

DOI: https://doi.org/10.3920/978-90-8686-877-3_07

Permanent link to this page (URI)

https://res.slu.se/id/publ/108695