ABSTRACT
During the twentieth century, scientific progress took
precedence over quality of life. The impressive devel-
opment of technology, its negative impact on the food
chain, and the ascendancy of productivity and profit-
ability over quality reduced public confidence in the
healthiness of foods. In the present century, however, it
is expected that goals connected with Food Safety, a
discipline concerned with the study of toxic substances
present in foods, will be a priority in developed
countries. The metals and metalloids present in the earth’s
crust, soils, water, atmosphere, and biosphere, and
consequently in foods, are stable compounds, persist-
ing in the environment, having a slow rate of eli-
mination, accumulating in tissues, and capable of
undergoing transformations that increase their toxi-
city. Among the metals and metalloids present in
foods, lead, cadmium, arsenic, and mercury stand
out because of their possible toxicological potential.
These four elements can be considered the star
elements, and systems of legislation in most countries
have established limits that regulate their presence in
foods. The criteria of toxicity for metals and metalloids
have traditionally been established on the basis of total
content. During recent decades, however, it has been
shown that their toxicity depends on their atomic or
molecular form. This has led to the need to carry out
