lead chambers of installations, reddish sediment was obtained. Initially, it was thought that arsenic

Overview

This source page is a mechanical bulk-ingest record for a PDF in the methylmercury infant-formula research pull. It preserves source-level identity, routeable product/analyte scope, and exact extracted numeric lines for later human or fresh-context audit. It does not derive HMTc thresholds, percentiles, or brand-by-brand comparisons.

Key numbers

The worker extracted the full PDF text with layout preservation twice and compared extraction hashes before commit. The following lines are copied from numeric/table-bearing regions of the PDF and retain the source units and wording where legible:

Selenium was discovered in 1817 in Gripsholm, a Swedish city, by a Swedish chemist Jacob
Berzelius (1), who was working in a chemical factory producing, among others, sulfuric acid and nitric
questioned this result. At the beginning of 1818, Berzelius repeated the experiments in a laboratory in
with properties similar to sulfur (2). This substance was called selenium, from the Greek word “selene”,
which means moon (3).
Increased interest in the biological role of selenium was observed in the 1950s, when it was
dystrophy of cardiac muscle or acute hepatic necrosis (4). In 1973, the biochemical role of this element
peroxidase. After 17 years, it was observed that other enzymes also include this element in their active
Molecules 2019, 24, 1298; doi:10.3390/molecules24071298 www.mdpi.com/journal/molecules
on the role of this element in human and animal organisms (1).
1. Physicochemical Properties of Selenium
Selenium is found in group 16 of the periodic table, which also includes oxygen, sulfur, polonium,
tellurium, and livermorium (5). This group is called oxoacids. Chemical properties of the elements in
this group vary significantly with the increase in the atomic mass of the elements (Table 1). Oxygen and
is found in elemental state (Se0 ), in the form of selenides (Se2− ), selenates (SeO4 2− ), or selenites
(SeO3 2− ) (6). This element is characterized by an ease of transition to adjacent oxidation states. These
Table 1. Selected physical and chemical properties of selenium.
Electronic configuration (Ar) 3d10 4s2 4p4
Melting temperature (◦ C) 220
Electron affinity −4.2 Ev
Ionization potential 9.75 Ev
remaining three are crystalline (8). It can form molecules of ring structure, consisting of eight atoms
of such alloy leads to the formation of gray amorphous selenium also known as vitreous selenium (9).
a temperature of 470 K. It is characterized by a very low electrical conductivity in the dark, which
from 75 Se radioactive isotope emitting β and γ radiations. In nature, the most widespread isotope of
1. Occurrence of Selenium in the Environment
lithosphere, biosphere, and hydrosphere of the Earth (11). This element circulating in the environment
(H2 Se), and selenium oxide (SeO2 ) are produced. The average selenium content in the arable layer
of soil varies from 0.33 to 2 mg/kg on a global scale (12). Soils that have arisen from parent rocks
content (7,13). For example, in the area of Olkiluoto Nuclear Power Plant (Japan) in the organic part of
the soil (humus), selenium is present at a level of 34 mg/kg. In mineral soil, regardless of its depth,
the content level of this element fluctuates ~14 mg/kg (14,15).
selenites (16). The amount of selenium in groundwater is much higher than that in seawater (13)
in selenium compounds (17). The selenium content determined in groundwater in Poznań (Poland) is
0.17–0.44 µg/L (18). According to the recommendations of the World Health Organization (WHO),
the acceptable amount of selenium in drinking water is 10 µg/L (19).
Selenium can be found in many minerals such as berzelianite (Cu2 Se), klaustalite (PbSe),
and naumanite (Ag2 Se) (16). It penetrates the soil as a result of anthropogenic activity through
where the selenium content in coal oscillates at the level of 6–8.4 g/kg (17). However, the greater part
of China surface exhibits a very low content of this element in the soil (<0.1 mg/kg).
the amount of selenium was observed at the level of 2.9 mg/kg. Soils rich in selenium are found
China (7). Soils rich in this element occur mainly in North America, Canada, Australia, Ireland, while

Methods (brief)

The results of sample analysis indicated a likely presence of tellurium; however, Berzelius
1. Kieliszek, M.; Błażejak, S. Speciation analysis of selenium in Candida utilis yeast cells using HPLC-ICP-MS
and UHPLC-ESI-Orbitrap MS techniques. Appl. Sci. 2018, 8, 2050. (CrossRef)
1. Lippman, S.M.; Klein, E.A.; Goodman, P.J.; Lucia, M.S.; Thompson, I.M.; Ford, L.G.; Parnes, H.L.;
1. Mao, J.; Pop, V.J.; Bath, S.C.; Vader, H.L.; Redman, C.W.; Rayman, M.P. Effect of low-dose selenium on
Symposium on Trace Elements in Human Health and Disease, edited by Jan Aaseth. J. Trace Elem. Med. Bio.

Implications

This page makes the source discoverable for category-level evidence routing. Values remain source-native and should be used only with the stated matrix, species, basis, geography, and censoring context from the paper. The page does not convert total mercury to methylmercury or use total arsenic as inorganic arsenic.

Wiki pages this source may touch

Verification notes

Identity check: DOI, raw handle, candidate cite-key, and SHA-256 were compared against existing wiki/sources/ pages before creation.
Full-PDF read: pdftotext -layout was run on the full PDF twice; extracted text hashes matched before the page was written.
Numeric verification: numeric/table-bearing lines were selected mechanically from the verified extraction and preserved without unit conversion or rounding.
Brand firewall: the worker skips PDFs when extracted numeric lines appear brand/manufacturer-sensitive; this page contains category-level or species-level evidence only.
HMTc firewall: no threshold, percentile, pass/fail, clean/dirty, or certification math is stated.

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. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
3171d06	2026-08-02	major	1 section added
bc84bfc	2026-08-02	major	6 sections added; narrative text revised