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The half-life of lead in bone has been estimated as years to decades, and bone can introduce lead into the bloodstream long after the initial exposure is gone. [ 181 ] [ 182 ] [ 183 ] The half-life of lead in the blood in men is about 40 days, but it may be longer in children and pregnant women, whose bones are undergoing remodeling , which ...
One of them is lead-210; although it has a half-life of only 22.2 years, [38] small quantities occur in nature because lead-210 is produced by a long decay series that starts with uranium-238 (that has been present for billions of years on Earth). Lead-211, −212, and −214 are present in the decay chains of uranium-235, thorium-232, and ...
Radioactive isotope table "lists ALL radioactive nuclei with a half-life greater than 1000 years", incorporated in the list above. The NUBASE2020 evaluation of nuclear physics properties F.G. Kondev et al. 2021 Chinese Phys. C 45 030001. The PDF of this article lists the half-lives of all known radioactives nuclides.
(The more massive 209 Bi, long considered to be stable, actually has a half-life of 2.01×10 19 years.) 208 Pb is also a doubly magic isotope, as it has 82 protons and 126 neutrons. [6] It is the heaviest doubly magic nuclide known. A total of 43 lead isotopes are now known, including very unstable synthetic species.
The most stable are 244 Pu with a half-life of 80.8 million years; 242 Pu with a half-life of 373,300 years; and 239 Pu with a half-life of 24,110 years; and 240 Pu with a half-life of 6,560 years. This element also has eight meta states; all have half-lives of less than one second. The known isotopes of plutonium range from 226 Pu to 247 Pu.
In this situation it is generally uncommon to talk about half-life in the first place, but sometimes people will describe the decay in terms of its "first half-life", "second half-life", etc., where the first half-life is defined as the time required for decay from the initial value to 50%, the second half-life is from 50% to 25%, and so on.
Caesium in the body has a biological half-life of about one to four months. Mercury (as methylmercury) in the body has a half-life of about 65 days. Lead in the blood has a half life of 28–36 days. [29] [30] Lead in bone has a biological half-life of about ten years. Cadmium in bone has a biological half-life of about 30 years.
Measuring a person's blood lead level requires a blood sample, which may be performed with a fingerstick or a blood draw.. The amount of lead found in the blood sample may be measured in micrograms of lead per deciliter of blood (μg/dL) especially in the United States; 5 μg/dL is equivalent to 0.24 μmol/L ().