Boron and other trace elements in human tissues and fluids.

The multielemental technique of inductively coupled plasma source mass spectrometry (ICP-MS) was used to measure the elemental concentration of boron and 28 other elements within blood and its fractions, saliva, urine, hair, nails, synovial fluid, brain and bone samples. A number of biological standard reference materials were also analysed: IAEA A13 animal blood and H4 animal muscle, NIST 1577A bovine liver and SRM909 human serum, and SINR 0920 Chinese hair. Boron levels were found to be in the order of 30-40ng/mL in saliva and synovial fluid, 150ng/mL in blood, 1mug/mL in urine, 2-4mug/g in hair, bone and brain, and 10mug/g in nails. Other elements ranged in concentration from sub-nanogram/gram (or mL) to percentage (%w/w) levels. Associations of boron with other trace elements, such as boron and calcium in blood, were also investigated in the various tissues and fluids, as were variations due to age and sex. Frequency distribution curves were plotted for trace elements and micronutrients in all tissues and fluids. Since most elements demonstrated a symmetrical distribution in blood, this was thought to be indicative of the amount of homeostatic regulation, rather than the essentiality of the element. The distribution of elements among the various sample matrices, and occurrences of elemental or matrix interdependence, were investigated. Rubidium and caesium, also calcium and strontium, for example, were consistently found to behave in similar ways among the clinical specimens. In addition, alterations in elemental levels due to factors such as age and sex were assessed in the range of tissues and fluids. Full descriptions of the elemental content of brain, bone and synovial fluid samples were obtained. Comparisons were made between rheumatoid arthritic (RA) and control subjects for brain and bone, and between RA and osteoarthritic (OA) patients for the synovial fluid. Boron was shown to be "very highly significantly" depleted in RA bone (at the 0.1% level). Other elements showing variations in bone and brain were lithium and iron. Iron was also at lower levels in RA synovial fluid compared to OA, in contrast to phosphorus, copper and zinc, where increases were seen. Elemental levels were linked with other clinical parameters in synovial fluid, such as crystal content and white blood cell count (a measure of the extent of inflammation), to assess any possible variations. Fluid containing crystals displayed elevated levels of scandium, strontium and caesium. Several elements showed a positive correlation with white blood cell count; these were caesium, magnesium, phosphorus, copper, zinc and rubidium