Elements present in very small concentrations, either as impurities or added intentionally, also affect the quality of materials. These elements present in small quantities are known as trace elements or ultra trace elements depending on their concentration. Generally an element with concentration less than 100 parts per million (ppm) is considered a trace element and those with less than 1 ppm levels are known as ultra trace elements.
Unwanted trace elements are regulated to keep their concentration levels below certain limits as these deteriorate the quality of materials if present above this limit. On the other hand, certain trace elements are essential for some materials to functional well.
The presence of trace elements in our blood and other body fluids can also give an indication about the diseases present in our body and also indicate the way to treat such diseases.
Trace elements in biological systems
Our health depends on the quality of blood flowing in ourarteries and veins. Often if the concentration of certain elements in our blood falls lower than the specified limits, it becomes necessary to add these elements in the form of dietary supplements to keep the body working optimally.
An example is the requirement of Calcium (Ca). The normal level of Ca in human body is in ppm levels. When the Ca level in blood decreases it draws Ca from the bones and if it increases it transfers it to the bones. Low level of Ca intake may lead to pain in the muscles, numbness or cramps. However, large amounts may lead to stones in kidney, constipation or sometimes heart related problems. The amount of Ca in the body is assessed by analyzing the blood.
Similarly, for assessing the body health condition it is also essential to determine the levels of elements such as O, Na, Mg, K, Cr, Fe, Zn, Se, Pb, Hg, U, etc. A concentration of 10 μg Pb/deciliter in children’s blood may lead to decrease in IQ. Significant differences in Zinc, Chromium, Cobalt, Manganese, Barium, and Lead between diabetic and nondiabetic patients have been observed.
Other body fluids e.g. saliva, blood plasma, tears, urine, tears, aqueous humor of cataract and dental plaque, nails, and hair can also serve to assess the levels of trace elements in our body in a painless manner. Such analysis can also give information about the cause of death by suspicious poisoning and may be helpful in forensic sciences also.
Trace elements in food
Trace elements necessary to keep our body fit to function inan optimum manner are obtained from food. For instance, specific amounts of Selenium (Se) in blood is needed to increase body immunity as it is an antioxidant, antiviral and anticancer agent. In recent studies it has been found that people with adequate Se levels in blood had low mortality rate due to Covid-19. However, high Se may lead to stomach upset, hair loss or even heart attacks.
An important source of Se is wheat which contains Se in ppm levels. The cost of Se-rich wheat is higher as compared to Se-deficient wheat. It is reported that Selenium content in wheat is in the range of 0–8270 μg kg–1. The normal level of selenium in human blood is 110 to 165 μg kg–1. Almost 80% of the world population has low levels of Selenium.
Similarly, some other elements like K, Mg, Fe, Cu, Zn up to a certain concentration levels in food are required as nutrients whereas elements like Cr, As, Pb, Sb, U, etc. are toxic and cannot be tolerated in human body above certain concentration levels (a few ppm only).