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Quality -> Chemical composition -> Micro components -> Lead



General characteristics

Lead belongs to group IVa of Periodic table of the elements and lead is poor metal. This element has big number of sulphides minerals (about 80), and the most important mineral is galenite- PbS. In naturally conditions galenite easy oxidizes and forms secondary lead mineral anglesite- PbSO4, which latter traverses in cerussite. Lead has big usage: for battery and lead accumulator production, cables, plumber pipes, armament, fuel production (tetraethyl- and tetramethyl- lead are using as anti-detonator and additions to oil for lubrication), for protection from radiation from nuclear reactors and roentgen equipment, in glass and paint industry. Nitrates and acetates are soluble salts.

Origin in water

Lead is very often metal in natural waters, because it occurs as Pb2+ in contents which are often for waters (mg/l). Lead can also find in water with very high pH values (to 10, 5). Meanwhile, concentrations of this ion decrease in neutral and low-alkali solutions. Maximal concentrations occur in acid underground waters with pH<5, 5. In surface and underground waters lead contents is from tracks to 0,04 mg/1, with average value from 0,01 mg/1. Industrial sources and mining can bring to local pollutions. Lead concentrations in water depend from many factors like pH, temperature and water harness.

Medical aspect

Saturnism has professional character, but there are also other cases. Children, babies fetus in uterus and pregnant women are very sensitive on lead effect. Lead transfer through placenta starts in 12th week of development and continues during the development. Children absorb 4-5 more times lead then adults and biological half-life can be longer at children then at adults.

Positive effect

Lead involves in calcium metabolism and directly effects on metabolism of D vitamin.

Negative effect

Lead is poison which accumulates in skeleton. Toxic effects are measured, based on lead concentration in blood. Lead is also toxic for central and lateral nerve system, causes subcephalopatic , nerve effects and effects in behaviour.  There are electro-physiologic evidences about lead effects on nerve system at children and small IQ at children for 4 points.  Results of lasting epidemiologic studies signify that prenatal lead effects can have early effects on mental development to 4 years. Several gastrointestinal symptoms connect with encefalopatic symptoms.  Still, there are evidences from studies on people that with very small lead concentrations can cause other effects like nerve-toxicities. Recommended value on that basis will be preventive also for cancer effects. Lead is cumulative poison   for people. Acute poisoning is rarely and typical symptoms are constipation, anaemia, gastrointestinal problems, gradual paralyse of muscles especially arms with possible cases of lethargy and grouch. The main effect at people is decreasing synthesis of haemoglobin and porphyry. 

Maximal allowable concentrations

According to recommendations of EU (Directive 98/83/EC) and in our rules for drinking water (Sl. list SRJ 42/98).limitary value for lead is 10 mg/1.


 






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