POLLUTION BY LEAD METAL

Lead is one of the most prominent metallic environmental contaminants today. Lead is the most prominent metallic pollutant, that is widespread in the environment due to human activities. Leaded gasoline and paint pigments are the largest sources for environmental lead.

Major sources of metallic lead particles present in the environment---

Leaded gasoline contains [gasoline + tetraethyl lead (CH₃CH₂)₄Pb]. Here tetraethyl lead [(CH₃CH₂)₄Pb] is mixed with gasoline due to its anti-knocking property, it provides more time to gasoline for its combustion and enables gasoline to burn at slow speed.

The disadvantage of leaded gasoline is that, due to the presence of tetraethyl lead [(CH₃CH₂)₄Pb] as an anti-knocking agent in the mixture, when the mixture [gasoline + tetraethyl lead (CH₃CH₂)₄Pb] is ignited in the combustion engine of the car, tetraethyl lead [(CH₃CH₂)₄Pb] in the presence of O₂ reacts with several dihalogen alkanes such as C₂H₄Cl₂ and C₂H₄Br₂. As a result of this reaction PbCl₂ and PbBr₂ are produced, which are volatile and hence go out of the car engine with the exhaust gases and get mixed with environmental air, and hence make the air polluted.

2Pb (CH₃CH₂)₄ + 32O₂ + C₂H₄Cl₂ + C₂H₄Br₂ -----> 20CO₂ + 24H₂O + PbCl₂ + PbBr₂

In the paint pigment, white lead [ basic lead carbonate, 2PbCO₃•Pb (OH)₂] was used for many years. Frequently under layers of more modern paint, older buildings still have lead-containing paint. Kids those living in these buildings, if they eat paint chips, they are likely to ingest significant amounts of lead.

Lead metal pollutant is also present in the environment due to various industrial activities, such as lead mining, extraction of lead metal, purification of lead and manufacture of various alloys by lead metal.

Harmful effects of lead---

In human body, most important organs such as kidneys, liver and intestine are damages by lead metal and this pollutant lead metal causes abnormalities in fertility and pregnancy.

In human body proteins are coagulated due to presence of toxic lead metal and red blood cells get stippled and lead causes anemia disease in human.

In human body, functioning of cells and nervous systems are disrupts due to presence of lead poisoning.

Lead causes skin diseases and breathing problems in human.

Due to the presence of lead pollutant in the environment, the life span of rats decreases by one-third to their average life span.

The death of birds are increases, due to the presence of lead pollutant in the environment.