Understanding Lead Poisoning (Lead Toxicity)

Lead! Lead!! Lead!!! You must have heard about the word Lead poisoning or put in another word, lead toxicity, and you might be thinking what is this? Well, A friend told me that in Zamfara state, Northern Nigeria, people suffer from lead poisoning. It doesn't matter how it gets into the body, either it is absorbed, swallowed or breathed-in, it will have the same health effects.

Lead is an environmental heavy metal, which is poisonous and causes serious and damaging health problems. Lead toxicity is a condition where there is an increased lead concentration in the blood. Children are majorly affected with lead poisoning. According to a research, the incident of lead poisoning was uncovered in over 4000 children, and more males are affected than females in adults. Lead can get into the body via inhalation of the lead particle or injestion of the lead contaminated water, or food.

Sources of lead toxication could go from occupational (refining lead, battery manufacturing, plastic manufacturing, lead crystals, lead fuel refining, and manufacturing of Military equipments), Environmental (from lead paints, drinking lead contaminated water, eating lead contaminated food, using leaded petrol/gasoline), Recreational (ash from cigarette, jewelry making from home), and from other events (such as bullet shot wound, Eye shadow/cosmetics with lead).

Pathway for Lead Toxicity

Lead gets into the bloodstream through the gastrointestinal tract and the respiratory tract from inhalation, it could get into the body via the skin, but on a less common case. According to the article Lead Poisoning: A Persistent health Hazard-General and oral aspects, respiration accounts for 30% -70% of all lead poisoning in the body, while gastrointestinal tract absorption account for about 10% in adult while in children, since children are regularly putting things in their mouth, gastrointestinal tract absorption poisoning accounts for about 50%. When Lead gets into the body, it is absorbed into the bloodstream, after which it starts to get deposited in body tissues, bones, organs such as the kidney, the brain, bone marrows, and so on. Lead has adverse effect on certain organs, the cardiovascular system, the central nervous system and the immune system.

Pathophysiology of Lead Toxicity

In the research titled Lead Toxicity and Heme Biosynthesis, Lead intoxication affecting Heme Synthesis is explained. Hemoglobin is responsible for carrying oxygen around the body in the red blood cell. Lead affects the Heme synthesis pathway by affecting heme synthesis enzymes Aminolevulinic acid dehydratase (ALA dehydrase), and Ferrochelatase which will cause an increase in precursors. Lead in the blood inhibits Glutathione Disulfide, and superoxide dismutase, which leads to an increase in Reactive Oxygen Species causing cell membrane damage to the erythrocyte. When the cell membrane of the Red Blood Cell (Erythrocyte) is destroyed, it will cause microcytic Anemia (Mean Corpuscular Volume is less than 80 causing the size of the red blood cell to be reduced).

Lead poisoning in the gastrointestinal tract could lead to abdominal pain, nausea, Diarrhea, vomiting, and constipation. Lead poisoning goes to the Central nervous system. This could have several neurological effects which includes, lead encephalopathy, decreased concentration, increased aggression, altered mental status and irritability, and radial neuropathy which causes loss of control in the arm or wrist, changes in activity level in children, and development delay in children (language, movement and so on).

Lead poisoning could lead to lead lines, such as Burton's lines in the mouth (teeth and gum). With Burton's line, a blue-purplish line can be found in the gum, as well as lead sulphide deposit in the teeth and gum. Lead poison could lead to renal impairment (reduced kidney function) such as Fanconi's syndrome, decreased urine output, Chronic lead Nephropathy. Exposures to lead to also cause severe cardiovascular impairment leading to hypertension.

Diagnosis and Treatment for Lead Poisoning

To identify lead poison, diagnosis such as white blood lead level measurement should be done. According to the Agency for toxic substance and disease registry, When patients have BLLs above 5µg/dL they are positive to lead, and when the result is above 10µg/dL, then the cause of the lead poisoning should be removed. Other ways to diagnose lead poisoning is via CBC-microcytic anemia, and Free erythrocyte protoporphyrin. When diagnosis is confirmed, the next step is treatment. Treating lead poisoning usually required removing the source of the lead in the body, Chelation Therapy with Succimer, and d-penicillamine


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