Lead poisoning happens when too much lead gets into the body through the skin or from breathing, eating, or drinking. When lead gets in the body, it can travel and cause harm wherever it ends up.
The main mechanism of the lead toxicity is due to increase in the generation of the reactive oxygen species resulting in generation of the antioxidants. Lead causes the generation of ROS like hydroperoxide, hydrogen peroxide and singlet oxygen. Reactive oxygen species are stabilized by glutathione in the body. The glutathione acts as an antioxidant defense mechanism. Glutathione stabilizes ROS and after being converted to glutathione disulfide it is reduced back to the form by the glutathione reductase. Lead inactivated glutathione by binding to sulfhydrl group of glutathione sulfahydryl ( an reduced form of the glutathione) . lead also interferes with the activity of other antioxidant enzymes including superoxide dismutase and catalase. The increase in oxidative stress leads to cell membrane damage due to lipid peroxidation. Lead blocks the activity of 5 – aminolevulinic acid dehydrates and leads to hemoglobin oxidation which along with the lipid peroxidation can resulting in red cell hemolysis.
Lead entering the intravascular space binds quickly to red blood cells. Lead has a half-life of approximately 30 days in the blood, from where it diffuses into the soft tissues, including the kidneys, brain, liver, and bone marrow.
Lead then diffuses into bone and is stored there for a period that corresponds to a half-life of several decades. Increased bone turnover with pregnancy, menopause, lactation, or immobilization can increase blood lead levels. Estimations of blood lead levels are more useful for diagnosing acute lead poisoning, whereas the extent of past lead exposure can be estimated by determining the body burden of lead on the basis of results from the edetate (EDTA) calcium disodium (CaNa2 EDTA) lead mobilization test.
Lead is excreted in urine and bile but the elimination rate varies depending on the tissues that absorbed the lead. The kidney excretes the maximum amount of the lead by the means of glomerular filtration and tubular secretion. Lead has bidirectional transport across the tubular epithelium. The clearance rate of the lead ranges from 1 to 3 mL/min and it independent of the kidney function.
The effects of lead poisoning on the brain are manifold and include delayed or reversed development, permanent learning disabilities, seizures, coma, and even death. The long-term effect of lead exposure is maximal during the first 2 or 3 years of life, when the developing brain is in a critical formative stage.
When excessive amount of the lead gets deposited in the body it results in symptoms.
Occasionally, it can occur from a single high dose, but more often it is a gradual build-up.
Excessive amount of lead in the body damages the following organ such as kidneys and central nervous system, eventually leading to seizures, unconsciousness, coma and even death
Symptoms vary across age groups.
Childrens:
Children are more at risk from lead poisoning for a number of reasons. Because they come into contact easily with the contaminated objects.
They are more likely to pick up lead contamination from the soil and to then consume it.
They are also closer to ground level more frequently and, therefore, more at risk of breathing in dust from the floor.
Signs and symptoms of acute lead poisoning include:
abdominal pain and vomiting
diarrhoea
lethargy
black diarrhoea
encephalopathy, which affects the brain and can lead to seizures, coma, and death
However, symptoms are more likely to appear over time. This is known as chronic poisoning.
These include:
slowed body growth
reduced IQ
loss of appetite and weight loss
constipation and mild abdominal pain
irritability
general fatigue
blue tinge around the gums
anemia
hearing loss and reduction on other senses
neurological weakeness in the later stages
In Adults:
abdominal pain is usually the first sign if a high dose of lead is ingested
raised blood pressure
joint and muscle pain
constipation
anaemia
tingling, pain, and numbness in the extremities .
memory loss and decline in mental functions
hallucinations
unusual taste in the mouth, often described as metallic
difficulty sleeping
mood disorders
reduction in sperm volume and quality
loss of pregnancy or preterm birth
foot or ankle drop, in the later stages
Adults tends to get the gout, carpel tunnel syndrome and low fertility
Electroencephalography:
It might shows any abnormal findings.
Bone Xray:
The x ray predicts any abnormal area in the bone
Computed tomography:
It reveals the slice of the bone. It uses both the combination of x ray and computer aided device.
It helps to analyse the size, shape and position of any lung tumour and also it helps in the detection of enlarged lymph nodes.
It also looks for any masses in the adrenal gland, liver, brain and other organs.
CT guided needle Biopsy:
CT scan might be used to guide a biopsy needle into this area to get the tissue for bone cancer.
MRI scan:
It uses the soft tissue image of the organ. It uses the both the magnet and radiowaves.
It often reveals whether the cancer cells has spread to the brain or spinal cord.
Lumbar puncture:
A spinal tap may be needed for the evaluation of the patients who has altered mental status. It is contraindicated in patients with the lead encephalopathy because of the risk of herniation from elevated intracranial pressure.
Provocative chelation test:
It is done in the acute lead poisoning . Urine is collected after administering a dose of a chelation agent. Edetate(EDTA) calcium disodium (CaNa2 EDTA) is most commonly used chelator for the test
Avoid exposure to chemicals
Watch the children if they are coming into contact with any lead materials
Use the cosmetic products carefully.
