Those who suffer the daily agony of waiting for public transport buses must be pretty aware of the offensively malodorous smoke emitted by those cavalcades of vehicles passing by. What they aren’t aware of is that it is not just the fetid smoke they are taking in, but a perplexed composition of poisonous gases and heavy metals too!
Lead is one of those heavy metals which are present in vehicle emission, lead dust or fumes etc. Lead contamination may also occur through contaminated hands, food, water, cigarettes or clothing and often leads to lead poisoning which is a pernicious, slow accumulation of lead in one’s body often with no immediate signs or symptoms.
It occurs when the lead entering the respiratory and digestive systems is carried through blood to various tissues and bones where it may get deposited and harm the normal physiology of respective organs! It has been reported that more than 90% of the total body burden of lead is accumulated in the bones, where it is either stored or re-released into the blood, re-exposing organ systems long after the original exposure.
The cytotoxicity of lead is well documented. Lead is known to affect various organs and their functions to varying degrees. The frequency and severity of symptoms among exposed individuals depend upon the amount of exposure. Neurological effects of lead poisoning may include peripheral neuropathy, fatigue, irritability, impaired concentration, hearing loss, seizures or encephalopathy etc. Lead poisoning may also lead to minor gastrointestinal effects like nausea, dyspepsia, constipation or a lead line on gingival tissue. Some recent research also indicates effects of lead on reproductive system. It has been reported to increase the number of miscarriages or stillbirths, reducing the sperm count and/or producing abnormal sperms in terms of motility or viability. Lead poisoning may also lead to chronic nephropathy with proximal tubular damage along with hypertension. There are reports that indicate a potential elevation in erythrocyte protoporphyrin & heme synthesis in cases of chronic lead poisoning. Some cases, anemia, joint pain, and pain in a muscle or group of muscles have also been associated with lead poisoning.
Lead poisoning can be diagnosed by a blood lead quantization test. Levels from 1 to 20μg/dl indicate that lead is building up in the body while 20-30μg/dl indicates potential physiologic problems due to regular exposure to lead. At lead levels between 30-50μg/dl, health damage may be occurring, even if the effects are asymptomatic while at levels above 80μg/dl, serious permanent health damage may have already occurred.
As soon as lead poisoning is diagnosed, the exposure to potential sources of lead should be immediately discontinued. Depending upon the blood lead levels, severity of clinical symptoms, biochemical and hematological indications, and the nature and history of exposure, further course of treatment is adjudicated. In most cases, however, when the blood lead levels rise to around 80μg/dl, chelation therapy is considered, particularly in the presence of supporting signs and symptoms. Depending upon the actual blood lead levels, repetitive courses of chelation therapy may be required, however, it must be kept in mind that therapeutic chelating agents have potentially adverse side effects and should be used cautiously and on an individual basis. Nevertheless, the best obvious thing to do is – Recognize potential sources of lead and stay away from them!