There is no safe threshold for lead exposure: Α literature review

Abstract

L ead was one of the most dangerous environmental toxic substances for a long time in western countries, and this is still the case for many places on earth today. Its neurotoxic potential is highly significant but its secure blood level concentration remains unknown. The aim of this study was to approach the above issue from the perspective of social psychiatry. A systematic search was made of Dialog and Datastar interfaces for data regarding the neuropsychiatric complications of direct or chronic exposure to lead, and a review of the relevant literature was conducted using the databases Medline, Embase, CAB Global Health and Cochrane. Lead affects the cholinergic, dopaminergic and gloutamergic systems, thus intervening in the normal function of neurotransmion. The consequence of neurotoxicity in the central nervous system includes apoptosis and excitotoxicity. Direct as well as chronic exposure causes serious neurological symptoms and possibly constant cognitive impairment. Acute encephalopathy, the most serious expression of lead poisoning, occurs in blood level concentrations over 100 μg/dL in adults and 80-100 μg/dL in children. Early symptoms of lead neurotoxicity include irritability, headaches and difficulties in concentration in both children and adults. Continuous exposure in children produces neurobehavioral symptoms, such as decreased concentration, inability to follow instructions, difficulty to play games and low IQ, which are associated with concentrations of 10-35 μg/dL. However, some studies claim that cognitive decline and low IQ can occur in concentrations <10 μg/dL. The commonest symptom in adults is peripheral neuropathy with foot drop. Prenatal exposure to lead has been correlated with antisocial behavior and schizophrenia. Long-term lead exposure causing low and medium lead concentration in blood has been linked to depression as well as generalized anxiety disorder and other behavioral disorders. High blood level concentrations correlate with psychotic symptoms like delusions and hallucinations but more rarely with psychotic syndromes. Despite the fact that lead has been banned from gasoline, paint and water pipes, quite significant quantities of lead still exist, particularly in deprived areas of modern cities, in transition zones and city centers,

Childhood lead poisoning: an overview

“…25 At the same time, with reference to the level of 'lead toxicity' in children, ACCLPP eliminated the term 'level of concern' for blood lead level (previously defined as 10 μg/dL) and replaced it with a reference level of 5 μg/dL, based on the 97.5th percentile of the population blood lead level in children aged between 1 and 5 years. 2,13,24 This was supported by the American Academy of Pediatrics who acknowledged that even the lowest degree of lead exposure might harm children, 13,23,26 and echoed the European Food Safety Authority who concluded that there is no known safe exposure to lead as evidenced by international studies in Europe. [27][28][29] In other words, there is no safe or 'non-toxic' blood lead level.…”

Modulation of Ethanol-Metabolizing Enzymes by Developmental Lead Exposure: Effects in Voluntary Ethanol Consumption

“…Alarmingly, early-life Pb exposure even in trace amounts induces neurobehavioral manifestations that may not be evident until later in life (Vorvolakos et al, 2016). They include hyperactivity, cognitive deficits and altered responses to drugs of abuse including EtOH.…”

New and unusual causes of foot drop

“…These include diseases affecting the central nervous system, trauma, diseases affecting the peripheral nervous system and diseases or trauma affecting the muscle and tendon. Many reasons have been reported such as ganglion cyst in the proximal tibiofibular joint [3], motor cortex contusion [4], long-term lead intoxication [5], tight application of compression bandage [6,7], after lateral decubitus position [8] following dislocation reduction after total hip arthroplasty and gluteal haematoma [9,10], a complication of disc surgery [11], peripheral nerve entrapment [12,13], poorly administered injections (14], sciatic nerve pressure, piriformis syndrome [15], knee dislocations [16], following spinal and spinoepidural anaesthesia [17], paraspinal abscess [18], myopathies [19], neuropathic demyelinisation, hereditary neuropathies [20], popliteal artery aneurism [21], stroke [22,23], neuromuscular diseases [24,25], degenerative lumbar spinal diseases [26], gluteal compartment syndrome [27], decompression in burns [28], parasitic diseases such as neuro schistomiasis [29], after lower extremity compartment syndrome [30], and after total knee prosthesis [31].…”