What are the effects of cadmium poisoning on the human body?

Effects of Cadmium Poisoning on the Human Body

Cadmium poisoning causes multi-organ toxicity with the kidney being the primary target organ, leading to proximal tubular dysfunction, bone demineralization, increased cancer risk (particularly lung, kidney, prostate, pancreatic, and breast), and potential cardiovascular and neurological effects, with an extremely long biological half-life of 15-20 years making it a cumulative toxin. 1, 2, 3, 4

Primary Target Organ: Renal System

The kidney, specifically the proximal tubular cells, is the critical organ and main site of cadmium accumulation following chronic exposure. 3, 4

• Cadmium accumulates preferentially in the proximal tubular cells of the kidney, causing progressive renal dysfunction 3
• Renal toxicity manifests as proteinuria and tubular dysfunction, which can progress to chronic kidney disease 2, 3
• The World Health Organization identified renal dysfunction as the critical effect of cadmium exposure 5
• Even low environmental exposures in industrialized countries can adversely affect kidney function in the general population 3
• Individuals with diabetes represent a particularly sensitive subgroup at risk for cadmium-induced renal dysfunction at very low exposure levels 5

Skeletal System Effects

Cadmium causes bone demineralization through both direct bone damage and indirect effects secondary to renal dysfunction. 3, 4

• Chronic cadmium exposure leads to disturbed calcium metabolism and bone effects 4
• The most severe manifestation is itai-itai disease, a form of cadmium-induced renal osteomalacia characterized by severe bone pain and fractures, first identified in Japan after World War II 5
• Bone effects were first reported in humans in the 1940s and represent a well-established consequence of chronic exposure 5

Respiratory System Effects

Occupational inhalation exposure to cadmium impairs lung function and significantly increases lung cancer risk. 1, 3, 4

• Excessive airborne cadmium exposure in industrial settings impairs lung function 3
• Cadmium and its compounds are classified as human carcinogens, causing lung cancer after inhalation 4
• The first reported health effects of cadmium in 1858 included respiratory symptoms among persons using cadmium-containing polishing agents 5

Carcinogenic Effects

Cadmium exposure is associated with multiple cancer types through mechanisms including oxidative stress, DNA repair interference, and replacement of essential metal ions. 1

• Primary cancer associations include lung, kidney, prostate, and pancreatic cancers 1
• Additional cancer risks include breast, urinary system, and bladder cancers 1
• Carcinogenesis mechanisms involve oxidative stress with inhibition of antioxidant enzymes, promotion of lipid peroxidation, and interference with DNA repair systems 1
• Cadmium can replace essential redox-active metal ions, disrupting normal cellular function 1

Cardiovascular System Effects

Long-term cadmium exposure causes cardiovascular system toxicity. 2

• Chronic exposure through air, water, soil, and food leads to cardiovascular toxicity 2
• The cardiovascular effects contribute to the overall organ system damage from cadmium accumulation 2

Nervous System Effects

Cadmium affects both central and peripheral nervous systems, though neurotoxic effects during development may be secondary to zinc metabolism interference rather than direct brain toxicity. 2, 4

• Long-term exposure causes central and peripheral nervous system toxicity 2
• The blood-brain barrier prevents direct cadmium entry into the CNS 4
• Reported neurotoxic effects during development are likely secondary to cadmium interference with zinc metabolism, particularly involving metallothionein III in the brain 4

Reproductive System Effects

Cadmium causes reproductive system toxicity, though quantitative assessment in humans remains uncertain. 2, 5

• Chronic exposure leads to reproductive system toxicity 2
• Reproductive effects were studied at an early stage, but quantitative human assessment is still subject to considerable uncertainty 5

Gastrointestinal Effects

Acute cadmium exposure causes gastrointestinal symptoms. 5

• The first reported health effects in 1858 included gastrointestinal symptoms among exposed individuals 5
• Acute poisoning requires gastrointestinal tract irrigation as part of initial management 2

Toxicokinetic Characteristics

Cadmium's extremely long biological half-life of 15-20 years makes it a cumulative toxin that the body cannot effectively eliminate. 4, 5

• The human body has limited ability to respond to cadmium exposure since it does not undergo metabolic degradation into less toxic species and is poorly excreted 1
• Cadmium is efficiently retained in the human body and accumulates throughout life 3
• Metallothionein, a low-molecular-weight protein with high metal affinity, plays a major role in cadmium kinetics and metabolism 4
• The balance between cadmium-metallothionein and non-bound cadmium in renal tissue is crucial for toxicity expression 4

Diagnostic Considerations

Cadmium levels can be measured in multiple biological samples to assess exposure and body burden. 2

• Cadmium can be measured in blood, urine, hair, nail, and saliva samples 2
• Urinary cadmium excretion is used to assess cadmium body burden and shows consistent associations with renal and bone biomarkers 3
• Biomarkers of susceptibility include metallothionein gene expression in peripheral lymphocytes and autoantibodies against metallothionein in blood plasma 5