Table 1.
Main Sources of Exposure, Pharmacokinetics, and Public Health and Regulatory Guidelines of Established Cardiotoxic Metals Relevant for General Populations
| Lead | Cadmium | Arsenic | |
|---|---|---|---|
| Sources of exposure |
Old paint Soil Water Smoking Drinks (wine) Ammunition Air (incinerators, combustion) Aviation fuels |
Smoking Food (organ meats, shellfish, root vegetables, green leafy vegetables) Air (incinerators, combustion, tires) |
Water Rice Drinks (apple juice, wine) Air and dust |
| Absorption |
Respiratory tract (100%) Gastrointestinal tract (<50%) Dermal contact (not relevant, except pica in children) |
Respiratory tract (100%) Gastrointestinal tract (<50%) Dermal contact (not relevant) |
Gastrointestinal tract (100% in water, <50% in food) Respiratory tract (<50%) Dermal contact (<5%) |
| Biotransformation | No | No | Methylation (via 1 carbon metabolism) |
| Accumulation |
Cortical bone (half‐life >30 y) Trabecular bone (half‐life 5–10 y) |
Liver, kidney, other soft tissues (half‐life >30 y) | No |
| Elimination | Minimal | Minimal | Urine |
| Established biomarkers |
Blood (half‐life 1 mo, reflects both external and bone levels) Bone (noninvasively through K‐shell XRF) |
Blood (half‐life 1 mo, reflects both external and soft‐tissue levels) Urine (half‐life of decades) |
Urine (half‐life in 3 phases, ranging from 1–4 d to 1 mo)* Toenail (past exposures ~6 mo ago) |
| Guidelines |
CDC blood reference value for children and pregnancy: 3.5 μg/dL OSHA occupational standard: 40 μg/dL ACOEM recommendation for regular blood testing: 10 μg/dL |
OSHA action urinary level: 3 μg/g creatinine OSHA action blood level: 5 μg/L |
Biological Exposure Index for the sum of inorganic and methylated arsenic in urine: 35 μg/g creatinine* EPA standard in drinking water is 10 μg/L |
ACOEM indicates American College of Occupational and Environmental Medicine; CDC, Centers for Disease Control and Prevention; EPA, Environmental Protection Agency; OSHA, Occupational and Safety Health Administration; and XRF, x‐ray fluorescence.
When assessing arsenic in the urine, it is important to either avoid seafood intake for at least 7 days (if only total arsenic is measured) or to analyze arsenic species including arsenobetaine (which is a specific biomarker of arsenicals in seafood). Arsenobetaine and other organic arsenic species in seafood are generally nontoxic.