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Cadmium is one of the most persistent toxins you will ever encounter. It enters your body through food, cigarette smoke, and polluted air, then lodges in your kidneys, liver, and bones for decades. Unlike most substances your body can break down and flush out, cadmium has a biological half-life estimated at 10 to 30 years, meaning your total body burden only grows with time. A single blood test can tell you whether your current exposure is higher than it should be.
What makes cadmium particularly concerning is that harm begins well below the levels that older safety guidelines considered problematic. Research now links even ordinary, everyday exposures to increased risk of kidney disease, heart attacks, stroke, osteoporosis, and several cancers. None of this shows up on a standard metabolic panel or lipid panel. If you have never measured your cadmium level, you have no idea where you stand.
Cadmium (Cd) is a naturally occurring heavy metal with no known beneficial role in human biology. Your body cannot make it, does not need it, and struggles to eliminate it. It enters through two main routes: diet and tobacco smoke. For non-smokers, food is the primary source, especially rice, wheat, leafy vegetables, and shellfish. For smokers, cigarettes deliver a concentrated dose with every puff, and kidney cadmium levels in smokers are roughly double those of non-smokers.
Once absorbed through the gut or lungs, cadmium binds tightly to a protective protein called metallothionein. This complex travels through the bloodstream and accumulates primarily in the outer layer of the kidney (called the kidney cortex) and liver. Your body absorbs roughly 3 to 7% of the cadmium you ingest, but that fraction increases significantly if your iron stores are low, which partly explains why women tend to carry higher cadmium levels than men despite similar dietary intake.
This test measures cadmium in whole blood, which primarily reflects your recent to intermediate exposure over the past several months. Think of it as a snapshot of what is currently circulating. Urine cadmium, by contrast, reflects your cumulative lifetime body burden, because the kidneys slowly release stored cadmium over years. Both measurements are useful, but they answer different questions.
If your blood cadmium is elevated, it suggests ongoing or recent exposure that may be actionable, such as active smoking, a high-risk diet, or an occupational source. A normal blood cadmium does not guarantee that your lifetime burden is low, because cadmium may already be locked in your kidney tissue. For a complete picture, pairing blood cadmium with urine cadmium is ideal.
The kidneys are cadmium's primary target. Cadmium-metallothionein complexes filter through your kidney's tiny tubes (called proximal tubules) and accumulate there, gradually damaging the cells that handle reabsorption. This can lead to protein leaking into urine, reduced kidney filtration, and eventual chronic kidney disease (CKD). In a study of over 12,500 U.S. adults from the National Health and Nutrition Examination Survey (NHANES), higher blood cadmium was associated with decreased kidney function and increased protein in the urine, with the effects varying by sex and whether the person had diabetes or high blood pressure.
What makes this especially relevant for prevention is how early the damage can start. Reviews of industrialized-country populations conclude that kidney effects may begin at blood cadmium levels as low as 0.18 µg/L, which is well within the range seen in the general population. Standard kidney markers like creatinine (a waste product used to estimate filtration) and eGFR (estimated glomerular filtration rate, a measure of how well your kidneys filter blood) may still look normal while cadmium is quietly injuring the tubules underneath.
A major meta-analysis pooling 37 studies and over 348,000 participants found that people in the highest third of cadmium exposure had about 33% higher risk of cardiovascular disease and about 72% higher risk of stroke compared to those in the lowest third. These associations held after adjusting for smoking, blood pressure, cholesterol, and diabetes.
The Strong Heart Study, which followed 3,348 American Indian adults for up to 19 years, provided some of the most detailed data. Comparing the 80th to the 20th percentile of urine cadmium, the study found about 43% higher risk of cardiovascular death, about 75% higher risk of stroke, and about 24% higher risk of any cardiovascular event. These associations persisted in never-smokers. A separate study of over 5,600 Swedish middle-aged adults found that higher blood cadmium was associated with increased coronary artery calcium, a direct measure of plaque buildup in the heart's arteries, even in never-smokers.
If your blood cadmium is above 0.5 µg/L and you have other cardiovascular risk factors, the combination may be accelerating arterial damage in ways that a standard lipid panel cannot detect. This is a concrete reason to measure cadmium alongside traditional heart risk markers.
Cadmium is classified as a Group 1 human carcinogen, meaning there is sufficient evidence that it causes cancer in people. The strongest links are with lung cancer and pancreatic cancer. In the Strong Heart Study of 3,792 American Indians, comparing the 80th to the 20th percentile of urine cadmium, the hazard ratio was 2.27 for lung cancer death and 2.40 for pancreatic cancer death. A separate meta-analysis of 11 studies estimated that people with higher cadmium exposure had roughly double the risk of pancreatic cancer.
The evidence for breast cancer is more mixed. A meta-analysis of case-control studies found that higher urinary cadmium was associated with about 2.2 times the risk of breast cancer, but a pooled analysis of three large prospective cohorts using blood cadmium found no positive association. This discrepancy may reflect differences in what blood versus urine cadmium captures, or residual confounding from smoking. The cancer signal is strongest and most consistent for lung and pancreatic cancers.
Cadmium weakens bones through two routes: it damages the kidney tubules that help activate vitamin D and regulate calcium, and it may also directly impair bone-building cells (based partly on animal research). A 10-year cohort study found that cadmium exposure increased osteoporosis risk and decreased bone mineral density, particularly in women, even at relatively low doses. Swedish data show that fracture risk begins to increase at urinary cadmium levels above 0.5 µg/g creatinine, a level many adults in industrialized countries reach.
A study of over 4,000 older U.S. adults found that those in the highest quartile of blood cadmium had a significantly increased risk of Alzheimer's disease mortality. Cross-sectional NHANES data from over 2,000 adults aged 60 and older linked higher blood cadmium to worse performance on cognitive tests. In children, cadmium exposure has been associated with neurodevelopmental problems, though the evidence is more limited than for lead.
Among the most striking findings comes from a study of over 17,600 U.S. adults with diabetes or prediabetes. Those in the highest quartile of blood cadmium had about 2.2 times the risk of dying from any cause (HR 2.17), about twice the risk of cardiovascular death (HR 2.06), and about 2.4 times the risk of cancer death (HR 2.38) compared to those in the lowest quartile, with a clear graded relationship across exposure levels. In postmenopausal women, higher blood cadmium was significantly associated with increased all-cause mortality.
These are large effect sizes for a single environmental exposure. If your cadmium level is elevated, it represents a modifiable risk factor sitting on top of every other risk factor you carry.
There is no universally adopted set of clinical decision thresholds for blood cadmium. The ranges below are derived from large observational studies (primarily NHANES and European cohorts) that linked specific blood cadmium levels to disease outcomes. They are empiric risk strata, not formal clinical cutpoints, and your lab may report results differently. Always compare your results within the same lab over time.
| Risk Tier | Blood Cadmium (µg/L) | What It Suggests |
|---|---|---|
| Low | Below 0.3 | Minimal exposure. Consistent with non-smoking and low dietary cadmium intake. |
| Borderline | 0.3 to 0.5 | Background-level exposure. Cardiovascular and kidney risks begin to appear in epidemiologic data at these levels. |
| Elevated | Above 0.5 to 1.0 | Associated with increased risk of cardiovascular disease, kidney damage, and bone loss, even in never-smokers. |
| High | Above 1.0 | Strongly associated with increased mortality, cancer risk, and organ damage. Warrants source identification and aggressive exposure reduction. |
A Polish cohort study found that blood cadmium above 0.71 µg/L was associated with increased cancer risk in men. U.S. trend data from 1999 to 2018 show that population blood cadmium levels have been declining over time, but significant variation persists by smoking status, sex, and comorbidities.
The biggest source of misinterpretation is smoking status. If you are a current smoker, your blood cadmium will be elevated primarily because of ongoing tobacco exposure, not necessarily because of a contaminated diet or workplace. This does not make the reading less meaningful (cadmium from tobacco is just as toxic), but it changes what action you should take. Quitting smoking is the single most effective way to lower your blood cadmium.
Age and sex also matter for interpretation. Blood cadmium rises naturally with age due to ongoing accumulation, and women tend to have 1.4 to 1.8 times higher blood and urine cadmium than men at the same dietary intake, largely because lower iron stores drive higher absorption.
Because cadmium accumulates over decades, a single blood reading provides a useful starting point but not the full story. Your first result establishes a baseline. If you then make changes, like quitting smoking, shifting your diet away from high-cadmium foods, or correcting an iron deficiency that was increasing your absorption, a follow-up test 6 to 12 months later can confirm whether those changes are translating into a lower circulating level.
The natural fluctuation in urinary cadmium measurements (corrected for creatinine) between tests in the same person averages about 18%. Because of this, you would need to see a change of roughly 54% or more between two readings to be confident the shift is real rather than normal fluctuation. Blood cadmium likely has similar variability. For this reason, do not overreact to small changes between tests. Look for consistent trends across two or more measurements before concluding your exposure has meaningfully shifted.
A reasonable cadence: get a baseline now, retest in 6 to 12 months if you are making active changes, then annually or every two years if your level is in the low or borderline range and your exposure profile has not changed.
If your blood cadmium is above 0.5 µg/L, the first step is identifying the source. Are you a current or recent smoker? Do you eat large amounts of rice, root vegetables, or shellfish from potentially contaminated regions? Do you work with batteries, pigments, or metal smelting? The answer determines what exposure reduction looks like for you.
Beyond source identification, consider ordering companion tests. A kidney function panel (including cystatin C and eGFR) can detect early filtration loss. A urine cadmium test reflects your lifetime body burden and adds context that blood cadmium alone cannot provide. Checking ferritin is also worthwhile, since low iron increases cadmium absorption and is itself correctable. If bone health is a concern, a bone density scan (DEXA) can assess whether cadmium-related bone loss has already begun.
For blood cadmium above 1.0 µg/L, or for any level paired with kidney or bone abnormalities, involving a toxicologist or occupational medicine specialist is reasonable. There is no widely used chelation therapy for cadmium in the general population (unlike for lead), so the mainstay of management is exposure elimination, nutritional optimization (especially iron, zinc, and calcium, which compete with cadmium for absorption), and ongoing monitoring of the organs most likely to be affected.
Evidence-backed interventions that affect your Cadmium level
Cadmium is best interpreted alongside these tests.