Lennart Hellström

Low level exposure to cadmium and early kidney damage: the OSCAR study

OBJECTIVES To study the dose-response relation between cadmium dose and renal tubular damage in a population of workers and people environmentally or occupationally exposed to low concentrations of cadmium. METHODS Early kidney damage in 1021 people, occupationally or environmentally exposed to cadmium, was assessed from cadmium in urine to estimate dose, and protein HC (α1-microglobulin) in urine to assess tubular proteinuria. RESULTS There was an age and sex adjusted correlation between cadmium in urine and urinary protein HC. The prevalence of tubular proteinuria ranged from 5% among unexposed people to 50% in the most exposed group. The corresponding prevalence odds ratio was 6.0 (95% confidence interval (95% CI) 1.6 to 22) for the highest exposure group, adjusted for age and sex. Multiple logistic regression analysis showed an increasing prevalence of tubular proteinuria with urinary cadmium as well as with age. After adjustment to the mean age of the study population (53 years), the results show an increased prevalence of 10% tubular proteinuria (taking into account a background prevalence of 5%) at a urinary cadmium concentration of 1.0 nmol/mmol creatinine. CONCLUSION Renal tubular damage due to exposure to cadmium develops at lower levels of cadmium body burden than previously anticipated.

Low-level cadmium exposure and osteoporosis

Osteoporosis is a major cause of morbidity worldwide. A number of risk factors, such as age and gender, are well established. High cadmium exposure causes renal damage and in severe cases also causes osteoporosis and osteomalacia. We have examined whether long‐term low‐level cadmium exposure increases the risk of osteoporosis. Bone mineral density (BMD) in the forearm was measured in 520 men and 544 women, aged 16–81 years, environmentally or occupationally exposed to cadmium, using dual‐energy X‐ray absorptiometry (DXA) technique. Cadmium in urine was used as the dose estimate and protein HC was used as a marker of renal tubular damage. There was a clear dose‐response relation between cadmium dose and the prevalence of tubular proteinuria. Inverse relations were found between cadmium dose, tubular proteinuria, and BMD, particularly apparent in persons over 60 years of age. There was a dose‐response relation between cadmium dose and osteoporosis. The odds ratios (ORs) for men were 2.2 (95% CI, 1.0‐4.8) in the dose group 0.5‐3 nmol Cd/mmol creatinine and 5.3 (2.0‐14) in the highest dose category (≥3 nmol/mmol creatinine) compared with the lowest dose group (<0.5 nmol Cd/mmol creatinine). For women, the OR was 1.8 (0.65‐5.3) in the dose group 0.5‐3 nmol Cd/mmol creatinine. We conclude that exposure to low levels of cadmium is associated with an increased risk of osteoporosis.

Cadmium Exposure and Distal Forearm Fractures

The aim of this study was to analyze the relationship between low‐level cadmium exposure and distal forearm fractures. Altogether, 1021 men and women exposed to cadmium in Sweden were included. The study indicates that cadmium exposure is associated with increased risk of forearm fractures in people over the age of 50.

Bone mineral density changes in relation to environmental PCB exposure

Background Bone toxicity has been linked to organochlorine exposure following a few notable poisoning incidents, but epidemiologic studies in populations with environmental organochlorine exposure have yielded inconsistent results. Objectives The aim of this study was to investigate whether organochlorine exposure was associated with bone mineral density (BMD) in a population 60–81 years of age (154 males, 167 females) living near the Baltic coast, close to a river contaminated by polychlorinated biphenyls (PCBs). Methods We measured forearm BMD in participants using dual energy X-ray absorptiometry; and we assessed low BMD using age- and sex-standardized Z-scores. We analyzed blood samples for five dioxin-like PCBs, the three most abundant non-dioxin-like PCBs, and p,p′-dichloro-phenyldichloroethylene (p,p′-DDE). Results In males, dioxin-like chlorobiphenyl (CB)-118 was negatively associated with BMD; the odds ratio for low BMD (Z-score less than −1) was 1.06 (95% confidence interval, 1.01–1.12) per 10 pg/mL CB-118. The sum of the three most abundant non-dioxin-like PCBs was positively associated with BMD, but not with a decreased risk of low BMD. In females, CB-118 was positively associated with BMD, but this congener did not influence the risk of low BMD in women. Conclusions Environmental organochlorine exposures experienced by this population sample since the 1930s in Sweden may have been sufficient to result in sex-specific changes in BMD.

Enzymuria in a population living near a cadmium battery plant.

OBJECTIVES--To study the body burden of cadmium and signs of tubular dysfunction in a rural population living near a closed nickel cadmium battery plant. METHODS--Cadmium and N-acetyl-beta-glucosaminidase (NAG) in urine were measured in 72 subjects who lived close to the plant. RESULTS--Residents living close to the plant had higher median urinary cadmium concentrations than those living farther away (1.01 v 0.46 nmol/mmol creatinine) and than a control group (0.2 nmol/mmol creatinine). There was a significant correlation between urinary cadmium and the excretion of NAG in urine as well as signs of tubular dysfunction in residents who excreted urinary cadmium above 0.5 nmol/mmol creatinine. CONCLUSION--Tubular dysfunction may appear in environmentally exposed subjects at lower cadmium body burdens than previously anticipated.

Using environmental concentrations of cadmium and lead to assess human exposure and dose

Objectives:Using environmental concentrations and Geographic Information Systems (GIS) to model human exposure is an emerging tool in environmental epidemiology. To evaluate the usefulness of this, we investigated to what extent cadmium and lead concentrations in soil and moss could be used as potential determinants for cadmium and lead exposure for a population living near a battery plant. Methods: Cadmium in urine and blood and lead in blood, as well as food, smoking habits, places of residence, occupations and health, were determined for 512 individuals living near a closed down battery factory in Sweden. Cadmium and lead contents in moss were available through previous assessments by the Geological Survey of Sweden. Soil samples had been collected at various distances from the factory, and analyzed for cadmium and lead contents in 1990. Kriging technique in GIS was used to create areas with different metal concentrations based on these measurements. By linking individual address coordinates to mapped concentration levels, each study subject home address received a value of cadmium and lead in moss and soil. Results: We found a statistically significant association between lead in soil and lead in blood, for female subjects eating homegrown vegetables regularly. No significant association was found between cadmium in soil and cadmium in urine for either gender in the study population. No clear associations were found for either gender regarding lead and cadmium in moss and lead in blood or cadmium in urine or in blood. Conclusion: In general, environmental concentrations may not be useful surrogates for assessing human exposure to lead and cadmium, but concentrations of metals in soil around emitting point sources can be a complement for estimating the exposure in certain subgroups.