Arsenic and ultraviolet radiation exposure: melanoma in a New Mexico non-Hispanic white population

Association between arsenic exposure and melanoma: a meta-analysis

BACKGROUND

Melanoma is a highly malignant tumor. Moreover, its prevalence is increasing at a rapid rate year after year. Currently, UV light is the leading cause of melanoma, although numerous other risk factors exist, including arsenic. The link between arsenic and the likelihood of developing melanoma has long been debated. As a result, we conducted a meta-analysis of the available data to investigate the association between arsenic exposure and melanoma.

METHODS

We identified seven non-randomized controlled studies with 41,949 participants by searching the Chinese CNKI, Embase, PubMed, and Cochrane Library databases. We then used random-effects or fixed-effects models to evaluate the pooled odds ratios (OR) and their 95% confidence intervals (CI). Subgroup analyses were also carried out with different included regions.

RESULTS

Participants in the study who were exposed to arsenic had a somewhat higher chance of developing melanoma than those who were not (OR = 1.47, 95% CI 1.01-2.13). A subgroup analysis was also carried out for the US region, and the findings were not statistically significant (OR = 1.40, 95% CI 0.94-2.07).

CONCLUSION

This meta-analysis shows that arsenic exposure relates to an increased risk of melanoma.

Automated Mass Screening for Comorbidities of Vitiligo Using the National Health Insurance Database

Although the study design for identifying specific disease associations using a health insurance database has been well-established, few studies explore unknown comorbidities. We conducted a series of automated case-control studies for all International Classification of Disease, Tenth Revision, Clinical Modification diagnostic codes (A01-Z99) using the Korean National Health Insurance database from 2007 to 2017 to reveal undiscovered disease associations of vitiligo. A total of 90,297 patients with vitiligo and 90,297 age- and sex-matched controls without vitiligo were included, and disease associations for 1,265 relevant diagnostic codes were screened. A meta-analysis of the individual ORs for each International Classification of Disease, Tenth Revision code was performed to identify the possibility of selection bias. Finally, the association with vitiligo was significantly increased in 45 diseases and decreased in 6 diseases. We not only reaffirmed the positive correlation between vitiligo and other autoimmune diseases but also observed associations with obsessive-compulsive disorder and melanoma. In contrast, femur fracture showed a negative correlation. In this study, we attempted an automated mass screening and suggested a possible selection bias. In the era of large-scale databases, a systematic and comprehensive approach might be needed.

Occupational exposure to arsenic, mercury and UV radiation and risk of melanoma: a case-control study from Italy

BACKGROUND

Melanoma is mainly caused by sunlight radiation, but other environmental risk factors are not well known. We investigated the association between cutaneous melanoma and occupational exposure to arsenic, mercury and UV radiation.

METHODS

A hospital-based case-control study was conducted in the inpatient wards of IDI-San Carlo Rome, Italy, including 304 incident cases of cutaneous melanoma and 305 frequency-matched controls. Detailed sociodemographic, clinical and host-related factors were collected, and all participants were physically examined using dermoscopy and following standard protocol for recording pigmented lesions. Four experts assessed exposure to arsenic, mercury and UV radiation based on occupational history. A multidimensional variable was created for each risk factor, by combining intensity and probability of exposure. Multivariable logistic regression models were run to calculate odds ratios (OR) and 95% confidence intervals (CI) of the association between exposure to these agents and melanoma.

RESULTS

A total of 5.4% of the cases vs 2.4% of the controls were exposed to arsenic (OR = 3.12; 95% CI = 1.10-8.86 for high probability and high exposure to arsenic) after controlling for sex, age, smoking status, number of nevi, phototype and history of sunburns in childhood/adolescence. Occupational exposure to mercury and UV radiation was not associated with the risk of melanoma.

CONCLUSIONS

Subjects exposed to arsenic at the workplace may be at increased risk of developing cutaneous melanoma in comparison to subjects not exposed to this agent. Further studies should be designed to investigate occupational exposure to arsenic and mercury and melanoma and confirm the findings are warranted.

Arsenic and cancer: Evidence and mechanisms

Arsenic is a potent carcinogen and poses a significant health concern worldwide. Exposure occurs through ingestion of drinking water and contaminated foods and through inhalation due to pollution. Epidemiological evidence shows arsenic induces cancers of the skin, lung, liver, and bladder among other tissues. While studies in animal and cell culture models support arsenic as a carcinogen, the mechanisms of arsenic carcinogenesis are not fully understood. Arsenic carcinogenesis is a complex process due its ability to be metabolized and because of the many cellular pathways it targets in the cell. Arsenic metabolism and the multiple forms of arsenic play distinct roles in its toxicity and contribute differently to carcinogenic endpoints, and thus must be considered. Arsenic generates reactive oxygen species increasing oxidative stress and damaging DNA and other macromolecules. Concurrently, arsenic inhibits DNA repair, modifies epigenetic regulation of gene expression, and targets protein function due its ability to replace zinc in select proteins. While these mechanisms contribute to arsenic carcinogenesis, there remain significant gaps in understanding the complex nature of arsenic cancers. In the future improving models available for arsenic cancer research and the use of arsenic induced human tumors will bridge some of these gaps in understanding arsenic driven cancers.

Ambient UVR and Environmental Arsenic Exposure in Relation to Cutaneous Melanoma in Iowa

Intermittent sun exposure is the major environmental risk factor for cutaneous melanoma (CM). Cumulative sun exposure and other environmental agents, such as environmental arsenic exposure, have not shown consistent associations. Ambient ultraviolet radiation (UVR) was used to measure individual total sun exposure as this is thought to be less prone to misclassification and recall bias. Data were analyzed from 1096 CM cases and 1033 controls in the Iowa Study of Skin Cancer and Its Causes, a population-based, case-control study. Self-reported residential histories were linked to satellite-derived ambient UVR, spatially derived environmental soil arsenic concentration, and drinking water arsenic concentrations. In men and women, ambient UVR during childhood and adolescence was not associated with CM but was positively associated during adulthood. Lifetime ambient UVR was positively associated with CM in men (OR for highest vs. lowest quartile: 6.09, 95% confidence interval (CI) 2.21–16.8), but this association was not as strong among women (OR for highest vs. lowest quartile: 2.15, 95% CI 0.84–5.54). No association was detected for environmental soil or drinking water arsenic concentrations and CM. Our findings suggest that lifetime and adulthood sun exposures may be important risk factors for CM.

Arsenic Exposure and Melanoma Among US Adults Aged 20 or Older, 2003-2016

OBJECTIVES

Chronic exposure to arsenic has been reported as a risk factor for nonmelanoma skin cancer, notably squamous cell carcinoma. However, current knowledge is limited about the association between arsenic exposure and melanoma. Our objectives were to (1) measure the association between total urinary arsenic levels and melanoma compared with nonmelanoma skin cancer and no cancer and (2) analyze the association between water source and melanoma and nonmelanoma skin cancer.

METHODS

We collected cross-sectional data from the 2003-2016 cycles of the National Health and Nutrition Examination Survey. We conducted univariate and multivariate logistic regressions. To evaluate the possible association of skin cancer with source of tap water, we calculated odds ratios for participants with melanoma and nonmelanoma skin cancer, compared with participants with no cancer.

RESULTS

White race, higher education, higher socioeconomic status, and smoking history were associated with melanoma and nonmelanoma skin cancer in the full study population. After adjusting for age and race/ethnicity, the adjusted odds ratio of participants with >50 μg/L of total urinary arsenic for melanoma or nonmelanoma skin cancer was 1.87 (95% CI, 0.58-6.05) and 2.23 (95% CI, 1.12-4.45) times higher compared with no cancer, respectively. Participants with nonmelanoma skin cancer had 2.06 increased odds of reporting a nonmunicipal water source compared with participants without cancer.

CONCLUSIONS

We did not find a relationship between the incidence of melanoma and exposure to arsenic among US adults. Nonmunicipal water sources were associated with nonmelanoma skin cancer and should be further investigated.

Toenails as a biomarker of exposure to arsenic: A review

This systematic review summarizes the current evidence related to the reliability of toenail total arsenic concentrations (thereafter "arsenic") as a biomarker of long-term exposure. Specifically, we reviewed literature on consistency of repeated measures over time, association with other biomarkers and metal concentrations, factors influencing concentrations, and associations with health effects. We identified 129 papers containing quantitative original data on arsenic in toenail samples covering populations from 29 different countries. We observed geographic differences in toenail arsenic concentrations, with highest median or mean concentrations in Asian countries. Arsenic-contaminated drinking water, occupational exposure or living in specific industrial areas were associated with an increased toenail arsenic content. The effects of other potential determinants and sources of arsenic exposure including diet, gender and age on the concentrations in toenails need further investigations. Toenail arsenic was correlated with the concentrations in hair and fingernails, and with urine arsenic mainly among highly exposed populations with a toenail mean or median ≥1 μg/g. Overall, there is a growing body of evidence suggesting that arsenic content from a single toenail sample may reflect long-term internal dose-exposure. Toenail arsenic can serve as a reliable measure of toxic inorganic arsenic exposure in chronic disease research, particularly promising for cancer and cardiovascular conditions.

Quantification of Elemental Contaminants in Unregulated Water across Western Navajo Nation

The geologic profile of the western United States lends itself to naturally elevated levels of arsenic and uranium in groundwater and can be exacerbated by mining enterprises. The Navajo Nation, located in the American Southwest, is the largest contiguous Native American Nation and has over a 100-year legacy of hard rock mining. This study has two objectives, quantify the arsenic and uranium concentrations in water systems in the Arizona and Utah side of the Navajo Nation compared to the New Mexico side and to determine if there are other elements of concern. Between 2014 and 2017, 294 water samples were collected across the Arizona and Utah side of the Navajo Nation and analyzed for 21 elements. Of these, 14 elements had at least one instance of a concentration greater than a national regulatory limit, and six of these (V, Ca, As, Mn, Li, and U) had the highest incidence of exceedances and were of concern to various communities on the Navajo Nation. Our findings are similar to other studies conducted in Arizona and on the Navajo Nation and demonstrate that other elements may be a concern for public health beyond arsenic and uranium.