Occupational exposures and risks of liver cancer among Shanghai female textile workers--a case-cohort study

Association of Combined Estrogen-Progestogen and Progestogen-Only Contraceptives with the Development of Cancer

Combined estrogen-progestogen contraceptives (oral contraceptives or OCs) and progestogen-only contraceptives (POCs) are synthetic steroids that bind to steroid hormone receptors, which are widespread throughout the body. They have a profound effect on cellular physiology. Combined OCs have been classified by the International Agency for Research on Cancer (IARC) as Group 1 carcinogens, but their findings have not been updated recently. In order to update the information and better understand the impact that OCs and POCs have on the risk of development of cancers, a comprehensive literature search was undertaken, focusing on more recently published papers. In agreement with the IARC, the recent literature confirms an increased risk of breast cancer and cervical cancer with the use of OCs. The recent literature also confirms the IARC conclusion that OCs decrease the risk of ovarian and endometrial cancers. However, there is little support from recent studies for the IARC conclusion that OCs decrease the risk of colorectal cancer or increase the risk of liver cancer. For liver cancer, this may be due to the recent studies having been performed in areas where hepatitis is endemic. In one large observational study, POCs also appear to increase the overall risk of developing cancer. OCs and POCs appear to increase the overall risk of cancer when carefully performed studies with the least intrinsic bias are considered.

Summary

OCs have been classified as cancer-causing agents, especially leading to increases in breast cancer and cervical cancer. A review of the recent scientific literature was performed to see whether this still appears to be the case. The recent literature supports the cancer-causing role of OCs especially for breast cancer and cervical cancer. Studies also indicate that progesterone-only contraceptives (such as implants and vaginal rings) also can cause cancer. This is especially true for breast cancer and cervical cancer.

Exploiting bilosomes for delivering bioactive polysaccharide isolated from Enteromorpha intestinalis for hacking hepatocellular carcinoma

Bile salts containing vesicles (bilosomes) represent a portentous vesicular carrier that showed prosperous results in delivering active moieties in the gastrointestinal tract (GIT). In this study, bilosomes were exploited to deliver sulfated polysaccharide-protein complexes of Enteromorpha intestinalis (EHEM) and enhance its activity against hepatocellular carcinoma as well as resist harsh GIT conditions. Bilosomes were prepared using the sodium salt of three different bile acids (cholic, deoxycholic, taurodeoxycholic) and two different nonionic surfactants (Span 40 and 65). The effects of experimental variables were thoroughly studied to obtain an optimum formulation loading EHEM. The selected formulation (EH-Bilo-2) prepared with sodium cholate and Span 65 displayed nano-sized (181.1 ± 16.80 nm) spherical vesicles with reasonable entrapment efficiency (71.60 ± 0.25%) and controlled release properties; and thus was investigated as anti-hepatocarcinogenic candidate for in vivo studies. Treatment of hepatocellular carcinoma (HCC) bearing rats with EH-Bilo-2 experienced significant decrease in serum α-fetoprotein, endoglin, lipocalin-2, and heat shock protein 70 levels vs. the untreated counterparts. Furthermore, the photomicrographs of their liver tissue sections showed focal area of degenerated pleomorphic hepatocytes with fine fibrosis originating from the portal area. Thus, the optimized bilosomal formulation is a promising delegate for tackling hepatocellular carcinoma owing to its powerful anti-cancer and anti-angiogenic activity.

Use of job-exposure matrices to estimate occupational exposure to pesticides: A review

The health effects of pesticides have been extensively studied in epidemiology, mainly in agricultural populations. However, pesticide exposure assessment remains a key methodological issue for epidemiological studies. Besides self-reported information, expert assessment or metrology, job-exposure matrices still appear to be an interesting tool. We reviewed all existing matrices assessing occupational exposure to pesticides in epidemiological studies and described the exposure parameters they included. We identified two types of matrices, (i) generic ones that are generally used in case-control studies and document broad categories of pesticides in a large range of jobs, and (ii) specific matrices, developed for use in agricultural cohorts, that generally provide exposure metrics at the active ingredient level. The various applications of these matrices in epidemiological studies have proven that they are valuable tools to assess pesticide exposure. Specific matrices are particularly promising for use in agricultural cohorts. However, results obtained with matrices have rarely been compared with those obtained with other tools. In addition, the external validity of the given estimates has not been adequately discussed. Yet, matrices would help in reducing misclassification and in quantifying cumulated exposures, to improve knowledge about the chronic health effects of pesticides.

Pesticide exposure and liver cancer: a review

PURPOSE

To review the epidemiologic literature examining pesticide exposure and liver cancer incidence.

METHODS

A search of the MEDLINE and Embase databases was conducted in October 2015. Eligibility criteria included examining hepatocellular carcinoma (HCC) or primary liver cancer, pesticides as an exposure of interest, and individual-level incidence. The review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Forty-eight papers were assessed for eligibility and 15 studies were included in the review. The majority of studies were conducted in China and Egypt (n = 8), used a case-control design (n = 14), and examined HCC (n = 14). Most studies showed no association between self-reported and/or occupational exposure to pesticides and liver cancer risk. Six studies demonstrated statistically significant positive associations, including three biomarker-based studies (two using pre-diagnostic sera) that reported higher serum levels of dichlorodiphenyltrichloroethane (DDT) were associated with increased HCC risk. Studies indirectly measuring pesticide exposure using self-reported exposure, occupation, job-exposure matrices, or geographic residence demonstrated inconsistent results. These studies were limited by exposure assessment methods, lack of confounder information, minimal case confirmation, selection bias, and/or over-adjustment.

CONCLUSIONS

There is mixed evidence suggesting a possible association between specific pesticides and HCC risk, with the strongest evidence observed in biomarker-based studies. In particular, organochlorine pesticides, including DDT, may increase HCC risk. Future research should focus on improved pesticide exposure assessment methods, potentially incorporating multiple approaches including biomonitoring while considering the chemicals of interest, historical exposure to address latency periods, and examining specific chemicals and exposure pathways.

Non‑infective occupational risk factors for hepatocellular carcinoma: A review (Review)

Liver cancer is the second leading worldwide cause of cancer‑associated mortalities. Hepatocellular carcinoma, which accounts for the majority of liver tumors, ranks fifth among types of human cancer. Well‑established risk factors for liver cancer include the hepatitis B and C viruses, aflatoxins, alcohol consumption, and oral contraceptives. Tobacco smoking, androgenic steroids, and diabetes mellitus are suspected risk factors. Current knowledge regarding non‑infective occupational risk factors for liver cancer is inconclusive. The relevance of liver disorders to occupational medicine lies in the fact that the majority of chemicals are metabolized in the liver, and toxic metabolites generated via metabolism are the predominant cause of liver damage. However, their non‑specific clinical manifestations that are similar in a number of liver diseases make diagnosis difficult. Furthermore, concomitant conditions, such as viral hepatitis and alcohol or drug abuse, may mask liver disorders that result from occupational hepatotoxic agents and block the demonstration of an occupational cause. The identification of environmental agents that result in human cancer is a long and often difficult process. The purpose of the present review is to summarize current knowledge regarding the association of non‑infective occupational risk exposure and HCC, to encourage further research and draw attention to this global occupational public health problem.

Hepatocellular carcinoma and the risk of occupational exposure

Hepatocellular carcinoma (HCC) is the most common type of liver cancer. The main risk factors for HCC are alcoholism, hepatitis B virus, hepatitis C virus, nonalcoholic steatohepatitis, obesity, type 2 diabetes, cirrhosis, aflatoxin, hemochromatosis, Wilson's disease and hemophilia. Occupational exposure to chemicals is another risk factor for HCC. Often the relationship between occupational risk and HCC is unclear and the reports are fragmented and inconsistent. This review aims to summarize the current knowledge regarding the association of infective and non-infective occupational risk exposure and HCC in order to encourage further research and draw attention to this global occupational public health problem.

In vitro and in vivo anticancer activity of surface modified paclitaxel attached hydroxyapatite and titanium dioxide nanoparticles

Targeted drug delivery using nanocrystalline materials delivers the drug at the diseased site. This increases the efficacy of the drug in killing the cancer cells. Surface modifications were done to target the drug to a particular receptor on the cell surface. This paper reports synthesis of hydroxyapatite and titanium dioxide nanoparticles and modification of their surface with polyethylene glycol (PEG) followed by folic acid (FA). Paclitaxel, an anticancer drug, is attached to functionalized hydroxyapatite and titanium dioxide nanoparticles. The pure and functionalised nanoparticles are characterised with XRD, TEM and UV spectroscopy. Anticancer analysis was carried out in DEN induced hepatocarcinoma animals. Biochemical, hematological and histopathological analysis show that the surface modified paclitaxel attached nanoparticles have an higher anticancer activity than the pure paclitaxel and surface modified nanoparticles without paclitaxel. This is due to the targeting of the drug to the folate receptor in the cancer cells.

Cotton dust, endotoxin and cancer mortality among the Shanghai textile workers cohort: a 30-year analysis

BACKGROUND

Although occupational exposure to cotton dust and endotoxin is associated with adverse respiratory health, associations with cancer are unclear. We investigated cancer mortality in relation to cotton dust and endotoxin exposure in the Shanghai textile workers cohort.

METHODS

We followed 444 cotton textile and a reference group of 467 unexposed silk workers for 30 years (26 777 person-years). HRs for all cancers combined (with and without lung cancer) and gastrointestinal cancer were estimated in Cox regression models as functions of cotton textile work and categories of cumulative exposure (low, medium, high), after adjustment for covariates including pack-years smoked. Different lag years accounted for disease latency.

RESULTS

Risks of mortality from gastrointestinal cancers and all cancers combined, with the exclusion of lung cancer, were increased in cotton workers relative to silk workers. When stratified by category of cumulative cotton exposure, in general, risks were greatest for 20-year lagged medium exposure (all cancers HR=2.7 (95% CI 1.4 to 5.2); cancer excluding lung cancer HR=3.4 (1.7-7.0); gastrointestinal cancer HR=4.1 (1.8-9.7)). With the exclusion of lung cancer, risks of cancer were more pronounced. When stratified by category of cumulative endotoxin exposure, consistent associations were not observed for all cancers combined. However, excluding lung cancer, medium endotoxin exposure was associated with all cancers and gastrointestinal cancer in almost all lag models.

CONCLUSIONS

Cotton dust may be associated with cancer mortality, especially gastrointestinal cancer, and endotoxin may play a causative role. Findings also indirectly support a protective effect of endotoxin on lung cancer.

Endotoxin and cancer chemo-prevention

Reduced rates of lung cancer have been observed in several occupational groups exposed to high levels of organic dusts contaminated by endotoxin. The underlying anti-neoplastic mechanism of endotoxin may be an increased secretion of endogenous anti-neoplastic mediators and activation of the toll-like receptors (TLR). A detoxified endotoxin derivative, Monophosphoryl Lipid A (MPL(®)) is marketed in Europe since 1999 as part of the adjuvant systems in allergy vaccines for treatment of allergic rhino-conjunctivitis and allergic asthma. Over 200,000 patients have used them to date (nearly 70% in Germany). Since detailed exposure (MPL(®) dose and timing of administration) and individual data are potentially available, an observational follow-up study could be conducted in Germany to investigate the protective effect of MPL(®) against cancer, comparing cancer incidence in two groups of patients with allergic rhinitis: those treated with allergoids plus MPL(®) and those treated with a vaccine including the same allergoids but not MPL(®). The protective effect of MPL(®) could be quantified in ever and never smokers. If this proposed observational study provides evidence of protective effects, MPL(®) could be immediately used as a chemo-preventive agent since it is already in use as adjuvant in human vaccines against cancer.

Health disparities among occupations in Taiwan: a population study

OBJECTIVES

The first large-scale population survey was conducted in Taiwan to examine if and to what extent health disparities of four major chronic physical conditions exist among occupations.

METHODS

Face-to-face interviews about two risk behaviors (i.e., cigarette and alcohol use) and four major chronic physical conditions (i.e., cardiovascular disease, diabetes, liver disease and asthma) were conducted with 13,741 workers from nine major categories of occupations.

RESULTS

Health disparities among occupations were found based on a series of hierarchical logistic regression analyses after controlling for age, sex and two risk behaviors. In general, prevalence rates of cardiovascular disease among elementary occupations and skilled agricultural and fishery workers were approximately two to four times higher than those among other occupations. The above two occupations and plant and machine operators also had higher prevalence rates in diabetes and liver disease.

CONCLUSIONS

The results concerning health disparities among occupations provide policymakers and researchers with invaluable benchmarks of chronic physical conditions among occupations. The findings also suggest the importance of investigating causal relationship between these diseases and exposures at work, identifying and reducing unique risk factors and hazard exposures experienced by workers and conducting targeted surveillance and health promotion programs for at-risk occupations.

Association between alcohol consumption and cancers in the Chinese population--a systematic review and meta-analysis

BACKGROUND

Alcohol consumption is increasing worldwide and is associated with numerous cancers. This systematic review examined the role of alcohol in the incidence of cancer in the Chinese population.

METHODS

Medline/PubMed, EMBASE, CNKI and VIP were searched to identify relevant studies. Cohort and case-control studies on the effect of alcohol use on cancers in Chinese were included. Study quality was evaluated using the Newcastle-Ottawa Scale. Data were independently abstracted by two reviewers. Odds ratios (OR) or relative risks (RR) were pooled using RevMan 5.0. Heterogeneity was evaluated using the Q test and I-squared statistic. P<.01 was considered statistically significant.

RESULTS

Pooled results from cohort studies indicated that alcohol consumption was not associated with gastric cancer, esophageal cancers (EC) or lung cancer. Meta-analysis of case-control studies showed that alcohol consumption was a significant risk factor for five cancers; the pooled ORs were 1.79 (99% CI, 1.47-2.17) EC, 1.40 (99% CI, 1.19-1.64) gastric cancer, 1.56 (99% CI, 1.16-2.09) hepatocellular carcinoma, 1.21 (99% CI, 1.00-1.46) nasopharyngeal cancer and 1.71 (99% CI, 1.20-2.44) oral cancer. Pooled ORs of the case-control studies showed that alcohol consumption was protective for female breast cancer and gallbladder cancer: OR 0.76 (99% CI, 0.60-0.97) and 0.70 (99% CI, 0.49-1.00) respectively. There was no significant correlation between alcohol consumption and lung cancer, colorectal cancer, pancreatic cancer, cancer of the ampulla of Vater, prostate cancer or extrahepatic cholangiocarcinoma. Combined results of case-control and cohort studies showed that alcohol consumption was associated with 1.78- and 1.40-fold higher risks of EC and gastric cancer but was not significantly associated with lung cancer.

CONCLUSIONS

Health programs focused on limiting alcohol intake may be important for cancer control in China. Further studies are needed to examine the interaction between alcohol consumption and other risk factors for cancers in Chinese and other populations.

Endotoxin and cancer

Exposure to endotoxin, a component of gram-negative bacterial cell walls, is widespread in many industrial settings and in the ambient environment. Heavy-exposure environments include livestock farms, cotton textile facilities, and saw mills. In this article, we review epidemiologic, clinical trial, and experimental studies pertinent to the hypothesis that endotoxin prevents cancer. Since the 1970s, epidemiologic studies of cotton textile and other endotoxin-exposed occupational groups have consistently demonstrated reduced lung cancer risks. Experimental animal toxicology research and some limited therapeutic trials in cancer patients offer additional support for an anticarcinogenic potential. The underlying biological mechanisms of anticarcinogenesis are not entirely understood but are thought to involve the recruitment and activation of immune cells and proinflammatory mediators (e.g., tumor necrosis factor α and interleukin-1 and -6). In view of the current state of knowledge, it would be premature to recommend endotoxin as a cancer-chemopreventive agent. However, further epidemiologic and experimental investigations that can clarify further dose-effect and exposure-timing relations could have substantial public health and basic biomedical benefits.

Endotoxin and cancer

OBJECTIVE

Exposure to endotoxin, a component of gram-negative bacterial cell walls, is widespread in many industrial settings and in the ambient environment. Heavy-exposure environments include livestock farms, cotton textile facilities, and saw mills. Concentrations are highly variable in non-occupational indoor and outdoor environments. Endotoxin is a potent inflammagen with recognized health effects, including fever, shaking chills, septic shock, toxic pneumonitis, and respiratory symptoms. Somewhat paradoxically, given the putative role of inflammation in carcinogenesis, various lines of evidence suggest that endotoxin may prevent cancer initiation or limit tumor growth. The hypothesis that components of bacteria may retard cancer progression dates back to William B. Coley's therapeutic experiments ("bacterial vaccine") in the 1890s.

DATA SOURCES

In this article, we review epidemiologic, clinical trial, and experimental studies pertinent to the hypothesis that endotoxin prevents cancer. Since the 1970s, epidemiologic studies of cotton textile and other endotoxin-exposed occupational groups have consistently demonstrated reduced lung cancer risks. Experimental animal toxicology research and some limited therapeutic trials in cancer patients offer additional support for an anticarcinogenic potential. The underlying biological mechanisms of anticarcinogenesis are not entirely understood but are thought to involve the recruitment and activation of immune cells and proinflammatory mediators (e.g., tumor necrosis factor alpha and interleukin-1 and -6).

CONCLUSIONS

In view of the current state of knowledge, it would be premature to recommend endotoxin as a cancer-chemopreventive agent. Nonetheless, further epidemiologic and experimental investigations that can clarify further dose-effect and exposure-timing relations could have substantial public health and basic biomedical benefits.

Occupational exposures and ovarian cancer in textile workers

BACKGROUND

Occupational risk factors for ovarian cancer have been investigated only to a limited extent. We conducted a case-cohort study to examine associations between occupational exposures and ovarian cancer in the textile industry.

METHODS

We compared 261 incident ovarian cancer cases diagnosed between 1989 and 1998 with an age-stratified reference subcohort (n = 3199) from a cohort of 267,400 textile workers in Shanghai, China. Occupational exposures were assessed by job-exposure matrices designed for the textile industry, and estimates of quantitative cotton dust and endotoxin. We calculated hazard ratios (HRs) and 95% confidence intervals (CIs) with Cox proportional hazards modeling adapted for the case-cohort design.

RESULTS

A decreased risk of ovarian cancer was associated with ever having worked in cotton manufacturing production (HR = 0.7; 95% CI = 0.4-1.0). An increased risk was associated with ever having worked in textile finishing (2.1; 0.9-5.0). We found an increasing risk of ovarian cancer associated with cumulative exposure to silica dust (for <10 years exposure, HR = 6.8 [CI = 0.6-76]; for > or =10 years, 5.6 [1.3-23.6]), although these results are based on only 8 exposed subcohort women (0.3%) and 4 cases (1.3%). We also detected inverse risk gradients for cumulative exposures to endotoxin when exposures were lagged by 20 years (in highest quartile, HR = 0.6 [CI = 0.4-1.1]).

CONCLUSION

Silica dust may increase the risk of ovarian cancer, and cotton dust and endotoxin may reduce risk.

Silymarin downregulates COX-2 expression and attenuates hyperlipidemia during NDEA-induced rat hepatocellular carcinoma

Silymarin is a naturally available bioflavonoid and is a strong antioxidant with a capacity to inhibit the formation of tumors in several cancer models. In the present study, we investigated whether dietary supplementation of silymarin has any role in lipid components, lipid-metabolizing enzymes, free fatty acid profile, and expression of cyclooxygenase-2 (COX-2) in N-nitrosodiethylamine (NDEA)-induced hepatocellular carcinoma in rats. NDEA-induced rats showed severe hyperlipidemia along with upregulated expression of COX-2 as revealed by western blotting and immunohistochemistry. Dietary silymarin supplementation attenuated this hyperlipidemia and downregulated the expression of COX-2. Thus we conclude that compounds like silymarin with potent hypolipidemic effect are strong candidates as chemopreventive agents for the treatment of liver cancer.

Selecting appropriate study designs to address specific research questions in occupational epidemiology

Various epidemiological study designs are available to investigate illness and injury risks related to workplace exposures. The choice of study design to address a particular research question will be guided by the nature of the health outcome under study, its presumed relation to workplace exposures, and feasibility constraints. This review summarises the relative advantages and limitations of conventional study designs including cohort studies, cross-sectional studies, repeated measures studies, case-control (industry- and community-based) studies, and more recently developed variants of the nested case-control

DESIGN

case-cohort and case-crossover studies.