The identification of human carcinogens and primary prevention of cancer

Emissions of volatile organic compounds from crude oil processing - Global emission inventory and environmental release

Airborne Volatile organic compounds (VOCs) are known to have strong and adverse impacts on human health and the environment by contributing to the formation of tropospheric ozone. VOCs can escape during various stages of crude oil processing, from extraction to refinery, hence the crude oil industry is recognised as one of the major sources of VOC release into the environment. In the last few decades, volatile emissions from crude oil have been investigated either directly by means of laboratory and field-based analyses, or indirectly via emission inventories (EIs) which have been used to develop regulatory and controlling measures in the petroleum industry. There is a vast amount of scattered data in the literature for both regional emissions from crude oil processing and scientific measurements of VOC releases. This paper aims to provide a critical analysis of the overall scale of global emissions of VOCs from all stages of oil processing based on data reported in the literature. The volatile compounds, identified via EIs of the crude oil industry or through direct emissions from oil mass, are collected and analysed to present a global-scale evaluation of type, average concentration and detection frequency of the most prevalent VOCs. We provide a critical analysis on the total averages of VOCs and key pieces of evidence which highlights the necessity of implementing control measures to regulate crude oil volatile emissions (CVEs) in primary steps of extraction-to-refinery pathways of crude oil processing. We have identified knowledge gaps in this field which are of importance to control the release of VOCs from crude oil, independent of oil type, location, operating conditions and metrological parameters.

Contamination by oil crude extraction - Refinement and their effects on human health

The harmful effects of oil on various species of flora and fauna have been studied extensively; however, few studies have studied the effects of oil exposure on human health. The objective of this research was to collect information on the acute health effects and serious psychological symptoms of the possible consequences of such exposure to crude oil. Some studies focused on the composition of different chemicals used in the extraction process, and wastes generated proved to be highly harmful to human health. Thus, studies have shown that individuals who live near oil fields or wells - or who take part in activities of cleaning oil spills - have presented health conditions, such as irritation to the skin, eyes, mucous membranes, kidney damage, liver, reproductive, among others. In Ecuador, this reality is not different from other countries, and some studies have shown increased diseases related with oil crude and oil spills, like skin irritation, throat, liver, lung, infertility, and abortions, and it has been linked to childhood leukemia. Other studies suggest a direct relationship between DNA damage because of oil resulting in a genetic instability of the main enzymes of cellular metabolism as well as a relationship with some cancers, such as leukemia.

Environmental justice and primary prevention of cancer: the odyssey and legacy of lorenzo tomatis

Lorenzo Tomatis [1929-2007] devoted his private and professional life to the betterment of mankind. As a physician, scientist, and humanitarian he championed against the plight of social injustice and promoted the obvious benefits of primary prevention of diseases compared to treatments that prevent or delay disease progression, especially occupational cancers. An avowed student and scholar of literature, the arts, the history of medicine and science, and chemical carcinogenesis, he believed in and wrote about these issues throughout his storied life. Some of his achievements, with excerpts from his writings, especially on primary prevention and on social injustice, are highlighted herein.

Clarifying carcinogenicity of ethylbenzene

Ethylbenzene has been evaluated for carcinogenic activity in Fischer rats and B6C3F1 mice exposed by inhalation (Chan et al., 1998; Chan, 1999) and in Sprague-Dawley rats after oral exposure (Maltoni et al., 1985,1997). Bioassay findings are summarized below to expand on those not stated clearly or completely in Saghir et al. (2010). Overall in these three studies animals exposed to ethylbenzene had increased tumors in rats for kidneys, testes, head (including rare neuroesthesioepitheliomas), and total malignant tumors, whilst in mice tumor incidences were increased in the lung and liver (Huff, 2002). Thus ethylbenzene was carcinogenic by two exposure routes to both sexes of two species of rodents, two strains of rats, and one strain of mice, causing collectively tumors in five different target organs and a composite of "total malignant" tumors.

Comparison of trace elements in the scalp hair of malignant and benign breast lesions versus healthy women

Trace elements including Al, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sb, Sr, and Zn were analyzed in the scalp hair samples of women with malignant breast lesions, women with benign breast lesions, and healthy donors using atomic absorption spectrophotometric method. In the scalp hair of malignant-tumor patients, the highest average concentration was shown by Ca (1,187 microg/g), followed by Na (655 microg/g), Mg (478 microg/g), Zn (391 microg/g), Sr (152 microg/g), Fe (114 microg/g), and K (89.8), while in the case of benign-tumor patients, the average estimated element levels were 1,522, 1,093, 572, 457, 217, 80.4, and 74.7 microg/g, respectively. Most of the elements exhibited non-normal distribution evidenced by large spread, standard error, and skewness values. Mean concentrations of Ca (634 microg/g), Zn (206 microg/g), Mg (162 microg/g), Fe (129 microg/g), and Na (82.1 microg/g) were noteworthy in the scalp hair of healthy women. Average levels of Na, Sr, K, Cd, Co, Pb, Mg, Ca, Zn, Ni, Sb, and Mn were revealed to be significantly higher in the hair of malignant and benign patients compared to the healthy women; however, Fe, Cu, Al, and Cr were not significantly different in the scalp hair of the three groups. The quartile distributions of Ca, Cd, Co, Cr, K, Mg, Mn, Na, Ni, Pb, Sb, and Sr revealed maximum spread in the scalp hair of malignant and benign groups; nevertheless, Al, Cu, Fe, and Zn exhibited almost comparable quartile levels in the three groups. Strong correlation coefficients were found between Fe and Cd, Al and Na, Mn and Sr, Co and Cr, Cd and Cr, Pb and K, Pb and Mn, Cu and Na, and Al and Fe in the scalp hair of malignant-tumor patients, while Fe and K, Cd and Co, Na and Co, and Cr and Pb showed strong correlations in the scalp hair of benign-tumor patients, both of which were significantly different compared with the healthy subjects. Multivariate cluster analysis also revealed divergent clustering of the elements in the scalp hair of malignant and benign patients in comparison with the healthy women.

Benzene-induced cancers: abridged history and occupational health impact

Benzene-induced cancer in humans was first reported in the late 1920s. Carcinogenesis findings in animals were not reported conclusively until 1979. Industry exploited this "discrepancy" to discredit the use of animal bioassays as surrogates for human exposure experience. The cardinal reason for the delay between first recognizing leukemia in humans and sought-after neoplasia in animals centers on poor design and conduct of experimental studies. The first evidence of carcinogenicity in animals manifested as malignant tumors of the zymbal glands (sebaceous glands in the ear canal) of rats, and industry attempted to discount this as being irrelevant to humans, as this organ is vestigial and not present per se in humans. Nonetheless, shortly thereafter benzene was shown to be carcinogenic to multiple organ sites in both sexes of multiple strains and multiple species of laboratory animals exposed via various routes. This paper presents a condensed history of the benzene bioassay story with mention of benzene-associated human cancers.

Distribution of trace metal concentrations in paired cancerous and non-cancerous human stomach tissues

AIM

To assess whether trace metal concentrations (which influence metabolism as both essential and non-essential elements) are increased or decreased in cancerous tissues and to understand the precise role of these metals in carcinogenesis.

METHODS

Concentrations of trace metals including Cd, Ni, Cu, Zn, Fe, Mg and Ca in both cancerous and non-cancerous stomach tissue samples were determined by atomic absorption spectrometry (AAS). Tissue samples were digested using microwave energy. Slotted tube atom trap was used to improve the sensitivity of copper and cadmium in flame AAS determinations.

RESULTS

From the obtained data in this study, the concentrations of nickel, copper and iron in the cancerous human stomach were found to be significantly higher than those in the non-cancerous tissues, by using t-test for the paired samples. Furthermore, the average calcium concentrations in the cancerous stomach tissue samples were found to be significantly lower than those in the non-cancerous stomach tissue samples by using t-test. Exceedingly high Zn concentrations (207-826 mg/kg) were found in two paired stomach tissue samples from both cancerous and non-cancerous parts.

CONCLUSION

In contrast to the literature data for Cu and Fe, the concentrations of copper, iron and nickel in cancerous tissue samples are higher than those in the non-cancerous samples. Furthermore, the Ca levels are lower in cancerous tissue samples than in non-cancerous tissue samples.

Comparison of trace element concentrations in cancerous and noncancerous human endometrial and ovary tissues

Question of whether trace metal concentrations in tissues are increased or decreased in cancerous patients in comparison with noncancerous patients has not been answered yet, due to the fact that the data known in this field are rare and have contradictory results. Although Zn and Cu concentrations in serum and tissues of cancerous patients have extensively been studied, the precise role of these metals in carcinogenesis is not clearly understood. There are few studies on the concentrations of essential and toxic trace/minor metals in human tissue samples in comparison with serum and plasma samples. Trace metal concentrations including Cd, Cu, Zn, Fe, Mg, Ca, and Ni in both cancerous and noncancerous endometrial, ovary, and cervix uteri tissues were determined by atomic absorption spectrometry. The tissue samples were digested by using microwave energy. Slotted tube atom trap was used to improve the sensitivity of copper and cadmium in flame atomic absorption spectrometry determination. The concentrations of iron in cancerous endometrial tissues were found to be significantly higher than those in noncancerous samples (P < 0.01). On the contrary Fe, Zn concentration in cancerous endometrial tissue was found to be lower significantly than those in noncancerous samples (P= 0.005), whereas the other studied metals were not observed different. Furthermore, Cu and Ca concentrations in cancerous ovary samples were observed to be higher than those in noncancerous ovary tissues (P < 0.01 for Cu and P= 0.1 for Ca), whereas Mg, Fe, and Zn levels in cancerous ovary samples were not found to be different than those in noncancerous tissues.

The Italian surveillance system for occupational cancers: characteristics, initial results, and future prospects

BACKGROUND

Occupational cancer monitoring is important for cancer prevention and public health protection. A surveillance system for identifying occupational cancer risks and cancer cases in Italy that are likely to be of occupational origin using information available in the Italian Social Security archives was created and assessed. Persons employed in the private sector, the employing company, its industrial sector, and years of employment are available in these archives.

METHODS

A method to find known occupational hazards was first tested using a case-control approach. Cases were from six Italian cancer registries (CRs) and controls were sampled from source populations and as "exposure" the economic sector of the employing company was used. The potential of using hospital discharge records as case sources was subsequently assessed: these cover larger populations and are available more quickly than CR case series.

RESULTS

In the CR-based study many known occupational cancer risks related to specific industrial sectors were identified. By using cases from hospital discharge records many industries at risk were identified, as well as cases of recent diagnosis likely to be of occupational origin. However, for some industrial sectors (e.g., the chemical industry) the approach was unable to detect any excess risk. Furthermore, information on employees in important areas like agriculture, self-employment, and the public sector is not available in the Social Security archives.

CONCLUSIONS

This approach appears to be a promising low-cost method for occupational cancer surveillance, at least for some industries, and can be easily implemented in other countries.