Occupational Epidemiology in Agriculture: A Case Study in the Southern African Context

Abstract

Some challenges facing occupational epidemiology in developing countries are outlined in this case study of agriculture drawing on Southern African research. These include the characterization of exposures in resource- and data-poor environments typical of developing countries, the assessment of outcomes where cross-cultural and socio-environmental confounders may be substantial obstacles, and the impact of environmental exposures on workplace health. Traditional assignment of low priority to the chronic effects of low-dose exposures relative to acute morbidity in developing countries must be critically examined, as must the gender bias of much occupational epidemiology in agriculture. Advocacy issues involving child labor and the ethics of research among vulnerable groups deserve rigorous attention. It is argued that, if occupational epidemiology is to have meaningful impact on the health of the most marginalized groups of workers in developing countries, it must redefine itself in terms of a public health approach. The boundaries of epidemiologic inquiry need to be broad, and amenable to interfacing with policy research, using qualitative methods and participatory approaches. More so than in other industrial settings, epidemiologists must move from research to practice, seeking to take action where interventions are needed, and to evaluate such actions.     

有机磷农药与再生障碍性贫血发病关系的Meta分析

目的 评价有机磷农药与再生障碍性贫血发病的关系,为一级预防提供科学依据。方法 检索1990年1月至2014年8月公开发表在中国生物医学文献数据库(CBM)、中国知网(CNKI)、PubMed和EMBASE关于有机磷农药与再生障碍性贫血发病关系的病例对照研究。制定纳入和排除标准,对符合纳入标准的文献进行质量评价,利用Review Manager 5.0软件计算有机磷农药的合并OR值及其95%CI,并对文献的研究人群和有机磷农药使用方式进行亚组分析。结果 最终共纳入9篇文献,5 833例研究对象,其中病例组1 404人,对照组4 429人。结果显示有机磷农药可增加再生障碍性贫血的发病风险(OR=1.97,95%CI:1.60～2.44)。亚组分析显示亚洲人群再生障碍性贫血的发病风险(OR=2.01,95%CI:1.52～2.66)高于欧美人群(OR=1.93,95%CI:1.39～2.67);使用单一有机磷类农药(OR=2.15,95%CI:1.60～2.88)比使用有机磷类农药的混配制剂(OR=1.82,95%CI:1.34～2.47)更易引发再生障碍性贫血。结论 有机磷农药可能是再生障碍性贫血的危险因素。在日常生活和工农业生产中,减少有机磷农药的暴露,可以预防再生障碍性贫血的发生。     

Application of the buccal micronucleus cytome assay and analysis of PON1Gln192Arg and CYP2A6*9(−48T>G) polymorphisms in tobacco farmers

Tobacco is a major Brazilian cash crop. Tobacco farmers apply large amounts of pesticides to control insect growth. Workers come into contact with green tobacco leaves during the tobacco harvest and absorb nicotine through the skin. In the present study, micronucleus frequency, cell death, and the frequency of basal cells were measured in tobacco farmers using the buccal micronucleus cytome assay (BMCyt), in parallel with measurement of blood butyrylcholinesterase (BChE) and nicotine levels. Polymorphisms in PONIGln192Arg and CYP2A6*9(?48T>G) were evaluated to verify the relationship between genetic susceptibility and the measured biomarkers. Peripheral blood and buccal cell samples were collected from 106 agricultural workers, at two different crop times (during pesticide application and leaf harvest), as well as 53 unexposed controls. BMCyt showed statistically significant increases in micronuclei, nuclear buds, and binucleated cells among exposed subjects in differentiated cells, and in micronuclei in basal cells. In addition, the exposed group showed higher values for condensed chromatin, karyorrhectic, pyknotic, and karyolitic cells, indicative of cell death, and an increase in the frequency of basal cells compared to the unexposed control group. A slight difference in mutagenicity using the BMCyt assay was found between the two different sampling times (pesticide application and leaf harvest), with higher micronucleus frequencies during pesticide application. Elevated cotinine levels were observed during the leaf harvest compared to the unexposed controls, while BChE level was similar among the farmers and controls. PONIGln192Arg and CYP2A6*9(?48T>G) polymorphisms were associated with DNA damage induced by pesticides and cell death. Environ. Mol. Mutagen., 2012. © 2012 Wiley Periodicals, Inc.     

Fatal poisoning by terbufos following occupational exposure

Context: Terbufos (TBF) is a class Ia (extremely hazardous) organophosphate pesticide (OP) and its distribution in industrialized countries has been severely restricted. Thus, acute occupational poisoning is rather uncommon. However, it still occurs in rural areas of some developing countries, where the sale of TBF is not controlled and its use is thus not properly regulated. We report a case of a 43-year-old female farmer who died after applying TBF granules.

Case: The patient died within 3?h after applying 20 bags of 5% TBF granules (900?g per bag). Investigation showed that her personal protective equipment (PPE) did not provide effective protection against dermal and inhalational exposure. Postmortem analysis revealed extremely low red blood cell acetylcholinesterase activity. Toxicological analysis of TBF showed 1.45?×?10^?2?μg/ml in the heart blood and 0.17?μg/g in the liver.

Discussions: This patient died as a result of toxicity from dermal and inhalational exposure to TBF. Over-application, improper equipment, inadequate and defective PPE, and lack of hygienic precautions were all contributing factors.

Conclusions: TBF is a highly toxic OP. Inadequate regulatory control, improper environmental application, and ineffective PPE resulted in a fatal human exposure.     

Highly Chlorinated Toxic Contaminants in Pesticide-Treated Wooden Art Objects

Although the contamination of wooden art objects with pesticides is well known, to the authors' knowledge no attempt has yet been made to investigate the eventual presence of other toxic compounds that have been produced during the degradation of pesticides or that may be present in the technical formulations. Here, the authors report on the presence of polychlorinated biphenyls (PCBs) and polychlorinated terphenyls (PCTs) in scrapings from wooden antique art objects, namely printing blocks, sculptures, and masks. These antiques belong to 2 fine art museums in Belgium—Antwerp's Ethnographic Museum and the Plantin-Moretus Museum. It is documented that these art objects were treated with pesticides in the 1950s. In addition, 2-heptachlorodibenzo-p-dioxin (HpCDD) isomers and octachlorodibenzo-p-dioxin (OCDD) were also identified. The presence of these toxic compounds in these antiques requires a better understanding of safety for the persons (conservators, museum employees, restorers, and visitors) coming in contact with these objects.     

Chlorinated pesticide residues in human breast milk collected from southern Jordan in 2012/2013

Chlorinated pesticide residues in human breast milk from five southern Jordan districts were analyzed in 2012/2013. The total number of samples from all districts was 100. The number of samples gathered from each district was collected according to their population densities. The present study shows that 59% of the samples which contained pesticides’ residues were p,p’-DDE, 30% contained β-HCH, 10% contained p,p′-DDT, 6% contained α-HCH, 2% contained heptachlor and 1% contained endrin. These human milk samples were free of aldrin, dieldrin, α-endosulfan, β-endosulfan, HCB, γ-HCH, o,p′-DDD, o,p′-DDT and o,p′-DDE. The levels of the six mentioned compounds detected in all mother’s milk samples were higher in Ghor El-Safi district compared with the other four districts. In this study, it is recommended to continue the pesticides residues monitoring in all parts of Jordan, particularly in Ghor El-Safi district and other regions in the cultivated Jordan Valley.     

Malaria vector control strategies. What is appropriate towards sustainable global eradication?

Malaria a mosquito-borne disease caused by Plasmodium remains to be a main global burden despite concerted efforts to eliminate it. While diverse control strategies have been put in place for mosquito-borne diseases, vector control continues to be a critical component in infection prevention. Vector control majorly focuses on the eradication of mosquitoes using a variety of chemical insecticides that includes organochlorides, carbamates, organophosphates, and pyrethroids. The use of conventional insecticide-based as mosquito control strategies poses several challenges such as the widespread development of insecticide resistance, environmental damage concerns, and effects on non-target organisms. These challenges create a demand for the development and use of alternative pest control strategies that are sustainable, safer, and environmentally friendly to mosquito vector management. This review provides insight into alternative sustainable interventions for mosquito vector control in the form of biorational pesticides. Biorational pesticides are pesticides that have little or no effect on humans and environments and include entomopathogenic microorganisms, insect growth regulators, and endosymbiotic bacteria. It also puts into perspective their environmental impacts, benefits, and challenges. Further, countries like Sri Lanka, that are certified as malaria free by World Health Organization (WHO) incorporated the use of entomopathogenic bacteria, insect growth regulators and larvivorous fish in their national vector control programs leading to the successful elimination of malaria in 2016. We therefore highlight success stories of the countries that have implemented these interventions bringing out the lessons for countries that are battling malaria epidemics.