The evaluation of internal exposure in workers
The evaluation of internal exposure in workers with omethoate is challenging. Unfortunately, OPs are metabolized and excreted quickly in the urine usually within 24–48 h of exposure, and the variation in metabolic rates exists. Many factors influence daily urinary output, such as salt intake, urea and drinking. Furthermore, the OPs metabolites are different, and the availability of analytic standards is lacking, it is not feasible to measure all of the specific metabolites at this time (Forsberg et al., 2011). Therefore, correlation of internal exposure concentration of omethoate with the cholinesterase activity and genetic polymorphisms of telomere binding proteins in this study was not evaluated.
To our knowledge, this is the first study to explore genetic variation within genes in telomere biology (POT1, TERF1, and TERT) and ChEs activity caused by long-term low level of exposure to omethoate. The mechanisms regarding declined ChEs activity influenced by TERF1 rs3863242 (AG+GG) also need to be explored in the future research.
In summary, the ChEs activities of whole blood, red blood rac1 inhibitor and plasma were decreased in the omethoate-exposed workers. Major influencing factors on ChEs activity include the level of omethoate-exposure, gender, drinking and TERF1 rs3863242 genetic polymorphism.
Acknowledgements The authors expressed their gratitude to all the individuals who volunteered to participate in this study. We are also thankful for the support from the Programs for Science and Technology Development of Zhengzhou (131PPTGG376) and the Outstanding Youth Grant of Zhengzhou University (1521329035).
Introduction The chemical pesticides are one of the important measures for controlling pests infesting agricultural crops in order to meet the increased world food requirements of rapidly growing population . According to the Food and Agricultural Organization , more than 500,000 tons of unused and obsolete pesticides are threatening the environment and public health in many countries. India is the fourth largest global producer of agrochemicals after the US, Japan and China. Agriculture sector in India generated a value of USD 4.4 billion in FY15 and is expected to grow at 7.5% per annum to reach USD 6.3 billion by FY20. The sector has remained backbone of the Indian economy and presently accounts for more than 15% of the country's GDP . Nearly 58% of the rural households rely on agriculture as their principal means of livelihood. Tea industry is regarded as one of the oldest organised agro based industries in India. Tea is grown in thirteen states in India and states like Assam, West Bengal, Tamil Nadu and Kerala are the largest producers. Today India accounts for 27.49% of the global tea production. The climatic conditions of the tea growing regions of India are conducive for a large number of insects and pests that needs to be managed below the economic injury levels to avoid huge crop loss. Significant increase in tea production entails the use of several pesticides for crop protection and pest control. Unlike other agricultural crops, 12.55 lakhs workers are employed in tea plantations. Women contributed about 50 percent of the workforce and they work in tea plantation for plucking tea leaves in bare hands. These workers are exposed simultaneously to a complex mixture of insecticides, such as organophosphates, pyrethroids, and organochlorines , as well as other chemicals in the preparation and application. Different formulations are often used simultaneously in complex mixtures, including a significant number of genotoxic compounds . Since long-term exposures to low doses of pesticides are often difficult to assess the associated signs and symptoms may not manifest clinically , the investigation on biomarkers have been used as sequence of events from exposure to disease. Studies pertaining to women workers exposed to pesticides and related health status outcome are not numerous, but negative effects, such as spontaneous abortions, congenital defects and prematurity have been observed  among women workers in other occupation. Human biomonitoring studies have shown that exposure to pesticides can alter the activities of biochemical indices [8,9], inhibit ChEs activity [10,11], increases in cytogenetic damage [, , , ], neuropsychological disorders, disruption of the endocrine system, developmental anomalies and disorders of the immune system and hypersensitivity . These toxic effects vary considerably, depending on the degree of exposure, absorption pathway, specific characteristics of pesticides and individual factors, such as age, gender, nutritional status, and general health .