Ocular toxicity from pesticide exposure: A recent review

Toxic effects on eyes result from exposure to pesticides via inhalation, ingestion, dermal contact and ocular exposure. Exposure of unprotected eyes to pesticides results in the absorption in ocular tissue and potential ocular toxicity. Recent literature on the risks of ocular toxicity from pesticide exposure is limited. Ocular toxicity from pesticide exposure, including the dose-response relationship, has been studied in different animal species. Cholinesterase enzymes have been detected in animal ocular tissue, with evidence of organophosphate-induced inhibition. Pathological effects of pesticides have been observed in conjunctiva, cornea, lens, retina and the optic nerve. Pesticide exposure has been associated with retinopathy in agricultural workers and wives of farmers who used pesticides. Saku disease, an optico-autonomic peripheral neuropathy, has been described in Japan in people living in an area where organophosphates were used. Pesticide exposure is also associated with abnormal ocular movements. Progressive toxic ocular effects leading to defective vision are a serious health concern. Agricultural workers are at high risk of exposure to pesticides and associated ocular toxicity. Primary prevention is the appropriate method of protecting eyes from pesticide-related damage. This includes improved eye safety and care in workplaces, and effective pesticide regulation for maintenance of public eye health.     

Sources of exposure to and public health implications of organophosphate pesticides.

OBJECTIVE: To review the public health significance of organophosphate pesticide exposure in the United States of America. Since the situation of high organophosphate pesticide exposure and the concomitant health risks in the developing countries of the world is well known, this article seeks to highlight the public health significance of organophosphate exposure in the United States, where it is less common than in many other nations. Looking at the situation in the United States would serve to further emphasize the seriousness of organophosphate pesticide-related health issues in developing countries. METHODS: A search for journal articles on organophosphate pesticides and organophosphate exposure was done on the PubMed electronic bibliographic database system of the National Library of Medicine of the United States. To supplement that search, information on organophosphate toxicity, biological monitoring, and regulation of pesticides was obtained from other published articles, textbooks, and relevant Internet sites. RESULTS: Organophosphate pesticides are a group of chemicals that are mainly used in agriculture. Organophosphates inhibit the activity of both the cholinesterase (ChE) enzymes-red blood cell (RBC) ChE and serum ChE-resulting in the cholinergic features of organophosphate toxicity. A 50% reduction in serum ChE activity from the baseline is an indication of acute organophosphate toxicity. The RBC ChE activity, which is less rapidly depressed than the serum ChE activity, is a measure of chronic exposure to organophosphates. Exposures to organophosphates are broadly classified into two categories: occupational and environmental. Occupational exposures occur among agricultural workers (including migrant farmworkers), industrial workers, pest control exterminators, and other workers. Nonoccupational exposure affects a large segment of the general population in the United States. Residential exposures come from organophosphate pesticide use by exterminators and by household residents as well as from dietary and accidental exposures. Other environmental exposures occur in public places and areas close to farms, and exposures could also happen from organophosphate use in chemical warfare or terrorism. In the United States some organophosphate pesticides are restricted by the Environmental Protection Agency in order to protect humans, animals, and the environment. In addition, the Food Quality Protection Act regulates dietary exposure to pesticides, particularly for infants and children. CONCLUSIONS: Organophosphate pesticides continue to pose a risk to human health in the United States. Biological monitoring should be used to strictly regulate occupational exposures to organophosphates and thus protect the health and safety of workers. Among the public there should be an increased awareness of environmental exposure to organophosphates as well as of the threat of chemical warfare or terrorism.     

Evaluating health risks from occupational exposure to pesticides and the regulatory response.

In this study, we used measurements of occupational exposures to pesticides in agriculture to evaluate health risks and analyzed how the federal regulatory program is addressing these risks. Dose estimates developed by the State of California from measured occupational exposures to 41 pesticides were compared to standard indices of acute toxicity (LD50) and chronic effects (reference dose). Lifetime cancer risks were estimated using cancer potencies. Estimated absorbed daily doses for mixers, loaders, and applicators of pesticides ranged from less than 0.0001% to 48% of the estimated human LD50 values, and doses for 10 of 40 pesticides exceeded 1% of the estimated human LD50 values. Estimated lifetime absorbed daily doses ranged from 0.1% to 114,000% of the reference doses developed by the U.S. Environmental Protection Agency, and doses for 13 of 25 pesticides were above them. Lifetime cancer risks ranged from 1 per million to 1700 per million, and estimates for 12 of 13 pesticides were above 1 per million. Similar results were obtained for field workers and flaggers. For the pesticides examined, exposures pose greater risks of chronic effects than acute effects. Exposure reduction measures, including use of closed mixing systems and personal protective equipment, significantly reduced exposures. Proposed regulations rely primarily on requirements for personal protective equipment and use restrictions to protect workers. Chronic health risks are not considered in setting these requirements. Reviews of pesticides by the federal pesticide regulatory program have had little effect on occupational risks. Policy strategies that offer immediate protection for workers and that are not dependent on extensive review of individual pesticides should be pursued.     

Toxicity due to organophosphorus compounds: what about chronic exposure?

The inappropriate use of toxic chemicals is common in developing countries, where it leads to excessive exposure and high risks of unintentional poisoning. The risks are particularly high with the pesticides used in agriculture, where poor rural populations live and work in close proximity to these compounds, which are often stored in and around the home. It is estimated that 99% of all deaths from pesticide poisoning occur in developing countries. Whilst the acute toxicity of pesticides has been well documented, there is still relatively little known of the effects on health of chronic pesticide exposure. Organophosphate insecticides have been extensively used in agriculture in developing countries, with little protection for the communities and individuals thus exposed. Given the indisputable chronic exposure of vulnerable groups to organophosphate compounds, including pregnant women, the fetus and young children, the potential for widespread adverse effects is considerable. Thus, whilst there is some evidence that chronic exposure may have adverse effects on health, there is an urgent need for high-quality observational and interventional studies of both occupational and environmental exposure to these compounds.     

The epidemiology of pesticide exposure and cancer: A review

Cancer is a multifactorial disease with contributions from genetic, environmental, and lifestyle factors. Pesticide exposure is recognized as an important environmental risk factor associated with cancer development. The epidemiology of pesticide exposure and cancer in humans has been studied globally in various settings. Insecticides, herbicides, and fungicides are associated with hemopoetic cancers, and cancers of the prostate, pancreas, liver, and other body systems. The involvement of pesticides in breast cancer has not yet been determined. In developing countries, sufficient epidemiologic research and evidence is lacking to link pesticide exposure with cancer development. Agricultural and industrial workers are high-risk groups for developing cancer following pesticide exposure. Children of farm workers can be exposed to pesticides through their parents. Maternal exposure to pesticides can pose a health risk to the fetus and the newborn. The organophosphates are most the commonly used compounds, but the organochlorines are still permitted for limited use in developing countries. Pesticide exposure, independently or in synergism with modifiable risk factors, is associated with several types of cancer.     

Economic development and occupational health in Latin America: new directions for public health in less developed countries.

Occupational Health is increasingly recognized as an area of importance in Latin American public health. In the agricultural sector of the region, the concentration of arable land into large holdings devoted to the production of export crops has resulted in the formation of a large migrant work force and greatly increased use of pesticides. The manufacturing sector of Latin America has grown rapidly in size and importance. Throughout the continent, increasing numbers of workers are employed in high-hazard industrial jobs. Limited studies of occupational disease in agriculture, mining, and manufacturing suggest that there is a high prevalence of work-related illness in the populations at risk. Trade unions are generally weak, and the high rate of unemployment and underemployment render occupational health a low priority for many workers. Engineering controls and personal protective equipment are unknown or inadequate in many industries, and there is a shortage of trained occupational health professionals in the region. Steps are being taken by many Latin American governments to begin to address this problem. Needed are: increased worker and professional training; a uniform set of exposure standards; control of multinational marketing and usage of hazardous substances; the development of technical equipment appropriate for local use and increased research on occupational exposure in populations in less developed countries.     

Exposición a plaguicidas en Chile y salud poblacional: urgencia para la toma de decisiones

In the last 25 years, Chile has had an expanding role as an agro-export country in the global economy, with efficient rates of productivity in the region, based on the technological development of agriculture, with of large monocultures whose productivity depends on the intensive application of agrochemicals. This form of agriculture has also lacked efficient regulations and surveillance, so it is difficult to estimate the real magnitude of the exposed population and its effects on health in the short or long term. This systematic review compiles the epidemiological evidence generated from studies conducted in several regions of Chile regarding pesticide exposure and health effects. Of the total number of articles, 50% included agricultural workers, 25% children, and 25% women of childbearing age, with the greatest effects being the neurotoxic (54%), genotoxic (31%) and reproductive (15%). The evidence collected shows that in Chile the levels of exposure to pesticides in the general and occupational population are higher than international studies levels. It is urgent to protect the health of both the occupational and general population and especially children through a stricter control of the sale and use of pesticides, with comprehensive surveillance systems in environmental health and educational actions in the social and cultural context of rural communities. It is a priority to strengthen research with national relevance on health effects, and strictly restrict the use of pesticides already prohibited in developed countries due to their high level of risk to human and environmental health.     

Pesticide application practices in agricultural workers

OBJECTIVE: We describe the sociodemographic characteristics and determinants of pesticide exposure in agricultural workers applying pesticides. METHODS: The workers selected were included in a case-control study carried out in the Autonomous Community of Valencia in Spain. Contact was made by telephone and individuals who had been involved in agricultural work during the relevant period of exposure were interviewed face-to-face to gain information on the following determinants of pesticide exposure: crops and periods worked, mixing of products, treatment equipment, participation in the washing of equipment, use of personal protection during the treatments and knowledge of the risks of pesticide exposure. RESULTS: Eighty-nine workers, aged between 16 and 46 years old, were included. Most of the interviewees had primary education or less. Pesticide treatments were mostly applied on high crops (82%), with manual equipment (61%) and throughout the year (45%). Workers frequently performed tasks involving additional exposure to pesticides (mixing chemicals, 66%, or washing equipment, 60%). Sixty-five percent of the workers used no personal protection or used it defectively. No differences were found in personal protection use according to age, family income or education. Most of the workers (90%) reported knowledge of the health risks of pesticide exposure and 21% of them rated the risk as null. CONCLUSIONS: Workers involved in pesticide application use personal protection measures very defectively. There is a clear need to develop specific prevention programs for these workers. The determinants of pesticide exposure in agricultural workers described in this study should be properly assessed in epidemiological studies of the health effects of pesticides on agricultural workers.     

Pesticide Use Practices in Rural Armenia

ABSTRACT

Pesticide use can have adverse effects on both human health and the environment. Inappropriate use of pesticides increases the health risk to those who work with or live around pesticides. Educational programs for agricultural workers on the proper use of pesticides and personal protective equipment coupled with pesticide regulations are important tools to reduce the associated health risks. The authors conducted a survey (N?=?2336) on pesticide use practices in the Ararat Valley of Armenia in 2000–2006. This study was a cross-sectional design. A multistage sampling method was implemented in the selection of the study population. The authors developed a questionnaire containing 173 questions to evaluate demographic characteristics, health conditions, and details of pesticides use practices. The intensity of pesticide use was high; 82.8% of respondents used them. More than 150 brand names of pesticides were in use. Unregistered, obsolete, expired, and banned compounds were found in active use. Poor compliance with the basic rules of pesticide safety was found throughout the study population, with 21.3% using gloves and only 11% using respirators. The agricultural workers’ knowledge of the toxic properties of these pesticides as well as basic hygienic norms was very low. In some instances, the number of agrichemical applications to crops, particularly cucumbers and melons, reached 40 applications during the growing season. Better protection and training of pesticide users in Armenia is needed.     

Paraquat in developing countries.

The herbicide paraquat is considered safe by industry and the bulk of regulators worldwide. However, determinants of exposure from 30 years ago persist in developing countries. Little is known about systemic absorption from occupational exposures. The relationships between exposure determinants, levels of external exposure, biomarkers of exposure, and outcomes are not clear. High rates of severe acute poisonings have been documented. In addition, topical injuries occur in as many as 50% of exposed workers. Non-worker populations are also at risk, particularly children. Long-term and delayed health effects include Parkinson's disease, lung effects, and skin cancer. Regulatory agencies have not fully recognized either the inherent toxicity of paraquat or the particular risks derived from exposures in developing countries. Independent risk assessment in the developing-country context and application of the precautionary principle are necessary to prevent adverse effects of dangerous pesticides in susceptible populations.     

South African farm workers' interpretation of risk assessment data expressed as pictograms on pesticide labels

Pesticide companies and regulators in developing countries use the United Nations Food and Agricultural Organization (FAO) recommended pictograms on pesticide labels to communicate risk information based on toxicological and environmental risk assessment data. The pesticide label not only is often the only access people have to pesticide risk information, but also in many countries is a legally binding document. As a result of the crucial role pesticide labels play in protecting health and the environment and as a legal instrument, pictograms are used to overcome literacy challenges in transmitting pesticide risk information. Yet, this risk communication tool is often prone to misinterpretations of the risk information which results in hazardous exposures to pesticides for farm workers and end-users generally. In this paper, results are presented from a study with 115 farm workers on commercial vineyards in the Western Cape, South Africa, assessing their interpretations of 10 commonly used pictograms. A standardized questionnaire based on four commonly used pesticide labels was administered. Overall, 50% or more of the study farm workers had misleading, incorrect and critically confused interpretations of the label pictograms. Interpretations often reflected farm workers’ social and cultural frames of reference rather than the technically intended risk information. For example, the pictogram indicating a pesticide's toxicity requires boots must be worn, evoked interpretations of “dangerous to pedestrians” and “don’t walk through pesticides”. Furthermore, there was a gender variation in pictogram comprehension whereby males generally had more correct interpretations than females. This is a result both of a lack of training for women who are assumed to not work with pesticides, as well as a lack of pictograms relevant for female exposures. These findings challenge the viability of the United Nations current initiative to globally harmonize pictograms used on all chemical labels under the new Globally Harmonized System for the Classification and Labelling of Chemicals (GHS). Particularly as the GHS pictograms were not piloted prior to adoption of the system and represent complex risk assessment data such as chronic hazards. Public health and pesticide policy, backed by relevant research, need to address developing applicable and effective pesticide risk communication tools, particularly for developing country populations. Merely providing risk assessment derived information in a pictogram does not ensure that an end-user will interpret the message as intended and be able to make risk decisions which mitigate risks from exposures to pesticides or chemicals in general.     

Pesticides in Lebanon: a knowledge, attitude, and practice study

Pesticides, despite their known toxicity, are widely used in developing countries. Evaluating the pattern of their use would be interesting to assess the appropriateness of adequate intervention. Using a standardized questionnaire, a knowledge, attitude, and practice study was performed in two Lebanese regions, in which a group of agricultural workers was compared to workers of the general population and a third group of pesticide distributors. Agricultural workers were exposed to pesticides during cropping, mixing, loading, and application (100%). They had low pesticide knowledge scales compared to pesticide distributors and to the general population workers (P<10(-7)). The preventive measures they took were low, and the lower their knowledge was, the lower were the preventive measures applied (P<10(-3)). Pesticide safety education is necessary in order to induce protective behavior among agricultural workers. The general population may also benefit from increasing their awareness regarding pesticides.     

Occupational health and safety in agriculture: situation and priorities at the beginning of the third millennium

Agriculture is a human activity, which includes a number of different tasks and occupies a huge number of people worldwide. Estimates of World Bank for 2003 suggest that 51% of globalpopulation lives in rural areas. ILO estimates that 1.3 billion of workers are engaged in agriculture, and they represent almost a half of the total number of economically active subjects (2,838,897,404). In developed countries, agriculture workers are only a small fraction of the whole work force (up to 9% according to ILO data), while in developing countries, especially in Asia, agriculture workers represent up to the 60% of the total work force. Most agriculture workers reside in Asia, in the Pacific (74%) and in Africa (16%). ILO estimates suggest that half of fatal occupational injuries in the world are attributable to agriculture. This means that around 170,000 agriculture workers die every year as a consequence of occupational injuries. Using the same estimate, half of the fatal accidents could be linked to agricultural activities (more than 130 million). Comparing this estimate with the 6.328.217 people injured in war in 2002 or with the 20-50 million injured victims of road accidents, one has a much clearer picture about the importance of preventing agricultural injuries. In a complicated situation such as occupational health and safety problems in agriculture, it is not so easy to select priorities clearly. But "legalization" of agriculture workers could be a key to solving all the other problems. Actual data on fatal and non-fatal occupational injuries in agriculture show that occupational health and safety issues are among the top priorities for that discipline.     

Rural work and pesticide poisoning

Pesticide use is intensive in Brazilian agriculture. Population-based studies on the characteristics of pesticide use and pesticide poisoning are scarce. This study describes the profile of occupational exposure and pesticide poisoning incidence. Farm characteristics and pesticide occupational exposure were evaluated using a cross-sectional design. Among 1,379 farmers/farm workers, annual incidence of pesticide poisoning was 2.2 episodes per 100 exposed. Based on Poisson regression, applying pesticide, reentering crop fields after spraying, and working with pesticides on more than one farm were the types of exposure that presented a positive correlation with pesticide poisoning. The results may be useful for planning activities aimed at reducing occupational pesticide poisoning among rural workers.     

Pesticide use among farmers in the Amazon basin of Ecuador

Pesticide use is one of the most significant occupational exposures for agricultural workers in the Amazon basin of Ecuador. A structured questionnaire was developed focusing on sociodemographic characteristics, knowledge and experience of adverse health effects related to pesticide use, details of work practices, and an inventory of pesticides used on the farm. Of the 112 farmers interviewed, 111 (99.1%) used pesticides. Paraquat was most commonly used (77.4%), followed by glyphosate (65.7%). Respondents had good knowledge about the acute health effects of pesticides and their exposure routes. Risk behaviors were identified as frequent pesticide use, washing pesticide equipment in water sources used by humans, inadequate disposal of empty pesticide containers, eating and drinking during pesticide application, and using inadequate protective clothing. Training and educational campaigns on pesticide use should be encouraged for this cohort, along with suggestions for alternative methods of pest control.     

Cancer among pesticide manufacturers and applicators

There are hundreds of studies of cancer and agriculture chemicals. However, few have focused on a single pesticide or class of pesticide. While cancer studies of nonspecific pesticide exposure among populations may provide hypotheses for additional testing, they contribute little to the understanding of the health risks of specific agricultural chemicals. This review concentrates on both the cancer findings and the exposure parameters in cohort studies of workers who manufacture or apply pesticides. Occupational studies of pesticide manufacturers and applicators provide important contributions to the causal assessment of the carcinogenicity of specific pesticides because the exposure is often longer, more intense, and better defined than for other study populations. Among the studies reviewed, there is little indication of increased cancer risk among pesticide manufacturers or sprayers. Limitations in sample size, exposure assessment, and the small number of studies make causal inference difficult. Additional methodological improvements with respect to exposure would contribute significantly to the understanding of the potential cancer risk from individual pesticides.     

Pesticide exposure, safety issues, and risk assessment indicators

Pesticides are widely used in agricultural production to prevent or control pests, diseases, weeds, and other plant pathogens in an effort to reduce or eliminate yield losses and maintain high product quality. Although pesticides are developed through very strict regulation processes to function with reasonable certainty and minimal impact on human health and the environment, serious concerns have been raised about health risks resulting from occupational exposure and from residues in food and drinking water. Occupational exposure to pesticides often occurs in the case of agricultural workers in open fields and greenhouses, workers in the pesticide industry, and exterminators of house pests. Exposure of the general population to pesticides occurs primarily through eating food and drinking water contaminated with pesticide residues, whereas substantial exposure can also occur in or around the home. Regarding the adverse effects on the environment (water, soil and air contamination from leaching, runoff, and spray drift, as well as the detrimental effects on wildlife, fish, plants, and other non-target organisms), many of these effects depend on the toxicity of the pesticide, the measures taken during its application, the dosage applied, the adsorption on soil colloids, the weather conditions prevailing after application, and how long the pesticide persists in the environment. Therefore, the risk assessment of the impact of pesticides either on human health or on the environment is not an easy and particularly accurate process because of differences in the periods and levels of exposure, the types of pesticides used (regarding toxicity and persistence), and the environmental characteristics of the areas where pesticides are usually applied. Also, the number of the criteria used and the method of their implementation to assess the adverse effects of pesticides on human health could affect risk assessment and would possibly affect the characterization of the already approved pesticides and the approval of the new compounds in the near future. Thus, new tools or techniques with greater reliability than those already existing are needed to predict the potential hazards of pesticides and thus contribute to reduction of the adverse effects on human health and the environment. On the other hand, the implementation of alternative cropping systems that are less dependent on pesticides, the development of new pesticides with novel modes of action and improved safety profiles, and the improvement of the already used pesticide formulations towards safer formulations (e.g., microcapsule suspensions) could reduce the adverse effects of farming and particularly the toxic effects of pesticides. In addition, the use of appropriate and well-maintained spraying equipment along with taking all precautions that are required in all stages of pesticide handling could minimize human exposure to pesticides and their potential adverse effects on the environment.     

Practices in pesticide handling and the use of personal protective equipment in Mexican agricultural workers

Practices related to the safe handling of pesticides and use of personal protective equipment (PPE) are largely unknown among agricultural workers in developing countries. The authors obtained information from 99 Mexican agricultural workers (35 women and 64 men) who answered questions on sociodemographic data, agricultural practices, use of pesticides, use of PPE, and risk perception. As expected, men handled pesticides more frequently than women (67% versus 20%). The workers carried out several agricultural tasks, as is customary in the case of fieldworkers who (1) work in small agricultural enterprises; use a great number of pesticide products (59 commercial brands of pesticides, 33 active ingredients, and 20 chemical families); (2) use mostly manual application equipment; (3) have a low rate of correct usage of PPE (2%), which does not vary according to the education level, the time of year, or the risk perception; and (4) have insufficient hygienic practices. In addition, storage of pesticide products and application equipment at home is frequent among this group of workers (42%), and provides a significant source of para-occupational exposure for the workers' families. These results show the need to develop prevention programs to reduce risks posed by pesticides to agricultural workers and their families.     

Spatial modeling of personalized exposure dynamics: the case of pesticide use in small-scale agricultural production landscapes of the developing world

Background  

Pesticide poisoning is a global health issue with the largest impacts in the developing countries where residential and small-scale agricultural areas are often integrated and pesticides sprayed manually. To reduce health risks from pesticide exposure approaches for personalized exposure assessment (PEA) are needed. We present a conceptual framework to develop a spatial individual-based model (IBM) prototype for assessing potential exposure of farm-workers conducting small-scale agricultural production, which accounts for a considerable portion of global food crop production. Our approach accounts for dynamics in the contaminant distributions in the environment, as well as patterns of movement and activities performed on an individual level under different safety scenarios. We demonstrate a first prototype using data from a study area in a rural part of Colombia, South America.     

京郊温室大棚农业人员自觉健康状况及其影响因素分析

目的:了解京郊地区温室大棚农业人员自觉健康状况并探讨其影响因素,为改善和促进温室农业人员职业健康相关策略的制定提供科学依据。方法:于2018年6月至2019年12月,依据京郊地区主要温室大棚农业区县生产特色和规模,分层随机抽取从事温室182名温室大棚农业人员作为研究对象,进行一般情况、职业情况和自觉健康状况调查,统计分...