摘要：Objective. This study investigates the possible influence of global climate change (GCC) on exposure to plant protection products (PPP) in the workplace. Methods. The paper has evaluated the main potential relationships between GCC and occupational exposure to pesticides, by highlighting how global warming might affect their future use and by reviewing its possible consequence on workers' exposure. Results. Global warming, influencing the spatial and temporal distribution and prolif- eration of weeds, the impact of already present insect pests and pathogens and the in- troduction of new infesting species, could cause a changed use of pesticides in terms of higher amounts, doses and types of products applied, so influencing the human exposure to them during agricultural activities. GCC, in particular heat waves, may also poten- tially have impact on workers' susceptibility to pesticides absorption. Conclusions. Prevention policies of health in the workplace must be ready to address new risks from occupational exposure to pesticide, presumably different from current risks, since an increased use may be expected. var currentpos,timer; function initialize() { timer=setInterval("scrollwindow()",10);} function sc(){clearInterval(timer); }function scrollwindow() { currentpos=document.body.scrollTop; window.scroll(0,++currentpos); if (currentpos != document.body.scrollTop) sc();} document.onmousedown=scdocument.ondblclick=initialize C limate Change and pestiCides at work 375 changes in climate through this century will affect crops differently because individual species respond different- ly to warming. Plant response to climate change may be actually dictated by complex interactions among CO 2 , temperature, solar radiation, and precipitation. Precipi- tation changes and temperature increases are the main pest infection determinants in terms of climate change [10]. About rainfall changes, the availability of water strongly influences any kind of agriculture: changes in total seasonal precipitation or in its pattern of vari- ability are both important. Climate change will modify rainfall, evaporation, runoff, and soil moisture storage. Precipitation may influence variations in crop yields, yield quality and pests in both a positive and negative way: by increasing yields in greater precipitation during the growing season and by damaging crop productiv- ity, especially for younger plants, during intense rainfall [11, 12]. Regarding temperature increases, higher tem- peratures and increased CO 2 concentrations, associat- ed with a substantial change in photosynthetic activity, promote plant growth and expansion [13]. In contrast, a temperature variability increase can adversely affect crops growing at low or high mean temperatures due to diurnal and seasonal canopy temperature fluctuations that exceed the crop's optimum range. Each crop spe- cies has indeed a temperature range for growth, along with an optimum temperature. Plants have specific temperature tolerances: as temperatures increase over this century, crop production areas may shift to follow the temperature range for optimal growth and yield of grain or fruit. One critical period in which temperatures are a major factor is the pollination stage; pollen release is related to development of fruit, grain, or fiber. Expo- sure to high temperatures during this period can greatly reduce crop yields and increase the risk of total crop failure. Plants exposed to high nighttime temperatures during the grain, fiber, or fruit production period expe- rience lower productivity and reduced quality. Insect pests Global warming improves overwintering, dispersal, migration and population characteristics such as re- production and growth rates. Although insects flour- ish in all climates, research reports an earlier appear- ance and activity in warmer circumstances. Elevations in temperature, for example, may affect the rates of extrinsic incubation in insect vectors (e.g., ticks and mosquitoes), extended vector transmission seasons and expanded distribution seasonally and spatially [14]. In addition, wet conditions may possibly bring on severe insect and plant pathogen infestations or effect a geographical shift of some pests. Insect profusion may be also determined by increases in CO 2 concen- tration, wind induced dispersal of pests, differences in soil nitrogen content and population density. Finally, extreme weather conditions seem to have divergent consequences on species' longevity reducing it in some species but not in others. In summary, climate change promotes distribution and abundance of pests due to migration and range shifts, increases pest outbreaks and alters the dissemination of vectors, all favoring pests compared to crops [10, 15]. Plant diseases Plant diseases are mainly affected by temperature, rainfall, humidity, and radiation [16]. Different life stages may vary in their climatic susceptibilities but the direct effects on pathogens are likely to be strongest. Wet conditions promote the germination, the spread and activity of spores as well as the proliferation of fungi and bacteria. This is also the case for extreme events and rainfall in particular, which aid the dispersal of dis- eases. Climate warming may improve pathogen over- wintering, development and dispersal, all resulting in an elevated disease severity and plant losses [17]. On the other hand, inverse correlations of pesticide use with arid and hot weather were recorded; in fact, warm and dry conditions can increase resistance to plant infec- tions resulting in a reduced fungicide need, which is also the case with high atmospheric CO 2 concentrations. However, as we have found about local agriculture, in- creased temperatures will also affect plant productivity, giving rise to a potential increase in volume and array of pesticides used. Other climate effects are seen for pathogens that cause overwintering diseases. Due to milder winters and less snow cover, the importance of these pathogens can decrease. In contrast, for example, late blight incidence on potato is expected to increase in the case of warmer springs, summers and more hu- mid conditions of the future [18]. In conclusion, it is difficult to seize completely the links between climate and disease processes, given the high degree of com- plexity in plant-pathogen systems and nonlinear thresh- olds in both. Nevertheless, an increased plant disease and physiological plant stress pressure is expected to increase host susceptibility and pesticide dependency. Weeds Climate change affects either crop or weed. A tem- perature increase appears to cause fundamentally al- tered weed communities and a geographic niche expan- sion of many species. Research also demonstrated that an increased atmospheric CO 2 concentration directly raises weeds' herbicide tolerance and severity because of the higher carbon dioxide fertilization effect and improved water use efficiency in comparison with ag- ricultural crops [13]. Finally, increasing leaf thickness and the partial stomatal closure in this case, may reduce herbicide absorption and efficacy [19]. Weed resistance to herbicides and the decline in efficacy can influence the future total amounts use of herbicides. PESTICIDE USE AND FATE UNDER GLOBAL WARMING CONDITIONS Any significant change in climate on a global scale should influence local agriculture, and indirectly may affect the world's pesticide use. However, given the mul- tivariate nature of climate change and nonlinear thresh- olds in natural processes, it is difficult to consider all the links between climate change and pesticide use. Never- theless, as we have remarked above, there is agreement among scientists that climate change may increase pest populations, including weeds, invasive species, insects, and insect-borne diseases, which will likely lead to large increases in the use of pesticides (Table 1).
关键词：climate change; global warming; pesticides; occupational exposure
