Christos A. Damalas

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.

Pesticide Use and Risk Perceptions among Farmers in Southwest Iran

ABSTRACT Pesticide use and farmers’ perceptions of risk of unsafe use of pesticides were explored in Fars Province, Iran. One hundred and fifty-five farmers engaged in pesticide handling were selected through a proportional stratified random sampling method with age as the stratification variable. Most of the farmers were not following basic pesticide safety measures and the majority of them (about 60%) were not using any protective equipment when spraying pesticides. Based on four identified factors, which explained 58% of the total variance in risk perceptions of unsafe use of pesticides, three segments of farmers were revealed. Segment A included 30.3% of the farmers who had the lowest perceived risk of unsafe use of pesticides (i.e., they perceived unsafe use of pesticides as not so dangerous). Segment B, which was the largest segment revealed, showed intermediate perceived risk of unsafe use of pesticides and all of four factors as well. However, segment C with 16.7% of farmers, reported the highest perceived risk of unsafe use of pesticides (i.e., they perceived unsafe use of pesticides as very dangerous). To develop a more targeted agricultural extension program, selected characteristics with respect to each segment were explored and compared.

Dicamba and Atrazine Antagonism on Sulfonylurea Herbicides Used for Johnsongrass (Sorghum halepense) Control in Corn (Zea mays)1

Abstract: Field experiments were carried out during 1997 and 1998 in northern Greece to investigate the effects of tank mixing rimsulfuron and primisulfuron with atrazine or dicamba against johnsongrass in corn. Sequential applications, where the johnsongrass herbicides were applied 5 d after the broadleaf herbicides, were also evaluated. Rimsulfuron applied alone at 10 g ai/ha gave very good control (91%) of johnsongrass, which was significantly higher than that provided by 30 g ai/ha of primisulfuron (43%). Rimsulfuron applied in tank mixture with atrazine (1.0 kg ai/ha) or dicamba (0.28 kg ai/ha) gave 12 and 17% lower johnsongrass control, respectively, than of rimsulfuron applied alone, whereas the corresponding reduction for primisulfuron was 18 and 43%. Efficacy of rimsulfuron applied 5 d after the application of atrazine or dicamba was similar to that applied alone; however, this was not the case for primisulfuron, where reduced antagonism was observed compared to that produced by its tank mixture treatments. Again, primisulfuron was affected more by dicamba than by atrazine. Corn yield with rimsulfuron and primisulfuron applied alone was more than double that of the untreated control and similar to that of the weed-free control. Also, rimsulfuron applied with atrazine or dicamba (in tank mixture or sequentially) produced similar corn yield to that applied alone. However, primisulfuron applied in tank mixture or sequentially with dicamba gave 22 and 14% lower yield, respectively, than when applied alone, and slightly lower when applied with atrazine. Nomenclature: Atrazine, dicamba, primisulfuron, rimsulfuron, johnsongrass, Sorghum halepense (L.) Pers. #3 SORHA; corn, Zea mays L. ‘Pioneer Costanza’. Additional index words: Sequential applications, tank mixtures. Abbreviations: DAT, days after treatment.

Farmers’ Exposure to Pesticides: Toxicity Types and Ways of Prevention

Synthetic pesticides are extensively used in agriculture to control harmful pests and prevent crop yield losses or product damage. Because of high biological activity and, in certain cases, long persistence in the environment, pesticides may cause undesirable effects to human health and to the environment. Farmers are routinely exposed to high levels of pesticides, usually much greater than those of consumers. Farmers’ exposure mainly occurs during the preparation and application of the pesticide spray solutions and during the cleaning-up of spraying equipment. Farmers who mix, load, and spray pesticides can be exposed to these chemicals due to spills and splashes, direct spray contact as a result of faulty or missing protective equipment, or even drift. However, farmers can be also exposed to pesticides even when performing activities not directly related to pesticide use. Farmers who perform manual labor in areas treated with pesticides can face major exposure from direct spray, drift from neighboring fields, or by contact with pesticide residues on the crop or soil. This kind of exposure is often underestimated. The dermal and inhalation routes of entry are typically the most common routes of farmers’ exposure to pesticides. Dermal exposure during usual pesticide handling takes place in body areas that remain uncovered by protective clothing, such as the face and the hands. Farmers’ exposure to pesticides can be reduced through less use of pesticides and through the correct use of the appropriate type of personal protective equipment in all stages of pesticide handling.

Factors preventing the adoption of alternatives to chemical pest control among Pakistani cotton farmers

Providing pest control solutions that are less harmful to the farmers and the environment, while maintaining effectiveness on pests is a major goal in modern crop protection. A survey of randomly selected cotton farmers from two districts of Punjab in Pakistan was conducted to study common crop protection practices and related behaviors of farmers in an attempt to identify factors preventing the adoption of alternatives to chemical pest control in the area. Almost all farmers reported using pesticides extensively as the only way of controlling pests and often by mixing two or more different pesticide products. Most farmers felt that spraying with chemicals is not only highly effective, but it is also the only viable option available at the moment. Thus, despite significant health concerns, they felt forced to use pesticides. Almost half (49%) of the farmers, irrespective of age, showed a tendency toward pesticide overuse by spraying higher quantities of pesticides than those required. To model farmers’ behavior toward environmentally sound alternatives of pest control, a binary probit regression model was used expressing behavior as a function of age, education, farm size, income, risk perception levels, adverse health effects by pesticides, and training. Education and training were the main determinants of environmentally sound behavior in pest control, in the sense that high levels of education and training appeared to discourage pesticide use in the study area. In contrast, experience of health problems was not associated with behaviors toward pesticide reduction or adoption of alternative pest control practices. Additionally, governmental policies, such as the outdated extension system and the easy availability of pesticides under a non-existing or poor regulation system, which encourage farmers to utilize pesticides, should be considered as extra major barriers in the adoption of alternative pest control practices.

Interference between corn and johnsongrass (Sorghum halepense) from seed or rhizomes

Abstract Field experiments were conducted in 1999 and 2000 in northern Greece to study interference between johnsongrass from seed or rhizomes and three corn hybrids (‘Dunia’, ‘Papea’, and ‘Costanza’). Fresh weight of each corn hybrid was lower with greater duration of johnsongrass interference, and it was lower for corn grown with johnsongrass from rhizomes than from seed. Corn-silage yield and corn-grain yield were 10 to 14% less than weed-free corn yield when grown with johnsongrass plants from rhizomes 4 wk after sowing (WAS) or from seed 6 WAS. Regression analysis indicated that a corn-grain yield loss of 10% was associated with an interference period of 2.6 to 2.7 WAS for johnsongrass from rhizomes and 4.3 to 5.1 WAS for johnsongrass from seed compared with weed-free corn. Corn-silage yield with season-long interference by johnsongrass from rhizomes or from seed was 83 and 62% lower, respectively, than was weed-free corn yield. Similarly, corn-grain yield with season-long interference by johnsongrass from rhizomes or from seed was 88 and 57% lower, respectively, than was the yield from weed-free corn. Corn-ear length of each hybrid was more affected by johnsongrass interference than was 1,000-seed weight. Johnsongrass plants from rhizomes emerged earlier, grew faster, and produced greater fresh weight than did plants from seed. However, fresh weight and stem number of johnsongrass plants from either seed or rhizomes were not affected by corn hybrids. Nomenclature: Johnsongrass, Sorghum halepense (L.) Pers. SORHA; corn, Zea mays L. ‘Pioneer Costanza’, ‘Pioneer Dunia’, ‘Pioneer Papea’.

Farmers' use of personal protective equipment during handling of plant protection products: Determinants of implementation

Understanding factors affecting the use of personal protective equipment (PPE) during handling of plant protection products (PPPs) is of major importance for the design of tailored interventions to minimize exposure among farmers. However, data regarding this issue are highly limited. Factors related to the use of PPE during handling of PPPs were explored in a survey of cotton farmers in northern Greece. Data were collected through face-to-face interviews with the farmers based on a questionnaire with structured items on the frequency of use of various personal protective devices during handling of PPPs. New evidence on patterns of PPE use and potential exposure of farmers to PPPs is provided. Most farmers (49.3%) showed potentially unsafe behaviour with respect to PPE use. Hat and boots were the most commonly used protective items during PPPs use, but most of the farmers surveyed reported low frequency of use for gloves, goggles, face mask, coveralls, and respirator. Especially the respirator was reported to be the least used PPE item amongst farmers. Farmers who perceived PPPs as harmful substances or those who had an episode of intoxication in the past reported more frequent use of several PPE items. Stepwise multiple regression analysis revealed that the variable episode of intoxication in the past exerted the strongest positive influence on PPE use, followed by the perception of PPPs being hazardous substances, upper secondary education, previous training on PPPs (i.e., spraying equipment, application parameters, risks to human health and environment, safety issues) and farm size under cultivation. Old age exerted a significant negative influence on PPE use, namely, elderly farmers tended not to use PPE. Strategies to maximize the protection of applicators of PPPs from hazardous exposures still require innovation to achieve increased effectiveness. Emphasis on lifelong training and education of farmers about hazards and risks of PPPs is crucial for changing wrong behaviours in handling of PPPs.

Morphological and Physiological Variation among Species of the Genus Echinochloa in Northern Greece

Abstract The variability of 12 Echinochloa populations with respect to certain morphological and physiological characteristics, sensitivity to certain POST rice herbicides, and activity of selected enzymes was studied. Three distinct groups (each one represented by four populations from different areas) were studied: E. crus-galli, E. oryzoides, and E. phyllopogon. All the E. oryzoides and E. phyllopogon populations showed earlier seed germination and higher germination percentages than the E. crus-galli populations. All the E. oryzoides and E. phyllopogon populations showed reduced susceptibility to propanil, cyhalofop, clefoxydim, and bispyribac compared with the E. crus-galli populations. With respect to plant prostrateness, the species order, averaged over the four populations, was E. crus-galli prostrate > E. oryzoides relatively erect > &Egr;. phyllopogon erect, while the species order with respect to leaf length and tillering ability was E. crus-galli > E. oryzoides > &Egr;. phyllopogon. Regarding leaf width, time of panicle emergence, height, and biomass accumulation, the order was E. crus-galli > E. oryzoides > &Egr;. phyllopogon, while that of seed weight, length and width was E. oryzoides > &Egr;. phyllopogon > E. crus-galli. The order of species susceptibility (averaged over the four populations) to most of the herbicide treatments was E. crus-galli > E. oryzoides > E. phyllopogon, which was exactly the opposite of that relating to their antioxidant enzyme activity. Finally, the order of herbicide efficacy, averaged over all Echinochloa populations, was penoxsulam > clefoxydim > bispyribac > cyhalofop > propanil. Variability in a number of traits among the most common Echinochloa species of rice fields in northern Greece as a result of different adaptive strategies of each species may be related to differential sensitivity to herbicides. This variability should be taken into account for the elaboration of effective weed management programs in rice. Where mixed populations of these species are present in a field, difficulties may arise in the successful chemical control of the Echinochloa complex in rice due to species differences in biology and herbicide sensitivity.

Pesticide exposure in the local community of Vehari District in Pakistan: An assessment of knowledge and residues in human blood

The present study is based on cross-sectional data collected from rural and market areas of Vehari District in Pakistan to assess public awareness of pesticide risks and determine the levels of exposure to organochlorine pesticides (OCPs) in the local community. Blood samples were collected from 56 volunteer donors (VDs) including children, female workers, farm workers involved in pesticide business, farm workers involved in pesticide spraying activities, and people who were living away from agricultural fields. Blood analysis showed that VDs who were involved in spraying activities had significantly higher levels of OCP residues in their blood samples than VDs from the other groups, with mean concentrations of 1.13, 0.92, 0.68 and 1.96ngmL-1 for pp-DDT, aldrin, dieldrin, and endosulfan, respectively. However, VDs who were living away from agricultural fields had significantly lower levels of pesticide residues in their blood samples, with mean concentrations of 0.30, 0.19, 0.14 and 0.41ngmL-1 for pp-DDT, aldrin, dieldrin, and endosulfan, respectively. A survey of 179 volunteer respondents (VRs) showed that a significant proportion of the VRs had little knowledge of using the recommended amounts of pesticides (65.9%). Furthermore, the majority of the VRs was found using limited protective measures during pesticide use (62.6%) and was practising unsafe storage of pesticides (87.7%). In addition, most farm workers (88.8%) reported an increasing trend in pesticide use in their farms each year. Knowledge of pesticide risks on human health increased with formal education and training. Poor knowledge regarding pesticide risks and handling among inhabitants of Vehari District contribute to high exposure levels to OCPs, particularly among farm workers. Findings are useful for policy formulation aimed at reduction of pesticide exposure in Pakistan.

Conservation tillage: a promising perspective for sustainable agriculture in Greece.

Conservation tillage has been widely implemented in the last decades in several parts of the world as an attractive alternative to conventional tillage due to its potential to protect soils from erosion and compaction, to conserve soil moisture, and to reduce production costs. Significant savings in fuel, labor, and machinery costs are realized with conservation tillage, mainly because fewer trips over the field are required during seedbed preparation. Conservation tillage in Greece has been tested on a limited scale by a minority of farmers on an empirical basis or on an experimental basis by research institutes. Research thus far has shown that, despite some disadvantages in certain cases, conservation tillage can be attractive to farmers because it can provide equal or even greater yields than conventional tillage and also because of its potential for reduced production costs. From this view point, conservation tillage should receive more attention among Greek producers, becoming a viable alternative to conventional tillage and gaining wide acceptance because of its multiple benefits for both the farmer and the environment. Education, technical assistance, and financial assistance to farmers will play a dominant role in this effort.