Safety impact and farmer awareness of pesticide residues

Abstract

Pesticide residues have always been an important concern in agricultural safety. Investigating farmers' awareness of pesticide residues and their behaviours regarding pesticide application is particularly important in order to reduce human factors that negatively affect agricultural safety. This review focuses on a summary of both domestic and foreign studies since 2000 regarding the effects of pesticide residues on agricultural safety, as well as farmers' awareness of these effects. This review also incorporates the actual performance of China on the issue of pesticide residues in order to provide the studies with a newer perspective.

Keywords:

• pesticide residue
• farmers awareness
• agricultural safety

Introduction

Although living standards in China are gradually rising, agricultural safety accidents keep occurring. They are becoming of great concern in both urban and rural areas. Wu et al. (2009) showed that approximately 86% of consumers believe, to varying degrees, that food product safety is a problem in their cities. Statistics from the Chinese Chamber of Commerce (2008) show that 95.8% of urban consumers and 94.5% of rural consumers are concerned with the quality and safety of agricultural food products. The Chamber recorded a 13.2% and 36.4% increase, respectively in quality and safety of these products in the 2006.

The quality of agricultural products is closely related to pesticide residues. Pesticide residues, especially that of highly toxic pesticides, have become important factors and threats to the safety and quality of agricultural products. The threat of pesticide residues not only depends on the quality and specificity of pesticides, but also on farmers' awareness of pesticide residues and their behaviour in applying these pesticides (Li, Fu, & Wu, 2007; Rother, 2005; Zhou, 2007). This article attempts to add new perspectives in the safe production of agricultural goods by focusing on the negative effects of pesticide residues, farmers' awareness of pesticide residues, and the factors that influence the behaviour of farmers in applying these pesticides.

Negative effects of pesticide residues

Agricultural safety and the resulting environmental and health problems from pesticide application are increasingly attracting global attention (Cooper & Dobson, 2007; Dinham & Malik, 2003; Leyk, Binder, & Nuckols, 2009). Since the dawn of the new century, scholars at home and abroad have continuously conducted extensive research on the negative effects of pesticide residues.

Pesticide residues affect the quality of agricultural goods. Chemical pesticides play an irreplaceable role in ensuring the adequate production of foods. However, a large input of pesticides leads to excessive residues that adversely affect the quality of agricultural goods (Qi, Fu, & Shi 2002). Although the impacts of pesticides on agricultural products vary according to the type of pesticide used, all pesticide residues cause nutrient imbalance and reduction in the quality of agricultural products (Bourn & Prescott, 2002). Munshi, Detlef, Schneider, and Zuberi (2004) reported that organochlorine pesticide residues have been found in fish in several different ports. When these fish are consumed by humans, pesticide residues accumulate in their muscles, liver and adipose tissues (Saqib et al., 2005). The studies conducted by Munshi et al. (2004), Parveen Khuhro, and Rafiq (2004) and Saqib et al. (2005) showed that the quality of milk, vegetable, fish and feeds are all adversely affected by pesticide residues.

Pesticide residues affect human health. In fact, pesticide application has become a great threat to human health (Buczynska & Szadkowska-Stanczyk, 2005; Elfvendahl Mihale, Kishimba, & Kylin, 2004; Leyk et al., 2009; Sivanesan, Krishnamurthi, Wachasunder, & Chakrabarti, 2004). Studies have shown that long-term low-dose exposure to pesticides leads to the development of respiratory diseases such as asthma (Hoppin et al., 2002). Such exposure also leads to reduced sperm quality and sperm count, causing sterility (Tuc et al., 2007). The impact of pesticides on the human immune system has also attracted attention from scholars (Beil et al., 2001; Christin et al., 2004; Galloway & Handy, 2007; Gu, 2005). Scholars agree that certain pesticides may affect the human endocrine and immune systems. They also agree that pesticides may promote the development of cancer. Xiurong and Liansheng (2000) showed that workers with long-term exposure to organophosphorus pesticides have reduced humoral and cell-mediated immunity; however, Colosio et al. (2005) stated that, currently, there is not enough evidence to derive the conclusion that pesticides affect the human immune system. Pesticide poisoning is more significant in developing countries compared to developed countries. Panuwet et al. (2008) conducted early urine tests to farmers who regularly apply pesticides in China and in Thailand. They found relatively high amounts of organophosphorus pesticide, malathion, 2,4-D, chlorpyrifos, methamidophos and other highly and moderately toxic pesticides in the urine samples. Pesticide application does not only cause negative impacts on the health of the applicator, but it also puts the health of other farm residents in danger (Nicol, 2003).

Pesticide residues affect environmental quality. Farmers serve as the main unit of agricultural production; their life and their daily production are closely related to the natural environment. Consequently, their irrational economic activities and unscientific ecological behaviour directly and inevitably worsens the ecological environment. Abrahams (2002), Bhattacharya, Sarkar, and Mukherjee (2002) and Guide (2008) believed that soil is the potential contact medium among pesticides, water, atmosphere, agricultural products, food and human health. Pesticide residues in soil can be persistent, gradually decomposing to become a source of pollution. Hildebrandt, Lacorte, and Barcelo (2007) utilised gas chromatography-mass spectrometry to investigate water and soil samples from Embro River Basin in the northeastern region of Spain. He found that triazine, organophosphorus pesticide and pesticide additives tributylphosphate (TBP) existed in all the water samples with concentrations of 0.57–5.37 µg/L. Nonylphenol and adjuvant alkylphenol were also found in all the soil samples. Chapman, McDonald, and Lawrence (2002) conducted a study based on the US Environmental Protection Agency Priority Testing Directory and found that chlordane, dichlorodiphenyldichloroethane (DDD), dichlorodiphenyl metabolite (DDE), dichlorodiphenyltrichloroethane (DDT), dieldrin, heptachlor, acrolein, tetrachlorodibenzo-p-dioxin (TCDD) and toxaphene can persist in sediments and can accumulate in biological bodies. They also found that endosulfan and endosulfan sulfate cannot be directly consumed by biological bodies. However, because endosulfan and endosulfan sulfate persist in sediments, they can still accumulate in biological bodies and can cause sustained effects on environmental quality.

Farmers' awareness of pesticide residues

Farmers serve as the main unit of pesticide application. Hence, their degree of awareness of pesticide residues inherently affects their methods of pesticide application. Whether they apply pesticides in a standardised method affects the generated amount of pesticide residues, thereby ultimately influencing the safe production of agricultural products.

Awareness of the danger of excessive pesticide residues

According to a survey of 1099 farms in 21 provinces conducted by the Pesticide Testing Institute of the Chinese Ministry of Agriculture in 2001, most farmers lack knowledge regarding the threats of excessive pesticide residues (Guangxue & Yuerong, 2002). Most farmers complain that pesticide labels are too abstruse and technical for them to understand; this ultimately increases the dangers of pesticide residues (Rother, 2005; Waichman, Evldice, & Celso da Silva 2007). A study by Zhongze and Qingjiang (2007) involving nine regions in seven provinces found that 75% of the surveyed farmers had a certain amount of knowledge on the regulations regarding pesticide use, while 25% of the farmers had no knowledge at all. Puyun et al. (2007) surveyed 360 small-scale vegetable farmers in six cities of Yunnan Province and found that 100% of the farmers perceive pesticide use as the most common method of controlling vegetable pests. In addition, small-scale farms tend to overestimate the loss caused by pests, and thus tend to apply pesticides excessively without adequately understanding the dangers of pesticide residues.

Awareness of how pesticide residues affect the quality of agricultural products

Juan and Lei (2009) surveyed aquaculture farmers in Changsha, Rudong City, in Jiangsu Province. They found that although farmers are generally concerned, they have a pessimistic attitude towards food quality issues. Furthermore, they tend to possess information regarding food quality and safety. Their main knowledge source is accumulated experience and shared knowledge amongst peers (Juan & Lei, 2009). Farmers in Sichuan Province lack knowledge on pesticide toxicity and do not follow specific guidelines. Rather, they utilise a random method when applying different kinds of pesticides on different kinds of agricultural products (Hongmei et al., 2007). Li and Ren (2008) conducted a study in six provinces, including Shandong, Heilongjiang and Jiangsu, and found that most farmers do not understand that highly toxic pesticide residues and the amount of pesticide input, as well as the withdrawal period, are all important factors that influence the quality of agricultural products. The study of Yuexiang et al. (2008) in Hebei Province confirmed that even when farmers fully understand the correct amount and method of pesticide application, they still lack the notion of how important it is to utilise the correct method, which leads to the accumulation of pesticide residues in agricultural products.

Awareness of standardised regulations in order to reduce pesticide residues

Farmers tend to apply pesticides excessively and irrationally because they do not understand the risks of pesticide residues, the guidelines on how much pesticide to use or the standardised regulations in pesticide application. This is the root of pesticide residue problems (Zhou & Jin, 2009). For example, many farmers, even without fully understanding the leaking problems in sprayers, continue to increase the amount of pesticides that they apply. The costs of health problems brought about by pesticides, particularly medical costs, are not usually accounted because local health officials do not often diagnose symptoms in relation to exposure, and they are not adequately trained to identify the adverse effects of pesticides (Ngowi, Maeda, & Partanen, 2001). Dinham and Malik (2003) and Epstein and Bassein (2003) found that farmers have the notion that using different kinds of pesticides is the most effective way of controlling agricultural pests; thus, they tend to apply pesticides excessively. Mekonnen et al. (2002) and Tariq et al. (2004) showed that 70% of farmers in developing countries encounter difficulties in reading instruction manuals, leading to the misuse of highly toxic pesticides. In Pakistan, the chances of pesticide misuse are relatively high for several reasons. Among farmers, there is low awareness regarding the safe use of pesticides. Furthermore, Pakistan records a low literacy rate where more than 70% of farming communities do not read or understand the national language (Urdu). To compound the problem, the awareness brochures of pesticides are printed in English and in Urdu (Mekonnen & Ejigu, 2005; Tariq, Hussain, & Afzal, 2003). More frequent application of highly toxic pesticides leads to more pesticide residues persisting in agricultural products (Hu, Chen, & Sun, 2006). However, due to the lack of awareness of farmers, the misuse of pesticides has become a serious problem in agricultural production (Abhilash, 2009; Brauw, Huang, & Rozelle, 2000; Huang, Rozelle, & Pray, 2002). In China, 22.3% of farmers tend to apply twice the amount of pesticides stated on the label to ensure higher production yields (Li, Li, & Fu, 2008). In Greece, more than half of the farmers tend to apply excess pesticide in order not to have any leftovers (Christos et al., 2008). In northern Tanzania, small-scale vegetable farmers have been applying increasingly more pesticides more often, at least five times per season (Ngowia et al., 2007). In Botswana, one-third of the pesticides applied by farmers are extremely or highly hazardous pesticides, as listed by the WHO (Obopile, Munthali, & Matilo, 2008). In the native regions of Costa Rica, 97% of banana farmers still utilise chlorpyrifos (a highly-toxic insecticide) to ensure production (Polidoro et al., 2008).

Factors that influence farmers' awareness of pesticide residues

Many factors influence farmers' awareness of pesticides and pesticide residues. For example, Nicol (2003) utilised a multi-variable model and concluded that the significant factors that influence farmers' awareness of pesticides include race, awareness of agricultural damage and awareness of health problems caused by pesticides, as well as whether they or their relatives have experienced damages caused by pesticides. Overall, studies in this field have focused on the following five factors.

Geographical factors

Due to different plantation structures and habits in different regions, levels of pest diseases, pesticide production and sales, as well as economic levels, are all different. Hence, the levels of pesticide awareness among farmers also differ. Dasgupta, Meisner, and Huq (2007), Yang (2006) and Yunhua, Zhang, Ma, and Kong (2004) believed that, among others, differences in annual income and geographical location can partly explain why farmers apply pesticides excessively. The amount of pesticides, especially highly toxic pesticides, applied in developing countries are considerably higher than in developed countries (Donald, 2001; Rahman, 2003; Tariq et al., 2003).

Gender and age

Gender tends to influence awareness of the dangers of having pesticide residues. In Brazil and in South Africa, male pesticide users tend to have higher awareness than females. This is shown in their action of wearing protective clothing while applying pesticides (Nicol, 2003). In Nepal, women do not have a strong notion of the dangers caused by pesticides because they have relatively lower education levels (Kishor, 2007). In China, male applicators tend not to adopt protection methods while applying pesticides, and they have a higher probability of randomly throwing away empty pesticide containers as compared to female applicators (Li et al., 2007). Ntow and Gijzen (2006) believed that age is an important factor in distinguishing the group that is more vulnerable to pesticide poisoning. Juan and Lei (2009) found that younger and more educated farmers are more aware of food quality and safety standards. Furthermore, farmers with children had significantly higher awareness than farmers without children.

Education

If a farmer is relatively less educated, his/her ability to absorb professional knowledge is weaker. Furthermore, his/her capability to recognise pest diseases is also weaker. Hence, the less-educated farmer tends to lack awareness of both pesticide residues and the importance of applying pesticide in standardised ways. Consequently, with less education, there is a higher chance that the farmer will apply prohibited pesticide excessively, leading to highly concentrated pesticide residues (Huang, Liu, & Pei, 2008; Xu, 2004). In India, Abhilash (2008, 2009) found that, due to the lack of adequate knowledge regarding pesticides, farmers tend to apply the same pesticide excessively rather than mixing different kinds of pesticides rationally. In Chengdu, Li et al. (2008) found that, due to the lack of pesticide knowledge, most farmers solely focus on the outcome of pesticide use when purchasing pesticides. They rarely pay attention to the toxic side effects of pesticides on human health.

Agricultural use

Zhou (2007) found that farmers who plant rice to feed their own households tend to pay more attention to pesticide residue problems, while farmers who plant rice for commercial purposes pay more attention to the quantity of production. Rahman (2003) showed that farms with larger plantation areas apply greater amounts of pesticides. Furthermore, farmers with more experience tend to use highly toxic pesticides because of their quick results. Agricultural products from larger plantations are mostly sold in the market (Zhao & Zhang, 2007).

Other factors

Dongmei (2006) found that the education and training provided by agricultural technology personnel affect farmers' awareness of pesticide residues. Zhongze and Qingjiang (2007) believed that a randomised security check of pesticide residues will increase the motivation of farmers to purchase low-toxicity pesticides with fewer residues or to apply pesticides in standardised ways. Furthermore, to a certain degree, the agricultural service environment (Zhou, 2007) and sale routes (Beth et al., 2008) directly affect the amount of pesticides being applied, and indirectly affect farmers' awareness of pesticide residues (Yang, Li, & Zhou, 2007).

Brief comments and research prospects

Scholars have long been conducting extensive research on the issues of pesticide residues and agricultural product safety and quality. The main conclusions of these studies include the following: (1) pesticide residues affect the quality of agricultural products in many complex ways; (2) farmers' lack of awareness regarding pesticide residues and their non-standardised and unscientific behaviour in applying pesticides increase the risks posed by pesticide residues; and (3) geographical differences, as well as the individual characteristics of farmers, are primary factors that affect farmers' awareness. All of these conclusions pave the way for further research.

However, existing studies have several shortcomings. The field lacks research on how to regulate pesticide application behaviour through governmental guidance. Furthermore, market mechanisms need to be studied in order to reduce the threats of pesticide residues to the quality and safety agricultural products. Amidst unprecedented changes (e.g. environmental and the climate changes, reduction in arable lands and population increases), the regulation of pesticide availability seems to be the most important, practical and effective way of reducing human factors that threaten the quality of agricultural products. International organisations have already conducted research in several countries and have proven the practicability of this proposal (Development Report of World Bank, 2008). The behaviours of farmers in relation to pesticide use, analysis of the factors that influence farmers' awareness of pesticide residues and the regulation pesticide availability will be the focus of further studies.

Meanwhile, in the case of China, research and development (R&D) should be further strengthened, and the use of pesticide residue detection technology should be promoted. Alternatively, relevant advanced foreign technology on pesticide residues should be introduced. For example, by promoting Song, Ma, and Li's (2007) rapid detection method, the minimum residues detection limit of organic phosphorus, organic chlorine and carbamates in China's agricultural products may gradually be increased to 0.01 mg/kg level. The antigen-coated and enzyme-linked immunosorbent assay of Jin et al. (2008), the antibody-coated and enzyme-linked immunosorbent assay and other methods to improve the detection of triazophos residues in water samples may also be adopted. Furthermore, Rekha and Murthy's (2008) bio-sensor technology can be used to address some problems in the organic phosphorus pesticide residues detection (e.g. slow and low-accuracy detection). Furthermore, by applying Skerritt, Guihot, Asha, Rani, and Karanth's (2003) immunoassay method for detecting and analysing organochlorine pesticides existing in plant-derived foods, as well as Anand et al.'s (2007) enzyme-linked immunosorbent assay (ELISA), which were developed for the N-methylcarbamate insecticide bendiocarb detection, to enhance China's food testing technology. Through advanced detection technology, pesticide residues in China's agricultural products can be further monitored. At the same time, the fact-based perceptions of farmers and the whole society towards the dangers of pesticide residues can be promoted.

Acknowledgements

Financial support was offered by the National Nature Science Youth Foundation of China (Grant 70901034). This research was supported by a grant from the Doctoral Scientific Research Fund Project of Jiangnan University in 2009. We wish to acknowledge the help of Prof. Qiang Fu of Arkansas University.