This report has gathered sufficient evidence showing that As in irrigation water can result in land degradation, adversely affecting incomes and agro-ecosystem services in terms of their ability to provide a sustainable source of sufficient and safe foods. The soil contamination can cause contamination of crops and foods, resulting in risks to food safety and thus to human health. The continuous contamination of soil is a growing threat to crop production itself, and thus to sustainable agriculture, because As in soils will become toxic to plants and other organisms at a certain level. This would result in reduced crop yields and thus pose a risk to incomes and the nutritional status of rural farming communities. To date, the risks of using As-contaminated groundwater resources for irrigation have not received sufficient attention and have not been addressed within the framework of land degradation. The current and future extent of land degradation caused by As-contaminated irrigation water is still unknown.
An overview of our knowledge and gaps in our knowledge is given below. It should be remembered that a number of points are based on results from Bangladesh only. These need to be validated in other countries, taking into account differences in agricultural practices, environmental conditions, food habits and other factors.
Any risk to crop production is of serious concern as raising crop production is necessary to keep up with population growth. Also, raising crop production is regarded as one of the key elements in rural poverty alleviation. Land degradation caused by As-contamination could thus pose a threat to sustainable development.
With the continuation of uncontrolled use of contaminated water in agriculture, it is expected that the risks will increase over time. In the long run, this may offset the ongoing efforts in the drinking-water sector to reduce the adverse impacts of As.
Rice production systems are of particular concern because flooded soil conditions are most favourable for As uptake and rice is the most important staple food in the region. Other crops under irrigation with contaminated water need to be addressed as well as there are great uncertainties about the As mass balance under different environmental conditions.
It is important to note that once arable soils are polluted to an unacceptable level, rehabilitation is unlikely to be cost effective. Preference should thus be given to prevention and control over rehabilitation.
Considering the potentially serious consequences of As-contamination in agriculture, the identified gaps need to be filled, for example through an integrated regional programme covering both crop production and food safety aspects within the framework of land degradation.
Most importantly, the scale of the problem needs to be quantified. This should be based on scientifically justified methodologies resulting in reliable results, conclusions and recommendations. Close involvement of stakeholders of different sectors is necessary to optimize integrated and cross-sectoral programme coordination and implementation, including data sharing, human resources and funding, and to optimize dissemination and integration of the outcomes in strategic planning and programming, thus ensuring sustainability.
Agricultural production is under pressure from multiple factors including As. In Bangladesh, it has recently been noted that rice production per ha is stagnating and declining. Deterioration of soil quality has been mentioned as one of the main factors, including depletion of nutrients and organic matter. Another increasing problem is access to water. Boro rice production depends heavily on irrigation with water from the shallow aquifer, but the water table is decreasing rapidly at many locations because of overextraction. The high salinity of irrigation water is also hampering crop production in the coastal areas. Similar problems are occurring elsewhere in the region. The continuous addition of As to the topsoil may pose additional risks to soil quality and crop production and therefore to nutrition and income.
The extent of land degradation caused by As in irrigation water needs to be quantified and weighted against other factors causing land degradation. This will require in-depth understanding of As levels in irrigation water, soil and crops, the behaviour of As in soil, uptake and toxicity in crops in the relevant agro-ecosystems, the influence of agricultural practices including irrigation water management on As, and the establishment of standards for As in irrigation water, soil and crops. This information would result in an evaluation of the current situation and would serve as a baseline for the future. Further, it will be of great importance to develop an effective and efficient water/soil/crop quality monitoring system for long-term monitoring of land degradation in agro-ecosystems. This system should include both As and other physical, chemical (nutrients and contaminants) and biological parameters that together determine the quality of agro-ecosystems.
The integrated approach to address the issue of using As-contaminated groundwater resources for irrigation offers substantial opportunities to assess the overall status of land degradation in agro-ecosystems, develop a system to monitor future trends in land degradation, and assist governments and development partners in developing policies and setting priorities.
Depending on the outcome of the initial evaluation, management options to prevent or mitigate As input to the agricultural system can be developed. Exploratory studies are needed to assess the potential risks of As in the environment to livestock and fisheries.
Arsenicosis is commonly observed in areas with high As levels in STWs used for drinking-water, with thousands of people suffering in Asia. It is generally accepted that drinking-water is the main source of exposure, but foods could be an important and possibly growing source as well. However, foods are not only a potential source of As, they are also the main source of micronutrients. Micronutrient deficiency is prevalent in Bangladesh, particularly among poor women and children. Improved nutrition is therefore high on the priority list in most Asian countries. Most well-known deficiencies are vitamin A and iron deficiencies. In general, nutrient deficiencies make people more sensitive to diseases and toxicants. There are indications that this is also the case for arsenicosis.
To determine the risk to human health posed by As in foods a reliable and representative database on inorganic As in foods is a necessary first step. This database can then be used with data on food consumption to estimate the dietary intake of As through foods and the resulting exposure levels can be compared to health guidelines to assess the risks. However, health guidelines may need to be evaluated first as there are some concerns about their reliability and applicability. Considering the high prevalence of nutrient deficiency in Asia, it will be of great importance to take the nutritional value of foods into consideration when evaluating the risks of As in foods.
Depending on the outcome of the human health risk assessment, options to minimize As exposure can be identified at field level, e.g. adapting dietary habits and/or food preparation techniques. Such measures can be combined with efforts to improve nutrient intake. An improved nutritional status is regarded as one of the keys to strengthening the human immune system, thus making people less vulnerable to many diseases.
The technical capacity of many national laboratories involved needs to be strengthened to ensure the quality of the data. Within a laboratory, the quality of data depends on all activities that take place including pretreatment of samples, maintenance of facilities and equipment, training of staff, chemical analysis, administration, data processing, etc. All activities should therefore be described in standard operating procedures (SOPs) to ensure maximum standardization and transparency. This should result in a high level of QA/QC. QA/QC does add additional costs but unreliable data are more expensive. One specific requirement now is the use of CRMs during chemical analysis. This is not yet common practice in, e.g. Bangladesh, partially because of the high costs of CRMs. To overcome this, secondary reference materials (SRMs) representative of As in food and agriculture should be developed. As a start, SRMs for water, soil, rice grains and rice straw are suggested. This should be a mutual effort from a number of national research institutes and universities both from the health sector, the agricultural sector and the water sector, assisted by at least one established laboratory from abroad. Such an effort will not only upgrade chemical analysis, but can also strengthen inter-institutional planning and collaboration as a whole.
The behaviour and toxicity of As depends on the form in which it is present. In most cases, various forms of As co-exist in the environment. To understand the behaviour of As and assess its risks, it is therefore necessary to segregate As species during chemical analysis. The necessary techniques are, however, complicated and hardly available in the region. It is recommended that at least one institute in each of the affected countries develop As speciation capacity.
A first inventory reveals a substantial number of stakeholders. This can be attributed to the cross-sectoral and multidisciplinary character of the issue. Below is a brief overview of the key stakeholders.
Governments are the key stakeholder. The issue requires involvement from various sectors including agriculture, water, food, health, and environment, and thus the responsible ministries. Considering the many gaps in our knowledge, a number of national research institutes under the relevant ministries need to play an important role, and collaborate with the national and international scientific community. With most of the countries in Asia considered to be developing countries and countries in transition, risks to food safety and agricultural sustainability should be seen in the light of governments' development agendas. Providing governments with reliable and representative information, for example through the national research institutes, should stimulate governments to take appropriate action. At the same time, commitment from governments is needed to provide an enabling environment in which the necessary work can take place.
Since 2000, FAO, UNICEF and WHO have been involved in the issue of As in food and agriculture. With the Millennium Development Goals as a target, the agencies are promoting sustainable agricultural production and improved access to safe and nutritious foods, particularly for the poor and vulnerable groups. Since 1999, FAO has been involved in the issue of As in irrigation water. The issue is now part of the Regular Programme and FAO experts regularly provide information, advice and inputs on the issue to governments, development partners and the scientific community. UNICEF is strongly involved in providing safe drinking-water in Asia, including mapping of groundwater quality. Although the aim is to provide safe drinking-water in terms of numerous parameters, As has received special attention. WHO is strongly involved in water quality issues and health aspects of arsenicosis, and together with UNICEF, provides guidance on the supply of sufficient and safe drinking-water. Both WHO and UNICEF have expressed concerns about possible risks of using As-contaminated irrigation water. Recently, WHO, FAO and UNICEF started the preparation of education, information and communication materials on As in drinking-water, and As in food and agriculture.
There is some concern about As-contaminated irrigation water among donors, as can be seen by the few projects funded by the Australian Agency for International Development (AusAID), the United States Agency for International Development (USAID) and the United Nations Development Programme (UNDP) in Bangladesh. However, the potential impacts of As on food safety and in particular on agricultural sustainability should be made clearer to the donor community through awareness raising activities so as to raise funds necessary to address the issue systematically and in an integrated manner. It is important for donors to realize that the continuation of As-contamination of agricultural land may in the long run offset the progress made in the drinking-water sector, which they are heavily supporting.
Universities & international research institutes
Universities from the region and elsewhere have been among the first to raise the issue and, mostly through their own initiatives and commitment, have developed and funded As-related projects. They will need to continue to play a key role as there are still many scientific gaps to be filled. A major challenge for the scientific community will be to improve the translation of the knowledge obtained through research into messages understandable by policy makers, donors, and the general public. Most of the countries in Asia facing As problems are classified as developing countries. It is therefore recommended to put the research outcomes into the perspective of the development agenda of governments and development partners. Part of the work to be done is challenging and will best be implemented through consortia of national and international research institutes. Consultative Group on International Agriculture Research (CGIAR) institutes such as the International Water Management Institute (IWMI), the International Rice Research Institute (IRRI) and the International Maize and Wheat Improvement Centre (CIMMYT) could play an important role in such consortia by providing leadership and/or contributing their technical expertise. Both IRRI and CIMMYT have already been involved in As-related activities in Bangladesh. IWMI has substantial expertise and experience in irrigation water quality issues in the region and elsewhere.
Farmers are facing multiple problems with regard to agricultural production. Strengthening their understanding and capacity to improve agricultural practices and minimize land degradation will enhance the sustainability of crop production and thus their livelihoods. This is of great importance to them and rural farming communities as a whole because agriculture is generally regarded as one of the keys to poverty alleviation in the region.
Throughout the course of preparing this report, a number of shortcomings and suggestions for improving future activities have been identified and are briefly outlined below.
LESSONS LEARNED FOR FUTURE ACTIVITIES
Methodology - Limitations in study designs including a localized approach and a lack of detail do not allow extrapolation of results and conclusions. Detailed information on the conditions under which As accumulates in the soil is still not available. Chemical analyses often do not comply with basic quality control principles, reducing the reliability of the results and conclusions. For Bangladesh, the limited technical capacity currently present in the country is a major constraint in delivering scientifically justified information on which policy can be based.
Data interpretation - The large difference in toxicity of the various forms of As present in foods has mostly been ignored. To evaluate obtained data on As in soil and foods, reference is often made to standards from other countries without evaluating the quality and suitability of that specific standard. In many cases, the use of those standards cannot be justified.
Crop production - By far, projects on As in irrigation water have only focused on As in the food chain, neglecting the threat to crop production. The issue has not been put in the necessary broader framework of land degradation. Management aspects related to the use of contaminated groundwater for irrigation have only received limited attention.
Long-term effects - Most projects have only evaluated the current levels of As in water, soil and crops, and have not considered future levels. Contamination via irrigation is likely to continue as long as contaminated sources are being used for irrigation. The problems are thus expected to increase over time, regardless of whether current levels in soil and foods are acceptable or not. This highlights the need for a strategic approach and the incorporation of the issue in long-term monitoring activities on land degradation.
Funding and coordination - The number and scale of activities/projects related to addressing As in irrigation water have been limited and there has been a lack of coordination between agencies and between sectors. This situation can be explained partly by a lack of awareness raising initiatives, limited project outcomes and little dissemination of these, and the low priorities of governments and donors in terms of addressing As related issues. It can also be explained by the overall management of the As crisis, for example, in Bangladesh. As was first identified as a drinking-water and health problem, logically leading to the establishment of coordinating and funding mechanisms in the water and health sectors. However, this focus on water and health is now hampering activities designed to address As in the food and agriculture sectors and so far there has been little collaboration between the water and health sectors and the food and agricultural sectors and little interest from the major donors in tackling the problem.