major effects on consumption patterns, resulting in high public health costs and externalities (Lang and Heasman, 2004). This has resulted in a convergence of consumption habits worldwide, with lower income groups increasingly exposed to energy dense foods, while high-income groups benefit from the global market (Hawkes, 2006).

Agrochemical use can have both positive and negative impacts on health.

Agrochemicals have been responsible for increasing food production and as part of the control of some important human diseases such as malaria. However, they can also cause a wide range of acute and chronic health problems (O'Malley, 1997; Kishi, 2005). Chronic health effects include reproductive, neurological, developmental/learning disabilities, endocrine-disruption, and some cancers. WHO has estimated that there are at least 3 million cases each year of pesticide poisoning worldwide, one million of which are thought to be unintentional poisoning and two million suicide attempts, leading to about 220,000 deaths annually (WHO, 1986). The majority of these cases occur in developing countries where knowledge of health risks and safe use is limited, and harmful pesticides, whose use may be banned in developed regions, are easily accessible (Smit, 2002). In developing countries, acute poisoning of agricultural workers can result from poor training and lack of proper safety equipment (Repetto and Baliga, 1996), as well as an inability to read and understand health warnings. Small-scale farmers may be too poor to purchase the necessary protective equipment (if available), and may not have access to washing facilities in the fields or at home. Studies of farm workers and children living in agricultural areas in the USA and in developing countries indicate that adverse health impacts are also experienced by children playing around pesticide treated fields, and people drinking pesticide contaminated water supplies (Curl et al., 2002; Fenske et al., 2002). Pesticide related illness results in economic losses (Cole et al., 2000).

Poor health has negative impacts on agricultural productivity and the application of AKST.

Agricultural production can be negatively affected by the poor health of agricultural workers, resulting from malnutrition, chronic noncommunicable diseases and infectious diseases (Croppenstedt and Muller, 2000; Jayne et al., 2004). Poor health also affects farmers' ability to innovate and develop farming systems (Jayne et al., 2004). Many studies show that communities with high disease prevalence experience financial and labor shortages. They respond by changing crops and reducing the area of land under cultivation, consequently decreasing productivity (Fox, 2004; Jayne et al., 2004). Ill health among families of producers can further reduce household income or other outputs of farm work as the able-bodied absent themselves from work in order to care for their sick family members (Jayne et al.,

2004). In developing countries these issues are most clearly illustrated by the impact of HIV/AIDS (Fox, 2004; Jayne et al., 2004), which, due to reductions in life expectancy, also results in loss of local agricultural knowledge and reduced capacity to apply AKST.

Agriculture has one of the worst occupational health and safety records.

Irrespective of age, agriculture is one of the three most dangerous occupations (with mining and construction) in terms of deaths, accidents and occupational-related ill-health (ILO, 2000). Half of all fatal accidents worldwide occur in agriculture. Many agricultural practices are potentially hazardous to the health of agricultural workers, including use of agrochemicals and increasing mechanization. Agriculture is traditionally an underregulated sector in many countries and enforcement of safety regulations is often difficult due to dispersed nature of agricultural activity and lack of awareness of the nature and extent of the hazards. It is estimated that some 132 million children under 15 years of age work on farms and plantations worldwide due to lack of policies to prevent agricultural child labor (ILO, 2006). This work exposes them to a number of health hazards, as well as removing them from education. AKST has not addressed the tradeoffs of policies and technologies to minimize harm and maximize the health and livelihoods benefits.

The limited availability of supplies of fresh potable water is a health issue, especially in dry areas with diminishing water resources and where there are threats from nitrate pollution of water bodies and aquifers.

The lack of access to clean drinking water is estimated to be responsible for nearly 90% of diarrheal disease in developing countries (Ezzati et al., 2003). Reducing this health hazard and improving the access to clean drinking water is one of the Millennium Development Goals; currently Africa is not on track to meet these targets. In some areas of the Sahel, aquifers are becoming seriously polluted by N pulses reaching water tables (Edmunds et al., 1992; Edmunds and Gaye, 1997). This N is probably of natural origin, since Nfixing plants used dominate in natural vegetation and, in the absence of land clearance, the N was probably recycled in the upper soil profile through leaf litter deposition and decomposition. However, following deforestation, the nutrient recycling process is lost and N is slowly leached down the profile. High N contamination has serious implications for the future potability of groundwater for the human population and their livestock.

The safety of GMO foods and feed is controversial due to limited available data, particularly for long-term nutritional consumption and chronic exposure.