or endocrinal alteration, which many can cause, they are responsible for serious population losses and for the feminization of male amphibians (Hayes, 2005) and alligators (Colborn et al., 1996; Crain et al., 1997). Some halogenated pesticides, particularly methyl bromide, contribute to the destruction of the ozone layer, which protects the earth (Miller, 1996; UNEP, 1999b).
     The impact of fertilizers and pesticides on the soil has been the subject of little research in LAC, yet food production ultimately depends on soil quality. This may be one of the main causes of declining crop yields and the diminution in levels of micronutrients in foods that the Green Revolution has suffered.
     Another source of high levels of agricultural soil contamination is to be found in the toxic waste of pesticides, such as the packages, bottles and leftover pesticide not used. In addition, illegal and clandestine burying of obsolete or expired products has been discovered in recent years in many Latin American and Caribbean countries, such as the northern coast of Colombia. Given that the Stockholm Convention on POPs entered into force in May 2004, in several countries of LAC inventories are being taken of obsolete (prohibited or expired) pesticides, which include POPs (UNEP, 2001).
     The conventional/productivist system also demands a large increase in water use, including an enormous expansion of irrigation facilities. This has reduced groundwater reserves and led to a drop in the water table in vast agricultural regions, as in Valle del Cauca in Colombia, where one finds sugarcane monoculture and the savannah of Bogotá, the main zone for the cultivation of flowers for export; wells for drawing water from the subsoil have to be dug deeper and deeper.

Coastal and marine ecosystems. The greatest impacts on marine ecosystems worldwide are caused by overfishing. Nevertheless, nutrient loading, largely due to agricultural use of fertilizers, is a major cause of degradation for coastal ecosystems (MA, 2005a).
     Sedimentation caused by erosion on agricultural fields and pollution caused by agrochemicals also represent significant threats to marine ecosystems (Clay, 2004). Coral reefs, which are generally close to shore and are important repositories of the world’s biodiversity, are particularly affected by these threats. Almost two-thirds of the reefs of Central America and the Caribbean are considered at risk and one-third is considered at high risk (Barker, 2002).

      Aquaculture represents a relatively new but growing source of impacts on coastal ecosystems. Shrimp farming often displaces mangroves, among the most valuable and highly threatened of coastal habitats, as well as wetlands and estuaries. Shrimp production is prevalent in coastal areas throughout Mexico, Central America and the Caribbean and northern South America, especially Ecuador. In addition to outright destruction of fragile and economically valuable coastal ecosystems, shrimp farming causes considerable water pollution in coastal areas. Aquaculture was virtually nonexistent at mid-century and now represents an important economic sector in many countries and with the growth in world demand for fish, its impact on coastal ecosystems can only accelerate (Clay, 2004).

1.7.4.2 Social impacts
     According to FAO (1986), the technological changes in agriculture over the last 50 years, such as the package of improved seeds, growing technologies, better irrigation and chemical fertilizers were very successful in attaining the essential objective of increasing agricultural production, crop yields and aggregate food supplies. Nonetheless, the swift modernization of agriculture and the introduction of new technologies, characteristic of the Green Revolution, had a differential impact on rural populations, depending on class and gender. The effects of modern agriculture were differentiated, depending on whether you were paid workers, growers, or consumers, from households with or without land, rich or poor, male-headed or female-headed. Moreover, there were two general trends: the rich benefited more than the poor from that technological change and men benefited more than women.
     In Latin America and the Caribbean, the intensification of agriculture entailed the transformation from traditional production to production using external inputs, along with the accompanying social changes. Yet the process was carried out conservatively in the region, if we compare it with what happened in Europe, which has implied a large debt to the external banking system and the exclusion of most of the population. Agriculture saw improvements in production, exports and incomes, although poverty and rural marginality expanded, especially for thousands of small-scale producers.

     However, the productive accomplishments of modern agriculture cannot be ignored; year after year millions of tonnes of food are produced, yet this is not enough to alleviate hunger and achieve food security in the region, since the poor don’t have access to the food. At the same time, agrarian policies have not been able to resolve the social right to access the benefits of technology, therefore there is a growing accumulation and concentration of the wealth generated by agriculture (Rosset et al., 2000).
     In addition, FAO (2000) indicates that one of the important social effects of modern agriculture has been demographic change, due to the substitution of a considerable part of the agricultural labor force by machinery, the increase in the area per worker and the consequent reduction in the number of farms, which has unleashed an intense rural exodus, also driven by the reduction in related activities (the trade in primary products, processed goods and crafts, as well as public services). This decline in the rural population has made it difficult to maintain the services (mail, schools, stores, physicians and pharmacies) and social life. The document The Millennium Development Goals: A Latin American and Caribbean Perspective identifies a lack of jobs as one of the main problems in the region (UNDP, 2005a).
     Indeed, it is argued that conventional/productivist agriculture, apart from the social impacts produced by poverty and inequality, has exchanged technologies for peasants, expelling thousands of families from rural communities and devaluing everything that farmers represent for the social, economic and environmental life of the rural world. At the same time, it has generated a major increase in inequality and the continuing dismemberment and disappearance of peasant communities and with that the major loss of cultural diversity (Riechmann, 2003).