Agriculture and Water Contamination, Rosario Pérez Espejo and Alonso Aguilar (coords.), iiec-unam, 2012.

Published in September 2012 by the unam Institute of Economic Research, this book reveals the reality of agricultural practices in our country and the challenges of designing public policy to minimize agricultural contamination in water. This book was written by an interdisciplinary group of researchers that use Irrigation District 011, Alto Río Lerma, Guanajuato, as a case study, located in one of the most studied, productive and controversial basins in Mexico, the Lerma-Chapala basin.

The authors demonstrate how the water that represents 78 percent of the water used in Mexico for agricultural purposes is wasted, due to imprecise accounting and perverse subsidies that foster misuse of this precious resource, which is free and has a system in place to subsidize its distribution. With data on the use of diverse pesticides and fertilizers, irrigation water management practices, agricultural return water, the absence of laws and standards that would be specifically applicable in this case and the perspective of workers and officials in the agricultural sector, the authors support their perspective of the grave situation facing the resource of water in the Mexican countryside.

With three sections and nine chapters, the reader is led through the issue of agricultural contamination and introduced to the study site, meant to represent the irrigation districts in the country, although this case is peculiar because it predominantly receives underground water for irrigation. The book breaks down the various perceptions of agro-environmental policy, as well as agricultural practices and how they alter the quality of water, with clear examples of the role of various pesticides and fertilizers, showing inconsistencies between how these agrochemicals are applied and the efficiency with which they act, a situation that reflects perverse subsidies for the land and those who work it, whether they are ejidatarios (owners of communal land), coproprietors or private owners.

Various authors point to the extremely important topic of human health effects. The book mentions carbamates and triazine, the most commonly used herbicides in Mexico. Exposure to these herbicides through inhalation, ingestion or the skin, with symptoms such as depression of the nervous system, convulsion and hypertension, largely affects infants. There is also a specific study on atrazine, an herbicide that can cause genetic damage and is potentially carcinogenic.

Organochlorine pesticides used as insecticides also tend to accumulate in the fatty tissues of living organisms and the soil. For years, officials have claimed that they will take them off the market because they have neurologically and genetically damaging effects, as well as negative effects on the liver and reproduction. However, they are still in circulation.

It is estimated that of the pesticides used in agriculture for purposes of prevention, whether or not there is something to be treated, only 1 percent ever reaches the crops, and the rest contaminates the soil, air and principally, bodies of water. In the Irrigation District under study, the presence of 25 pesticides was reported. The thirteen most-used include five triazines, four carbamates and four organochlorine pesticides, all in concentrations that exceed the limits of the Official Mexican Standard (nom-127-ssa1-1994) for water to be used and consumed by humans.

The field research found that corn, sorghum, wheat and barley crops used 15 active substances applied in quantities above what is recommended. In Mexico, pesticides that have been prohibited in other countries are authorized for use: paraquat, lindane, parathion, malathion, endosulfane, ddt and atrazine. One of the most commonly used insecticides is methyl parathion, banned in many countries but allowed in Mexico. The book provides a simulation exercise that proposes a 100 percent tax on methyl parathion; if this were the case, although the price of pesticides is inelastic, its use would fall to half.

Other relevant themes include the environmental effects and human health consequences of fertilizers that contain nitrogen, phosphorous, sodium and potassium, which lead to the eutrophication of bodies of water, salinization of soil and other damaging effects on human health as they enter water supply sources.

This book also addresses elements related to the legal and regulatory framework in Mexico with regards to production, handling, distribution and application of various types of pesticides and the waste they generate. The book specifically analyzes laws and federal programs that regulate the use of water in agriculture, but which are not applicable to the diffuse discharges generated by agricultural activities. Looking at the regulatory framework for water quality in Mexico, made up of Official Mexican Standards nom-001, 002 and 003, it is notable that not one is applicable to agriculture.

Specifically, Guanajuato has a Technical Environmental Standard (nta 005, since 2008) that could have positive effects on water quality, but will require greater coordination between institutions to ensure its application and oversight, which up to now, has been non-existent. This standard was issued as part of the agro-environmental policies and agreements proposed on the international scale to manage toxic and/or dangerous substances and greenhouse gases, in which Mexico is involved.

The big question remains as to how regulatory policies regarding availability, regulation, commercialization and use of agrochemicals will look, in order to ensure that agricultural activities still receive benefits, but we avoid public health risks and guarantee the welfare of people and the environment. One issue that affects everyone is toxic waste from various sources, which are difficult to identify and quantify, and alter the quality of water. They result from activities to produce food, but they affect water supply sources and the survival of the ecosystems that provide goods and environmental services, an issue largely ignored by officials and producers.

This work also delves into the perception of agricultural producers on how they have contributed to pesticide pollution, addressing the issue of land ownership, which is fundamental in Mexico. It explores the voluntary reduction in using agrochemicals and the role of the government in changing agricultural practices, concluding that workers have very little education and information in this field. Producers also tend to deny that agriculture is a significant cause of contamination. The book concludes that government participation will be required to change agricultural practices.

From the perspective of economic theory, the book makes clear that there are no practical, cost-effective, politically acceptable and environmentally efficient and feasible instruments to control contamination. As such, only voluntary measures are likely.

In summary, this book is an updated contribution to a topic related to food security in Mexico and its effects on climate change. Moreover, if this is the situation in the Bajío region, one of the most important agricultural zones in the country, what will happen in other less technically advanced regions with a lower degree of economic development and education?

This book is a must-read for environmental, health, rural development, agriculture and livestock officials, as well as legislators. We should be aware of its contents and conscious of the environmental and health implications of producing the food we all consume.

Marisa Mazari
Institute of Ecology – unam