Look just about anywhere in Japan and you'll find prawns. Fried, boiled, baked, frozen and fresh, they fill acres of shelves in department stores and supermarkets and are staples in sushi and tempura shops -- as well as being found in even the most unlikely bowl of noodles.

Now, if you ask people what are their food-related environmental concerns, you'll get an earful about pesticides on vegetables, mercury in fish, genetically modified foods and the hormones and antibiotics going into livestock (as well as the methane coming out the other end). Prawns hardly get a mention.

However, innocuous as these little pink crustaceans may seem, the prawn industry that delivers them to our plates, whether through farming or trawling, has become a case study in how to destroy the environment and undermine social harmony.

According to a recent report from the Environmental Justice Foundation, a London-based environment and human rights charity, shrimp farming, which has burgeoned in recent decades, is responsible for a litany of environmental and social ills.

Called ebi in Japanese and shrimp in the United States, prawns come in various sizes, with the largest being warm-water tiger prawns. The EJF report, titled "Smash & Grab: Conflict, Corruption and Human Rights Abuses in the Shrimp Farming Industry," is one of several by the charity that documents the impacts of shrimp production and consumption.

Ponds for raising shrimp are made by converting wetlands, clearing coastal forests (primarily mangrove) and inundating farmland with saline water. Fortunes can be made in prawns, so local communities eagerly convert huge areas of coastline to shrimp farming. Success can be fleeting, however, as shrimp farming often leads to declining environmental quality accompanied by social upheaval, as people find their farmland and marine resources degraded, themselves consequently unemployed, and their villages exposed to greater damage from the ravages of storms.

While there is big money to be made, the worldwide prawn rush didn't come about through mere word of mouth, the report notes. "The industry has been actively promoted by organizations such as the World Bank, the Asian Development Bank and the Food and Agriculture Organization of the United Nations (FAO) as a means of creating jobs, bringing in foreign exchange and alleviating poverty in developing nations," according to EJF.

Aquaculture -- the farming of water plants and animals -- has long been seen as a "blue revolution," a way to increase food production while reducing pressure on shrinking fish stocks. As a result, since the 1970s, global aquaculture has grown by about 9 percent annually. "In recent years, shrimp aquaculture, which is undertaken largely in Asia and Latin America, has experienced particularly spectacular growth," the EJF report notes. "Annual production in 2000 was 1,083,641 metric tonnes, valued at over $6.8 billion. Today, 28 percent of shrimp consumed are farmed, compared to about 5 percent in the early 1980s."

Nations that export farmed shrimp include Thailand, Vietnam, Indonesia, Pakistan, Bangladesh, Ecuador, Honduras, Guatemala and Mexico, according to Felicity Lawrence, writing in The Guardian on June 19. Shrimp farmers primarily raise large tiger prawns, which in Britain sell for £18 ($30) per kg headless and £35 ($57) per kg for large whole ones, says Lawrence.

As business has blossomed, though, so have problems. "The expansion of export-oriented shrimp culture has met with strong opposition from some sectors of society, and serious political, socioeconomic and environmental concerns have been raised," notes the EJF report. Nevertheless, when there's a market, there will be suppliers, and each year more and more prawns are shipped off to consumers in Europe, the United States and Japan.

So specifically what ills are we swallowing each time we chomp on a succulent shrimp?

The EJF raises four main concerns: pollution problems, loss of mangrove forests, depletion of wild fish and shrimp stocks, and the social impacts of shrimp farming. (In a second report, "Squandering the Seas: How Shrimp Trawling is Threatening the Ecological Integrity and Food Security Around the World," the EJF also documents the threats posed by shrimp trawlers.)

As with fish farming, shrimp aquaculture requires intensive care. "Farmers stock shrimp at high densities and use high levels of feed, pesticides, antibiotics and other chemicals in order to maximize profits and combat disease," reports the EJF. "Both chemical and organic wastes from shrimp farms pollute the marine environment, and . . . salinization and depletion of ground and surface water can reduce the productivity of agricultural land surrounding shrimp farms and leave water unusable for drinking."

To profit from shrimp, vast areas are needed. Often the easiest, and sometimes the only, way to build ponds is to clear coastal mangrove forests. Unfortunately, mangrove habitats are already globally threatened ecosystems. As the EJF reports: "Over half of the world's mangroves have been destroyed and they continue to decline at an alarming rate. Shrimp aquaculture development has been a major cause of recent mangrove loss . . . responsible for as much as 38 percent of global loss."

Mangrove forests, found along tropical and some subtropical coastlines, "are among the most productive ecosystems in the world, providing the basis for complex habitats at the interface of terrestrial, freshwater and marine ecosystems," says the report. Mangrove ecosystems also provide crucial breeding grounds for countless marine, bird and animal species, and shelter coastal homes, farms and villages from ocean storms.

Shrimp farming also depletes wild fish and shrimp stocks. Without mangrove forests, juvenile fish have no nursery and feeding grounds, while shrimp-farm wastes further reduce wild marine populations. The EJF notes that in areas of Malaysia where mangroves were cleared, "local fishermen reported a drop in income of up to 86 percent within a few years."

Prawns also consume valuable protein, as much as twice their own weight in fish feed. While this is a better conversion rate than for livestock and poultry meat from grain (about 7:1 and 3:1 respectively), it is "a net loss of protein" for local villagers. This places additional pressure on marine species as invaluable dietary protein is lost.

However, perhaps most shocking are the social impacts of shrimp farming. Forget idyllic scenes of children playing on beaches while fisherfolk tend ponds as the sun slips huge and crimson below the horizon. Instead, the EJF documents cases of intimidation, violence, murder, sexual abuse in processing plants, abusive child labor, land seizures and displacement of local villagers.

"People have died in social conflict related to shrimp farming in at least 10 countries," according to the EJF, which also reports that "hundreds of thousands of coastal people have been displaced, in some cases following land seizures involving use of force."

Isn't that enough to put you off your shrimp tempura for lunch?