There are 12 countries that want to join the European Union. Each will bring a wealth of new life and potential problems into the EU.

Conversely, becoming a member of the EU will bring new environmental threats, as well as benefits, for applicant countries.

In this week's Earth Report we look at what joining the EU will mean for the environments of three of the countries knocking on Europe's door: Hungary, Poland and Latvia.

Hungary: family farms or factory farms?

Time was when grasslands stretched all the way from Hungary through Central Asia to the Pacific. Today, only a few thousand hectares of this ancient landscape remains. It's part of the rich natural heritage that Hungary will bring to the EU when it joins.

Already, the authorities are taking the protection of their environment seriously. The National Parks are rigorously policed in order to protect the 40,000 animals and 2,000 plant species native to Hungary.

But joining the EU may also bring with it a new threat to the environment: big business agricultural.

Much of Hungarian farming is extensive and uses low levels of pesticides and fertilisers. Great for the environment, but not so good for profit margins. The challenge for Hungary will be to resist the pull of heavy industrial agriculture - a mistake already made by many EU Member States - and use EU funds to promote sustainable rural development and environmentally-friendly farming.

Poland: poisoning the rivers

Rivers are one of the greatest natural assets that Poland will bring to the EU when it joins in 2003.

But pollution is a serious problem for Poland's rivers with more than half of all city and factory sewage and waste water discharged straight into river systems without treatment. So, will joining the EU help save Poland's rivers?

Yes and no.

The EU's tough policies will undoubtably cut pollution but many fear that joining will lead to a drive towards intensive farming practices - unleashing a new type of pollution into Poland's rivers: pesticides and chemical fertilisers. With farmland covering some 60% of Poland, whatever happens to agriculture will have a big impact on the environment. Again, the challenge for the farming sector will be how to embrace sustainable, organic agriculture.

Latvia: in sickness and in health

A decade after independence from the Soviet Union, Latvia also wants to join the EU.

When the Soviet military machine pulled out, a host of environmental problems were left in its wake. In the military port of Liepaja, which once housed 25,000 soldiers and their families, abandoned ships slowly rust away and a metre thick toxic sludge from oil and heavy metals coats the river bed. Now the Latvians are left with the clean-up.

Elsewhere, Latvia's natural environment is flourishing. Around 44% of Latvia is forested, many of its rivers and lakes are healthy, and its landscapes are rich with biodiversity - boasting many species which are almost extinct or endangered in the EU like the Roller bird.

But in the cities, it's a different story. Post-communism, all eyes turned to the west and the lifestyle it offered. Now everyone aspires to own a car. Traffic, not industry, is now the number one air polluter and doctors have seen a dramatic increase in respiratory problems - from asthma in children to acute bronchitis in adults.

The EU: the road to prosperity?

The next 10 years will bring great changes for the citizens of East and Central Europe. Many hard choices, that will affect their environments and their quality of life, lie ahead.

It's clear that the EU's tough policies will bring many benefits but the pull of western-style economic 'development' - particularly in the agricultural sector - could bring new environmental threats.

It's a difficult choice. But, perhaps the EU's strict standards, coupled with the hard lessons learnt from mistakes made by other EU countries, may be just enough to set applicants on a different track.

They have a lot to gain from joining the EU. But the EU will also be enriched by its new members.