What is the main responsibility of the, United Nations Population Fund according to the passage?

A new report says the growing population around the world is harming the environment. More people are using more of the Earth’s natural resources than ever before. Experts say poor people around the world will suffer most in the future unless environmental damage is stopped, They say more should be done to balance human and environmental needs.
    The United Nations Population Fund is responsible for studying population growth. It has released a report about the subject. It examines the links between environmental conditions, population growth and efforts to help poor people in developing countries.
    The world population is now more than 6 billion people. That number has increased by 100M since 1990. The population is expected to increase to more than 9 billion by the year 2050. The report says about 2 billion people lack food security. Water supplies and agricultural lands are heavily used. In 50 years, experts say, more than 4 billion people will be living in countries that can not meet people’s daily needs.
    The report says all of the expected growth in world population will take place in developing countries. The 49 least developed countries are expected to increase by almost 200% in 50 years. Yet, the UN agency says people in the richest countries use more of the world’s resources than people in developing countries. It says a child born today in the United States, France or Japan will do more harm to the environment during his lifetime than as many as 50 children born in developing countries.
    The UN Population Fund says international policies need to be put into effect to improve poor conditions, increase social development and ease pressure on the environment. It also says women need more control over their lives. It says empowering women would lead to smaller families and slower population growth. The UN Population Fund says these measures would help improve the well being of growing populations while protecting the natural world.