Passage
although levels of ddt contamination are gradually falling in countries where the pesticide has been banned, new scientific research suggests that the chemicals are still a serious threat everywhere. studies show that even small amounts of pesticides can disrupt the working of human hormones, interfering with reproduction and the functioning of the immune system. that's why representatives of more than 100 nations gathered at a u.n. meeting in nairobi to work toward a global treaty that would phase out ddt and 11 other pesticides. known as the "dirty dozen."
why does the writer refer to the new scientific research
1. to state the impact linked to ddt and other pesticides.
2. to illustrate the serious threats caused by ddt and other pesticides.
3. to show the amounts of ddt and other pesticides involved with human hormones.
4. to explain the effectiveness of ddt and other pesticides in controlling mosquitoes.