These tests were done in the lab under controlled conditions. This kind of study is a useful screening tool, but I disagree their result "...shows that tested extracts and essential oils could replace use of methylparaben..." Positive results -- especially those in a screening type of study -- are not proof of efficacy.
This overstatement should have been criticized by their peer reviewers. Trained researchers should look at the actual results, however, not the spin these authors wanted to put on their results. The problems will occur if everyday people take this kind of comment as literal truth and run wild with it.
Earlier in the report, it acknowledges that the study was done in a lab, and that other factors come into play when other ingredients are used in different cosmetics. The study notes that most allergic reactions are from the preservatives, and this was an early study to find safe and effective alternatives with a lower risk of allergic reactions. My take away on this was that many essential oils and extracts have excellent antimicrobial properties, and are well worth further study, especially since the lab results were so much more impressive than methylparaben. Some of the oils mentioned were not oils most would want or could tolerate in a lotion. But, this study is a great starting point for further testing.