In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Although the reliance on self - reported drinking is a limitation in this study , these findings support the benefits of early abstinence and the potential for ultrasound examinations in the detection of fetal alcohol effects .
### Output Text:
Although the reliance on self - reported drinking is a limitation in this study , these findings support the benefits of early abstinence and the potential for ultrasound examinations in the detection of fetal <span class="chemical">alcohol</span> effects . 