diff --git a/bw2io/extractors/ecospold2.py b/bw2io/extractors/ecospold2.py
index ac39989..7639a6e 100644
--- a/bw2io/extractors/ecospold2.py
+++ b/bw2io/extractors/ecospold2.py
@@ -587,7 +587,7 @@ def extract_exchange(cls, exc):
         if exc.get("mathematicalRelation"):
             data["formula"] = exc.get("mathematicalRelation")
         if exc.get("casNumber"):
-            data["CAS number"] = exc.get("casNumber")
+            data["CAS number"] = exc.get("casNumber").lstrip("0")
         
         data.update(cls.extract_uncertainty_dict(exc))
         return data