The NASA article doesn't list any sources. The Aliso Canyon article points out "While methane is considered benign toward human health, the report conducted an independent survey of other hazardous chemicals, such as benzene, which also can be released during a well blowout".

Further in the article we find: "benzene levels in the Porter Ranch Estates neighborhood sat at 3.7 parts per billion on Nov. 10, which was seven times higher than the normal range for the Los Angeles area (0.1 to 0.5 parts per billion). However, by late December, two months after the blowout, benzene levels in Porter Ranch fell within the regular range." .

Note that this well was an antique that should have been replaced long ago. Its not the modern wells being proposed.

Finally, there are lots of natural seeps over an oil patch.