Filter one list by another using power query

Here is one way to do that:

• Read in the two tables
• Do an Inner Join

let
    //get original data
    Source = Excel.CurrentWorkbook(){[Name="Data"]}[Content],
    data  = Table.TransformColumnTypes(Source,{{"Impurity", type text}, {"Amount (ppm)", type number}}),

    //get Filter
    Source2 = Excel.CurrentWorkbook(){[Name="Prop65"]}[Content],
    filter = Table.TransformColumnTypes(Source2,{"Simplified Prop65 List", Text.Type}),

    //Join them
    filteredData = Table.Join(data,"Impurity", filter, "Simplified Prop65 List",JoinKind.Inner),

    //Remove unneeded column
    #"Removed Columns" = Table.RemoveColumns(filteredData,{"Simplified Prop65 List"})
in
    #"Removed Columns"

Another method would be a filter (Table.SelectRows) method, but it may be slower with a large dataset. At least, in a single instance where I had an opportunity to compare, the Table.Join method was faster on a 100,000 row data set.

let
    //get original data
    Source = Excel.CurrentWorkbook(){[Name="Data"]}[Content],
    data  = Table.TransformColumnTypes(Source,{{"Impurity", type text}, {"Amount (ppm)", type number}}),

    //get Filter
    Source2 = Excel.CurrentWorkbook(){[Name="Prop65"]}[Content],
    filter = Table.TransformColumnTypes(Source2,{"Simplified Prop65 List", Text.Type})[#"Simplified Prop65 List"],

    //filter the rows
    filteredData = Table.SelectRows(data, each List.Contains(filter,[Impurity]))
in
    filteredData