385
When considered with the known neurotoxic effects on children of " low levels " of exposure to lead , these results also suggest that either an excessively narrow margin of safety or insufficient safety is provided by present U . S . guidelines , which classify an elevated blood lead concentration as 25 micrograms / dl or greater .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
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