9440
Above a threshold , which varied according to the chemical used , the gradient of herbicide concentrations correlated with a gradient of severity of abnormality ranging from normal larvae to arrested development ( an " old embryo " stage ) .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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