You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

A study of parabens and bisphenol A in surface water and fish brain tissue from the Greater Pittsburgh Area. Pollution from xenoestrogens has been discovered in the aquatic environment of the Greater Pittsburgh Area and is suspected to be caused by the failing sewer system. Personal care products and plasticizers have the potential to enter the water supply though treated and untreated sewage. Many of these compounds are suspected xenoestrogens. Paraben detection in surface waters was as follows: methyl paraben ranged between 2.2 to 17.3 ppt; ethyl paraben was not detectable; propyl paraben was detected at 9.2 and 12.0 ppt; butyl paraben was detected at 0.2 ppt. BPA was detected between 0.6 and 15.4 ppt. Estrogenic potential of extracts from fish brain tissue was tested via Bromodeoxyuridine MCF-7 analysis and paired with HPLC-MS to investigate the presence of xenoestrogens. All samples were non-detectable for parabens. BPA was detected in 44 of the 58 samples, with a range from non-detectable to 120 pg/g. BCFs were calculated. Results were statistically significant for location of capture (p < 0.05) and correlation existed between estrogenicity and BPA.
{"Chemical": ["butyl paraben", "ethyl paraben", "propyl paraben", "xenoestrogens", "BPA", "parabens", "Bromodeoxyuridine", "methyl paraben", "bisphenol A", "Paraben"]}