US EPA - PPCPs Bibliographic Citation Database
- Synopsis of Project —

This on-going project provides a comprehensive, publically accessible bibliographic listing of literature
citations that are directly or peripherally relevant to the many aspects of pharmaceuticals and personal care
products (PPCPs) as environmental contaminants. The listing of bibliographic citations is currently
available in both TXT and PDF versions from the US EPA's PPCPs web page:
http: //www. epa. gov/ppcp/lit .html.

A much more comprehensive and versatile version is available to EPA researchers as a full digital database,
which is compiled using commercial bibliographic citation software. An abbreviated version of the
electronic database (which includes full abstracts but not PDF reprints of the individual references) is
available to the public [for more information, contact: daimhton.christian a epa.govl.

To cite this page or the database:

Daughton CG and Scuderi MST, 2013. "Pharmaceuticals and Personal Care Products (PPCPs):
Bibliographic Database of Relevant Published Literature," U.S. Environmental Protection Agency, Las
Vegas, Nevada (a comprehensive database of literature references compiled and curated by Daughton and
Scuderi; first implemented 19 February 2008); available: http: //www .epa. gov/ppcp/lit .html

The compiled PPCPs literature citations cover all facets of the risk paradigm (including: Origins, Sources,
Occurrence, Transport, Fate, Exposure, Effects, Stewardship, Pollution Prevention, Monitoring, Waste &
Water Treatment Technologies, Risk Assessment, Risk Communication, etc.) as well as many aspects that
are peripherally related (e.g., major citations dealing with low-dose effects, mixture effects, and databases
for medications, physicochemical properties, and toxicology, among others). The scope of the covered
literature spans not just journal articles, but also books (and book chapters), proceedings, databases, web
pages, reports, miscellaneous gray literature, and select presentations and news stories. By default, the
scope of the database also includes many documents on emerging contaminants, as PPCPs are often
included as a subset of contaminants of concern.

In May of 2010, the main PPCPs database of published literature exceeded 10,000 entries, making it more
cumbersome to perform searches (or browse) for those restricted to working with the text-based reference
files. Since one of the main aspects of the PPCPs topic that attracts broad interest involves drug disposal
and environmental stewardship, the subset of references that pertain to the many aspects of this specific
aspect of PPCPs were compiled in a separate listing (termed the DDS database)-, note, however, that these
references will remain an integral part of the main PPCPs listing since many of them are also relevant to
other aspects of the general topic.

This new listing devoted to drug disposal and stewardship provides comprehensive coverage of the many
issues that touch upon this subject - one that is intertwined with a bewildering array of factors involving
society's relationship with drugs, including: manufacturing (e.g., drug formulation), packaging, prescribing
practices and customs, dispensing practices (including the health insurance industry), design of drug
delivery (especially delivery devices), consumer behavior (numerous behaviors that lead to the generation
of leftover drugs, a major one being patient non-compliance/adherence), drug collection programs (e.g.,
take-backs), poisonings (human and animal), diversion, expiry (including stability testing), environmental
stewardship, pollution prevention, and legislation, among many others. As of 14March 2013, the DDS
database comprised 1,955 references, representing about 12.5% of the total PPCPs database.

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The major advantage of the PDF versus the TXT version of the literature listings from the database is that it
serves as a simple, but effective searchable database. Character-string searches can almost instantly locate
all of the citations containing a keyword or expression; when using Acrobat, users must select "use
advanced search options" (located at the bottom of the basic search panel). The full first line of context for
each hit is displayed in the search panel, allowing fast visual examination of the results, as well as instantly
locating the citation. The TXT version is useful for importing as a character-delimited file directly into any
of the many available commercial bibliographic citation databases. A typical entry in the public listing (for
a journal article) displays the full citation information in the following format:

Kolpin DW, Furlong ET, Meyer MT, Thurman EM, Zaugg SD, Barber LB, et al. "Pharmaceuticals,
hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000: a national
reconnaissance," Environmental Science & Technology 2002, 36(6): 1202-1211; doi: 10.1021/esO 11055j.

The need for a PPCPs citation database was born from the difficulties in performing comprehensive
literature searches and the incompleteness of all commercial published-literature databases and
inadequacies of Internet search engines for this topic. One of the major inefficiencies in the development
and advancement of the PPCPs field is the difficulty in distilling the large and continually growing body of
literature into useful knowledge. The published literature contains a wealth of data and insights. Major
portions have never been examined or summarized and evaluated. Lack of a comprehensive bibliographic
database is one of the reasons; another reason is that synoptic reviews and compilation of databases,
although invaluable, are generally not valued in science as much as the publication of new data.

For more perspective on the growth of the published PPCPs literature and on the importance of knowledge
mining, see the following two articles:

Page 2491 in: Daughton CG "Chemicals from the Practice of Healthcare: Challenges and Unknowns Posed by

Residues in the Environment," Environmental Toxicology & Chemistry 2009, 28(12):2490-2494;

doi:10.1897/09-138.1; available: http://www3.interscience.wilev.com/cgi-bin/fulltext/123234134/PDFSTART

Daughton, C.G. "Literature Forensics? Door to What Was Known but Now Forgotten," Environmental Forensics

2001, 2: 277-282; doi: 10.1006/enfo.2001.0065;

available: http://www.epa.gov/nerlesdl/bios/daughton/forensics.pdf

[Also see follow-up commentary: Daughton, C.G. "Literature Forensics: Navigating through Flotsam,

Jetsam, and Lagan," The Scientist 2002, 16(4): 12 (Feb. 18);

available: http://www.the-scientist.com/7articles.view/articleNo/13842/title/Literature-Forensics-Navigating-
Through-Flotsam-Jetsam-and-Lagan/1

Even with commercially available scientific literature databases, and with the growing power and
comprehensiveness of free search engines such as Google Scholar, coupled with ever-expanding Internet
content, locating literature specific to PPCPs can be extremely difficult because of the complexities in
filtering out the countless search results that are not relevant to PPCPs as environmental contaminants;
these irrelevant search results are usually pertinent instead to healthcare, clinical research, clinical practice,
pharmacy, or human and veterinary pharmacology. Locating the relevant literature is one of the major
challenges to maintaining a literature database on PPCPs. It is not a topic conducive to quick key-word
searches of the undistilled literature. Use of cited-citation analysis (e.g., using Science Citation Index or
Google Scholar's "cited by" feature) - based on highly cited relevant publications as the starting point - is
one of the more direct ways to locate and compile the relevant literature. But cited-citation analysis is a
very time-consuming task and one that must be performed on an ongoing basis.

Currently, the limitations of the PPCPs bibliographic database are: (i) lack of comprehensive coverage of
the non-English literature (which may be extensive), (ii) abstracts, URLs, DOIs, or PDFs are missing for a
limited number of citations, and (iii) lingering typographic errors and formatting inconsistencies, as well as
errant duplicate entries, prove difficult to eliminate entirely.

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The EPA in-house digital database (from which the text files are exported) is updated on nearly a daily
basis. The public version text files, accessible from the PPCPs web site, are updated periodically (roughly
every 3 months). New additions include not just the newly published and in-press literature, but also many
past publications that had not yet been captured as well as corrections and updates to existing entries.

As of 14March 2013, the PPCPs literature database contained citations for 15,690 references. In part,
these comprised 11,473 journal articles, 1,065 reports, 844 books/chapters, 423 theses, 378 web sites/pages,
160 government documents (not including reports), and 112 databases. In the on-line text version of the
database, 97% of the entries had DOIs or URLs (allowing direct access to full articles - assuming the end-
user has subscription access); for a DOI locator, see: http://www.crossref.org/. In the complete digital
version of the database, 94% had abstracts and 91% had PDFs (usually of the complete article). The PPCPs
Bibliographic Literature Citation Database should prove useful to anyone with an interest in this field, as it
makes locating pertinent references much easier.

For EPA scientists having bibliographic citation software, the most recent version of the complete PPCPs
Bibliographic Literature Citation Database can be obtained by contacting Christian Daughton
(daughton.christian@epa.gov). The size of the complete database (about 6.5GB) restricts distribution to
shipment via solid state drives (SSD); for the public, the size of the database (without PDFs) is only about
32.5MB, which allows distribution via a file-sharing service. Some of the advantages of using the
electronic database (instead of the simple text listings of citations available on this web page) are: (1)
References can be effortlessly cited and formatted in MS Word documents using on-the-fly citation
capabilities. (2) References can be formatted in whatever style is required (for example, to meet a journal's
requirement for submitting manuscripts). (3) Abstracts and PDFs (when available) can be searched on full
text and directly accessed (searching all attached PDFs requires additional third-party software - or
EndNote X4 or later); "deep" full-text searching allows ready retrieval, for example, of documents that
mention rare terms (such as seldom-used active pharmaceutical ingredients). (4) Queries can be restricted
to a specific type of publication (e.g., books, journal articles, reports, theses, etc.) or field (e.g., all papers
authored by a particular scientist). (5) Boolean searches can be performed; as one example, "ethynyl OR
ethinyl" finds all citations containing: ethynylestradiol, ethynyl estradiol, ethinylestradiol, or ethinyl
estradiol, together with all the variants with oestradiol.

updated: 14 March 2013

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Update History of PPCPs Bibliographic Citation Database (number of records in database):

2008

5,471: 28 August
5,663: 11 September
5,865: 22 October
6,100: 12 November
6,440: 9 December

2009

7,094: 19 February
7,548: 4 May
7,985: 30 July
8,882: 2 December

2010

9,561: 11 March
10,096: 20 May
10,700: 12 August

2011

11,454: 21 January
11,881: 28 April
12,419: 22 July
12,976: 8 November

2012

13,598: 1 March
14,358: 28 June
14,898: 4 October

2013

15,690: 14 March

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