Over the past 50 years, there has been a tremendous expansion
in
the measurement of chemical contaminants in environmental media. But
how many chemicals have actually been determined, and do they represent
a significant fraction of substances in commerce or of chemicals of
concern? To address these questions, we conducted a bibliometric survey
to identify what individual chemicals have been determined in environmental
media and their trends over the past 50 years. The CAplus database
of CAS, a Division of the American Chemical Society, was searched
for indexing roles “analytical study” and “pollutant”
yielding a final list of 19,776 CAS Registry Numbers (CASRNs). That
list was then used to link the CASRNs to biological studies, yielding
a data set of 9.251 × 106total counts of the CASRNs
over a 55 year period. About 14,150 CASRNs were substances on various
priority lists or their close analogs and transformation products.
The top 100 most reported CASRNs accounted for 34% of the data set,
confirming previous studies showing a significant bias toward repeated
measurements of the same substances due to regulatory needs and the
challenges of determining new, previously unmeasured, compounds. Substances
listed in the industrial chemical inventories of Europe, China, and
the United States accounted for only about 5% of measured substances.
However, pharmaceuticals and current use pesticides were widely measured
accounting for 50–60% of total CASRN counts for the period
2000–2015.