Scientific American - USA (2022-06)

June 2022, ScientificAmerican.com 21

Source: “Pharmaceutical Pollution of the World’s Rivers,” by John L. Wilkinson et al.,
in^ Proceedings of the National Academy of Sciences USA,

Vol. 119; February 22, 2022

Graphic by Amanda Montañez

Africa

Asia

KEY

Europe

North America

South America

Oceania Antarctica

Circle size shows mean cumulative concentration

of pharmaceuticals found in each campaign

Color shows country’s

income level

(per the World Bank)

50,000

nanograms

per liter (ng/L)

5,000 500 50

Low

Lower-middle

Upper-middle

High

Not listed

Each circle represents

a sampling campaign

consisting of water

collection from sites

within a city, town

or local area. Most

campaigns included

5 to 11 sites.

Lahore, Pakistan

70,700 ng/L

La Paz, Bolivia

68,800 ng/L

Addis Ababa,

Ethiopia

51,300 ng/L

Bukavu,

Democratic Rep.

of Congo

35,500

Tunis, Tunisia

39,700

Hyderabad, India

46,700

Yerevan,

Armenia

32,000

20,500 15,700

Montevideo,

Uruguay

Madrid, Spain

Dallas, Texas

Las Vegas,

Nevada

Sofia, Bulgaria

Luxembourg City,

Luxembourg

Buenos Aires,

Argentina

17,100 ng/L 12,700 10,700

10,200 5,170

San José,

Costa Rica

25,800 ng/L

In Barisal, Bangladesh, concentrations of the antibiotic metronidazole were

over 300 times the threshold for development of antimicrobial resistance.

In Nairobi, Kenya, high pollution levels

were attributed in part to trucks emptying

waste from septic tanks into local rivers.

The Rio Seke in La Paz contained 227,000 ng/L of paracetamol (known in the U.S.

as acetaminophen), the highest concetration of any chemical measured in the study.

ENVIRONMENT

Mainstream

Drugs

Many of the world’s rivers are

coursing with pharmaceuticals

For more than 20 years scientists have

known that the drugs we take, for mala­

dies ranging from headaches to diabetes,

eventually make their way into our

waterways—where they can harm the

ecosystem and potentially promote anti­

biotic resistance.

But most research on pharmaceutical

contaminants has been done in North

America, Europe and China and has exam­

ined just a small subset of compounds.

The studies also use a variety of sampling

and analysis methods, making it hard to

compare results. Such limitations mean

scientists may be missing a big piece of

the pollution puzzle.

A new paper published in the Proceed-

ings of the National Academy of Sciences USA

provides a more comprehensive look. A

network of 127 scientists sampled 258 rivers

in 104 countries for 61 different chemicals,

producing “a sort of ‘pharmaceutical finger­

print’ of nearly half a billion people across all

the world’s continents,” says study lead

author John L. Wilkinson, an environmental

chemist at the University of York in England.

Many of the most drug­polluted rivers

were in Africa and Asia, “in areas and coun­

tries that have been largely forgotten by the

scientific community” on this issue, Wilkin­

son says. Waterways with the biggest phar­

maceutical concentrations also tended to

be in lower­middle­income countries; the

authors say this could stem from improved

medication access in places that still lack

sufficient wastewater infrastructure.

Four compounds—caffeine, nicotine,

acetaminophen and cotinine (a chemical

produced by the body after exposure to

nicotine)—showed up on every continent,

including Antarctica. Another 14, including

antihistamines, antidepressants and an

antibiotic, were traced on all continents

except Antarctica. Some drugs were

detected only in specific places, such as

an antimalarial found in African samples.

Overall, the study shows that “more

of this kind of global assessment of aquatic

pollution” is needed, particularly for other

chemicals that pose more of a human health

risk, says Elsie Sunderland, a Harvard

University environmental scientist who

was not involved with the new research.

It also suggests, she adds, that “we need

wastewater treatment.”

— Andrea Thompson