In Shanghai, a study of 110 mothers found that their breastmilk was contaminated with alarming levels of two highly fluorinated chemicals. If these levels were found in drinking water, it would be classified as unsafe under current United States health advisory limits. Nevertheless, experts recommend breastfeeding because the benefits outweigh the risks.
For more than 50 years, the West produced the two chemicals for domestic and global use. After learning of their toxicities, they were phased out of consumer goods through voluntary company action.
But Western production has been replaced by manufacturing in countries with few environmental safeguards – fluorochemical factories continue to release the same two substances into rivers, fields, and oceans. Today, China produces both of these chemicals and is thought to be the world’s largest emitter of perfluorooctanoic acid, or PFOA, and the only remaining producer of perfluorooctane sulfonic acid, known as PFOS.
What are PFOA and PFOS?
PFOA and PFOS are the best known members of a group of manmade chemicals known as per- and polyfluoroalkyl substances, or PFASs. Highly fluorinated chemicals are unrivalled in their utility because their carbon fluorine bond is nearly unbreakable under natural conditions. When chains of carbon-fluorine bonds are linked together, they form water- and oil-resistant coatings on clothing, carpets, and cookware that will not wash away, dissipate with extreme heat, or fade in sunlight over extended use.
The same basic carbon-fluorine chains can also create robust firefighting products able to withstand, and even extinguish, the blazes of scorching aircraft fires.
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But the durability that make these chemicals useful also makes them a concern. They persist in the environment for thousands of years, affecting us and future generations as an everlasting legacy.
Scientific research in a highly contaminated US community has linked PFOA and PFOS exposure to numerous health disorders, including testicular cancer, kidney cancer, high cholesterol, ulcerative colitis, thyroid disease, and pregnancy-induced hypertension.
The minuscule amounts of PFOA and PFOS we acquire from the water we drink and the food we eat accumulate in the body day-after-day, year-after-year. And as PFOA and PFOS firmly lodge themselves in blood proteins and critical organs, even small amounts of regular exposure may impact health far into the future.
Today, researchers find highly fluorinated chemicals in the blood of 98% of Americans. Similar studies in China have yet to be conducted. However, a small study in Fuxin, a city in northwest Liaoning province with fluorochemical production plants, has discovered residents with PFOA blood concentrations comparable to the US.
The US experience
In light of the toxicity and bioaccumulation potential of PFOA and PFOS, the US Environmental Protection Agency (EPA) set an advisory limit for drinking water of 70 parts-per-trillion, an equivalent of four small drops in an Olympic swimming pool.
In 2016, the drinking water of more than six million Americans was found above this level. Their water was largely contaminated by emissions from fluorochemical factories, waste treatment sites, and the use of fluorinated firefighting products.
Contamination in the United States has been costly. The US Air Force has spent US$137 million (910 million yuan) to investigate military bases polluted by fluorinated firefighting products, and the cost of complete remediation around these sites will likely be far higher. Over 3500 lawsuits against a chemical manufacturer over contamination in the Ohio River Valley have been settled for a total cost of US$670 million (4.5 billion yuan). Affected communities have bought activated carbon filtration systems to ensure safe drinking water, a short-term solution costing these communities millions.
After decades of production, the primary US manufacturer voluntarily agreed to phase out PFOS in 2000. Shortly thereafter, other leading fluorochemical manufacturers joined the PFOA Stewardship Program and agreed to eliminate 95% of PFOA factory emissions and product content by 2010, with complete elimination by 2015.
PFOS blood-levels in the US have declined by 84% from 1999 to 2014, in part due to these actions. Efforts in China to reduce usage are more recent; in 2017, the World Bank approved a US$24 million (162 million yuan) grant to support Chinese reduction efforts of PFOS.
Are short chains better?
Both PFOA and PFOS are known as long-chain C8 chemicals because they have eight carbons linked together. As US production of C8 chemicals halted, many manufacturers transitioned to short-chained chemical cousins, nearly identical except that the length of the chain is reduced from eight carbons (C8) to six or four (C6/C4).
After human exposure, well-studied short-chain compounds typically last for months in blood serum, while long-chain compounds last for years. Because these short-chain compounds are not found in the general population’s blood, manufacturers suggest they do not bioaccumulate and are therefore safe.
However, short-chains have been shown to aggregate in organs in one animal study, and have even been found in human organs, including the kidneys, lungs, and brain. Preliminary studies suggest negative health effects similar to those of C8 chemicals like PFOA and PFOS.
Most worryingly, short-chain fluorinated chemicals spread faster in the environment and are difficult, if not impossible, to contain with current technologies. The tools used to protect drinking water from C8, like activated carbon filtration, may not be applicable to regions contaminated by short-chained C6 and C4 chemicals. These short-chain chemicals will similarly last for thousands of years.
Long-chain fluorinated chemicals are highly bioaccumulative in animals, while short-chains tend to be more bioaccumulative in plants. Food crops, including lettuce, tomatoes, wheat, and strawberries, have been demonstrated to bioaccumulate short-chain fluorinated chemicals when grown in contaminated soil or irrigated with contaminated water.
An industrial park producing highly fluorinated chemicals in China’s Huantai County in north-central Shandong province, represents an extreme case. When county residents look to the sky, they may be struck by rainwater contaminated up to thirty-nine times higher than the PFOA drinking water advisory limit set by the EPA.
When they eat food from nearby agricultural fields, they are likely ingesting unsafe levels of fluorinated chemicals. Researchers modelling daily PFOA exposure found that Huantai residents eating wheat and maize grown near the industrial park almost exceeded a dietary health limit set by health authorities. This limit is likely far exceeded after accounting for PFOA in drinking water and foods other than wheat and maize. In addition, the short-chain fluorinated chemicals with unknown toxicities far surpassed the PFOA and PFOS levels in Huantai crops meant for human consumption.
What to do?
Fluorinated chemicals can be useful, and there are applications where they are currently irreplaceable. A mountaineer heading for the summit of Mt. Everest should use the best water-resistant gear available. Fluorinated chemicals have been used for their extreme durability on the International Space Station, the Martian rovers, and astronaut spacesuits in order to protect from outer space’s harsh environment.
And yet, the need for highly fluorinated chemicals in extreme situations does not justify their pervasiveness nor their lack of environmental safeguards. In the Madrid Statement, 252 scientists representing 44 countries called for reduction in the use of PFASs and the development of safe, non-fluorinated alternatives. A necessary three-pronged approach will (1) implement safeguards to reduce factory emissions, (2) reduce the use of fluorinated chemicals when appropriate, and (3) develop safer, fluorine-free alternatives.
After decades of uncontrolled production, major US manufacturers successfully reduced C8 factory emissions and eliminated C8 usage in consumer products. This success has been achieved, in part, by transitioning from well-studied hazards of C8 to unfamiliar chemical cousins with concerning similarities. By learning from decades of US mistakes, China can avoid future harm.
Fluorinated chemicals represent a special concern because of their persistence and their ability to concentrate in organisms. Non-persistent chemicals discovered to be toxic can be removed from use. Over time, they will degrade and dilute; present generations will heal and future generations will be spared from danger. But when chemicals last for perpetuity, society can be forever impacted.