A strange catastrophe struck Spain’s pig farmers in the spring of 2010. On 41 farms across the country—each home to between 800 and 3,000 pigs—many sows suddenly ceased bearing young.
On some farms, all the sows stopped reproducing. On others, those that did become pregnant produced smaller litters.
When investigators examined the sows and the semen that had been used to artificially inseminate them—it had been collected from different boar studs and refrigerated—they couldn’t find anything wrong. The sperm cells weren’t misshapen. None of the sows were diseased. No microbes or fungal toxins were detected in their feed or water.
Only one factor was common to all the farms and studs: The plastic bags used for semen storage all came from the same place.
Investigating those bags has led Cristina Nerín, an analytical chemist at the University of Zaragoza who studies packaging materials, to publish new research that traces the pigs’ infertility to chemical compounds in the plastics.
This is “the first time that the correlation between reproductive failures and compounds migrating from plastic materials [has been] studied and demonstrated,” says Nerín, whose team published last month in the journal Scientific Reports.
The implications could extend far beyond the farm.
Some of the same chemicals found in the pigs’ semen storage bags are routinely used in packaging food for humans and are known to migrate into food. The strange case of the Spanish pigs, Nerín says, “shows the real risks we face.” (Explore an interactive showing toxic chemicals that may be lurking in your home.)…
[continues at National Geographic]