Because I spend a lot of time in coffee shops working on my dissertation, I get to watch a lot of moms and soon-to-be-moms drop in for their morning dose of Joe, sometimes with kids in toe. I notice that many of them tend to order decaf, and for good reason: caffeine has a questionable impact on fetal health, and caffeine in breast milk can make for an irritable baby. (UPDATE: I received my PhD in May 2014!)

But there is one thing to keep in mind when choosing where you buy your decaf coffee: the caffeine extraction method used.

There are several methods of caffeine extraction. Some use chemicals known as decaffeination solvents, such as methylene chloride or ethyl acetate. Methylene chloride used to be found in hairsprays and cosmetics until it was was banned by the FDA after it was found to be carcinogenic, but it’s still used to make decaf coffee. Ethyl acetate is another carcinogenic substance, used in nail polish remover and to kill insects. Because it’s found in small amounts in fruit, some coffee companies using ethyl acetate claim that they are using a “natural” extraction method, however it is far from that. (More scientific analysis on the possible health effects of exposure to MC can be found here and here; on EA, look here and here).

Safer methods of extraction include one that is completely water-based (sometimes called the “Swiss water method”), another that uses water along with a carbon filter, and one that uses water along with carbon dioxide. More info on all of these methods can be found here.

Naturally, it’s probably best to avoid decaf coffees that have been processed with chemical solvents and to opt for coffee using the Swiss water (preferable), carbon filtration or carbon-dioxide methods. But, you may have to do your research to find out which extraction method is used to make your favorite coffee.

If you like to buy already-brewed coffee from a shop or stand, ask a barista how the caffeine was removed. Chances are, they won’t know and you’ll have to ask to speak to a supervisor, who may or may not be equally unhelpful. If you like to get your coffee at one of the big chain coffee shops, then it’s best to call their customer service number and ask. Here’s the result of the research I’ve done on some of the national brands. (NOTE: THE INFO BELOW IS CURRENT AS OF MARCH, 2015):

SAFE BREWED COFFEE: Starbucks uses the carbon dioxide extraction method (source: web site). Wholefoods’ Allegro brand coffee uses the carbon filter method (source: web site).

BRANDS TO AVOID: Dunkin’ Donuts and Coffee Bean use methylene chloride (source: DD customer service line; CB web site, here).

If you like to brew your coffee at home, then you will have to dig around to learn how the caffeine was extracted from the coffee beans. Most manufacturers will not advertise the extraction method on the package–of course, this probably means that they use chemical solvents. You will have to call their customer service line to find out for sure. A good rule of thumb for packaged decaf coffee is this: the brands that use one of the safer methods are usually organic and often advertise their extraction method right on the package. Examples of such brands, for whole beans, include Allegro (found at Wholefoods), Jeremiah’s Pick and Seattle’s Best Organic (both use the water-based method). The only organic brand of instant cofee on the market, Mount Hagen, also uses the carbon dioxide process.

So, to sum up: if you are pregnant, nursing, or otherwise concerned with ingesting potentially harmful chemicals along with your decaf coffee, do your research to find out how the caffeine was extracted. You should assume that potentially-toxic chemical solvents were used, unless proven otherwise. Starbucks and organic decaf coffees are typically safe options.