CFLs, Mercury and Why I Don’t Eat Tuna

My husband often sends me news articles, links and other tidbits of green and sustainable information he thinks I might find interesting. I know he thinks I don’t read these things, but I do – just usually several days (up to a couple of weeks) after he first sends them to me. What? I’m a busy girl. But I digress. The last two factoids he sent me were totally unrelated, until I waited long enough to read them at the same time and pow! they fit together like a couple of puzzle pieces.

The first notable news comes from Green Tech Media in an article by Michael Kanellos where he tells us that, “LightFair, the big lighting confab, opened today. Osram Sylvania, to celebrate, announced a 100-watt equivalent LED that consumes 14 watts of power. It will put out 1,500 lumens of light. In layman’s terms, that’s a lot. Don’t look straight at it. U.S. regulations will impose efficiency regulations on bulb makers that will directly impact the ability of many to sell 100 watt incandescents in 2012 and beyond. Some are stocking up (“You can have this light bulb when you pry it out of my cold dead hand’) but other consumers seem to be intrigued about the future of LEDs. Some 60-watt equivalent bulbs will cost around $20 by the end of the year and save over $10 a year in power.” [1]

Pretty cool.

cfl bulb

Then I read the next email that had been patiently waiting for my attention, and I learned that some people have been concerned about possible mercury exposure from broken CFL bulbs. If you’ve read other articles of mine, you may know that I am not a worrier. At all. In fact, I don’t wear a helmet when I ride my bicycle and would ride a motorcycle without one if they’d let me. But I digress again. Some folks got part of the mercury story and misunderstood the core message to be that they should be afraid of CFL bulbs. Not so. Check out this cool, but disturbing, fact list of how much mercury is in tuna and learn why I stopped eating the stuff:

“* A single CFL contains 5 milligrams (abbreviated as mg) of mercury. See link (4)
* When a CFL is shattered only 17% to 40% of the mercury is actually released into the air. The rest remains attached to the CFL glass fragments. See link (2).
* So of the total 5mg of mercury in a CFL only 0.85mg (17% of 5mg) to 2mg (40% of 5mg) make it into the air.
* In addition, only 1/3rd of that 17% to 40%, makes it into the air in the first 8 hours from the time the CFL shatters. See link (2).
* So only 0.28mg (1/3rd of 0.85mg) to 0.67mg (1/3rd of 2mg) of mercury will make it into the air if the shattered CFL is not disposed in 8 hours.
* 1 milligram equals 1000 micrograms (abbreviated as ug).
* 0.67mg = 670ug

Bottom line, if you absolutely shatter a CFL, and leave it there for 8 hours, it will release at most 670ug of mercury into the air.

Now on tuna… here is what eating tuna means in terms of mercury:
* The average mercury content in tuna is about 0.31 micrograms (abbreviated as ug) per gram (abbreviated as g) of tuna. See link (3) and (5).
* A 6 oz can of tuna is 170g
* This means there are 52.70 ug (170 * 0.31 ug) of mercury in a 6 oz can of tuna.
* 13 cans of tuna would introduce about 685 ug of mercury into your body.

The above are all factual numbers, no conclusions or assumptions. 13 cans of 6oz tuna contain the same amount of mercury as you would release from a shattered CFL in 8 hours.

Now, for the analysis and conclusions drawn from the facts…
* Keep in mind that you actually do ingest the entire 685ug of mercury in eating those 13 cans of tuna.
* The 670ug from a shattered CFL will take 8 hours to disperse into the air.
* If you inhaled directly from the shattered CFL pile for 8 hours, you wouldn’t inhale all 670ug of mercury potentially released, because of air flow.” [2]

If that’s not enough to stop you from eating tuna, at least try not to inhale directly from any broken CFLs this week.

- Jocelyn Broyles


[1] “Mixed Greens: Hawaii’s Smart Grid, Osram’s New LED Bulbs, Hara Gets $25M, and More,” by Michael Kanellos, May 17, 2011

[2]† Taken from a Facebook post by R9.12, which is short for the website Rutherford912.

Headline image © Augapfel on Flikr


Jennifer C.
Past Member 6 years ago

Worth reading and good to know. Thanks.

Bianca D
Bianca D6 years ago

Not sure how having less mercury than tuna makes CFLs ok.

It's a shame CFLs or a similar technology cannot be produced because mercury - at any dose/concentration - has toxic effects. And there is evidence that inhaling it even in minute amounts can wreak havoc with one's health as the lungs provide direct access to the bloodstream. Of course the other part of the problem is disposal. When CFLs are tossed into the trash (few can be bothered to dispose of them properly; see for example they convert whatever dump they end up in into a toxic site. At the very least that mercury will be in the soil and then leached into the water table. It's not uncommon for such sites to be "reclaimed" and schools or residential developments built on them...

It's time to figure out ways to really lighten our footprint and produce toxin free technology.

Eternal Gardener
Eternal G6 years ago


Maggie F.
Margaret F6 years ago

CFLs are pretty sturdy light bulbs and do not break easily.

Sue H.
Sue H6 years ago

Thanks for this very informative

Steve O.
Steve Mitchell6 years ago

Greennii missed one tiny piece of the puzzle, or maybe her hubby did.

13 cans of tuna [ mercury accumulates in your flesh ] probably is enough in the scalp to start significant hair loss. Okay for all those skinheads, and the wig industry but for me, no thank you.

Eileen Novak
Eileen Novak6 years ago

Wow. Is the same true for fresh tuna?

K s Goh
KS Goh6 years ago

Thanks for the article.

KrassiAWAY B.
Krasimira B6 years ago

Bluefin tuna is an endagered species.

Wioletta S.
Wioletta S6 years ago

watch out for too much