Monday, August 30, 2010

Mercury in Fish

My girl asked me one day:

"Mummy, is fish smart?"
"Hmm.. I don't think so. They have very small brains."
"Then why did Grandma say I must eat fish to be smart?"

That really cracked me up! ;D

The old wives' tale that eating fish is good for brains has its place. 

I am, however, more concerned about the level of mercury in fish as nowadays, our rivers and seas are superbly toxic what with oil spills, toxic waste and chemicals conveniently dumped into our global waters. I have a friend who used to work off shore on an oil rig and he said that whatever liquid chemicals that weren't needed anymore were poured into the sea-- on a daily basis!

What is considered a dangerous level of mercury in our bodies?
"Most non-exposed people have mercury levels of 0 to 2 (all blood measurements are in micrograms of mercury per deciliter of blood, or ug/dl). Levels above 2.8 ug/dl are required to be reported to the Health Department. This test can be influenced by eating fish, because fish (particularly certain deep sea fish) may contain mercury."
Source: Mercury (read more for the side effects on health)

So I compiled a list of fish which has the lowest to the highest content of mercury as a guideline. Hope you'll find it helpful.

LOWEST MERCURY

Eat 2-3 servings a week (pregnant women and small children should not eat more than 12 ounces (2 servings):
  • Anchovies
  • Catfish
  • Clam
  • Crab
  • Crawfish
  • Flounder
  • Haddock
  • Herring
  • Mackerel
  • Mullet
  • Oyster
  • Perch
  • Pollock
  • Salmon
  • Sardine 
  • Scallop
  • Shrimp
  • Sole
  • Squid
  • Tilapia
  • Trout
  • Whitefish

MODERATE MERCURY

Eat six servings or fewer per month (pregnant women and small children should avoid these):
  • Bass
  • Carp
  • Cod
  • Halibut
  • Lobster
  • Mahi Mahi
  • Monkfish
  • Perch
  • Snapper
  • Tuna (Canned Chunk light)

HIGH MERCURY

Eat three servings or less per month (pregnant women and small children should avoid these):
  • Bluefish
  • Grouper
  • Sea Bass
  • Tuna (Canned Albacore, Yellowfin) 

HIGHEST MERCURY

Avoid eating (everyone):
  • Marlin
  • Orange Roughy
  • Shark
  • Swordfish
  • Tilefish
  • Tuna (Ahi)
Sources:
Food and Drug Administration (FDA). Mercury Levels in Commercial Fish and Shellfish
Food and Drug Administration (FDA). What You Need to Know About Mercury in Fish and Shellfish
National Resource Defense Council. Mecury Contamination in Fish.
Centers for Disease Control. Public Health Statement for Mercury. Agency for Toxic Substances and Disease Registry.
Carpe Diem, ladies!
Becky

10 comments:

alicia said...

want to ask what is 'ma yau' fish in english? grandparents recommend that fish coz it's easy to remove the bones and has lots of meat... i've been feeding jamie with that 2x a day since she was 6mo! hope it doesn't have mercury...

Mad About Writing said...

oh goodness.. I have no idea ...anybody???
That's cantonese right? i don't speak cantonese at all, dear.

Actually, I welcome anyone who can do a translation of some of the fish above to our local dialect/language.

e.g. ikan tenggiri, ikan parang...etc

anyway, I follow this food guideline for babies and apparently, the recommended age to start taking fish is 12 to 18 months of age.. and even then, the recommended fish is salmon (lowest in mercury)
Frankly, I don't know about our local fish- is 'ma yau' sea water/fresh water fish?

Any help is welcome here!

Mad About Writing said...

BTW, alicia, in response to your comment in the last post.. ya, it's probably a good idea to balance everything out instead of too much of one thing...just in case.

I mean, unless we plant the vege ourselves or rear the animals in our yard, we really don't know what they might put in our food nowadays...

laifchan said...

yeah, its really difficult to decide what's safe to eat nowadays, especially in babies.

Alicia, I'm not quite sure what ma yau actually is but a google search says its ikan kurau, famed for making toddler's porridge:
http://www.good4u.com.my/v3/category.jsp?pager.offset=5&catId=1#551List

Some local mummies who quote paediatrician's advice also seem to think its ok as baby food together with salmon, organic perch (no idea what it is)which are supposedly availabble in Jusco - http://my.meadjohnsonasia.com/amn/viewmessages.cfm/Forum/16/Topic/7866/cboSort/Both-Malaysia
Then again, not sure whether jusco's salmon is wild or farmed (more chemicals).

The main problem in being sure about mercury levels in local fish is the lack of research and data, so far some culprits seem to be ikan kembung & tenggiri but its hard to comment whether other fish are safe or not, i guess its dependent on where the fish are caught, high level of mercury contamination or not. Grouper in the US is also not recommended.

My colleague recently joked that since almost every type of food ie chicken, fish, vege etc is unsafe now, one day breastmilk would be deemed unsafe too! Hmmm, if breastfeeding mums are not careful with what we consume, that has some truth in it!

So how?

Well, i think for chicken, going for the 'kampung' chicken which is usually available in wet markets for a higher price or the antibiotic-free ones in Cold Storage/Jaya supermarket seems safer.

For fish, i guess the safest would be salmon (wild) and ikan bilis. As for local fish, moderate amounts seem reasonable (1 serving per week?)

Not sure whether there's such a thing as organic pork or beef...

laifchan said...

Just found a more recent article that found that lowest mercury level in local fish is sardine (non-predatory, they eat plankton), highest level in long-tailed tuna and mackerel (kembong or tenggiri) but apparently still within safe limits.


A caveat is that the fish samples were taken from a major retail store in Selangor sourced from South China Sea. Older studies (including source from Straits of Malacca) found higher mercury levels.


Becky, I'll send you the scientific article via email

Mad About Writing said...

thanks laifchan!

alicia said...

managed to google and found out that ' ma yau' is threadfin in english. here's a link regarding threadfins http://en.wikipedia.org/wiki/ Threadfin

hope it's the correct translation!

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Mad About Writing said...

ok thanks

Leo said...

I know that this post was like 7-8 years ago but I hope anyone else who stumble upon this blog will benefit from it.

Ma Yau Yu (Cantonese)/午鱼 / 马友鱼 / Ngor Her is a saltwater fish & refers to basically all fish that look like threadfin BUT there are 2 common threadfin that Malaysia & Singapore are usually consume (not sure which is for baby first fish though).

The first one is Indian Threadfin which is called Ikan Kurau in Malay & differentiate by the Hokkien as Orh (Black) Ngor. As it Hokkien name implies, this fish have darker color.

The second one is Fourfinger Threadfin which is called Ikan Senangin in Malay & differentiate by the Hokkien as Peh (White) Ngor. As it Hokkien name implies, this fish have lighter color.

For more details, about name of fish (English, Mandarin, Malay) that we consume in Malaysia & Asia. You may refers to:

https://forum.lowyat.net/topic/4503695?author=xxhenry89xx

P.S The list of fish that you provided might most probably from USA source. The type of fish listed might be different/different name from what we know in Malaysia and/or Asia. (e.g. lobster - they refers to the saltwater variety, the freshwater variety are called crayfish/crawfish in USA, bass such as sea bass, black bass are not our Asian Sea Bass/Barramundi/Kim Bak Lor).