Monday, October 03, 2011

Arsenic In Chicken

I was curious about Dr. Greger's arsenic-in-chicken post. I looked at this study, which claims to be the first report of arsenic in national samples of poultry in the US:

Mean Total Arsenic Concentrations in Chicken 1989-2000 and Estimated Exposures for Consumers of Chicken, Environmental Health Perspectives, 2004

It found:
  • The mean concentration of total arsenic in young chickens was 0.39 ppm, 3- to 4-fold higher than in other poultry and meat.
  • At consumption of 60 g chicken/day (about 2 ounces), people may ingest 1.38-5.24 µg/day of inorganic arsenic.
  • At consumption of 350 g chicken/day (about 12 ounces), people may ingest 21.13-30.59 µg inorganic arsenic/day and 32.50-47.07 µg total arsenic.
Look at those arsenic levels in young chickens floating above the rest. This was a decade ago, maybe things have changed:

I don't understand how bad that is, 0.39 parts per million (or 390 ppb) doesn't sound like much. Here's some background from Lasky's literature review:

Arsenic is a heavy metal. Chronic exposure in the range of 0.01-0.04 mg/kg/day (10-40µg/kg/day) has been associated with:
  • Increased incidence of lung cancer, bladder cancer, skin cancer, and all cancers in Taiwan.
  • Respiratory cancers in Montana
  • Bladder cancer in Finland
  • Increased mortality from hypertensive heart disease, nephritis and nephrosis, and prostate cancer in Utah
  • Late fetal mortality, neonatal mortality, and postnatal mortality in Chile
  • Genetic damage in Mexico
So, if someone weighed 120 pounds (54.4kg), exposure of 544µg per day might cause health problems. But...

In January, 2006, 2 years after Lasky published his study, the EPA officially lowered their maximum contamination level in water from 50µg/L to 10µg/L. It was based on work by the National Research Council which found that chronic low-level exposure to arsenic may be associated with an increased risk of hypertension, diabetes, skin disorders, gastrointestinal diseases, and cancer.1

The NRC and now EPA say that chronic exposure to more than about 20µg arsenic in a day (assuming 2 liters water @ 10µg/L) is a human health risk?

Back to chicken ... Three pieces of chicken, say a thigh, breast, and drumstick (sans bone, skin, breading) weighs about 188 grams,2 supplying, according to Lasky's work, up to 25µg total arsenic. A small bucket of KFC, with 8 pieces (2 each wing/thigh/breast/drumstick) contains about 402g chicken flesh supplying up to 54µg total arsenic ... 5 times the amount you would find in one liter of water containing the EPA's maximum contamination level!

Two final points:

1. The amount of arsenic in chicken may be more, as Silbergeld describes:3
"Lasky et al. (2004) probably underestimate the true risks. First, as the authors carefully noted, they had to estimate the concentrations of arsenic in muscle using the only U.S. Department of Agriculture (USDA) data available, analyses of liver concentrations. It would be interesting to know why the USDA does not analyze arsenic in muscle, the tissue most commonly consumed by humans. In 1981, Westing et al. (1981) reported higher levels of arsenic in edible muscle tissue from cattle given feeds containing poultry litter.
Under repeated doses (Hughes et al. 2003, in mice), the ratio of liver to muscle arsenic changed dramatically over time, and at day 17, arsenic in muscle was higher than in liver.
Thus, it is likely that the actual concentrations of arsenic in edible portions of broiler poultry are higher than the estimates of Lasky et al. (2004)."
2. The arsenic we get from chicken is in addition to that which we get from other sources, notably water, but also, dust, fumes, poultry litter (sold in organic soil blends, fed to cattle), and other arsenic-containing foods (seafood, rice, mushrooms, pork, eggs, apple juice...)

Why is arsenic in chicken?
"Arsenic is an approved animal dietary supplement and is found in specifically approved drugs added to poultry and other animal feeds."
- Lasky et al., 2004
Arsenic is toxic to organisms that infect chicken's intestines. By controlling these parasites, chickens grow faster and bigger. So, it's used as a growth promoter.

There really does appear to be a lot of arsenic in chicken.
1Arsenic In Drinking Water, 2001 Update, NAP
2Weight of chicken pieces sans breading, skin, and bones from NutritionData:
Thigh: 52g
Breast: 86g
Drumstick: 50g
Wing: 13g
3 Arsenic In Food, Silbergeld, Environmental Health Perspectives, 2004


virginia said...

between the chicken tenders my mother loved, and the high levels of arsenic in new mexico's drinking water, it's no wonder she had heavy metal deposits in her brain.

and new mexico isn't doing anything about those levels.

Anonymous said...

Why is the arsenic concentration so much worse in young chickens than in mature chickens?

Would most chicken one encounters be young or mature? (From memory, in the supermarket, young chickens are cheaper, but they're also smaller. To use your example, do the pieces in a KFC bucket look small?)

I think I may try to stick to large chicken breasts.

Bix said...

virginia, That's sad about your mother. How did you know about her brain deposits?

New Mexico doesn't treat their water? Sheesh. I suppose we get the politicians we vote for. (That link for the Army Corps of Engineers I have (where it says "EPA officially...") lists methods of treating water to achieve the EPA's new arsenic limit.)

Bix said...

@Anonymous, I don't know. I think that young chickens are the ones grown and sold as broilers and birds used for fast food and retail stores. I recall reading that they taste better than older ones and are preferred.

I think the mature ones may be used for pet food. That's just from memory. Maybe someone can fill in.

Bix said...

I thought this was notable:

It would be interesting to know why the USDA does not analyze arsenic in muscle, the tissue most commonly consumed by humans.

She goes on to say that muscle tissue can harbor more arsenic than liver.

Dr. Mel said...

I'm pretty sure from what I've read that chicken you buy in a supermarket (or most anywhere) is quite young. A year, maybe less.

virginia said...

the deposits were discovered during an MRI or CAT scan - it's been quite a few years, but i'm thinking an MRI.

my sister, an RN, showed the scan/report to a dr. she knew/trusted. the dr's first question was: your parents' relationship, what is it like?

my sister laughed and said: horrid, and i know what you're getting at, but they divorced 4 years before he died, and he died more than two decades ago.

Bix said...

How about that. That would be a neat study, heavy metal deposits in people in various places across the country. At least an MRI isn't as invasive as a CT. I don't think.