TRANSCRIPT - Dr. David Carpenter
David Carpenter is a Professor of Environmental Health and
Toxicology in the School of Public Health at the University
of Albany. He is also the Director of the Institute for Health
and the Environment at the University of Albany.
What was the
purpose of the farmed salmon study?
of the study was to determine whether or not there were hazardous
contaminants in farmed salmon that would counterbalance the benefits
of eating a fish that's high in protein and some essential fatty
What were you looking at?
This was a very
large study. We analyzed in the portion of the study that's in our
publication over two metric tons of salmon. These salmon were wild
Alaskan salmon from several places in Alaska and Northern Canada.
They included salmon from eight major salmon farming countries purchased
directly from the suppliers. They included salmon purchased in supermarkets
in 16 cities in North America and Europe. In addition, we purchased
salmon fish food from the two major suppliers that provide the majority
of fishmeal and fish oil in the world.
What were you looking for? How many different toxins?
It's true that
there have been three previous studies published in peer review
publications plus a small report from the Environmental Working
Group that demonstrated contaminants in farmed salmon. In none of
these studies were there more than 10 fish sampled. In most of them,
they were sampled only for one or two contaminants; primarily PCBs.
Our results are consistent with the results of those other studies.
But they're much more systematic - they're much larger. We analyzed
for a much larger number of contaminants. We do our sample from
most of the major farmed salmon regions of the world plus having
analysis of the food. So I think that it's very difficult to criticize
our results on the basis of size. This is a very large systematic
study. We have analyzed for all of the major contaminants of concern.
Were there thousands of assays?
459 fish from farms, and from those 459 fish we got 153 samples.
In other words, we pooled several fish, ground them up, made a mixture
and analyzed them as one unit. But it's a large number of fish.
So, the procedure was we purchased 10 fish from each farm, and chose
nine of them to make into composites of three fish each. So these
are large salmon, and we tried to get salmon of more or less the
same size from the different farms. In addition to that, for the
supermarket samples, we went to 16 different cities in North America
and Europe and in each city went to three different supermarkets
where we bought supermarket salmon fillets - three different fillets
from each supermarket and then ground them together.
Now, many times
in the supermarket people didn't know where the salmon came from.
If it says Atlantic salmon were pretty confident that it's a farmed
salmon because there is no significant commercial harvesting of
Atlantic salmon. Almost all of the farmed salmon are, in fact, Atlantic
salmon. In some cases, people did know where the salmon came from
but that was unusual. For the wild salmon, we purchased 135 salmon
from suppliers of wild Alaskan and British Columbian salmon. These
were handled in the same way. We made composites of three fish,
ground them all together and analyzed them as one unit.
What about the fishmeal sample?
Well, the details
about how they make the salmon feed, we don't really know in great
detail. We purchased 13 samples of the feed that's fed to salmon.
And they came primarily from Scotland, from British Columbia and
from Chile. The production of fish food is a very international
industry. And there are two major companies that control the lions'
share of the world's market. Each of them, we expect, produce feed
from regions in which it's marketed. So that the feed fed to salmon
in the North Atlantic probably comes from trash fish from the North
Atlantic. That from Chile probably comes from trash fish in the
South Pacific. But we don't really know that. The point that is
so clear from our study is that the contaminant loads in the feed
fed to the farmed salmon is very similar to the contaminant loads
that we see in the salmon that are farmed in that region.
What were the results of your study?
In this paper
we report the analysis of 14 substances that fall into the category
of persistent organic pollutants. These include PCBs, dioxins, and
dioxin like compounds and 12 persistent pesticides, all of them
chlorinated. The fact that they're persistent means that they're
not easily degraded, either in the fish or in our bodies. They do
last for a long time in the environment. Now, we found in general,
that for 13 of these 14 substances, there were significantly higher
levels in the farmed salmon than in the wild salmon. For most of
them, it wasn't just a small difference; it was about a 10-fold
difference in the farmed salmon.
We went on to
do a careful analysis of four of them because of the fact that for
these four there are advisories on fish consumption and health based
indicators that have been developed and distributed by the Environmental
Protection Agency and by the World Health Organization. The four
are PCBs, dioxins, dieldrin and toxaphene. Dieldrin and toxaphene
are pesticides that were used primarily in the South, but they distributed
over the world primarily by spreading through atmospheric transport.
We used EPA fish advisories that were originally developed for Great
Lakes fish consumption for PCBs, dieldrin, and toxaphene. On the
basis of these advisories, the most contaminated fish have such
levels of containments that one should eat no more than one meal
every other month.
Could you say more about the Great Lakes advisories?
EPA has issued
advisories for the consumption of Great Lakes fish on the basis
of PCBs, dieldrin and toxaphene. We applied these advisories in
calculating the numbers of meals of farmed salmon that should be
eaten per week from different places, from different countries,
from different supermarkets. In the most severe restriction advice
would be for salmon primarily from the Baltic Sea area - from Norway
and Scotland, where the consumption should be limited to not more
that one meal every other month. For all of the farmed salmon, there
were significant advisories. Now we did find that the farmed salmon
from Northern Europe was more contaminated than that from Chile
or British Columbia. This probably reflects the fact that the food
that's fed to farmed salmon in Northern Europe comes from the Baltic
Sea, which is a highly industrialized area, and it's known to be
quite contaminated. The food that's fed to the Pacific Ocean farmed
salmon is less contaminated. However, for PCBs, dioxins and dieldrins,
all the farmed salmon from Chile still had significantly higher
levels than the wild Alaskan salmon.
If we calculate
in terms of advisories on meals per month, or meals per week, for
the wild Alaskan salmon up to eight meals a month is not dangerous
on the basis of these EPA advisories. For the farmed salmon, there
would be recommendations for restricted consumption even of the
least contaminated salmon - those coming from Chile. The World Health
Organization values for dioxin equivalents led to restriction advisories
that were somewhat less severe than that for the PCBs, dieldrin
and toxaphene. But in every case the same pattern was there. The
wild salmon could be consumed with relative comfort that you're
not getting significant numbers of contaminants, whereas the farmed
salmon, including those from the least contaminated sites in Chile
that we studied, there should not be unrestricted consumption of
Why do wild salmon have fewer toxins?
from our study is that the source of the contaminants is the food
that the farmed salmon are fed. This is not a totally negative conclusion
because it means that we can get the contaminants out of the farmed
salmon for the most part by finding a clean food to feed them. But
the source of contaminants for wild salmon must also be primarily
the food they eat. The reality is that wild salmon do eat small
fish. They eat a lot of crustaceans; they eat a lot of shrimp. The
color, the red or pink color of the wild salmon, comes from the
food they eat naturally. This is unlike the situation with the farmed
salmon where the color is an added dye. Because farmed salmon, if
this dye is not added, have flesh color that's sort of a dirty gray.
So the color that we see in the fillets in the supermarket is all
an added dye.
Why are there less accumulated toxins in salmon?
do eat fish but they eat a lot of crustaceans. In fact the crustaceans,
the shrimp and that sort of little animal is where the wild salmon
get their natural pink or red color. The fish that they eat are
lower on the food chain. They have fewer contaminants. But another
conclusion from this that I think is very important is that we have
sufficiently contaminated our oceans, that now if we concentrate
the fish meal and fish oil from trash fish that nobody wants to
eat, then shove it to fish in a cage and push their weight gain,
we can develop animals that are dangerous to eat because of the
accumulations of toxins.
Can you address the issue of fat content between farmed and wild
salmon have much higher fat levels than do wild salmon. I believe
in our study it was a tenfold greater fat content. Salmon in general
are a fatty fish and contaminants do accumulate in fat. However,
even if one adjusts for the greater fat content in the farmed salmon,
they still have more of these contaminants. It's not just that they're
fatter. I should talk a little about the benefits of the Omega-3
fatty acids. Omega-3 fatty acids are a special kind of fat that's
known as the good fat. There is very clear evidence the Omega-3
fatty acids help reduce the incidence of heart disease and there's
building evidence that they may have beneficial effects against
other diseases as well. So this is one of the reasons that many
organizations, for example the American Heart Association recommends
eating fish one or two meals per week. Well, no one denies that
the Omega-3 fatty acids are heart healthy. It's also clear that
these contaminants are heart damaging.
The PCBs and
the dioxins cause the liver to make more cholesterol, and more lipids.
People who are exposed to these compounds have higher circulating
lipid levels, in general. We know that the biggest risk factor for
heart attack is the level of cholesterol in serum lipids. It's interesting
to compare these results with the recent studies on methylmercury.
Methylmercury also accumulates in fish. Methylmercury also causes
increases in susceptibility to heart disease. In a study published
last November, it was demonstrated that men that ate a lot of ocean
fish, which had high levels of methylmercury, actually suffered
more heart attacks than men that didn't eat fish.
Now when they
looked carefully, they could demonstrate the beneficial effect of
the Omega-3 fatty acids. But this was counteracted and over-balanced
by the harmful effects of the methylmercury. Now, there's another
consideration with regard to the Omega-3 fatty acids. In recent
studies, comparing people that had one fish meal a week or one fish
meal a month as compared to people that didn't eat fish, it was
found that clearly there were no added benefits beyond one fish
meal a week. In other words, eating salmon four days a week is going
to help you prevent heart disease. In fact, the health hazards from
the contaminants will greatly overshadow the beneficial effects
of the Omega-3 fatty acids. These studies looked at consumption
of all seafood, all kinds of fish, plus shellfish in calculating
the one meal per week. Therefore, while the non-fatty fish don't
have as high Omega-3 fatty acids, they all have some. There are
also other sources of Omega-3 fatty acids. Certain oils, certain
beans -pinto beans, soybeans - all have Omega-3 fatty acids. So
the question of the Omega-3 fatty acids as a health benefit does
not constitute a reason to advocate high levels of consumption of
farmed salmon or any other fish for that matter.
Can you compare FDA and EPA standards?
Well it's true
that none of these salmon exceed the FDA standard of two parts per
million for PCBs. However, that standard is not a health-based standard.
It's not the FDA's fault because it's actually Congress that has
mandated the FDA to set levels that regulate levels for interstate
transport of foods. Those levels should reflect considerations of
economic impact on industry and the considered heath effects. The
two parts per million per PCBs standards was set a large number
of years ago. It is not health protective and was never designed
to be health protective. Now, the EPA standard is much more rigorous.
For example, for PCBs, the EPA says it's safe to eat an unlimited
number of fish if the PCB level is 0.05 parts per million. So what
you see is a 400 fold lower value for safe consumption of fish.
What the EPA
does in the standards that they developed for the Great Lakes is
say, "All right, if fish have a contaminant at a level that
is such you shouldn't eat them all the time as many as you want,
then, at this level you should have not more than one meal per month."
At this level, you should have not more than one meal per week.
At this level, you shouldn't eat any at all. We think that standard,
being based entirely on health effects outcomes is the appropriate
one for the consumer to consider when they make decisions about
whether or not they are going to eat farmed salmon.
Using the EPA standard, how often can people eat farmed salmon?
it depends on where the salmon comes from and what its contaminant
levels are. Of course, the consumer when they go into a supermarket
has no idea. If the salmon you see in the supermarket says Atlantic
salmon - it's a farmed salmon. But, one of the recommendations from
our report is that it should be labeled as to what part of the world
it comes from. We did find that salmon from the North Atlantic had
significantly higher concentrations than salmon from the Pacific-both
north and south.
also did a systematic study of salmon filets purchased in 16 cities
in Europe and North America. While most of the contaminated salmon
purchased in supermarkets came from Europe, especially Frankfurt
Germany, we found that salmon from Boston and from San Francisco
were almost as high, whereas salmon purchased in Chicago and New
Orleans were considerably lower. Now, the point is that in the salmon
we happened to sample, it's almost certain that the salmon purchased
in Chicago and New Orleans came from Chile, whereas those from Boston
and San Francisco came from Europe. But the consumer doesn't know
this-at least with present information. So I think the punch line
is when you go to your supermarket you're not going to have any
idea where that salmon comes from. And therefore, it's best to be
Since fishmeal is fed to poultry and swine as well as farmed fish,
why the specific concern about farmed salmon, and not these other
The levels of
contaminants we found in the farmed salmon are much higher than
are found in the other commonly consumed meats-beef, pork, chicken,
eggs, and butter -all of the animal products. Now, that's not to
say that there's no concern about the levels in these other products.
I've just been on a National Academy of science panel looking at
dioxin-like substances in the food supply where one of our major
recommendations is we must stop the recycling of contaminated animal
products into animal food. I think the worst situation is what we
have with the farmed salmon. The degree to which that applies to
other farmed fish is not clear at present, because there has not
been this kind of study. It is true that fishmeal and fish oil are
often used in the animal's foods for other kinds of animals. Although
usually those foods contain fat from other kinds of animals as well.
So, the problem goes beyond what we've found with the farmed salmon
industry, but it's worse than any other previous demonstrated situation
in this particular industry.
Why are dioxin and enzyme interrupters a health risk?
the clearest example because dioxin is rated by every national international
agency as a proven human carcinogen. PCBs are rated as probable
human carcinogens on the basis of evidence that they cause cancer
in animals and consistent evidence of that conclusion that they
cause cancer in people. Those compounds also suppress the immune
system. These effects have been known for a long time, but I should
say that if your immune system is suppressed, it makes you more
vulnerable to every kind of infection. When you get a cold it's
going to last longer. So those are serious issues.
In my judgment,
the most dangerous things are more difficult to quantify, and we've
had enormous progress in the last few years in understanding what
they are. Perhaps, reflecting my own background in neuroscience,
I think the most dangerous thing is the exposure to these compounds
before birth. They cause a reduction in IQ of a child, a shortened
attention span, a greater difficulty in dealing with frustrations,
so there's more hostility-symptoms of ADHD that sort of thing in
children. In addition, exposure before birth, in the early years
of life, disrupts the endocrine systems.
This is particularly
well demonstrated for the thyroid hormonal system which regulates
our metabolism and the sex hormones system. Dioxins are anti-estrogenic,
which means they tend to masculinize little girls. PCBs are dominantly
estrogenic, which means they tend to feminize little boys. It's
been well demonstrated that the cancers of the reproductive systems
that occur at older than infancy are related to these alterations
of the sex hormones. The relative balance of male and female sex
hormones determines all of our sexual responses, physiology, and
mess that up. They are associated with decreased fertility. Especially
in men, decreased sperm counts in adult men. They are associated
with increased birth defects of the reproductive tract. There are
increased incidents of undescended testicles or hypospadias, which
is a birth defect in which the urethra doesn't empty at the end
of the penis as it does in a normal person. So, they can alter both
the cognitive intellectual function and reproductive function for
the duration of a persons' life as a result of exposure before birth.
Now, one of
the major recommendations of our National Academy report was that
we try to have the public understand better the vulnerability of
little girls. These compounds are persistent, by which we mean they
stay in the human body for many years. For PCBs and dioxins, it
takes about 10 years before you get rid of half of what you ate
in that farmed salmon meal for dinner last night. That means if
a 10-year-old girl is exposed to these compounds whether from eating
salmon or other sources, if she gets pregnant and has a child at
age 20, she's going to have half of those contaminants in her body.
The child will get them when the child is growing in her body. If
she breast feeds, breast milk is the only way in which humans excrete
body fat. That contaminated body fat goes into the infant. Now there
are lots of benefits of breast-feeding, but this is the negative.
And that child is vulnerable to reduced IQ that will last for life,
suppressed immune system, more vulnerability to infection, increased
risks of cancer, increased risks of birth defects, and increased
risk of having their reproductive sexual life altered by these prenatal
exposures. It is a very, very frightening situation.
Anything we might want to add?
No, I think
you've covered it very well. It's more important to get the punch
line out than to go on forever. The punch line is that this is very
dangerous stuff. What's so amazing to me is that the message just
hasn't gotten to people. Partly it's because of organizations like
the American Heart Association. It's almost that saying eating fish
can be dangerous to your health is as bad as saying you shouldn't
breast feed your child. It's interesting because I've gotten involved
in just the last few weeks in a major debate on whether or not there
are reasons to consider not breast-feeding, and also changing this
message that fish consumption is always healthy with the International
Joint Commission on issues around the Great Lakes focused primarily
around mercury. But the issues are the same, though the distribution
is somewhat different.
Could you comment on how we've polluted up the oceans?
important conclusion from this study is that we have fouled our
nest. That even the oceans now, are sufficiently contaminated, that
if we take the fish that nobody wants to eat, grind them up, concentrate
them and feed them in large amounts to fish in a cage, those fish
in a cage end up with contaminant levels that are dangerous to our
health. Now, most people think the ocean is still an unlimited resource
and that it's clean and will remain clean. But we have our contaminated
rivers, one of which is right out here that flows right into the
ocean. It carries with it contaminated sediments and water that
contains low concentration of contaminants. Since that's happening
from rivers all around the world, we now are in the situation where
even concentrated meal from ocean fish is dangerous.
What about uncontaminated fish?
fish that are not contaminated is very healthy. Eating fish that
are contaminated can be very dangerous. And for most of us there
is some middle ground. Since all of them are contaminated to some
degree, it's important that the consumer understand which are more
contaminated, which are less. In general, small fish that eat plants
are much healthier than big fish that eat medium size fish, because
contaminants get bio-concentrated. So the tuna, the swordfish, the
shark all have high levels of mercury. They are not farmed and they
don't have particularly high levels of the organochlorines. The
farmed fish that are fed contaminated fishmeal are going to accumulate
that fishmeal. It's going to go into their bodies and when we eat
them, we are going to bring those contaminants into our bodies.
That is very dangerous.