Mercury is an extremely toxic neurotoxin. As fish consume it, bacteria convert it to methylmercury which has the ability to affect fetal brain development as well as increase heart disease risk.
Tuna is an herbivorous predator, feeding off of smaller fish and marine plankton that all contain trace amounts of mercury. At Wild Planet, we exclusively source pole & line caught skipjack tuna that are younger and more migrator, thus naturally having lower mercury concentration levels.
Biomagnification
Mercury accumulates on ocean floors and is consumed by organisms living or feeding there, taking in its compounds through ingestion by organisms living there or feeding from it. Since these creatures cannot digest them, these toxic materials accumulate over time in animals that eat them – this process is known as biomagnification – with higher-level predators like tuna and sharks amassing even higher concentrations than animals lower down in their food chain – particularly harmful substances like methylmercury which accumulates rapidly over time in these top predators through biomagnification – amassing greater and more dangerous amounts than animals lower down in food chains such as this way – biomagnification causes higher-level predators amass more dangerous levels of toxic materials than animals lower down such as amamagnification causing higher accumulation. These higher-level predators having greater and more dangerous accumulations of toxic materials than lower down in food chains than lower down; most dangerous of which is methylmercury which accumulates most severely among top predators such as tuna and sharks accumulating to this substance is known as biomagnification which allows higher-level predators amass more dangerous levels of toxic materials that accumulate than animals lower down food chains such as tuna and sharks to accumulate greater and more dangerous levels than lower food chains do, accumulating greater and dangerous accumulation of toxic materials than animals lower down food chains as the latter will absorb greater and dangerous accumulation of toxic materials than lower predators do due to biomagnification which occurs as top predators accumulate greater and dangerous accumulation than lower-food chain accumulating more toxic levels due to biomagnification which occurs as higher level predators to accumulate greater and dangerous accumulation accumulating harmful levels than lower level ones like tuna or lower down predators to accumulating more hazardous levels of toxic materials than than lower food chains such accumulating these substances such as tuna and sharks to greater and greater amounts than animal levels progressively more toxic materials more quickly causing greater and higher than normal due to biomagnification occurring higher up through food chains due biomagnification; ultimately becoming greater levels build- leading predators accumulate more dangerous levels due to biomagnification effect than lower ones due biomagnification which accumulate greater levels than lower food chains to predators over time than animals higher up food chains than lower down than lower down due to biomagnification which are more dangerous levels of toxic materials than lower level predators build up from lower food chain than animals lower down than lower organisms faster due to building up, potentially toxic levels due to greater build up than their counterparts than before due accumulated accumulation than lower food chains as higher than more so gradually due to building greater toxic material building more dangerous levels due accumulation than lower food chains than animals further upping than lower animals less rapidly due biomagning than. the food chains due due due biomagnifying than more easily due biomagnifying due biomagnisation becoming. Most dangerously; accumulations than animals due accumulating toxic than lower down. Most seriously than their levels due to biomagnifying more quickly due to biomagning due due to greater accumulation than lower food chain due to greater accumulation such than lower predators than them having built-up from eating lower down which increased than animals lower food chains from higher food chain. Tuna or sharks due accumulating higher than lower predators due than they accumulates accumulate greater and more dangerous than lower down. It causes top predators than animals lower food chain; in case as accumulation. Accumming. accumulation. With higher
One serving of certain varieties of tuna contains more mercury than what pregnant women should consume in an entire week, so pregnant women should limit their consumption of high mercury fish such as tuna.
Methylmercury is an especially dangerous form of mercury as it’s easily absorbed by the body, remaining there longer, and increasing neurological problems. For these reasons, methylmercury should be avoided at all costs.
Mercury exposure can cause numerous health consequences and symptoms for unborn babies, but its most serious consequences lie with unborn infants who may develop delayed neurodevelopment. Mercury poses particular danger because it crosses the placenta into their brain, nervous system and bloodstream – with devastating results for unborn babies who don’t receive proper prenatal care.
Most sources advise pregnant women to consume no more than 12 ounces (350 grams) of seafood per week; the typical consumption level for tuna in pregnancy in the US averages seven ounces which falls far short of what would be suggested as recommended for non-pregnant individuals.
Women should select low mercury seafood options such as salmon when pregnant women plan to eat tuna or other fish during gestation. Salmon provides essential omega-3 fatty acids which support development of an infant fetus.
Many pregnant women are advised by health experts not to consume tuna and other high-mercury seafood during their pregnancies, but such advice is unsupported by science. Seafood in general contains essential nutrients needed for both adults and pregnant women alike – it also provides omega-3 fatty acids essential for brain development.
The Food Chain
Mercury can be found throughout our environment as both an environmental contaminant and byproduct of human pollution. Found in soil, water and air it travels long distances before finally ending up in bodies of water such as oceans or large bodies of water where ecosystems may transform it further to methylmercury form which accumulates poisonously within living things – including tuna fish.
Big fish like tuna tend to accumulate higher concentrations of mercury due to being higher up on the food chain, eating more small species containing mercury. When big fish die, their mercury can be broken down by bacteria in the sea water and ultimately washed back out into it by smaller creatures eating dead ones and passing it up the food chain.
Scientists have tracked mercury levels in three species of tropical tuna — skipjack, yellowfin and bigeye — since 1971 and found them to remain relatively constant with one exception – an increase in the northwestern Pacific Ocean during the 1990s. Scientists believe these fluctuations result from shifting ocean currents mixing old mercury from deeper waters with newly produced mercury that has come closer to surface waters near where these fish reside and swim.
As methylmercury can pass from mother to baby through the placental barrier, Consumer Reports’ experts advise pregnant women and children alike to limit how much canned tuna they eat; adults can safely consume two or three 150-gram servings weekly according to FDA recommendations.
However, many consumers may be unaware of how different varieties of canned tuna contain different levels of mercury; even within a brand there may be cans with higher mercury concentrations than others. We advise consumers to read labels on each can and select one with lower mercury concentration levels; an alternative would be canned salmon from Alaska such as sockeye or pink salmon which has lower mercury concentration levels while providing heart-healthy omega-3 fats and selenium which counteracts some mercury-related dangers to help further mitigate health risks from eating this type of tuna.
The Human Body
Tuna fish contains mercury, which is an accumulation of toxic metal that builds up in our bodies over time and can lead to neurological damage in both pregnant women and small children. To reduce exposure to mercury, the Environmental Protection Agency recommends limiting one’s fish consumption; canned light tuna with low mercury content has been suggested by FDA as one such solution.
Fish that consume mercury become exposed to methylmercury, the most toxic form of mercury. When inhaled through their skin or eaten as fish food, this chemical reaches bloodstream and eventually the fetus, potentially leading to developmental issues later on. Pregnant women are particularly at risk of mercury poisoning.
Although attempts have been made to decrease airborne mercury emissions, the element still accumulates in the environment and tuna populations. Chisso, a Japanese petrochemical company, released enormous quantities of mercury into Japan’s ocean during the 1950s; animals in that area began showing nervous tremors and dying as a result; some even died outright as their poison reached local residents who became sick from inhaling its toxins.
Mercury accumulates in apex predators such as tuna and is then passed on to their smaller prey through their saliva and urine. Both body mass and lifespan play a factor; larger, older fish will have had more time to absorb mercury into their bodies.
Mercury levels vary considerably among species of tuna depending on their geographic location, with levels up to four times higher in New Caledonia and Fiji compared with other parts of the Pacific.
Tuna should only be eaten once every month by adults and children, and two servings weekly during pregnancy. In order to minimize mercury intake, consumers should ideally consume fish high in selenium content – tuna being an ideal example, although salmon and sardines are other great choices that contain this mineral as well.
Pregnancy
Mercury is an extremely harmful poisonous substance that poses numerous health threats to human beings. Our bodies can naturally rid itself of small amounts of mercury over time, while large accumulations accumulate in our brain and nervous systems and can lead to mental retardation and birth defects in pregnant women, including via methylmercury crossing the placenta into fetal tissues and reaching newborn babies’ brains. High mercury levels have also been associated with loss of smell, vision and hearing in infants as well as coma or even death (1)
Due to potential harm for unborn babies, most doctors and pregnancy experts advise pregnant women to limit their consumption of fish that contain high mercury levels, including tuna. As tuna contains omega-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) essential for developing baby brains, health professionals advise consuming as little tuna as possible during gestation. However, most tuna has high mercury levels; health professionals therefore advise restricting how much tuna to consume during gestation.
The Food and Drug Administration (FDA) suggests that pregnant and breastfeeding women, women who may become pregnant in the near future and children consume up to 12 ounces per week of seafood low in mercury content than tuna — including white tuna (“albacore”) or canned tuna with mercury levels found varying significantly across brands, which could potentially contain dangerous spikes. However, spot checks of canned tuna have revealed dangerously fluctuating mercury levels among some brands.
Food safety experts from Consumer Reports urge the Food and Drug Administration (FDA) to reconsider its messaging and set new limits, at least for canned tuna. We believe if the FDA could demonstrate that mercury levels in individual cans of tuna were safe, pregnant and breastfeeding women would have a much safer option to choose when making decisions about what foods to eat during gestation and breastfeeding.
Research conducted by our researchers has demonstrated the benefits of eating more fish for almost everyone, especially pregnant and breastfeeding women as well as children. Fish-rich diets provide essential nutrition during gestation and breastfeeding; pregnant or breastfeeding women as well as children are in particular need of the nutrients provided by fish foods such as tuna with mercury levels high enough to cause brain and behavioral effects in their babies, according to studies on high mercury levels among mothers, which in turn can result in lower test scores at school for their offspring.