Sardines and PCBs

“PBCs" is the general term used to refer to one member of the "dioxin" family of compounds which consist of dioxins, furans, and PCBs. This family of chemicals are sometimes referred to as "dioxin-like compounfs" (DLCs). There are 75 dioxins, 135 furans, and 209 PCBs. Each different form is called a "congener." Not all of these "dioxin-like" chemicals have dioxin-like toxicity, and the toxic ones are not equally toxic. The least toxic of these compounds is estimated to be about 10,000 times less toxic than the most toxic. Only 7 of the 75 dioxins, 10 of the 135 furans, and 12 of the 209 PCBs have dioxin-like toxicity.
There are seven dioxin and ten furan congeners thought to be most toxic to humans. Most studies measuring human exposure to dioxin and furans focus on this group. The term "dioxin" is sometimes used to refer to this group of 17 congeners.
Because dioxin congeners are not all equally toxic, scientists have developed toxic equivalency factors (TEF) to compare the relative toxicity of congeners. The dioxin congener 2,3,7,8-tetrachlorodibenzo dioxin (TCDD) is the most toxic form of dioxin. It is assigned a toxic equivalency factor (TEF) of 1. Each of the 17 toxic dioxins/furans and 12 PCBs is then assigned a "toxicity factor" that estimates its toxicity relative to TCDD. Congener TEFs range from 0.0001 to 1.0. The 12 PCBs with a toxicity factor are not included in the group of 17 as their toxicity is lower.
The Toxic Equivalent (TEQ) of a food is its toxicity. TEQs are obtained by multiplying the concentration of each congener found by its relative potency (its "toxic equivalency factor," or TEF) and summing up the results for all of the congeners. The toxic equivalent of a foods is most often given as pg/g (picograms / gram) which is equal to parts per trillion. The TEQ system is not perfect, but it is a reasonable way of estimating the toxicity of a mixture of dioxin-like compounds.
The FDA’s Total Diet Study collects residue data for approximately 300 pesticides, radionuclides, and industrial chemicals in approximately 280 core foods in the U.S. food supply. Four market baskets are generally collected each year, once in each of four (West, North Central, South, Northeast) geographic regions of the U.S. For each market basket, food samples are collected from grocery stores and fast food restaurants in three cities within the region, The samples from the three cities within each region are combined into one ‘‘market basket.’’ The foods sampled include processed foods (bottled, canned, and frozen), fresh foods including fruits and vegetables, baby foods, dairy products, fresh meats, cereals, peanut butter, and prepared foods such as pizza. The three samples of like foods are combined into one sample, prepared as for consumption, and analyzed for contaminants. FDA's Dioxin Monitoring Program analyzed selected TDS samples from one market basket each year in 2001 to 2004. In addition to TDS food samples, FDA's Dioxin Monitoring Program involves the collection and analysis of additional non-TDS food samples to complement TDS findings by further estimating dietary DLC exposure from specific types of foods (e.g., species of fish). Non-TDS food samples collected and analyzed by FDA include dairy products, eggs, fats/oils, fruits/vegetables, grains/cereals, seafood (finfish/shellfish), tree nuts/peanuts, and dietary supplements. Samples were assigned and collected by one of ten FDA District Offices at retail, as domestic imports or at the grower for certain domestic aquaculture finfish samples (e.g., catfish, salmon, striped bass, tilapia, trout). Unlike TDS foods, non-TDS food samples were not prepared as consumed (i.e., cooked) prior to DLC analysis though only the edible portion was analyzed.
Three TEQ values were generated for each food, reflecting assignment of zero, half the limit of detection (LOD), or LOD. Some contaminates are below the level of detection and are referred to as "non-detects." The assigning of zero to the non-detects means that the non-detects are not taken into account and the results given are the actually results of the test done. The assigning of LOD means that any non-detects are fully contaminated. Using zero and the LOD provide lower and upper bounds on the range of contamination.
In 2003 the FDA collection and analyzed canned sardines. The seven dioxin and ten furan congeners thought to be most toxic to humans were analyzed. The 12 PCBs with a toxicity factor are not included in the group of 17, as their toxicity is lower. The total toxicity for the 7 dioxins total 2.31, the total for the 10 furans is 1.07, while the total for the 12 PCBs is .136.

The results (TEQ (pg/g) ND=0 and ND=LOD) were:
2003 176166 "Sardine, Canned" 0.5206 0.5557
2003 180879 "Sardine, Canned" 1.3861 1.3877
2003 180880 "Sardine, Canned" 0.2670 0.2675
2003 183769 "Sardine, Canned" 0.0061 0.0247
2003 184696 "Sardine, Canned" 1.5655 1.6271
2003 192530 "Sardine, Canned" 0.3111 0.3190
2003 200492 "Sardine, Canned" 0.1980 0.4014
2003 200534 "Sardine, Canned" 0.0943 0.1451
2003 200535 "Sardine, Canned" 1.1017 1.1236
2003 200536 "Sardine, Canned" 0.2559 0.2644
2003 208241 "Sardine, Canned" 0.5971 0.5975
2003 211491 "Sardine, Canned" 0.1315 0.2729
2003 211492 "Sardine, Canned" 0.2710 0.4419
2003 217013 "Sardine, Canned" 0.8647 0.8654
2003 218749 "Sardine, Canned" 0.0371 0.2009
2003 219412 "Sardine, Canned" 0.0130 0.2443
2003 219413 "Sardine, Canned" 0.0120 0.2254
2003 221597 "Sardine, Canned" 1.8935 1.8937
These sardines would have been purchased in Albuquerque, New Mexico, Riverside-San Bernardino, California, and Salem, Oregon.
Information such as how canned (in oil or water), where canned or where harvested is not given.
The EPA set their "virtually safe dose" for dioxin at 0.006 pg/kg bw/day.
And raised it in 1994 to 0.01 pg TEQ/ kg bw/day.
The World Health Organization sets their dioxin limit at 1 to 4 pg / kg bw/day.
So, for a 160 pound man the originally EPA limit would be .43 pg/day.
Their revised 1994 figure would allow the same man to consume .72 pg/day.
And the WHO says its ok to eat 72 to 290 pg/day.
I get it!!! Just keep raising the limit and we will all be fine.
For comparison, their average results for:
Flounder 0.0147 0.0275
Halibut 0.0010 0.0126
Swordfish 0.0493 0.1689
Tuna - Canned 0.0021 0.1790
Beef Sirloin Steak- Broiled 0.1095 0.1297
Butter 0.5545 0.4135
The highest single results they have for salmon is in 2002:
Salmon - Farmed 0.5545 0.9270
Salmon - Wild 0.4220 0.6458
The Natural Resources Defense Council
PCBs are a complex and hazardous group of chemicals. While their acute toxicity is much lower than many of the organochlorine pesticides and the dioxins, they have serious long-term health effects at relatively low levels. High levels of exposure can cause effects in infants ranging from low birth weight; to abnormalities of the skin, hair and nails; to hearing loss.
Dioxins and Furans are among the most hazardous chemicals known - extremely tiny doses have been shown to cause negative health effects. These chemicals are listed by several governmental agencies as known causes of cancer in humans. Indeed, studies have linked dioxins and furans to many types of cancer, as well as to reproductive problems, abnormalities in fetal development, immune alterations, and disruption of hormones. Because dioxins and furans are attracted to fat and are resistant to metabolism, they are notorious for accumulating in the animals humans eat, and by that route accumulating in humans.
Environmental Defense Fund
PCBs are not highly toxic with a single dose (as in a single meal), but continued low levels of exposure (for example, eating contaminated fish over an extended period of time) may be harmful. EPA rates PCBs as "probable human carcinogens," since they cause cancer in laboratory animals. Other tests on laboratory animals show damage from PCBs to their circulatory, nervous, immune, endocrine and digestive systems.
Dioxins are highly toxic byproducts of industrial processes. Like many other contaminants found in fish, these chemicals are slow to break down and they accumulate in the bottom sediments of streams, rivers, lakes and coastal areas. Dioxins can build up in the fatty tissues of fish and other animals, and in high enough concentrations pose serious health risks to people who frequently eat contaminated fish.
Based on studies done on laboratory animals, exposure to dioxins and furans is known to cause a variety of cancers and can harm the immune system. Effects on reproductive, endocrine, circulatory and nervous systems have also been observed. TCDD (the most hazardous of the dioxin compounds) exhibits the highest cancer potency of any chemical ever studied in animals.

Just Thinkin: Why all the commotion is over PCBs when its the dioxins and dioxin-like chemicals that are going to hurt or kill us. All the reports I see are about how many PCBs are found in farmed salmon, not the toxicity of those PCBs.

FDA’s Food Contaminants & Adulteration
http://www.fda.gov/Food/FoodSafety/FoodContaminantsAdulteration/default.htm

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