NOTE TO READER: The text below was developed by the CIBRT and reproduces information readily available in other reports. In Section III.A.9 of this document, we provided information sufficient to justify recovery criteria and actions addressing pollution. Additional information about pollution and contaminants reviewed for Cook Inlet and CI belugas follows.
Pollution is the introduction of contaminants into the environment that causes adverse change. For the purpose of this review, pollution is synonymous with acute or chronic events that release notable/reportable quantities of chemicals or substances into the environment. Exposure to industrial chemicals as well as to natural substances released into the marine environment is a potential health threat for CI belugas and their prey.
Available literature was reviewed by NMFS for the Cook Inlet Beluga Whale Conservation Plan (NMFS 2008a) and by URS Corporation (2010). The reviewed publications vary in their use of terminology regarding lipid, blubber, dry weight, and wet weight. In particular, some authors consider blubber and lipid to be synonymous and interchangeable terms, whereas others consider blubber to be a combination of lipids and water. Therefore, it is important to ensure that comparisons of tissue concentrations and threshold levels are based on consistent assumptions of measurement media and units.
There is little information on the potentially deleterious effects of chemicals on CI belugas. Potential sources of anthropogenic contaminants include wastewater treatment, freshwater runoff, airport de-icing chemicals, ballast water discharges, gas and oil releases or spills, military training areas, and other industrial development and activities. While NMFS has some data about levels of traditionally studied contaminants in CI belugas (e.g., Dichlorodiphenyltrichloroethane [DDT], polychlorinated biphenyls [PCBs], polycyclic aromatic hydrocarbons [PAHs], etc.), virtually nothing is known about other emerging pollutants of concern and their effects on CI belugas. The emerging pollutants of concern include endocrine disruptors (substances that interfere with the functions of hormones), pharmaceuticals, personal care products, and prions (proteins that may cause a disease), amongst other bacterial and viral agents that are found in wastewater and biosolids.
URS (2010) evaluated the level of concern for various classes of chemicals that were of probable, possible, or unlikely concern. Chemicals of concern for which data are available are described in Table 8, and representative values from various beluga populations and marine mammals in Cook Inlet are listed in Table G1. Table G2 lists those chemicals of possible concern for which there are no data available for any beluga population. Chemicals considered by URS (2010) to be unlikely of concern for CI belugas include: hydrocarbons (other than PAH compounds), glycols, diagnostic agents, dietary supplements, personal care products, engineered particles (<100 nanometers), or prions. Figure G1 summarizes data for known concentrations of various contaminants found in the blubber of male belugas from North America.
Male Mean or median concentration ± 1SD (range)
Female Mean or median concentration ± 1SD (Range)
|Organochlorides (mg/kg wet)|
|Total PCBs||CI (1992–97)b||1.49 ± 0.70||0.79 ± 0.56||blubber|
|Pt Lay (1990, 1996)b||5.20 ± 0.90||1.50 ± 1.12||blubber|
|SLE (1986–87)b||75.8 ± 15.3||37.3 ± 22.0||blubber|
|Total DDTs||CIb||1.35 ± 0.73||0.59 ± 0.45||blubber|
|Pt Layb||3.63 ± 0.90||0.93 ±0.85||blubber|
|SLEb||101 ± 32.6||23.0 ± 17.3||blubber|
|Toxaphene||CIb||2.40 ± 1.06||2.02 ± 0.46||blubber|
|Pt Layb||3.93 ± 1.16||2.62 ± 2.07||blubber|
|SLEb||14.7 ± 2.46||6.34 ± 3.51||blubber|
|Chlordane compounds||CIb||0.56 ± 0.25||0.30 ± 0.22||blubber|
|Pt Layb||2.42 ± 0.46||0.79 ± 0.61||blubber|
|SLEb||7.43 ± 0.63||3.55 ± 1.99||blubber|
|Dieldrin||CIb||0.09 ± 0.05||0.06 ± 0.05||blubber|
|Pt Layb||0.39 ± 0.09||0.12 ± 0.10||blubber|
|SLEb||0.93 ± 0.12||0.56 ± 0.31||blubber|
|Hexachlorobenzene (HCB)||CIb||0.22 ± 0.09||0.15 ± 0.13||blubber|
|Pt Layb||0.81 ± 0.12||0.23 ± 0.28||blubber|
|SLEb||1.34 ± 0.44||0.60 ± 0.43||blubber|
|Hexachlorocyclohexane (Sum HCH)||CIb||0.21 ± 0.07||0.17 ± 0.05||blubber|
|Pt Layb||0.33 ± 0.76||0.25 ± 0.12||blubber|
|SLEb||0.37 ± 0.11||0.24 ± 0.10||blubber|
|Mirex||CIb||0.01 ± 0.01||0.01 ± 0.00||blubber|
|Pt Layb||0.06 ± 0.02||0.02 ± 0.01||blubber|
|SLEb||1.00 ± 0.64||1.11 ± 0.99||blubber|
|Perfluorooctane sulfonate ng/g ww (PFOS)||CI 1992 to 2006c||22.5 (14.4–30.4)||13.0 (4.61–70.3)||liver|
|E. Chukchi 1989 to 2000c||9.2 (4.29–28.4)||4.76 (1.81–38.1)||liver|
|Perfluorooctane sulfonamide (PFOSA)||CI 1992 to 2006c||11.4 (4.52–17.9)||18.4 (10.4–27.8)||liver|
|E. Chukchi 1989 to 2000c||31.8 (17.7–63.8)||27.8 (11.2–65.7)||liver|
|Perfluorononanoic acid (PFNA)||CI 1992 to 2006c||1.79 (0.454–3.08)||1.66 (<0.502–5.67)||liver|
|E. Chukchi 1989 to 2000c||0.670 (0.170–2.55)||0.960 (<0.180–5.46)||liver|
|Polycyclic aromatic hydrocarbons (PAHs) μg/g lw|
|Total PAHs||CId||2.6 ± 3.8||1.2 ± 1.9||liver|
|CId||6.9 ± 7.4||27.8 ± 29.4||blubber|
|Polybrominated diphenyl ethers (PBDEs) (ng/g lipid)|
|CI 1989 to 2006e||13.8 (6.56–45.6)||14.6 (7.40–32.0)||blubber|
|E. Chukchi 1989 to 2000e||12.8 (4.33–32.2)||5.05 (1.90–19.4)||blubber|
|SLE 1988 to 1999f||430 (170–780)||540 (300–1060)||blubber|
|SLE 2000 to 2003g||2,210 (246–3030)||liver|
|Metals/Inorganics (mg/kg dry)|
|Pt Layb||9.38 ± 3.39||liver|
|SLEb||0.53 ± 0.41||liver|
|Mercury (Hg)||CIb||16.3 ± 13.0||liver|
|Pt Layb||179 ± 78.6||liver|
|SLEb||126 ± 161||liver|
|Copper (Cu)||CIb||162 ± 130||liver|
|Pt Layb||61.6 ± 42.3||liver|
|SLEb||0.58 ± 0.41||liver|
|Mercury (Hg)||CIb||16.3 ± 13.0||liver|
|Pt Layb||179 ± 78.6||liver|
|SLEb||126 ± 161||liver|
|Selenium (Se)||CIb||14.3 ± 7.0||liver|
|Pt Layb||97.2 ± 76.7||liver|
|SLEb||79.2 ± 110||liver|
a CI – Cook Inlet belugas, Pt. Lay – Point Lay belugas, SLE – St. Lawrence Estuary belugas. Sources: b. Becker et al. 2000 (males, n = 10; females, n = 10); c. Reiner et al. 2011 (CI, PFOS and PFOSA: males, n =11, females, n = 16; CI, PFNA: males, n = 11, females, n = 15; E. Chukchi PFOS and PFOSA: males, n = 25, females, n = 16; E. Chukchi, PFNA: males, n = 25, females, n = 13); d. Wetzel et al. 2010; e. Hoguet et al. 2013 (CI: males, n = 15, females, n = 12; E. Chukchi: males, n = 25, females, n = 15); f. Lebeuf et al. 2004 (males, n = 15; females, n = 14); g. McKinney et al. 2006 (males, n = 3, females, n = 3).
Class Of Substance
|Organophosphatesa/carbamates||Commonly used as broad-spectrum insecticides: Malathiona, methyl- parathion, chlorpyrifos, diazinon, carbaryl, aldicarb|
|Phthalates||Commonly used in vinyl softeners in flooring and in adhesives, plastic clothing, toys, and kitchen ware: Diethyl phthalate, butyl benzyl phthalate|
|Prescription and over the counter drugs||Commonly used medicinally for humans and animals: Penicillins, tetracyclines, clofibric acid, aspirin, ibuprofen, prozac, agricultural animal growth promoters, aminoglycosidesa, aspirina, furosemidea|
|Alkylphenols||Commonly used in detergents and cleaning agents: Nonylphenol, octylphenol|
|Consumer plastics||Commonly used in CDs, DVDs, eyeglasses lenses, and bottles: Bisphenol A (BPA) (2,2-bis(4-hydroxydiphenyl) propane)|
|Natural and synthetic hormones||Commonly used medicinally for humans and animals: Estradiols, thyroxine analogs|
|Surfactants||Commonly used in detergents, cosmetics, and spermicides: 4- nonylphenol; "alkylphenol polyethoxylate surfactants"; o-, m-, or p- nonylphenol|
|Pesticides/Herbicides||Commonly used to control “pests” including insects, fungi, plants, rodents, birds, spiders, mites: Lindane, methyl-parathion; permethrin; triazines, bifenthrin, cypermethrin, esfenvalerate; pyrethroidsa, paraquata|
a Denotes compounds with known ototoxic effects. Source: URS 2010.
PCBs were used in hundreds of industrial and commercial applications including electrical, heat transfer, and hydraulic equipment; as plasticizers in paints, plastics, and rubber products; in pigments, dyes, and carbonless copy paper; and many other industrial applications. Though their production has been banned in North America since 1979, PCBs still pose a risk to humans and wildlife because they are highly toxic and persist in the environment. These and other organochlorines such as DDT have high-fat, low-air, and poor-water solubility, allowing them to accumulate in fatty tissues. Being highly persistent in the environment, these compounds bioaccumulate through trophic transfer, resulting in higher concentrations in upper level predators such as marine mammals. High concentrations in animals are associated with poor health and reproduction. Concentrations of various organochlorines in CI belugas were consistently lower than levels observed in belugas from Point Lay and one to two orders of magnitude lower than levels seen in SLE belugas (Becker et al. 2000). The PCB values for CI belugas were at levels associated with endocrine disruption, lower than established thresholds for immunosuppression, but close to levels that disrupted immune function in free ranging harbor seals (as low as 2.5 milligrams [mg] per kilogram [kg] of PCBs; Levin et al. 2005, Shaw 2005).
The perfluorinated compounds (PFCs), which include Teflon, are compounds commonly used as water and oil repellants in protective coatings in food packaging, textiles, and carpeting. While PFCs are not well studied in marine mammals, PFCs have recently become contaminants of possible concern. CI belugas had higher concentrations of most PFCs compared to beluga from the eastern Chukchi but a lower median concentration of one particular type of PFC, namely perfluorooctane sulfonamide (Reiner et al. 2011). Temporal trends indicated most PFC concentrations have steadily increased from 1989 to 2006, whereas a study involving sea otters from lower Cook Inlet has shown a general decrease since about 2001 (Hart et al. 2009). Previous studies examining PFCs in beluga livers from the Canadian Arctic have found individual PFC concentrations >150 ng/g (Kelly et al. 2009 and Tomy 2009 as cited in Reiner et al. 2011), notably higher than values from CI belugas. Differences suggest different sources or transport pathways for these compounds, which can be related to the geographic differences in the long-range atmospheric transport of PFCs, oceanic transport of PFCs, local releases, and/or feeding habits (Reiner et al. 2011).
Polycyclic Aromatic Hydrocarbons
This class of compounds is naturally occurring in fossil fuels and is also released from forest fires, industrial products (e.g., asphalt and coal tar), and the incomplete combustion of coal, oil, gas, or organic waste (compounds of particular concern are benzo(a)pyrene, anthracene, and pyrene). These are some of the most widespread organic pollutants. The PAH compounds are lipophilic (oil-loving), with larger compounds even less water-soluble and less volatile. Because of these properties, PAHs in the environment are found primarily in soil, sediment, and oily substances, as opposed to water or air. However, they are also a component of concern in particulate matter suspended in air. Representing the most toxic components of oil, and including 16 compounds, PAHs are considered priority pollutants by the World Health Organization and the U.S. Environmental Protection Agency (EPA). The PAHs can enter the environment in a number of ways, including, but not limited to: oil and gas development activities; run-off from streets or parking areas; leakage from watercraft; oil spills; natural oil seeps and forest fires. One PAH, benzo(a)pyrene, has been identified as the most likely cause of high numbers of cancers in belugas from the SLE; in addition, PAHs have numerous known effects besides carcinogenesis in mammals, and these include effects on reproduction and survival of offspring.
A study analyzed PAH levels in belugas, prey species, and sediments from Cook Inlet. The highest PAH levels in the sampled sediments were found in Eagle Bay (Wetzel et al. 2010). Although naphthalenes, anthracenes, and phenanthrenes were the most ubiquitous classes of PAHs found, benzo(a)pyrene was also detected in all sediment samples (Wetzel et al. 2010). The data suggested inputs from both combustion and fresh oil. Total PAH levels were moderate, relative to those found in other locations known to have environmental problems with PAH contamination (Wetzel et al. 2010). The same general patterns occurred in the salmon, eulachon and saffron cod, but the fish contained slightly higher amounts of pyrene and fluorine constituents than did the sediments (Wetzel et al. 2010). The highest PAH values were in eulachon taken from the Little Susitna River (Wetzel et al. 2010). Some Chinook salmon from Ship Creek contained notable levels of total PAHs in their flesh; roe from some sockeye salmon was also notably high in total PAHs (Wetzel et al. 2010).
As noted above, an especially strong correlation was found between high levels of PAHs and illness and mortality of belugas in the SLE and humans living in the vicinity (Martineau et al. 1994, 2002), underscoring the susceptibility of both species to this class of contaminants. Although the correlation suggests a cause and effect relationship, none has been proven for the beluga. The chronic PAH contamination in SLE represents a clear threat to the health status of resident species; SLE belugas have shown a greater prevalence of cancer than any other group of cetaceans in the world (Martineau et al. 2002). One particular PAH, benzo(a)pyrene, appears to be the primary culprit.
CI belugas appear to bioaccumulate PAHs from the environment, including from their prey. CI belugas have much higher PAH levels than do subsistence-harvested belugas from MacKenzie River Delta (Wetzel et al. 2010). Highest PAH levels in CI beluga livers were found in three adult males and a female fetus; the highest levels in blubber were from adult females and fetuses (Wetzel et al. 2010). The most prevalent types of PAHs found in beluga liver samples were fluorenes, anthracenes, and phenanthrenes (Wetzel et al. 2010). No benzo(a)pyrene was detected. PAH concentrations in the blubber of females were statistically higher than in males (Wetzel et al. 2010). The most prevalent types of PAHs found in beluga blubber were naphthalenes, fluorenes, anthracenes, and fluoranthracenes; small amounts of benzo(a)pyrene were found in some blubber samples (Wetzel et al. 2010).
CI belugas had lower levels of metals of concern than other beluga populations, including mercury, which was below the liver threshold value of concern of 60mg/kg. The one element that did not follow this pattern was copper; copper levels in livers of CI belugas were two to three times higher than in Arctic Alaska belugas and similar to Hudson Bay belugas (Becker 2000). While copper has not been associated with toxic effects in CI belugas, these levels are substantially higher than the renal damage values (29 mg/kg) reported for Australian bottlenose dolphins (Lavery et al. 2009).
Becker (National Institute of Standards and Technology, pers. comm.) reported that CI belugas have significantly higher total levels of the brominated flame retardant Hexabromocyclododecane than the Eastern Chukchi Sea belugas from Point Lay, but demonstrated that levels in Alaskan belugas are lower than those measured in SLE belugas (Lebeuf et al. 2004) and California sea lions (Stapleton et al. 2006). However, other studies report that another class of flame retardants, PBDEs, are increasing over time in Chukchi Sea belugas and in CI Inlet belugas (Hoguet et al. 2013) as they are in SLE belugas (Lebeuf et al. 2004).
Data for the other chemicals of possible concern (Table G2) are either not available or could not be evaluated at this time due to a lack of readily available threshold concentrations. However, toxicity reference values are available for some non-cetacean marine mammals, and these could be used to develop body burden-based screening levels for belugas.
In general, for the contaminants that have been studied, CI belugas appear to have lower levels of contaminants stored in their bodies than do other populations of belugas. Additionally, chemical analyses of water and dredging sediments from Cook Inlet found that contaminants analyzed were below management levels, and some were below detection limits (Frenzel 2002; U.S. Army Corps of Engineers [Corps] 2003). However, new chemicals of concern are developed or recognized on a regular basis. One study of organohalogen contaminants in Canadian beluga whale liver contained previously unidentified compounds and metabolites which may be impacting the health of Canadian beluga whale populations (McKinney et al. 2006).
Ototoxins are substances that temporarily or permanently damage hearing. These compounds include several chemicals already discussed (Table 8 and G2) and come from several classes of chemicals including: organic solvents (carbon disulphide, heptane, hexane, perchloroethylene, Stoddard solvent, trichloroethylene); pesticides; alcohols (butanol, ethanol); heavy metals (arsenic, lead, manganese, mercury, organic tin); drugs (aminoglycosides, aspirin, furosemide); PAHs (toluene, benzene, styrene, xylene); and other miscellaneous compounds (acrylonitrile, carbon monoxide, cyanide, organophosphates, paraquat) (Morata and Little 2002, Teixeira et al. 2002, Steyger 2009). Organic solvents include alcohols, paints, adhesives, and fuels, including jet fuel (both commercial and military grade), which contain a variety of ototoxic aromatic hydrocarbons including toluene, styrene, ethyl benzene, and xylene (Steyger 2009). These chemicals can be absorbed through the respiratory tract, the skin, or the gastrointestinal tract. Our understanding of the effects of these compounds on the hearing of marine mammals is limited; however, hearing deficits have been established in cetaceans, including belugas, which were treated with aminoglycosides, a class of antibiotics known to be ototoxic (Finneran et al. 2005). When exposure to ototoxic chemicals is combined with exposure to noise, hearing loss is exacerbated by increasing both the breadth and severity of permanent threshold shifts; hearing loss can even occur at subtoxic chemical and sub-traumatic noise levels, which would cause little or no hearing loss in the absence of the other agent (Steyger 2009). The synergistic effect of noise and organic solvents is more serious after repeated exposure at lower levels (Steyger 2009).