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Toxic equivalency factors (TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife

An expert meeting was organized by the World Health Organization (WHO) and held in Stockholm on 15-18 June 1997. The objective of this meeting was to derive consensus toxic equivalency factors (TEFs) for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and dioxinlike polychlorinated biphenyls (PCBs) for both human, fish, and wildlife risk assessment. Based on existing literature data, TEFs were (re)evaluated and either revised (mammals) or established (fish and birds). A few mammalian WHO-TEFs were revised, including 1,2,3,7,8-pentachlorinated DD, octachlorinated DD, octachlorinated DF, and PCB 77. These mammalian TEFs are also considered applicable for humans and wild mammalian species. Furthermore, it was concluded that there was insufficient in vivo evidence to continue the use of TEFs for some di-ortho PCBs, as suggested earlier by Ahlborg et al. [Chemosphere 28:1049-1067 (1994)]. In addition, TEFs for fish and birds were determined. The WHO working group attempted to harmonize TEFs across different taxa to the extent possible. However, total synchronization of TEFs was not feasible, as there were orders of a magnitude difference in TEFs between taxa for some compounds. In this respect, the absent or very low response of fish to mono-ortho PCBs is most noticeable compared to mammals and birds. Uncertainties that could compromise the TEF concept were also reviewed, including nonadditive interactions, differences in shape of the dose-response curve, and species responsiveness. In spite of these uncertainties, it was concluded that the TEF concept is still the most plausible and feasible approach for risk assessment of halogenated aromatic hydrocarbons with dioxinlike properties.

Environmental Health Perspectives↗

Assaying environmental nickel toxicity using model nematodes

Although nickel exposure results in allergic reactions, respiratory conditions, and cancer in humans and rodents, the ramifications of excess nickel in the environment for animal and human health remain largely undescribed. Nickel and other cationic metals travel through waterways and bind to soils and sediments. To evaluate the potential toxic effects of nickel at environmental contaminant levels (8.9-7,600 µg Ni/g dry weight of sediment and 50-800 µg NiCl 2 /L of water), we conducted assays using two cosmopolitan nematodes, Caenorhabditis elegans and Pristionchus pacificus . We assayed the effects of both sediment-bound and aqueous nickel upon animal growth, developmental survival, lifespan, and fecundity. Uncontaminated sediments were collected from sites in the Midwestern United States and spiked with a range of nickel concentrations. We found that nickel-spiked sediment substantially impairs both survival from larval to adult stages and adult longevity in a concentration-dependent manner. Further, while aqueous nickel showed no adverse effects on either survivorship or longevity, we observed a significant decrease in fecundity, indicating that aqueous nickel could have a negative impact on nematode physiology. Intriguingly, C. elegans and P. pacificus exhibit similar, but not identical, responses to nickel exposure. Moreover, P. pacificus could be tested successfully in sediments inhospitable to C. elegans . Our results add to a growing body of literature documenting the impact of nickel on animal physiology, and suggest that environmental toxicological studies could gain an advantage by widening their repertoire of nematode species.

PLoS ONE↗

Nitrogen limitation, toxin synthesis potential, and toxicity of cyanobacterial populations in Lake Okeechobee and the St. Lucie River Estuary, Florida, during the 2016 state of emergency event

Lake Okeechobee, FL, USA, has been subjected to intensifying cyanobacterial blooms that can spread to the adjacent St. Lucie River and Estuary via natural and anthropogenically-induced flooding events. In July 2016, a large, toxic cyanobacterial bloom occurred in Lake Okeechobee and throughout the St. Lucie River and Estuary, leading Florida to declare a state of emergency. This study reports on measurements and nutrient amendment experiments performed in this freshwater-estuarine ecosystem (salinity 0–25 PSU) during and after the bloom. In July, all sites along the bloom exhibited dissolved inorganic nitrogen-to-phosphorus ratios < 6, while Microcystis dominated (> 95%) phytoplankton inventories from the lake to the central part of the estuary. Chlorophyll a and microcystin concentrations peaked (100 and 34 μg L -1 , respectively) within Lake Okeechobee and decreased eastwards. Metagenomic analyses indicated that genes associated with the production of microcystin ( mcyE ) and the algal neurotoxin saxitoxin ( sxtA ) originated from Microcystis and multiple diazotrophic genera, respectively. There were highly significant correlations between levels of total nitrogen, microcystin, and microcystin synthesis gene abundance across all surveyed sites ( p < 0.001), suggesting high levels of nitrogen supported the production of microcystin during this event. Consistent with this, experiments performed with low salinity water from the St. Lucie River during the event indicated that algal biomass was nitrogen-limited. In the fall, densities of Microcystis and concentrations of microcystin were significantly lower, green algae co-dominated with cyanobacteria, and multiple algal groups displayed nitrogen-limitation. These results indicate that monitoring and regulatory strategies in Lake Okeechobee and the St. Lucie River and Estuary should consider managing loads of nitrogen to control future algal and microcystin-producing cyanobacterial blooms.

Florida↗

Using semipermeable membrane devices (SPMDs) to assess the toxicity and teratogenicity of aquatic amphibian habitats

Environmental contamination has been suspected of being partially responsible for recent declines in amphibian populations. It is often not feasible to identify all of the compounds in an environment, nor the concentrations in which they are present. SPMDs are passive sampling devices that uptake lipophilic compounds from the environment in a manner similar to aquatic organisms. The extracts from the SPMDs, therefore, contain a composite sample of the compounds that are present in the environment. In this paper, we outline the methods from studies in which we have used extracts from SPMDs in toxicity tests on amphibian larvae. Using SPMD extracts makes it possible to establish potential links between amphibian deformities and declines and environmental contamination by lipophilic compounds.

ASTM Special Technical Publication↗

Control of nuisance populations of crayfish with traps and toxicants

Crayfish have long been a nuisance in fishrearing ponds at fish hatcheries. The rusty crayfish ( Orconectes rusticus ) has displaced endemic species and caused serious declines of aquatic plants in some ponds and lakes in the midwestern USA. We attempted to evaluate the effect of intensive trapping on a crayfish population and to identify a selective chemical control agent and evaluate its effectiveness under field conditions. A crayfish population in a small pond was suppressed but not eliminated by trapping; adults were effectively harvested but efficiency diminished sharply as the population declined. Of 19 chemicals tested as possible control agents for crayfish, a synthetic pyrethroid (Baythroid) was by far the most toxic; 25 μg/L produced a complete kill of crayfish in the pond and was also the most selective for crayfish in laboratory tests.

Progressive Fish-Culturist↗

Acute sulfamethazine toxicity in young salmon

Adverse effects from the medication of fish diseases with sulfonamides have been reported by several workers. A decreased growth rate (Gutsell and Snieszko 1949, Snieszko and Wood 1955), the production of drug resistant strains of pathogens (Snieszko 1952), sterility and kidney damage (Wood et al., 1955), and mortalities (Johnson and Brice 1953) have been described. Recently, increased mortalities and tissue damage were observed in young silver salmon after a single day's treatment with sulfamethazine. Subsequently an attempt to reproduce the conditions experimentally was made. The purpose of this paper is to describe the pathology of acute sulfamethazine toxicity and to discuss certain factors of possible importance in the etiology of losses among fish treated with sulfonamides.

Progressive Fish-Culturist↗

Standards for reporting fish toxicity tests

The growing impetus of studies on fish and pesticides focuses attention on the need for standardized reporting procedures. Good methods have been developed for laboratory and field procedures in testing programs and in statistical features of assay experiments; and improvements are being made on methods of collecting and preserving fish, invertebrates, and other materials exposed to economic poisons. On the other had, the reporting of toxicity data in a complete manner has lagged behind, and today's literature is little improved over yesterday's with regard to completeness and susceptibility to interpretation.

Progressive Fish-Culturist↗

Some factors influencing susceptibility of rainbow trout to the acute toxicity of an ethyl mercury phosphate formulation (Timsan)

This study determined the influence of water temperature (55&ndash;68&deg; F), dissolved oxygen (4&ndash;12 ppm), water hardness as CaCO 3 (20&ndash;256 ppm), and chloride ions (to 2 mM) on the susceptibility of rainbow trout ( Salmo gairdneri ) to the acute toxicity of ethyl mercury phosphate (EMP). The fish were exposed for one hour to 0.125 ppm EMP, the active ingredient of Timsan, a commercial EMP formulation. The death rate because of the exposure to EMP increased with an increase in water temperature, a decrease in dissolved oxygen, and an increase in chloride ions; calcium appeared to have no effect. The effect of water temperature and dissolved oxygen was ascribed to changes in the respiration rate of the fish, and a chemical explanation is presented for the effect of chloride ions.

Transactions of the American Fisheries Society↗

Effects of environmental pH and calcium on ammonia toxicity in channel catfish

The twenty-four-hour median lethal concentrations (24-hour LC50) of total ammonia nitrogen (TA-N) to channel catfish (Ictalurus punctatus) at pH 7, 8, and 9 (total hardness, 40 mg/liter; temperature, 21&ndash;25 C) were 263.6 &plusmn; 11.3 (SE), 38.8 &plusmn; 1.8, and 4.5 &plusmn; 0.2 mg/liter, respectively. The 24-hour LC50 of un-ionized ammonia nitrogen (UIA-N) concentration at pH 8 was significantly higher (1.82 &plusmn; 0.06 mg/liter) than at pH 7 or 9 (1.39 &plusmn; 0.06 and 1.49 &plusmn; 0.12 mg/liter). Enrichment of the water to 440 mg/liter total hardness at pH 7 significantly increased the 24-hour LC50 of TA-N and UIA-N (356.3 &plusmn; 16.4 and 1.79 &plusmn; 0.07). Fish exposed to 25 mg/liter TA-N for 12 hours at pH 7 and 8 showed no differences from control fish in hematocrit, percent total plasma protein, or plasma and muscle chloride. Plasma sodium showed no difference between control and experimental groups at pH 7; however, a significant decrease occurred in fish exposed to 25 mg/liter TA-N at pH 8. No differences in blood pH were found between the control groups and fish exposed to 100 and 200 mg/liter TA-N at pH 7, and to 10 and 25 mg/liter TA-N at pH 8. Plasma sodium depletion is suggested as a contributing mechanism of ammonia toxicity.

Transactions of the American Fisheries Society↗

Toxicity of 5% rotenone to nonindigenous Asian swamp eels

Our primary goal was to determine whether rotenone would be a useful control against introduced populations of Asian swamp eels (family Synbranchidae, genus Monopterus). We report the results of a laboratory experiment comparing the efficacy of various rotenone concentrations (1, 2, 4, and 8 mg of 5% liquid rotenone/L of water) in killing nonindigenous swamp eels of various sizes (1-350 g) from the three known Florida populations. Although most small swamp eels were killed at concentrations of 2 and 4 mg/L. 100% mortality of adult swamp eels was achieved only at 8 mg/L. We conclude that the effective use of rotenone to control established Florida swamp eel populations would be difficult, based on the relatively high concentration of rotenone needed to kill swamp eels; the complexity of the swamp eel's habitat; and our observations of the species' habitat use and behavior, including its widespread distribution and life history characteristics (e.g., burrowing and overland movement) that enhance its invasion and survival in multiple environments. Nevertheless, control of swamp eels may be achieved in certain situations. A combination of rotenone and electroshocking may be an effective way to eradicate swamp eels from small water bodies and to control populations in larger habitats. However, we are cautious in this recommendation and provide details related to the technical aspects of this type of strategy and caveats related to the toxicity of the chemical.

North American Journal of Fisheries Management↗

Dietary exposure of mink (Mustela vison) to fish from the Housatonic River, Berkshire County, Massachusetts, USA: Effects on organ weights and histology and hepatic concentrations of polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalence

The effects of feeding ranch mink ( Mustela vison ) diets containing polychlorinated biphenyl (PCB)-contaminated fish (88 gold fish [ Carassius auratus ] weighing a total of 70.3 kg and 16 carp [ Cyprinus carpio ] weighing a total of 77.3 kg) collected from the Housatonic River (HR; Berkshire County, MA, USA) in October 1999 on organ weights and histology and hepatic concentrations of total PCBs (&Sigma;PCBs) and 2,3,7,8-tetrachlorodibenzo- p -dioxin toxic equivalence (TEQ) were evaluated. Diets contained 0.22 to 3.54% HR fish, which provided 0.34 to 3.7 &mu;g &Sigma;PCBs/g feed (3.5-69 pg TEQ/g feed). Female mink were fed the diets eight weeks before breeding through weaning of kits at six weeks of age. Offspring were maintained on their respective diets for an additional 180 d. The dietary concentration of PCBs that caused a decrease in kit survival (3.7 &mu;g &Sigma;PCBs/g feed [69 pg TEQ/g]) resulted in a maternal hepatic concentration of 3.1 &mu;g &Sigma;PCBs/g wet weight (218 pg TEQ/g). Organ weights were not consistently affected. Mandibular and maxillary squamous cell proliferation was apparent in 31-week-old juveniles exposed to as low as 0.96 (xg &Sigma;PCBs/g feed (9.2 pg TEQ/g). Juveniles in this treatment group had a liver concentration of 1.7 &mu;g &Sigma;PCBs/g wet weight (40 pg TEQ/g). Because inclusion of PCB-contaminated fish, which comprised approximately 1% of the diet, resulted in mandibular and maxillary squamous cell proliferation, it is possible that consumption of up to 30-fold that quantity of HR fish, as could be expected for wild mink, would result in more severe lesions characterized by loss of teeth, thus impacting survivability.

Environmental Toxicology and Chemistry↗

Use of the oligochaete, Lumbriculus variegatus, as a prey organism for toxicant exposure of fish through the diet

The oligochaete, Lumbriculus variegatus, has several characteristics that make it desirable as a prey organism for conducting dietary exposure studies with fish. We conducted 21- and 30-d experiments with young fathead minnows (Pimephales promelas) and rainbow trout (Oncorhynchus mykiss), respectively, to determine whether a diet consisting solely of L. variegatus would support normal growth and to compare performance with standard diets (Artemia nauplii, frozen brine shrimp, or trout chow). All diets were readily accepted, and fish survived and grew well. Food conversion in both fathead minnows and rainbow trout was as high as or higher for the oligochaete diet compared with others, although this comparison is influenced by differences in ration, ingestion rate, or both. The oligochaete diet had gross nutritional analysis similar to the other diets, and meets fish nutrition guidelines for protein and essential amino acids. Methodologies and practical considerations for successfully using oligochaetes as an experimental diet are discussed. Considering their ready acceptance by fish, their apparent nutritional sufficiency, the ease of culturing large numbers, and the ease with which they can be loaded with exogenous chemicals, we believe that L. variegatus represents an excellent choice of exposure vector for exposing fish to toxicants via the diet. ?? 2006 SETAC.

Environmental Toxicology and Chemistry↗

Influence of in-stream diel concentration cycles of dissolved trace metals on acute toxicity to one-year-old cutthroat trout (Oncorhynchus clarki lewisi)

Extrapolating results of laboratory bioassays to streams is difficult, because conditions such as temperature and dissolved metal concentrations can change substantially on diel time scales. Field bioassays conducted for 96 h in two mining‐affected streams compared the survival of hatchery‐raised, metal‐näive westslope cutthroat trout ( Oncorhynchus clarki lewisi ) exposed to dissolved (0.1‐μm filtration) metal concentrations that either exhibited the diel variation observed in streams or were controlled at a constant value. Cadmium and Zn concentrations in these streams increased each night by as much as 61 and 125%, respectively, and decreased a corresponding amount the next day, whereas Cu did not display a diel concentration cycle. In High Ore Creek (40 km south of Helena, MT, USA), survival (33%) after exposure to natural diel‐fluctuating Zn concentrations (range, 214–634 μg/L; mean, 428 μg/L) was significantly ( p = 0.008) higher than survival (14%) after exposure to a controlled, constant Zn concentration (422 μg/L). Similarly, in Dry Fork Belt Creek (70 km southeast of Great Falls, MT, USA), survival (75%) after exposure to diel‐fluctuating Zn concentrations (range, 266–522 μg/L; mean, 399 μg/L) was significantly ( p = 0.022) higher than survival (50%) in the constant‐concentration treatment (392 μg/L). Survival likely was greater in these diel treatments, both because the periods of lower metal concentrations provided some relief for the fish and because toxicity during periods of higher metal concentrations was lessened by the simultaneous occurrence each night of lower water temperatures, which reduce the rate of metal uptake. Based on the present study, current water‐quality criteria appear to be protective for streams with diel concentration cycles of Zn (and, perhaps, Cd) for the hydrologic conditions tested.

Environmental Toxicology and Chemistry↗

The effects of ultraviolet-B radiation on the toxicity of fire-fighting chemicals

The interactive effects of ultraviolet (UV) and fire-retardant chemicals were evaluated by exposing rainbow trout (Oncorhyncus mykiss) juveniles and tadpoles of southern leopard frogs (Rana sphenocephala) to six fire-retardant formulations with and without sodium ferrocyanide (yellow prussiate of soda [YPS]) and to YPS alone under three simulated UV light treatments. Yellow prussiate of soda is used as a corrosion inhibitor in some of the fire-retardant chemical formulations. The underwater UV intensities measured were about 2 to 10% of surface irradiance measured in various aquatic habitats and were within tolerance limits for the species tested. Mortality of trout and tadpoles exposed to Fire-Trol?? GTS-R, Fire-Trol 300-F, Fire-Trol LCA-R, and Fire-Trol LCA-F was significantly increased in the presence of UV radiation when YPS was present in the formulation. The boreal toad (Bufo boreas), listed as endangered by the state of Colorado (USA), and southern leopard frog were similar in their sensitivity to these chemicals. Photoenhancement of fire-retardant chemicals can occur in a range of aquatic habitats and may be of concern even when optical clarity of water is low; however, other habitat characteristics can also reduce fire retardant toxicity.

Environmental Toxicology and Chemistry↗

The toxicity of p,p'-DDT to the clapper rail

The LC50 (concentration of toxicant in the diet expected to kill half of the test birds in 5 days) for p,p' -DDT in clapper rails (Rallus longirostris) was found to be 1,612 ppm for males and 1,896 ppm for females. Amounts of DDT + DDD in the brains of birds that died were significantly greater (P < 0.01) than those in the brains of survivors. Thirty ppm DDT + DDD approximated the lower limit of these compounds in the brains of rails diagnostic of death from DDT poisoning. Residues in livers and carcasses are reported. Considering the relatively high resistance of the clapper rail to DDT poisoning, we concluded that exposure to this pesticide in marshes is not likely to be a significant factor in mortality of adult rails. Effects other than direct mortality were not evaluated in this study.

Journal of Wildlife Management↗

Lead exposure in American black ducks after implementation of non-toxic shot

Lead poisoning from the ingestion of spent shotgun pellets has been recognized as an important disease of North American waterfowl since Bellrose's (1959) research >40 years ago. Nation-wide regulations banning the use of lead shot for waterfowl hunting were established in 1991. We compared the prevalence of lead exposure in American black ducks ( Anas rubripes ) wintering on 2 areas in Tennessee before (1986-88) and after the ban (1997-99) to assess the effect of the ban on lead shot on this species. Prevalence of elevated blood lead in black ducks declined by 44% from before (11.7% prevalence) to after (6.5% prevalence) the implementation of non-toxic shot. The reduction in lead exposure was pronounced in adult black ducks (from 14.3% to 5.3%). However, prevalence in lead exposure remained similar in juvenile black ducks (from 8.2% to 8.3%). Additional evidence from lead ingestion and lead poisoning mortality events also indicates that lead exposure has declined in waterfowl in the Mississippi flyway. We believe that lead ingestion will continue to decline, despite the persistence of lead shot in some wetlands. The impact of reduced lead exposure on waterfowl populations needs to be assessed.

Tennessee↗

USGS Toxic Substances Hydrology Program, 2010

The U.S. Geological Survey (USGS) Toxic Substances Hydrology Program adapts research priorities to address the most important contamination issues facing the Nation and to identify new threats to environmental health. The Program investigates two major types of contamination problems: * Subsurface Point-Source Contamination, and * Watershed and Regional Contamination. Research objectives include developing remediation methods that use natural processes, characterizing and remediating contaminant plumes in fractured-rock aquifers, identifying new environmental contaminants, characterizing new and understudied pesticides in common pesticide-use settings, explaining mercury methylation and bioaccumulation, and developing approaches for remediating watersheds affected by active and historic mining.

Fact Sheet↗

Occurrence of organic compounds and trace elements in the upper Passaic and Elizabeth Rivers and their tributaries in New Jersey, July 2003 to February 2004: Phase II of the New Jersey toxics reduction workplan for New York-New Jersey Harbor

Samples of surface water and suspended sediment were collected from the Passaic and Elizabeth Rivers and their tributaries in New Jersey from July 2003 to February 2004 to determine the concentrations of selected chlorinated organic and inorganic constituents. This sampling and analysis was conducted as Phase II of the New York-New Jersey Harbor Estuary Workplan—Contaminant Assessment and Reduction Program (CARP), which is overseen by the New Jersey Department of Environmental Protection. Phase II of the New Jersey Workplan was conducted to define upstream tributary and point sources of contaminants in those rivers sampled during Phase I work, with special emphasis on the Passaic and Elizabeth Rivers. Samples were collected from three groups of tributaries: (1) the Second, Third, and Saddle Rivers; (2) the Pompton and upper Passaic Rivers; and (3) the West Branch and main stem of the Elizabeth River. The Second, Third, and Saddle Rivers were sampled near their confluence with the tidal Passaic River, but at locations not affected by tidal flooding. The Pompton and upper Passaic Rivers were sampled immediately upstream from their confluence at Two Bridges, N.J. The West Branch and the main stem of the Elizabeth River were sampled just upstream from their confluence at Hillside, N.J. All tributaries were sampled during low-flow discharge conditions using the protocols and analytical methods for organic constituents used in low-flow sampling in Phase I. Grab samples of streamflow also were collected at each site and were analyzed for trace elements (mercury, methylmercury, cadmium, and lead) and for suspended sediment, particulate organic carbon, and dissolved organic carbon. The measured concentrations and available historical suspended-sediment and stream-discharge data (where available) were used to estimate average annual loads of suspended sediment and organic compounds in these rivers. Total suspended-sediment loads for 1975–2000 were estimated using rating curves developed from historical U.S. Geological Survey (USGS) suspended-sediment and discharge data, where available. Average annual loads of suspended sediment, in millions of kilograms per year (Mkg/yr), were estimated to be 0.190 for the Second River, 0.23 for the Third River, 1.00 for the Saddle River, 1.76 for the Pompton River, and 7.40 for the upper Passaic River. On the basis of the available discharge records, the upper Passaic River was estimated to provide approximately 60 percent of the water and 80 percent of the total suspended-sediment load at the Passaic River head-of-tide, whereas the Pompton River provided roughly 20 percent of the total suspended-sediment load estimated at the head-of-tide. The combined suspended-sediment loads of the upper Passaic and Pompton Rivers (9.2 Mkg/yr), however, represent only 40 percent of the average annual suspended-sediment load estimated for the head-of-tide (23 Mkg/yr) at Little Falls, N.J. The difference between the combined suspended-sediment loads of the tributaries and the estimated load at Little Falls represents either sediment trapped upriver from the dam at Little Falls, additional inputs of suspended sediment downstream from the tributary confluence, or uncertainty in the suspended-sediment and discharge data that were used. The concentrations of total suspended sediment-bound polychlorinated biphenyls (PCBs) in the tributaries to the Passaic River were 194 ng/g (nanograms per gram) in the Second River, 575 ng/g in the Third River, 2,320 ng/g in the Saddle River, 200 ng/g in the Pompton River, and 87 ng/g in the upper Passic River. The dissolved PCB concentrations in the tributaries were 563 pg/L (picograms per liter) in the Second River, 2,510 pg/L in the Third River, 2,270 pg/L in the Saddle River, 887 pg/L in the Pompton River, and 1,000 pg/L in the upper Passaic River. Combined with the sediment loads and discharge, these concentrations resulted in annual loads of suspended sediment-bound PCBs, in grams per year (g/yr), of 37 in the Second River; 132 in the Third River; 2,320 in the Saddle River; 352 in the Pompton River; and 644 in the upper Passaic River. Annual loads of dissolved PCBs, in grams per year, are 9.2 in the Second River; 47 in the Third River; 212 in the Saddle River; 349 in the Pompton River; and 549 in the upper Passaic River. Concentrations of total suspended sediment-bound polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-p-difurans (PCDD/PCDFs) were 6,000 pg/g (picograms per gram) in the Second River; 11,300 pg/g in the Third River; 37,700 pg/g in the Saddle River; 7,140 pg/g in the Pompton River; and 9,640 pg/g in the upper Passaic River. Total toxic equivalence quotients (TEQs), which included PCDD/PCDFs and coplanar PCBs, ranged from 2.7 pg/g in the Second River to 132 pg/g (as 2,3,7,8-TCDD) in the Saddle River. Average annual loads of PCDD/PCDFs were from 1.1 g/yr in the Second River to 71 g/yr in the upper Passaic River. The load of TEQs (as 2,3,7,8-TCDD) from PCDD/PCDFs and coplanar PCBs in the tributaries were 0.5 mg/yr (milligrams per year) in the Second River, 5.8 mg/yr in the Third River, 130 mg/yr in the Saddle River, 46 mg/yr in the Pompton River, and 100 mg/yr in the upper Passaic River. These loads represent an addition to the TEQ load estimated to cross the head-of-tide of 0.1 percent by the Second River, 0.7 percent by the Third River, and 15 percent by the Saddle River. Loads of sediment-bound trace elements mercury, methylmercury, lead, and cadmium were calculated using concentrations obtained from grab samples, which were assumed to represent average annual concentrations in these rivers. Loads of sediment-bound mercury were estimated to be 1,200 g/yr in the Second River; 130 g/yr in the Third River; 4,200 g/yr in the Saddle River; 3,400 g/yr in the Pompton River; and 6,500 g/yr in the upper Passaic River. Loads of sediment-bound lead were estimated to be 56 kg/yr (kilograms per year) in the Second River; 89 kg/yr in the Third River; 1,140 kg/yr in the Saddle River; 310 kg/yr in the Pompton River; and 1,040 kg/yr in the upper Passaic River. Loads of sediment-bound cadmium were estimated to be 1 kg/yr in the Second River; 0.59 kg/yr in the Third River; 60 kg/yr in the Saddle River; 16 kg/yr in the Pompton River; and 11 kg/yr in the upper Passaic River. These loads indicate the importance of the sediment-bound contributions of organic compounds and trace elements to the upper Passaic and Saddle Rivers. Concentrations of suspended sediment-bound PCBs in the main stem and the West Branch of the Elizabeth River were 806 ng/g and 3,100 ng/g, respectively, representing loads of 40 g/yr and 1,150 g/yr, respectively. These loads were estimated using assumed discharge conditions. Concentrations of suspended sediment-bound PCDD/PCDFs were 7,270 pg/g and 9,980 pg/g in the main stem and West Branch, respectively, representing average annual loads of 0.36 g/yr and 3.7 g/yr, respectively. Total TEQ loads (sum of PCDD/PCDFs and PCBs) were 2.1 mg/yr (as 2,3,7,8-TCDD) in the main stem and 34 mg/yr in the West Branch, respectively. These load estimates, however, were directly related to the assumed annual discharge for the two branches. Long-term measurement of stream discharge and suspended-sediment concentrations would be needed to verify these loads. On the basis of the concentrations measured in this work, it appears that the West Branch is the principal source of PCBs, PCDD/PCDFs, total TEQs, and metals to the main stem of the Elizabeth River. Additional sources of these constituents may exist between the confluence and the head-of-tide.

New Jersey, New York↗