Frederick W. Kutz

The international toxicity equivalency factor (I-TEF) method of risk assessment for complex mixtures of dioxins and related compounds☆

Abstract The International Toxicity Equivalency Factor (I-TEF) method of risk assessment is an updated interim procedure for estimating the risks associated with exposures to complex mixtures of chlorinated dibenzo-p-dioxins and dibenzofurans (CDDs and CDFs). The I-TEF approach facilitates risk communication internationally by reducing large volumes of analytical data into a single number-International Toxicity Equivalents (I-TEQ). The I-TEF method has been officially adopted in Canada, the Netherlands, the Nordic countries, the United Kingdom, and the United States. As a result, the I-TEF method represents an improvement in an already useful risk assessment/regulatory tool.

Organochlorine pesticides and polychlorinated biphenyls in human adipose tissue.

Halogenated organic compounds are highly lipophilic chemicals that are persistent in the environment as a result of their use and chemical stability. Some of these compounds are also present in the environment as metabolites or oxidation products of a parent compound or as by-products formed in the production of chlorinated compounds. Chronic exposure to the general population results mainly through the food chain. Because they are lipophilic, and because many are metabolized slowly, these chemicals tend to concentrate in body fat tissue. This contribution has described these halogenated organic compounds, discussed their use, regulation and prohibition throughout the world, and reviewed published studies on the levels of these chemicals found in the adipose tissue of humans and animals. For many years, residues of halogenated organic compounds have been detected in the human adipose tissue of individuals in a number of countries, including those in Europe, Asia, and Africa, as well as in the U.S. The levels detected have been used as an index of the level of general population exposure of these compounds over time. Over the past two decades, most countries have observed a steady decline of this level of exposure, reflecting a reduction in the use of these compounds, restrictions on or banning of their use, and a corresponding decrease in their environmental levels. The levels of concentrations vary from chemical to chemical as well as from isomer to isomer. Since the use of aldrin and dieldrin has now been banned or restricted in the U.S. and a number of other countries, residue levels have slowly decreased. Mean values in human adipose tissue in the U.S. and some foreign countries ranged from 0.04 to 0.40 ppm for dieldrin. Aldrin was detected only in Argentina and Poland in the 1970s and endrin was not detected anywhere at anytime. By 1978, all products containing BHC registered in the U.S. has been either discontinued or reformulated to incorporate lindane rather than BHC. The potential for exposure to BHC is virtually nonexistent in the U.S.; however, exposure to lindane is possible since products containing this chemical are still marketed, and used particularly in the manufacture of human medicine. DDT was banned for agricultural purposes in the U.S. in 1972, although it is still used elsewhere for public health vector control. Since the decline in use of DDT, however, the average levels of concentration have also declined. Heptachlor, chlordane, and trans-nonachlor (a component of both heptachlor and chlordane) are chlorinated cyclodienes.(ABSTRACT TRUNCATED AT 400 WORDS)

The international toxicity equivalency factor (I‐TEF) method for estimating risks associated with exposures to complex mixtures of dioxins and related compounds∗

The International Toxicity Equivalency Factor (I‐TEF) method of risk assessment is a revised interim procedure for assessing the risks associated with exposures to complex mixtures of chlorinated dibenzo‐p‐dioxins and dibenzofurans (CDDs and CDFs). This updated scheme was developed by a working group of the North Atlantic Treaty Organizations Committee on the Challenges of Modern Society and has been officially adopted by the U.S. Environmental Protection Agency (EPA), Canada, Ontario Ministry of the Environment, the Nordic countries, the Netherlands, and the United Kingdom. Prior to the development of the I‐TEF method, at least ten slightly different schemes had been used throughout the world which complicated communication among scientists and regulatory agencies concerning the toxicological significance of complex mixtures of CDDs and CDFs. The I‐TEF approach facilitates risk communication internationally by reducing large volumes of analytical data into a single number‐International Toxicity Equivale...

Selected pesticide residues and metabolites in urine from a survey of the U.S. general population.

Residues of toxic chemicals in human tissues and fluids can be important indicators of exposure. Urine collected from a subsample of the second National Health and Nutrition Examination Survey was analyzed for organochlorine, organophosphorus, and chlorophenoxy pesticides or their metabolites. Urine concentration was also measured. The most frequently occurring residue in urine was pentachlorophenol (PCP), found in quantifiable concentrations in 71.6% of the general population with an estimated geometric mean level of 6.3 ng/ml. Percent quantifiable levels of PCP were found to be highest among males. Quantifiable concentrations of 3,5,6-trichloro-2-pyridinol (5.8%), 2,4,5-trichlorophenol (3.4%), para-nitrophenol (2.4%), dicamba (1.4%), malathion dicarboxylic acid (0.5%), malathion alpha-monocarboxylic acid (1.1%), and 2,4-D (0.3%) were found, but at much lower frequencies. No quantifiable levels of 2,4,5-T or silvex were found. Preliminary analyses showed an apparent relationship between residue concentration and two measures of urine concentration (osmolality and creatinine). A large segment of the general population of the United States experienced exposure to certain pesticides, including some considered biodegradable, during the years 1976-1980.

An Estuarine Benthic Index of Biotic Integrity for the Mid-Atlantic Region of the United States. II. Index Development

A benthic index of biotic integrity was developed for use in estuaries of the mid-Atlantic region of the United States (Delaware Bay estuary through Albemarle-Pamlico Sound). The index was developed for the Mid-Atlantic Integrated Assessment Program (MAIA) of the U.S. Environmental Protection Agency using procedures similar to those applied previously in Chesapeake Bay and southeastern estuaries, and was based on sampling in July through early October. Data from seven federal and state sampling programs were used to categorize sites as degraded or non-degraded based on dissolved oxygen, sediment contaminant, and sediment toxicity criteria. Various metrics of benthic community structure and function that distinguished between degraded and reference (non-degraded) sites were selected for each of five major habitat types defined by classification analysis of assemblages. Each metric was scored according to thresholds established on the distribution of values at reference sites, so that sites with low scoring metrics would be expected to show signs of degradation. For each habitat, metrics that correctly classified at least 50% of the degraded sites in the calibration data set were selected whenever possible to derive the index. The final index integrated the average score of the combination of metrics that performed best according to several criteria. Selected metrics included measures of productivity (abundance), diversity (number of taxa, Shannon-Wiener diversity, percent dominance), species composition and life history (percent abundance of pollution-indicative taxa, percent abundance of pollution-sensitive taxa, percent abundance of Bivalvia, Tanypodinae-Chironomidae abundance ratio), and trophic composition (percent abundance of deep-deposit feeders). The index correctly classified 82% of all sites in an independent data set. Classification efficiencies of sites were higher in the mesohaline and polyhaline habitats (81–92%) than in the oligohaline (71%) and the tidal freshwater (61%). Although application of the index to low salinity habitats should be done with caution, the MAIA index appeared to be quite reliable with a high likelihood of correctly identifying both degraded and non-degraded conditions. The index is expected to be of great utility in regional assessments as a tool for evaluating the integrity of benthic assemblages and tracking their condition over time.

PCDDs and PCDFs in human adipose tissue from the EPA FY82 NHATS repository

Abstract Analysis for tetra- through octachloro-PCDDs and PCDFs was completed for 46 tissue samples prepared from the U.S. Environmental Protection Agency (EPA) National Human Adipose Tissue Survey (NHATS). The samples were prepared as composites from over 900 specimens to represent the nine U.S. census divisions and three age groups (0–14, 15–44, and 45 plus years). The data demonstrate that PCDDs and PCDFs are prevalent in the general U.S. population and that differences exist with age.

Survey of selected organochlorine pesticides in the general population of the United States: fiscal years 1970-1975.

In decisions regarding the uses of aldrin, dieldrin, heptachlor, and chlordane, the Administrator of the U.S. Environmental Protection Agency cited and considered the findings of these chemicals in human tissues. Findings of pesticide residues and their metabolites in representative samples from the general population provide a major element in pesticide regulatory decision-making. These residues demonstrate the extent of the environmental distribution of particular pesticides and, when coupled with laboratory animal data showing adverse biologic effects, signal a potential public health hazard. One program that examines pesticide residues and associated chemicals in human tissues and fluids is the National Human Monitoring Program for Pesticides. This program, operated by the U S . Environmental Protection Agency, monitors on a national scale, the prevalence and level of exposure to selected pesticides experienced by the general population. These data are used to identify trends in this exposure and to assess the effects of regulatory actions. Residues of pesticides and their metabolites in various human tissues and body fluids represent the total body burden of these pesticides and reflect past and present exposure to them. Pesticides may gain entrance into the human body through the gastrointestinal tract subsequent to ingestion; through the respiratory tract as a result of inhalation of airborne pesticide-laden dusts, vapors, and aerosols; by penetration through the intact skin and mucus membranes; and (rarely) by absorption directly into the bloodstream through broken skin. This paper reports findings of selected organochlorine pesticide residues and their metabolites in human adipose tissue collected annually on a national basis from fiscal years 1970 through 1975. During this period, a fiscal year began on July 1 and extended to the end of June of the following year. For example, fiscal year 1970 began on July I . 1969, and ended on June 30, 1970.

The Ecological Condition of Dead-End Canals of the Delaware and Maryland Coastal Bays

Manmade, dead-end canals are common in residential developments along the coastal bays of Delaware and Maryland. The close proximity of housing to the water and the concentration of boating activities enhances the potential for anthropogenic stress to living resources in these poorly flushed aquatic systems. Measurements of water quality, sediment contaminants, and benthic macroinvertebrate assemblages were taken in 25 randomly selected canals and compared to 175 non-canal sites located throughout the coastal bays. The mean bottom dissolved oxygen concentrations in canals was half that found in non-canal sites. Mean water-column and benthic chlorophyll concentrations were, respectively, two times and four times higher in the canals. Sediment contaminant concentrations were significantly higher in the canals compared to the coastal bays, and exceeded published guideline values indicating possible adverse ecological effects. The contaminants of greatest concern in the canals included arsenic, copper, polyaromatic hydrocarbons, polychlorinated biphenyls, and several banned, persistent pesticides (DDT, dieldrin, endrin, and chlordane). Benthic macroinvertebrate assemblages in canals were severely degraded; mean species richness, abundance, and biomass were 1/7, 1/10, and 1/20, respectively, of the values for the remaining coastal bays. A single pollution-tolerant polychaete species (Streblospio benedicti) comprised approximately three-fourths (70%) of the community in the canals. Deep (>1 m) and muddy canals were in poorer condition than shallow and sandy ones.

Survey of Pesticide Residues and Their Metabolites in Urine from the General Population

The National Human Monitoring Program for Pesticides is collaborating with the U.S. Public Health Service in a three year study to assess the exposure of the general population of the United States of America through analysis of human urine for residues of selected pesticides and their specific metabolites. Samples are collected on a national probability design and analyzed for selected organochlorine, carbamate, chlorophenoxy and organophosphorous pesticides. Medical, nutritional and pesticide usage data are available from each donor. Preliminary results of the urine analyses indicate that the general population is being exposed to some of these types of pesticides.

Restored Riparian Buffers as Tools for Ecosystem Restoration in the MAIA; Processes, Endpoints, and Measures of Success for Water, Soil, Flora, and Fauna

Riparian buffer restorations are used as management tools to produce favorable water quality impacts, moreover among the many benefits riparian buffers may provide, their application as instruments for water quality restoration rests on a relatively firm foundation of research. However, the extent to which buffers can restore riparian ecosystems; their functionality and species composition, are essentially unknown. In light of the foregoing, two broad areas of research are indicated. First, data are needed to document the relative effectiveness of riparian buffers that differ according to width, length, and plant species composition. These questions, of managing buffer dimension and species composition for functionality, are of central importance even when attenuation of nutrient and sediment loads alone are considered. Second, where ecosystem restoration is the goal, effects to in-stream and terrestrial riparian biota need to be considered. Relatedly, the effects of the restoration on the landscape need to be considered. Particularly, at what rate do the effects of the riparian buffer on in-stream water quality, biota, and habitat diminish downstream from restored sites? Answers to these important questions are needed, for streams and watersheds of different size and for areas of differing soil type within watersheds. U.S. EPA-NRMRL has initiated as research project that will document the potential for buffers to restore riparian ecosystems; focusing on water quality effects, but also, importantly, documenting effects on biota. While substantial riparian buffer management initiatives are already underway, the extent of landscapes that influence riparian ecosystems in the eastern United States is large; leaving ample opportunity for this suggested research to provide improved buffer designs in the future. The ultimate goal of research projects developed under this paradigm of ecosystem restoration is to develop data that are needed to implement riparian buffer restorations in the mid-Atlantic and elsewhere, especially the eastern United States.