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D T Burton

Publications and source records attributed to D T Burton.

33 records · Page 2Linked to original sources
PubMed1981

Acclimation temperature: an important factor in power plant chlorination studies with larval white perch, Morone americana.

Larval white perch were subjected to interacting power plant conditions of total residual chlorine (0.00-0.30 mg/l), elevated temperature (2, 6, and 10 degrees C), and exposure time (0.08, 2.0, and 4.0 h) at acclimation temperatures of 15 and 23 degrees C. Mortality observations were conducted up to 96 h after exposure. Acclimation temperature was a significant factor contributing to the effects of simulated power plant conditions during the low and high thermal conditions. Larvae tested at 23 degrees C generally showed greater mortality at all treatment levels than those tested at 15 degrees C. Mortality of test organisms during a 4-h exposure at the higher acclimation temperature was greater than 85% at elevated temperatures greater than 6 degrees C regardless of other treatment factors. Mortalities as low as 30% were observed at the lower acclimation temperature.

Acclimatization↗
PubMed1981

Toxicity of bromate to striped bass ichthyoplankton (Morone saxatilis) and juvenile spot (Leiostomus xanthurus).

Striped bass (Morone saxatillis) eggs (12 h after fertilization) and larvae (4 d after hatching) and juvenile spot (Leiostomus xanthurus) were exposed to a series of bromate concentrations for 4, 10, and 10 d, respectively, using static replacement bioassay techniques. Three-dimensional mortality response surfaces were constructed by computerized probit regression techniques. Newly hatched striped bass prolarvae were most sensitive to bromate and had a 96-h LC50 of 30.8 mg/l (as BrO3-). Four-day-old striped bass larvae were less sensitive, with 2- to 10-d LC50s ranging from 605.0 to 92.6 mg/l BrO3-, respectively. Juvenile spot were least sensitive, with 1- to 10-d LC50s ranging from 698.0 to 278.6 mg/l BrO3-, respectively.

Animals↗
PubMed1975

A comparison of food habits of white perch (Morone americana) in the heated effluent canal of a steam electric station and in an adjacent river system.

Analysis of the stomach contents of 97 white perch, Morone americana, taken from the effluent canal of a steam electric station (S.E.S.) and 106 white perch from adjacent Patuxent River waters indicated similar food habits from September 1970 through August 1971. However, 35% of all white perch taken from the heated effluent canal contained small pieces of coal and cinders, whereas only 3% of the river specimens contained such items in their stomachs. Fly ash and coal dust are present on the bottom of the S.E.S. canal, whereas little such material, if any, can be found on the river bottom in the study area. This suggests the canal fish were actively feeding in the heated effluent and not simply moving into the canal after feeding in the river. No significant difference (Pgreater than0.05) was found between the average wet weight stomach contents of the river and canal fish within the same mouth.

Animals↗
PubMedDate not supplied

FETAX interlaboratory validation study: phase III--Part 1 testing.

The Frog Embryo Teratogenesis Assay-Xenopus (FETAX) is a 96-h whole embryo developmental toxicity screening assay that can be used in ecotoxicology and in detecting mammalian developmental toxicants when an in vitro metabolic activation system is employed. A standardized American Society for Testing and Materials (ASTM) guide for the conduct of FETAX has been published, along with a companion atlas that aids in embryo staging and identifying malformations. As part of the ASTM process, a three-phase interlaboratory validation study was undertaken to evaluate the repeatability and reliability of FETAX. Seven different participants collaborated in the study. In Phase I, FETAX proved to be more repeatable and reliable than many bioassays. However, some excessive variation was observed in a few laboratories. An initial lack of assay experience by some technicians caused variation. Phase II showed far less intra- and interlaboratory variability than Phase I. Non-teratogens showed the most consistent results, while more variability was observed for the two teratogens tested. Interlaboratory coefficient of variation values for all endpoints ranged from 7.3 to 54.7. Phase III--Part 1, using coded samples and test concentration ranges selected by each laboratory, showed results similar to Phase I. Analysis of the causes of variation suggested that some technicians judged some embryos to be malformed while others consistently judged similar embryos as normal. Concentration ranges tested by some of the laboratories varied greatly and a new protocol for selecting concentrations for initial testing was written to reduce variation from this source. Testing to date suggests that FETAX is as repeatable and reliable as other standard bioassays.

Aminopropionitrile↗
PubMedDate not supplied

Initial interlaboratory validation study of FETAX: phase I testing.

An interlaboratory validation study was undertaken to evaluate the repeatability and reliability of the Frog Embryo Teratogenesis Assay-Xenopus (FETAX), which is a whole embryo developmental toxicity screening assay. A three-phase experimental program with seven participants was carried out. Phase I was a training and protocol evaluation phase where the identity of the three test materials was known. Hydroxyurea, isoniazid and 6-aminonicotinamide were tested in Phase I. Because the chemicals has been tested previously in FETAX, the same concentrations needed to establish the 96-h median lethal concentration (LC50) and the concentration inducing malformations in 50% of the surviving embryos (EC50) were used by all laboratories. The results of Phase I are presented in this report, and FETAX has proved to be as repeatable and reliable as many other bioassays. Some excess variation was observed in individual laboratories. Some of this variation may have been due to training difficulties. One change in protocol design necessitated by this study was the use of 6-aminonicotinamide as a reference toxicant. While 6-aminonicotinamide provided excellent concentration-response data in most laboratories, the protocol was written too strictly based on historical FETAX data. Phases II and III are currently in progress.

6-Aminonicotinamide↗
PubMedDate not supplied

Histopathology of Japanese medaka (Oryzias latipes) chronically exposed to a complex environmental mixture.

Japanese medaka (Oryzias latipes) were used to evaluate the carcinogenicity of a complex groundwater that contained 5 U.S. Environmental Protection Agency priority pollutant heavy metals and 13 chlorinated aliphatic hydrocarbons. A test protocol that used 10 mg/L diethylnitrosamine (DEN) prior to groundwater exposure was designed to assess both initiation and promotion. The fish were exposed continuously for 9 mo with 0, 1, 5, or 25% groundwater, by volume, with either West Branch of Canal Creek water (Aberdeen Proving Ground-Edgewood Area, Aberdeen Proving Ground, MD) or dechlorinated tap water as the diluent, while concurrent controls were run in the laboratory. Incidental findings included various neoplasms in the nares, ovary, skeletal muscle, skin, swim bladder, testis, thymus, and thyroid. Factors evaluated during statistical analyses of fish neoplasm prevalence included diluent type, groundwater percentage, fish gender, and DEN initiation. Liver neoplasm prevalence was higher in DEN-initiated fish and was frequently higher in males. Concentrations of up to 25% groundwater, by volume, showed no evidence of being a complete carcinogen and showed no consistent, conclusive evidence of being a promoter.

Adenoma↗