Herman O. Sanders

Toxicity of the herbicide glyphosate and several of its formulations to fish and aquatic invertebrates

Studies were initiated to determine the acute toxicity of technical grade glyphosate (MON0573), the isopropylamine salt of glyphosate (MON0139), the formulated herbicide Roundup® (MON02139), and the Roundup® surfactant (MON0818) to four aquatic invertebrates and four fishes: daphnids (Daphnia magna), scuds (Gammarus pseudolimnaeus), midge larvae (Chironomous plumosus), mayfly nymphs (Ephemerella walkeri), Rainbow trout (Salmo gairdneri), fathead minnows (Pimephales promelas), channel catfish (Ictalurus punctatus), and bluegills (Lepomis macrochirus). Acute toxicities for Roundup ranged from 2.3 mg/L (96-h LC50, fathead minnow) to 43 mg/L (48-h EC50, mature scuds). Toxicities of the surfactant were similar to those of the Roundup formulation. Technical glyphosate was considerably less toxic than Roundup or the surfactant; for midge larvae, the 48-h EC50 was 55 mg/L and for rainbow trout, the 96-h LC50 was 140 mg/L. Roundup was more toxic to rainbow trout and bluegills at the higher test temperatures, and at pH 7.5 than at pH 6.5. Toxicity did not increase at pH 8.5 or 9.5. Eyed eggs were the least sensitive life stage, but toxicity increased markedly as the fish entered the sac fry and early swim-up stages. No changes in fecundity or gonadosomatic index were observed in adult rainbow trout treated with the isopropylamine salt or Roundup up to 2.0 mg/L. The aging of Roundup test solutions for seven days did not reduce toxicity to midge larvae, rainbow trout or bluegills. In avoidance studies, rainbow trout did not avoid concentrations of the isopropylamine salt up to 10.0 mg/L; mayfly nymphs avoided 10.0 mg/L of Roundup, but not 1.0 mg/L. In a simulated field application, midge larvae avoided 2.0 mg/L of Roundup. Application of Roundup, at recommended rates, along ditchbank areas of irrigation canals should not adversely affect resident populations of fish or invertebrates. However, spring applications in lentic situations, where dissolved oxygen levels are low or temperatures are elevated, could be hazardous to young-of-the-year-fishes.

Toxicities of Several Pesticides to Two Species of Cladocerans

Abstract Laboratory bioassays were conducted with some chlorinated hydrocarbon insecticides, organophosphate insecticides, other insecticides and acaricides, and with herbicides to determine their relative toxicities and immobilization values for two species of daphnids, Daphnia pulex and Simocephalus serrulatus. Both species are satisfactory bioassay organisms for the determination of a wide variety of pesticides, with D. pulex being the more sensitive. The organophosphate insecticides were generally more toxic than the chlorinated hydrocarbons to both species. DDVP was the most toxic compound investigated. DDT was the most toxic chlorinated hydrocarbon tested, and lindane the least. There was a wide range in the toxicity of hydrocarbons to D. pulex, with 48-hour EC50 values ranging from 0.36 to 460 ppb. DDT was 2.9 times more toxic at 50 F than at 80 F. Malathion was 8.8 times more toxic at 50 F than at 70 F to S. serrulatus. Endrin was 12 times more toxic than dieldrin to D. pulex. DDT was 2.6 times mo...

Residue dynamics and biological effects of polychlorinated biphenyls in aquatic organisms

Toxicity, residue dynamics, and biological effects of polychlorinated biphenyls (Aroclor® series) were investigated in several freshwater invertebrates and fishes. Acute static toxicities (LC50) of PCBs ranged from 3.2 to 2,400Μg/L for invertebrates and from 1.2 to 61 mg/L for fish. The LC50s for invertebrates exposed in flow-through diluter systems for 5 to 10 days were 0.6 to 80Μg/L and those for fish exposed for 30 days were 3.0 to 433Μg/L. Invertebrates accumulated Aroclor 1254 residues up to 6,300 times greater than those to which they were exposed. Biological accumulation of Aroclors 1248 and 1254 by channel catfish (Ictalurus punctatus) was 56,370 to 61,190 times the levels in water after 77 days. Dietary exposures of coho salmon (Oncorhynchus kisutch) to Aroclor 1254 at rates of 1.45 to 14,500Μg/kg body weight per day had no effect on growth; no observable toxicosis was produced until 260 days; all fish in the group treated with the highest concentration died after 260 to 265 days. Thyroid activity, as measured by 72-hr thyroidal125I uptake, increased significantly. Thyroid activity in channel catfish fed Aroclors 1232, 1248, 1254, or 1260 at concentrations of 2.4 and 24Μg/g was altered only by Aroclor 1254.

Toxicity, residue dynamics, and reproductive effects of phthalate esters in aquatic invertebrates

Abstract Aquatic invertebrates were exposed to di-n-butyl and di-2-ethylhexyl phthalate esters in water to determine toxicity, accumulation, and reproductive effects of these compounds. The acute toxicities were low and ranged from 2.1 mg/liter to greater than 32 mg/liter. Residue accumulation was rapid resulting in body residues 70-13,600 times that of the water concentration. Phthalate residues were essentially gone after 10 days in fresh water. A reproductive impairment of 60% occurred in Daphnia magna exposed continuously to 3 μg/liter of di-2-ethylhexyl phthalate.

Biological magnification of a polychlorinated biphenyl (Aroclor® 1254) from water by aquatic invertebrates

Polychlorinated biphenyls (PCBs) are chemical mixtures of chlorinated biphenyl isomers. These mixtures have a wide range of industrial~pplication and are marketed in the United States as the Aroclo~m-1200 series. A recent report describes the widespread occurrence of PCBs in the environment and their potential detrimental effects on organisms in aquatic ecosystems (I). Their insecticidal properties are well documented in literature (2,3). Only a few studies report the toxicity of PCBs to aquatic invertebrates (4,5). Some excellent reviews by Peakall and Lincer (6); Gustafson (7); and Veith and Lee (8) summarize and evaluate our current knowledge concerning contamination of the environment by PCBs. Results of previous bioassay experiments with aquatic invertebrates indicated that crustacea and immature insects rapidly accumulate total body concentrations of DDT or aldrin many thousands of times that of surrounding water (9). Although concentrations of PCBs entering the aquatic environment are generally below levels acutely toxic to aquatic invertebrates, these pollutants can be accumulated to appreciable concentrations by aquatic invertebrates. Thus, organisms at higher trophic levels may be exposed to significant amounts of PCBs via the food chain. The purpose of this study was to determine the rate nf accumulation and biological magnification of 36Cl-labeled Aroclor~1254 from water by eight species ~f aquatic invertebrates. The invertebrates were exposed to Aroclor ~ 1254 at concentrations less than 3 ppb, which is similar to levels detected in the water of Escambia Bay, Florida (4). l~addition to measurements of accumulation, scud exposed to Aroclor~Y1254 were analyzed by gas-liquid chromatography to investigate potential shifts in residue composition which may have occurred as a result of metabolism.

Biological effects of Kepone and mirex in freshwater invertebrates

Acute and chronic toxicity studies of Kepone® (chlordecone) and mirex were conducted with daphnids (Daphnia magna), amphipods (Gammarus pseudolimnaeus), and larvae of a midge (Chironomus plumosus). Acute toxicities of Kepone ranged from a 48-hr EC50 of 350μg/L for midges to a 96-hr LC50 of 180μg/L for amphipods, whereas the acute toxicities of mirex to all three taxa exceeded 1000μg/L. Maximum acceptable toxicant concentrations (MATCs) for Kepone and mirex were estimated by measuring reproduction of daphnids, growth of amphipods, emergence of midges, and survival of all organisms. MATC for Kepone was estimated to be between 9 and 18μg/L for daphnids, between 1 and 2μg/L for amphipods, and between 8.4 and 18μg/L for midges; MATC for mirex exceeded 34μg/L for daphnids and midges, but less than 2.4μg/L for amphipods. The concentration of Kepone and mirex accumulated by daphnids was 760 and 8025 times, respectively, the concentration in water. Estimated times for elimination of 50% of the residues by daphnids were 141 hr for Kepone and 12 hr for mirex.