Effects of the herbicide surfactant MON 0818 on oviposition and viability of eggs of the ramshorn snail (Planorbella pilsbryi).

The surfactant mixture MON 0818 is an adjuvant in various commercial formulations of the herbicide glyphosate. Initial studies have shown that MON 0818 is more toxic to aquatic animals than the active ingredient. However, few studies have examined the effect of exposure to MON 0818 on species of mollusks, and no studies have examined the effect on gastropods. The present study investigated the effect of acute exposure (96 h) of MON 0818 to the eggs, juveniles, and adults of the file ramshorn snail (Planorbella pilsbryi). Concentrations of MON 0818 up to 9.9 mg/L did not have a significant effect on the viability of eggs (p > 0.05). Juvenile snails (50% lethal concentration [LC50] = 4.0 mg/L) were more sensitive than adult snails (LC50 = 4.9-9.1 mg/L). Oviposition was inhibited by exposure to MON 0818 (median effective concentration [EC50] = 0.4-2.0 mg/L). However, oviposition resumed when snails were removed to clean water, even after 96-h exposure to up to 4.9 mg/L of MON 0818. Exposure to a concentration ≥2.7 mg/L caused visible damage to the tentacles of adult snails, which could potentially impact chemoreception. A deterministic hazard assessment indicated that environmentally relevant concentrations of MON 0818 could pose a hazard to the deposition of eggs. However, because of the relatively short half-life of MON 0818 in aquatic systems and the ability of snails to resume oviposition following the dissipation of MON 0818, environmentally relevant concentrations of MON 0818 likely pose a de minimis risk to populations of ramshorn snails. Environ Toxicol Chem 2017;36:522-531. © 2016 SETAC.

Prosser RS ，Rodriguez-Gil JL ，Solomon KR ，Sibley PK ，Poirier DG ... -  《-》

Aquatic hazard assessment of MON 0818, a commercial mixture of alkylamine ethoxylates commonly used in glyphosate-containing herbicide formulations. Part 2: Roles of sediment, temperature, and capacity for recovery following a pulsed exposure.

A series of toxicity tests with MON 0818, a commercial surfactant mixture of polyoxyethylene tallow amines, were performed: 1) in the presence of sediment for benthic invertebrates and fish: 2) to examine the recovery capacity of Daphnia magna and 4 primary producers after a pulsed (24-h) exposure; and 3) to examine the potential effect of increased water temperature on toxicity of MON 0818 to 2 cold-water fishes. In the presence of sediment, no acute (24-h) mortality was observed for 3 of the 5 species up to 10 mg L-1 . The median effective concentrations for the other 2 species were significantly greater than for water only tests. The EC50 at 15 °C for Salvelinus alpinus was statistically lower than that at 10 °C. Latent effects of a 24-h exposure (1 mg L-1 ) were observed for Rhabdocelis subcapitata and Chlorella vulgaris, as indicated by delayed growth during recovery phase; however, both cultures were able to recover, as indicated by a lack of changes in maximum absolute growth rates. No significant effects of a 24-h exposure to MON 0818 were observed for Oophila sp. (1.5 mg L-1 ) or Lemna minor (100 mg L-1 ). Latent mortality after a 24-h exposure to 5 mg L-1 was observed during the recovery phase for D. magna; however, reproduction endpoints on surviving individuals were not altered. The results indicate that quick dissipation of MON 0818 in the presence of sediment can reduce the effects on exposed organisms, and that full recovery from 24-h exposures to concentrations of MON 0818 equal to, or greater than, those expected in the environment is possible. Environ Toxicol Chem 2017;36:512-521. © 2016 SETAC.

Rodriguez-Gil JL ，Prosser R ，Hanta G ，Poirier D ，Lissemore L ，Hanson M ，Solomon KR ... -  《-》

Aquatic hazard assessment of MON 0818, a commercial mixture of alkylamine ethoxylates commonly used in glyphosate-containing herbicide formulations. Part 1: Species sensitivity distribution from laboratory acute exposures.

The sensitivity of 15 aquatic species, including primary producers, benthic invertebrates, cladocerans, mollusks, and fish, to MON 0818, a commercial surfactant mixture of polyoxyethylene tallow amines, was evaluated in standard acute (48-96-h) laboratory tests. In addition, the potential for chronic toxicity (8 d) was evaluated with Ceriodaphnia dubia. Exposure concentrations were confirmed. No significant effects on any endpoint were observed in the chronic test. A tier-1 hazard assessment was conducted by comparing species sensitivity distributions based on the generated data, as well as literature data, with 4 exposure scenarios. This assessment showed moderate levels of hazard (43.1% of the species exposed at or above median effective concentration levels), for a chosen worst-case scenario-unintentional direct over-spray of a 15-cm-deep body of water with the maximum label application rate for the studied formulations (Roundup Original, Vision Forestry Herbicide; 12 L formulation ha-1 , equivalent to 4.27 kg acid equivalent [a.e.] ha-1 ). The hazard decreased to impairment of 20.9% of species under the maximum application rate for more typical uses (6 L formulation ha-1 , 2.14 kg a.e. ha-1 ), and down to 6.9% for a more frequently employed application rate (2.5 L formulation ha-1 , 0.89 kg a.e. ha-1 ). Finally, the percentage (3.8%) was less than the hazardous concentration for 5% of the species based on concentrations of MON 0818 calculated from maximum measured concentrations of glyphosate in the environment. Environ Toxicol Chem 2017;36:501-511. © 2016 SETAC.

Rodriguez-Gil JL ，Prosser R ，Poirier D ，Lissemore L ，Thompson D ，Hanson M ，Solomon KR ... -  《-》

Relative toxicity of the components of the original formulation of Roundup to five North American anurans.

The responses of five North American frog species that were exposed in an aqueous system to the original formulation of Roundup were compared. Carefully designed and un-confounded laboratory toxicity tests are crucial for accurate assessment of potential risks from the original formulation of Roundup to North American amphibians in aquatic environments. The formulated mixture of this herbicide as well as its components, isopropylamine (IPA) salt of glyphosate and the surfactant MON 0818 (containing polyethoxylated tallowamine (POEA)) were separately tested in 96 h acute toxicity tests with Gosner stage 25 larval anurans. Rana pipiens, R. clamitans, R. catesbeiana, Bufo fowleri, and Hyla chrysoscelis were reared from egg masses and exposed to a series of 11 concentrations of the original formulation of Roundup herbicide, nine concentrations of MON 0818 and three concentrations of IPA salt of glyphosate in static (non-renewal) aqueous laboratory tests. LC50 values are expressed as glyphosate acid equivalents (ae) or as mg/L for MON 0818 concentrations for comparison between the formulation and components. R. pipiens was the most sensitive of five species with 96 h-LC50 values for formulation tests, for the five species, ranging from 1.80 to 4.22 mg ae/L, and MON 0818 exposures with 96 h-LC50 values ranging from 0.68 to 1.32 mg/L. No significant mortality was observed during exposures of 96 h for any of the five species exposed to glyphosate IPA salt at concentrations up to 100 times the predicted environmental concentration (PEC). These results agree with previous studies which have noted that the surfactant MON 0818 containing POEA contributes the majority of the toxicity to the herbicide formulations for fish, aquatic invertebrates, and amphibians. These study results suggest that anurans are among the most sensitive species, and emphasize the importance of testing the herbicide formulation in addition to its separate components to accurately characterize the toxicity and potential risk of the formulation.

Moore LJ ，Fuentes L ，Rodgers JH Jr ，Bowerman WW ，Yarrow GK ，Chao WY ，Bridges WC Jr ... -  《-》

Assessing the Impacts of Methoxychlor Exposure on the Viability, Reproduction, and Locomotor Behavior of the Seminole Ramshorn Snail (Planorbella duryi).

In the present study, the effects of short-term methoxychlor exposure on the viability, reproduction, and locomotor behavior of adult seminole ramshorn snails (Planorbella duryi) was assessed. To examine impacts on viability and behavior, individuals were exposed to a water control, vehicle control, or 12.5, 50, 100, 250, 500, or 1000 μg/L of methoxychlor for 48 h; and differences in mortality and locomotor behavior assessed using the freely available ToxTrac software. To determine impacts on reproduction, pairs of snails were exposed to a vehicle control and 12.5, 25, 50, 100, and 250 μg/L of methoxychlor for 9 d; and the number of clutches and eggs laid quantified every 24 h. Methoxychlor concentrations in treatments were determined using gas chromatography. Complete mortality was observed in the 500 μg/L and 1000 μg/L treatments after 48 h and in the 250 μg/L treatment after 9 d. Decreases in the number of egg clutches were observed in all treatments, and the number of eggs laid decreased starting in the 25 μg/L treatment. Decreases in average speed, mobile speed, and total distance traveled, as well as a significant increase in frozen events, were also observed. Our results suggest that methoxychlor exposure causes detrimental effects on several nonlethal endpoints in a nonmodel aquatic invertebrate species and that the analysis of locomotor behaviors serves as a reliable, sensitive endpoint for ecotoxicology testing. Environ Toxicol Chem 2019;39:220-228. © 2019 SETAC.

Frankel TE ，Bohannon ME ，Frankel JS 《-》