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Se revisa la experiencia del Hospital San Juan de Dios de Bogotá Universidad Nacional en fiebre tifoidea entre 1979 y 1986. Se presentaron 24 casos; 17 hombres y 7 mujeres con edad promedio de 22.2 años (rango entre 15 y 40 años), la mayoría proveniente de aéreas urbanas. La duración promedio de la sintomatología antes de consultar fue de 18.7 días y la estancia hospitalaria promedio fue de 19.5 días.

The ASTM International standard test method for freshwater mussels (E2455-13) recommends 4-week toxicity testing with juveniles to evaluate chronic effects on survival and growth. However, concerns remain that the method may not adequately address the sensitivity of mussels to longer term exposures (>4 weeks), particularly in relation to potential reproductive impairments. No standard method directly evaluates toxicant effects on mussel reproduction. The objectives of the present study were to (1) evaluate toxicity endpoints related to reproduction in fatmucket (Lampsilis siliquoidea) using two common reference toxicants, potassium chloride (KCl) and nickel (Ni); (2) evaluate the survival and growth of juvenile fatmucket in standard 4-week and longer term (12-week) KCl and Ni tests following a method refined from the standard method; and (3) compare the sensitivity of the reproductive endpoints with the endpoints obtained from the juvenile mussel tests. Reproductive toxicity tests were conducted by first exposing female fatmucket brooding mature larvae (glochidia) to five test concentrations of KCl and Ni for 6 weeks. Subsamples of the glochidia were then removed from the adults to determine three reproductive endpoints: (1) the viability of brooded glochidia; (2) the viability of free glochidia in a 24-h exposure to the same toxicant concentrations as their mother; and (3) the success of glochidia parasitism on host fish. Mean viability of brooded glochidia was significantly reduced in the high KCl concentration (26 mg K/L) relative to the control, with a 20% effect concentration (EC20) of 14 mg K/L, but there were no significant differences between the control and any Ni treatment (EC20 > 95 µg Ni/L). The EC20s for viability of free glochidia after the additional 24-h exposure and parasitism success were similar to the EC20s of brooded glochidia. The EC20s based on the most sensitive biomass endpoint in the 4-week juvenile tests were 15 mg K/L and 91 µg Ni/L, similar to or greater than the EC20s from the reproductive KCl and Ni tests, respectively. When exposure duration in the juvenile tests was extended from 4 to 12 weeks, the EC20s decreased by more than 50% in the KCl test but by only 8% in the Ni test. Overall, these results indicate that a standard 4-week test with juvenile mussels can prove effective for estimating effects in chronic exposures with different life stages although a longer term 12-week exposure with juvenile mussels may reveal higher sensitivity of mussels to some toxicants, such as KCl. Environ Toxicol Chem 2024;43:1097-1111. © 2024 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA., (© 2024 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Elevated concentrations of potassium (K) often occur in effluents from wastewater treatment plants, oil and gas production operations, mineral extraction processes, and other anthropogenic sources. Previous studies have demonstrated that freshwater mussels are highly sensitive to K in acute and chronic exposures, and that acute toxicity of K decreases with increasing water hardness. However, little is known about the influence of hardness on the chronic toxicity of K. The objective of our study was to evaluate the chronic toxicity of K (tested as KCl) to a commonly tested unionid mussel (fatmucket, Lampsilis siliquoidea) at five hardness levels (25, 50, 100, 200, and 300 mg/L as CaCO 3 ) representing most surface waters in the United States. Chronic 28-day K toxicity tests were conducted with 3-week-old juvenile fatmucket in the five hardness waters using an ASTM International standard method. The maximum acceptable toxicant concentrations (geometric mean of the no-observed-effect concentration and the lowest-observed-effect concentration) increased from 15.1 to 69.3 mg K/L for survival and from 15.1 to 35.8 mg K/L for growth (length and dry wt) and biomass when water hardness was increased from 25 mg/L (soft) to 300 mg/L (very hard). These results provide evidence to support water hardness influence on chronic K toxicity to juvenile fatmucket. However, the chronic effect concentrations based on the more sensitive endpoint (growth or biomass) increased only 2.4-fold from the soft water to the very hard water, indicating that water hardness had a limited influence on the chronic toxicity of K to the mussels. These results can be used to establish chronic toxicity thresholds for K across a broad range of water hardness and to derive environmental guideline values for K to protect freshwater mussels and other organisms. Environ Toxicol Chem 2023;42:1085-1093. Published 2023. This article is a U.S. Government work and is in the public domain in the USA., (Published 2023. This article is a U.S. Government work and is in the public domain in the USA.)

The Grand Calumet River (GCR), located in northern Indiana, is contaminated due to a wide range of historical industrial activities. This study was conducted to determine the influence of sediment remediation within the GCR on concentrations of chemical contaminants and toxicity to sediment-dwelling organisms. Between 2005 and 2016, sediments with high concentrations of metals and toxic organic compounds were remediated through a combination of removal, addition of activated carbon and organoclay amendments, and capping with sand or relatively uncontaminated sediment. Short-term and long-term sediment toxicity tests with the amphipod Hyalella azteca, the midge Chironomus dilutus, and the mussel Lampsilis siliquoidea were conducted with samples collected in 2013, 2015, and 2017, from 29 sites, including both remediated and non-remediated sites. Sediment chemistry and toxicity data for three groups of remediated sites (US Steel, West Branch, and East Branch) were compared to samples from contaminated but unremediated sites and to relatively uncontaminated reference sites. In general, remediated sediments had lower levels of PAHs, PCBs and metals, although sediments from the US Steel area still had elevated levels of PAH, PCB and chromium. Sediments from the three remediated sites and from reference sites showed significantly reduced toxic effects in short-term sediment bioassays, compared to unremediated sites. Variation in the long-term success of remediation may reflect site-specific factors such as the type of remediation and the potential for recontamination from uncontrolled sources., (Published by Elsevier Ltd.)

Elevated nitrate (NO 3 ) and sulfate (SO 4 ) in surface water are of global concern, and studies are needed to generate toxicity data to develop environmental guideline values for NO 3 and SO 4 . The present study was designed to fill existing gaps in toxicity databases by determining the acute and/or chronic toxicity of NO 3 (tested as NaNO 3 ) to a unionid mussel (Lampsilis siliquoidea), a midge (Chironomus dilutus), a fish (rainbow trout, Oncorhynchus mykiss), and 2 amphibians (Hyla versicolor and Lithobates sylvaticus), and to determine the acute and/or chronic toxicity of SO 4 (tested as Na 2 SO 4 ) to 2 unionid mussels (L. siliquoidea and Villosa iris), an amphipod (Hyalella azteca), and 2 fish species (fathead minnow, Pimephales promelas and O. mykiss). Among the different test species, acute NO 3 median effect concentrations (EC50s) ranged from 189 to >883 mg NO 3 -N/L, and chronic NO 3 20% effect concentrations (EC20s) based on the most sensitive endpoint ranged from 9.6 to 47 mg NO 3 -N/L. The midge was the most sensitive species, and the trout was the least sensitive species in both acute and chronic NO 3 exposures. Acute SO 4 EC50s for the 2 mussel species (2071 and 2064 mg SO 4 /L) were similar to the EC50 for the amphipod (2689 mg SO 4 /L), whereas chronic EC20s for the 2 mussels (438 and 384 mg SO 4 /L) were >2-fold lower than the EC20 of the amphipod (1111 mg SO 4 /L), indicating the high sensitivity of mussels in chronic SO 4 exposures. However, the fathead minnow, with an EC20 of 374 mg SO 4 /L, was the most sensitive species in chronic SO 4 exposures whereas the rainbow trout was the least sensitive species (EC20 > 3240 mg SO 4 /L). The high sensitivity of fathead minnow was consistent with the finding in a previous chronic Na 2 SO 4 study. However, the EC20 values from the present study conducted in test water containing a higher potassium concentration (3 mg K/L) were >2-fold greater than those in the previous study at a lower potassium concentration (1 mg K/L), which confirmed the influence of potassium on chronic Na 2 SO 4 toxicity to the minnow. Environ Toxicol Chem 2020;39:1071-1085. © 2020 SETAC., (© 2020 SETAC.)

Freshwater mussels are generally underrepresented in toxicity databases used to derive water quality criteria, especially for long-term exposures. Multiple tests were conducted to determine the chronic toxicity of sodium chloride (NaCl) or potassium chloride (KCl) to a unionid mussel (fatmucket, Lampsilis siliquoidea). Initially, a 4-wk NaCl test and a 4-wk KCl test were conducted starting with 2-mo-old mussels in water exposures with and without a thin layer of sand substrate. A feeding study was conducted later to refine test conditions for longer-term 12-wk exposures, and 3 chronic NaCl tests were then conducted following the refined method to assess the influence of test duration (4-12 wk) and age of organisms (starting age ∼1 wk to 2 mo) on mussel sensitivity. Biomass (total dry wt of surviving mussels in a replicate) was generally a more sensitive endpoint compared to survival and growth (length and dry wt). In the 4-wk NaCl or KCl test started with 2-mo-old juveniles, a 20% effect concentration (EC20) based on biomass (264 mg Cl/L from the NaCl test or 8.7 mg K/L from the KCl test) in the exposure with sand was 2-fold lower than the EC20 in the exposure without sand. The longer-term 12-wk NaCl tests started with the 1-wk-old and 2-mo-old juveniles were successfully completed under refined test conditions based on the feeding study, and younger juveniles were more sensitive to NaCl than older juveniles. The NaCl toxicity did not substantially change with extended exposure periods from 4 to 12 wk, although the 4-wk EC20s for biomass were slightly greater (up to 37%) than the 12-wk EC20s in the 2 longer-term exposures. Including the toxicity data from the present study into existing databases would rank fatmucket the most sensitive species to KCl and the second most sensitive species to NaCl for all freshwater organisms. Environ Toxicol Chem 2018;37:3050-3062. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America., (Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.)

Freshwater mussels (order Unionoida) are one of the most imperiled groups of animals in the world. However, many ambient water quality criteria and other environmental guideline values do not include data for freshwater mussels, in part because mussel toxicity test methods are comparatively new and data may not have been available when criteria and guidelines were derived. The objectives of the present study were to evaluate the acute toxicity of sodium chloride (NaCl) and potassium chloride (KCl) to larvae (glochidia) and/or juveniles of a unionid mussel (fatmucket, Lampsilis siliquoidea) and to determine the potential influences of water hardness (50, 100, 200, and 300 mg/L as CaCO 3 ) and other major ions (Ca, K, SO 4 , or HCO 3 ) on the acute toxicity of NaCl to the mussels. From the KCl test, the 50% effect concentration (EC50) for fatmucket glochidia was 30 mg K/L, similar to or slightly lower than the EC50s for juvenile fatmucket (37-46 mg K/L) tested previously in our laboratory. From the NaCl tests, the EC50s for glochidia increased from 441 to 1597 mg Cl/L and the EC50s for juvenile mussels increased from 911 to 3092 mg Cl/L with increasing water hardness from 50 to 300 mg/L. Increasing K from 0.4 to 1.9 mg/L, SO 4 from 13 to 40 mg/L, or HCO 3 from 44 to 200 mg/L in the 50 mg/L hardness water did not substantially change the NaCl EC50s for juvenile mussels, whereas increasing Ca from 9.9 to 42 mg/L increased the EC50s by a factor of 2. The overall results indicate that glochidia were equally or more sensitive to NaCl and KCl compared with juvenile mussels and that the increased water hardness ameliorated the acute toxicity of NaCl to glochidia and juveniles. These responses rank fatmucket among the most acutely sensitive freshwater organisms to NaCl and KCl. Environ Toxicol Chem 2018;37:3041-3049. © 2018 SETAC. This article is a US government work and, as such, is in thepublic domain in the United States of America., (© 2018 SETAC. This article is a US government work and, as such, is in thepublic domain in the United States of America.)

We performed toxicity tests with two species of pulmonate snails (Lymnaea stagnalis and Physa gyrina) and four taxa of nonpulmonate snails in the family Hydrobiidae (Pyrgulopsis robusta, Taylorconcha serpenticola, Fluminicola sp., and Fontigens aldrichi). Snails were maintained in static-renewal or recirculating culture systems with adults removed periodically to isolate cohorts of offspring for toxicity testing. This method successfully produced offspring for both species of pulmonate snails and for two hydrobiid species, P. robusta and Fluminicola sp. Toxicity tests were performed for 28 days with copper, ammonia, and pentachlorophenol in hard reconstituted water with endpoints of survival and growth. Tests were started with 1-week-old L. stagnalis, 2-week-old P. gyrina, 5- to 13-week-old P. robusta and Fluminicola sp., and older juveniles and adults of several hydrobiid species. For all three chemicals, chronic toxicity values for pulmonate snails were consistently greater than those for hydrobiid snails, and hydrobiids were among the most sensitive taxa in species sensitivity distributions for all three chemicals. These results suggest that the toxicant sensitivity of nonpulmonate snails in the family Hydrobiidae would not be adequately represented by results of toxicity testing with pulmonate snails.

The acute and chronic toxicity of sulfate (tested as sodium sulfate) was determined in diluted well water (hardness of 100 mg/L and pH 8.2) with a cladoceran (Ceriodaphnia dubia; 2-d and 7-d exposures), a midge (Chironomus dilutus; 4-d and 41-d exposures), a unionid mussel (pink mucket, Lampsilis abrupta; 4-d and 28-d exposures), and a fish (fathead minnow, Pimephales promelas; 4-d and 34-d exposures). Among the 4 species, the cladoceran and mussel were acutely more sensitive to sulfate than the midge and fathead minnow, whereas the fathead minnow was chronically more sensitive than the other 3 species. Acute-to-chronic ratios ranged from 2.34 to 5.68 for the 3 invertebrates but were as high as 12.69 for the fish. The fathead minnow was highly sensitive to sulfate during the transitional period from embryo development to hatching in the diluted well water, and thus, additional short-term (7- to 14-d) sulfate toxicity tests were conducted starting with embryonic fathead minnow in test waters with different ionic compositions at a water hardness of 100 mg/L. Increasing chloride in test water from 10 mg Cl/L to 25 mg Cl/L did not influence sulfate toxicity to the fish, whereas increasing potassium in test water from 1 mg K/L to 3 mg K/L substantially reduced the toxicity of sulfate. The results indicate that both acute and chronic sulfate toxicity data, and the influence of potassium on sulfate toxicity to fish embryos, need to be considered when environmental guidance values for sulfate are developed or refined., (Published 2015 SETAC. This article is a US Government work and is in the public domain in the United States.)

Chronic toxicity of cadmium, copper, lead, or zinc to white sturgeon (Acipenser transmontanus) and rainbow trout (Oncorhynchus mykiss) was evaluated in water-only exposures started with newly hatched larvae or approximately 1-mo-old juveniles. The 20% effect concentration (EC20) for cadmium from the sturgeon tests was higher than the EC20 from the trout tests, whereas the EC20 for copper, lead, or zinc for the sturgeon were lower than those EC20s for the trout. When the EC20s from the present study were included in compiled toxicity databases for all freshwater species, species mean chronic value for white sturgeon was in a relatively low percentile of the species sensitivity distribution for copper (9th percentile) and in the middle percentile for cadmium (55th percentile), zinc (40th percentile), or lead (50th percentile). However, the species mean chronic value for rainbow trout was in a high percentile for copper, lead, and zinc (∼68th-82nd percentile), but in a low percentile for cadmium (23rd percentile). The trout EC20s for each of the 4 metals and the sturgeon EC20s for cadmium or lead were above US Environmental Protection Agency chronic ambient water quality criteria (AWQC) or Washington State chronic water quality standards (WQS), whereas the sturgeon EC20s for copper or zinc were approximately equal to or below the chronic AWQC and WQS. In addition, acute 50% effect concentrations (EC50s) for copper obtained in the first 4 d of the chronic sturgeon test were below the final acute value used to derive acute AWQC and below acute WQS for copper., (Published 2014 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.)