It
is generally believed that Bacillus thuringiensis var. israelensis (Bti) biopesticides are harmless
to non-target organisms; however, new research shows controversial
results. We exposed acutely and chronicallyLithobates
sylvaticusandAnaxyrus americanus tadpoles until metamorphic climax to VectoBac 200G (granules) and
VectoBac 1200L (aqueous suspension) at 300–20,000 ITU/L covering
field-relevant concentrations and higher. The data show that the exposure
parameters tested did not affect significantly the survival, total
length, total weight, hepatosomatic index, gonadosomatic index, the
expression of genes of interest (i.e., related to xenobiotic exposure,
oxidative stress, and metamorphosis), and the intestine tissue layer
detachment ofL. sylvaticusandA. americanus in a concentration–response
pattern. In contrast, VectoBac 200G significantly increased the median
time to metamorphosis ofL. sylvaticus tadpoles by up to 3.5 days and decreased the median by up to 1 day
inA. americanus. VectoBac 1200L significantly
increased the median time to metamorphosis ofL. sylvaticusandA. americanustadpoles by up to
4.5 days. Also, the exposure to VectoBac 200G and 1200L altered the
intestine bacterial community composition inA. americanus at application rates recommended by the manufacturer, which led
to an increase in the relative abundance of Verrucomicrobia, Firmicutes,
Bacteroidetes, and Actinobacteria. Changes in the intestine microbiota
might impact the fitness of individuals, including the susceptibility
to parasitic infections. Our results indicate that the effect of Bti
commercial products is limited; however, we recommend that Bti-spraying
activities in amphibian-rich ecosystems should be kept minimal until
there is more conclusive research to assess if the changes in the
time to metamorphosis and microbiota can lead to negative outcomes
in amphibian populations and, eventually, the functioning of ecosystems.
Cytostatics are compounds used in chemotherapy, known to be genotoxic, mutagenic, and teratogenic at low concentrations. The amount of cytostatic drugs prescribed increases every year as does their release into the aquatic ecosystems, which possibly is a major concern for the health of aquatic organisms. This study aimed to evaluate the putative toxicity of five cytostatics to fathead minnow (Pimephales promelas) larvae: tamoxifen, capecitabine, methotrexate, cyclophosphamide, and ifosfamide. Eggs collected post-fertilization were exposed for 6 days to a range of concentrations, including one above environmental level. At all environmental concentrations, no significant difference in mortality, hatching time, length, heart rate, and presence of malformations were found. Altogether, these cytostatics seems not embryotoxic.Although, an increased proportion of complete swim bladder were found after ifosfamide's exposure, suggesting an interaction with the thyroid axis, involved in swim bladder development. Complementary work should address other endpoints, such as behavioral changes, reproductive success, and transgenerational effects.
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