Jesus Olivero-Verbel

Contact with the pesticide dichlorodiphenyltrichloroethane (p,p′-DDT) can be the cause of various harmful effects in humans, wildlife, and the environment. This pesticide is known to be persistent, lipophilic, resistant to degradation, and bioaccumulive in the environment and to be slowly released into bloodstream. Growing evidence shows that exposure to DDT is linked to type 2 diabetes mellitus. Individuals exposed to elevated levels of DDT and its metabolite have an increased prevalence of diabetes and insulin resistance. To evaluate these possible relationships, experiments were performed on eight-week-old female mice, divided into three groups (n = 10 per group): Group 1 received a vehicle-control intraperitoneal (i.p.) injection of sesame oil; Groups 2 and 3 received an i.p. dose of 50 and 100 µg/g p,p′-DDT respectively, dissolved in sesame oil. All groups were treated once daily for four days. Real-time PCR analysis of several genes was undertaken. Additionally, biochemical parameters and histopathological changes were measured. NQO1, HMOX1, NR1I3 and NR3C1 were up-regulated in DDT-exposed animals compared to the vehicle control group, while only SREBP1 was down-regulated in the 100 µg/g group. MTTP and FABP5, not previously reported for DDT exposure, but involved in regulation of fatty acid fluxes, could also function as biomarkers cross-talking between these signaling pathways. These results suggest that beyond epidemiological data, there is increasing molecular evidence that DDT may mimic different processes involved in diabetes and insulin resistance pathways.

Fish belonging to several trophic levels from Cartagena Bay, a tropical estuary, were collected and analyzed for total mercury (T-Hg) concentrations in muscle. T-Hg concentrations varied from 0.010–0.526 μg/g, and the overall average was 0.051 ± 0.002 μg/g. Carnivorous species presented the highest T-Hg mean value (0.100 ± 0.006 μg/g), followed by omnivorous (0.076 ± 0.014 μg/g) and detritivorous (0.028 ± 0.001 μg/g). The relationships between weight and T-Hg content were found for the carnivorous species Sciades herzbergi (r = 0.508, p < 0.001) and not for the detritivorous Mugil incilis (r = 0.086, p = 0.207). Although results suggest fish from the bay pose a low health threat for humans in terms of Hg exposure, vulnerable groups such as pregnant women, should avoid eating large size carnivorous species. Knowledge about species with low Hg content should be widespread within fishing communities, guaranteeing adequate nutrition by including fish in the diet and reducing the risk of Hg poisoning.

Mercury (Hg) used in gold amalgamation is a major source of contamination in developing countries. Water, sediments, plankton, fish, and human samples from Grande Marsh, a Hg-polluted marsh located in the south of Bolívar, municipality of Montecristo, Colombia, were collected during both the rainy and the dry seasons (2003–2006), at three different sampling sites, and analyzed for total Hg (T-Hg) content. Water, sediment, seston, phytoplankton, and zooplankton T-Hg concentrations were 0.33 ± 0.03 μg/L, 0.71 ± 0.03, 1.20 ± 0.06, 0.52 ± 0.03, and 0.94 ± 0.05 μg/g dry weight (wt), respectively. T-Hg levels in these compartments were highly pair-correlated (p < 0.05), and for all of them, except sediments, greater values were found during the dry season. Significant differences were observed for T-Hg concentrations in fish according to their trophic position. Average highest T-Hg values were found in carnivorous species such as Caquetaia kraussi (1.09 ± 0.17 μg/g fresh wt), Hoplias malabaricus (0.58 ± 0.05 μg/g fresh wt), and Plagioscion surinamensis (0.53 ± 0.07 μg/g fresh wt), whereas the lowest were detected in noncarnivorous species such as Prochilodus magdalenae (0.157 ± 0.01 μg/g fresh wt). In those fish species where seasonal comparisons were possible, specimens captured during the dry season had greater T-Hg levels in muscle. Although the T-Hg mean level for all fish samples (0.407 ± 0.360 μg/g fresh wt) did not exceed the recommended limit ingestion level, risk assessment based on the hazard index suggested that a fish intake of 0.12 kg per day (a small carnivorous specimen) could increase the potential health effects related to Hg exposure in the local human population, whose hair T-Hg median value was 4.7 μg/g, and presented a low but significant correlation with fish consumption (r = 0.250, p = 0.016). In short, Hg pollution from gold mining around Grande Marsh has permeated the food web, and currently levels in fish represent a serious concern for human health.

Nematode infection indices were recorded in Lisa, Mugil incilis, from Cartagena Bay and Totumo Marsh, north of Colombia, during an 8-mo period (February to September 2002). Parasite prevalence (74.67% vs. 53.48%), intensity (9.73 +/- 2.98 vs. 2.73 +/- 1.07), and abundance (7.49 +/- 2.21 vs. 2.04 +/- 1.17) were significantly greater in Cartagena Bay, an estuary polluted by domestic sewage and industrial discharge, compared with those of Totumo Marsh, a body of water with low levels of contamination. Parasites were found below the spine, within the liver and the intestinal mesenteries, and a small percentage in muscle. Morphological analysis of nematodes indicated the presence of the third larval stage of several species belonging to the Anisakidae. Size correlated moderately and significantly with parasite intensity in fish collected from Totumo Marsh (R = 0.336; P < 0.001); in Cartagena Bay the correlation was also significant, but low and negative (R = -0.212; P = 0.003), clearly showing differences in host-parasite ecology. Fish health status, as represented by condition factor and hepatosomatic index, did not show any correlation with the parasite prevalence in fishes collected in either sampling areas. These results suggest, for the first time, that the consumption of Lisa from the Atlantic coast of Colombia could represent a risk for human infection.