Influence of parasitism in dogs on their serum levels of persistent organochlorine compounds and polycyclic aromatic hydrocarbons

Biomonitoring of organic pollutants in pet dog plasma samples in North-Western Spain

Most of organic pollutants (OPs) have the ability to interfere with biological systems causing negative effects in living beings, including humans. In the last decades, pets have been used as bioindicators of human exposure because they share the same habitat with their homeowners. We sought to determine levels of approximately 70 OPs, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated biphenyl ethers (PBDEs), organophosphate pesticides (OPPs), polycyclic aromatic hydrocarbons (PAHs) and pyrethroids (PYRs) in plasma samples from 39 pet dogs from Ourense (north-western Spain). The results revealed that PAHs were the dominant OPs (mean value 175 ± 319 ng/g lipid weight (lw)), followed by PYRs (132 ± 352 ng/g lw), PCBs (122 ± 96 ng/g lw), OCPs (33 ± 17 ng/g lw), PBDEs (19 ± 18 ng/g lw) and OPPs (2.1 ± 2.7 ng/g lw) in plasma samples. We have previously detected the target OPs in hair samples of pets, collected simultaneously and similar trend of some OPs has been observed. Moreover, pyrene and chrysene showed correlations between levels detected in both matrices.

Bioaccumulation of additives and chemical contaminants from environmental microplastics in European seabass (Dicentrarchus labrax)

Marine microplastic pollution is one of the biggest environmental problems we face. The growth of plastic production has not ceased since the 1950s and it is currently estimated that 368 tons of plastic were produced in 2019 (PlascticsEurope, 2020). Geyer et al. (2017) estimate that 79% of the plastic produced in the world still remains in the environment; this plastic due to the effect of degradation and subsequent fragmentation, is present in the form of microplastics in all oceans and, due to its small size can be ingested by fish and filter-feeding organisms. In addition, microplastics have additives and chemical contaminants associated with them, and the potential effect of microplastic ingestion on marine organisms, and through them, the potential risk to humans, is unknown. In the present study, European seabass (Dicentrarchus labrax) were fed for 60 days with three treatments: Control (feed), MP (feed with 10% virgin microplastics) and EMP (feed with 10% environmental microplastics), being the first study to evaluate long-term accumulation of contaminants due to ingestion of environmental microplastics (EMP) in fish. Both plastic additives such as PBDEs, and chemical contaminants adsorbed from the environment such as PCBs and DDE, were analyzed in the EMP, feed and liver. The concentration of microplastics in the feed was calculated based on the MPs/zooplankton wet weight (WW) ratio of 0.1 found in an area of maximum accumulation in the Canary Islands. Therefore, it is an experiment that simulates real conditions, but in the worst-case scenario, using both, concentrations based on data obtained in oceanographic campaigns and microplastics collected from the environment. Our results show that in this scenario, additives and chemical contaminants adsorbed on EMPs bioaccumulate in fish liver due to long-term ingestion of microplastics.

Benefits of Parasitism in Polluted Environments: A Review and Perspectives

The frequency and strength of biotic interactions are thought to be shaped by environmental conditions. In this study, we reviewed and discussed the potential effects of toxic chemicals in driving shifts along the parasite-mutualist continuum. Some parasites have the astonishing capacity to accumulate trace metals and organic pollutants from various taxa within freshwater, marine, and terrestrial ecosystems. Recent studies have provided evidence of clear benefits for the host: when exposed to contaminants, infected organisms exhibited reduced contamination levels, less severe oxidative stress, and histological alterations, as well as higher body condition and survival rate compared with their uninfected conspecifics. Such effects might arise when the costs of parasitism are lower than their benefits in specific environmental conditions. Assessing the potential outcomes for parasites exploiting contaminated hosts is a crucial but neglected issue, since ecotoxicological effects on parasites may alter interspecific relationships. We identified possible avenues for future research using innovative tools and long-term experimental manipulations of both parasitism and pollution to better understand how toxic chemicals can modulate the strength and direction of host-parasite interactions.

Human biomonitoring of persistent organic pollutants in elderly people from the Canary Islands (Spain): A temporal trend analysis from the PREDIMED and PREDIMED-Plus cohorts

The population of the Canary Islands has been exposed to high levels of persistent organic pollutants (POPs). Biomonitoring studies are essential to know the temporal trend in residue levels, particularly of substances banned decades ago. The purpose of this study was to analyze the distribution of plasma concentrations of 59 POPs in 175 participants from the PREDIMED-Plus trial (2014-2016), and to compare them with the distribution of these POPs in 343 participants in the PREDIMED trial (2006-2009). All participants had metabolic syndrome. No difference in the distribution of age, gender or BMI was observed between trials. POPs were determined by gas chromatography-mass spectrometry. Density plots -POP Geoffrey Rose curves- were used to represent the full population distribution of each compound. Three out of 59 POPs were detected and quantified in ≥95% of the samples (p,p'-DDE, median = 694.7 ng/g lipid; HCB, median = 57.0 ng/g lipid; and β-HCH, median = 75.7 ng/g lipid). PCB congeners 138, 153 and 180 were detected in 64.6, 40.0 and 88.0% of the samples. Females showed highest concentrations of organochlorine pesticides and those subjects who lost ˃ 5 kg showed significant higher plasma concentrations of POPs. In a range of 6-14 years, plasma concentrations of POPs decreased 3.3-21.6 fold, being notable the decrease of 28.7-fold observed for HCB among women. Despite this sharp decline, levels of POPs are still higher than those reported in other regions, since one third of the subjects included in the present report had high concentration of more than three pollutants. Continuous biomonitoring studies are required to know the evolution of the levels of residues and to evaluate the effectiveness of environmental policies.

Levels of polychlorinated biphenyls and organochlorine pesticides in donkey milk: Correlation with the infection level by intestinal strongyles

AIM

The study aimed at evaluating the concentration levels of organochlorine pollutants in donkey milk and their modulation on the intestinal strongyle infection. Risk evaluation for consumer health was also investigated.

METHODS

We analyzed milk of grazing donkeys living in areas of Southern of Italy affected by organochlorine compounds environmental pollution and parasite infection. The presence of pollutants was assessed through summary statistics; regression analysis of intestinal strongyle on pollutant concentration was performed to investigate the relationship between the two variables.

RESULTS

PCB concentrations (mainly non-dioxin-like (ndl)-PCBs) were higher than OCP ones. Mean values of ndl-PCBs across areas ranged from 93.13 to 263.64 ng g^-1. In all sample units we detected the six indicator PCBs with the prevalence of the PCB 153, followed by the PCB 28 and the PCB 101. Among the dioxin-like (dl)-PCBs, non-ortho PCB 169, 77 and 126 were assessed in some milk samples; in all areas we detected the mono-ortho PCB 118 and PCB 105. Positive correlation between infection level and six indicator PCBs as well as between the former and HCB, on WW and LW, were observed (at least statistically significant at 5 percent). In some cases, Dl-PCB concentrations emerged as dangerous given the EU maximum residue limit for PCDD/Fs and dl-PCBs.

CONCLUSION

Evidence supports the hypothesis of an immunosuppressive role of organochlorine pollutants; risk evaluation reveals the potential health impact of dl-PCB intake, particularly for major donkey milk consumers such as infants, children with cow milk and multiple food intolerance, and elders.

Potential Benefits of Acanthocephalan Parasites for Chub Hosts in Polluted Environments

Some parasites are expected to have beneficial impacts on wild populations in polluted environments because of their bioaccumulation potential of pollutants from their hosts. The fate of organic micropollutants in host-parasite systems and the combined effect of parasitism and pollution were investigated in chub Squalius cephalus, a freshwater fish, infected (n = 73) or uninfected (n = 45) by acanthocephalan parasites Pomphorhynchus sp. from differently contaminated riverine sites. Several ubiquitous pollutants (polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl-ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), phthalates, insecticides, pyrethroids, and N,N-diethyl-meta-toluamide (DEET)) and some of their metabolites were characterized for the first time in parasites and various fish matrices (muscle, liver, and stomach content). Most organic pollutants reached higher levels in parasites than in chub matrices. In contrast, metabolite levels were lower in parasite tissues compared to fish matrices. Infected and uninfected chub exhibited no significant differences in their pollutant load. Body condition, organo-somatic indices, and immunity were not affected by parasitism, and few correlations were found with chemical pollution. Interestingly, infected chub exhibited lower oxidative damage compared to uninfected fish, irrespective of their pollutant load. In light of these results, this correlative study supports the hypothesis that acanthocephalan parasites could bring benefits to their hosts to cope with organic pollution.

Association between prenatal exposure to multiple persistent organic pollutants (POPs) and growth indicators in newborns

Despite the fact that many of persistent organic pollutants (POPs) have been banned for decades, they still constitute a group of harmful substances to human health. Prenatal exposure can have adverse effects on one's health as well as on their newborns. The present cross-sectional study, which includes 87% of the births registered in La Palma Island (Canary Islands, Spain) during 2016 (n = 447), aims to evaluate the potential adverse health effects exerted by a wide range of POPs on newborns. We quantified blood cord levels of twenty organochlorine pesticides, eighteen polychlorinated biphenyls (PCBs), eight bromodiphenyl ethers (BDEs), and sixteen polycyclic aromatic hydrocarbons (PAHs) using the method of gas chromatography-mass spectrometry. By groups, p,p'-DDE, PCB-28, BDE-47, and phenanthrene were the most frequently detected compounds (median values = 0.148, 0.107, 0.065, and 0.380 ng/mL, respectively). p,p'-DDE was found to be significantly associated with an increase in neonatal birth weight, with a special emphasis on girls. An inverse association between PCB-28 and PCB-52 with birth weight was observed, and these associations were determined by the gender. A similar trend was obtained for BDE-47 but not for any of the PAHs. When assessing the effect of mixtures, boys exhibiting ≥ 3 OCPs were at lower risk of having higher birth weight (OR = 0.25; 95% CI = 0.07 - 0.89; P = 0.032). The effect of these pollutants on birth weight does not go in the same direction, a fact that is conditioned by several factors, including the chemical nature of the substance or the gender of the newborn. Additional research is needed to understand the role of POPs on fetal development.

Body burden of organohalogenated pollutants and polycyclic aromatic hydrocarbons in Romanian population: Influence of age, gender, body mass index, and habitat

Persistent organochlorine pollutants (POPs) are highly lipophilic and resistant to degradation, hence these substances are commonly found in the environment even decades after their prohibition. The aim of the present study was to determine human serum concentrations of POPs and polycyclic aromatic hydrocarbons (PAHs) in the Romanian population, investigating the role of demographic variables on the body burden of such chemicals. A cross-sectional study including a total of 121 subjects from Brasov (Transylvania region) was designed. The concentration of 62 chemicals, including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (BDEs) and PAHs, was measured by gas chromatography-mass spectrometry (GC-MS) in the serum of the participants. p,p'-DDE and β-HCH were detected in 100% and 62% of the series (median values = 2.1 and 0.5 μg/L); PCB-153 was detected in 77.7% of the subjects and PCB-28 showed the highest median concentration (0.5 μg/L); BDE-47 was detected at a low concentration in 11.6% of the individuals; phenanthrene and naphthalene were present in 98.3% and 38.8% of the serum samples (median values = 0.9 and 6.5 μg/L, respectively). Age was the main determinant of the total body burden of OCPs and PCBs. A positive correlation was observed between p,p'-DDE and age (Spearman Rho = 0.312, P < 0.0001), suggesting the prevalence of higher levels of pollutants at older ages. The present results showed a significant decrease in serum levels of p,p'-DDE and HCH in Romania -a country which has traditionally reported higher values than other Eastern European countries- as well as low levels of PCBs and BDEs. The presence of PAHs suggests an unknown source of exposure that deserves further investigation.

Supplemental feeding and other anthropogenic threats to green turtles (Chelonia mydas) in the Canary Islands

Green turtles are found in the waters of the Canary Islands but little is known about the ecology and anthropogenic pressures that threaten them. Our results have revealed that juvenile green turtles, ranging in curve carapace length from 26.9-81.0cm, are regularly found in the archipelago and originate from rookeries in both the eastern and western Atlantic. Photo-identification and satellite tracking showed high levels of site fidelity to coastal foraging grounds associated with seagrass meadows, but stable isotope analysis indicated animal-based omnivorous diets after settlement on the continental shelf, with no increase in the consumption of macrophytes as the turtles grew. Most turtles exhibited high levels of some blood biochemical markers associated with a high consumption of proteins and fat. In addition, we determined levels of some organic and inorganic pollutants. Supplemental feeding may also contribute to explain the high prevalence of hooking and boat strikes in the green turtles brought to wildlife rescue centers as compared with loggerhead turtles. Regulatory measures and surveillance should be urgently implemented in order to improve the status of the species in the archipelago.

Potential Role of Pet Cats As a Sentinel Species for Human Exposure to Flame Retardants

Flame retardants are a wide group of chemicals used by the industry to avoid combustion of materials. These substances are commonly found in plastics, electronic equipment, fabrics, and in many other everyday articles. Subsequently, ubiquitous environmental contamination by these common chemical is frequently reported. In the present study, we have evaluated the level of exposure to polychlorinated biphenyls (PCBs), brominated diphenyl ethers (BDEs), and organophosphorous flame retardants (OPFRs) in pet cats through the analysis of their serum. We also analyzed the level exposure to such chemicals in a series of 20 cat owners, trying to disclose the role of pet cats as sentinel species of human exposure to FRs. Our results showed that PCBs, banned 40 years ago, showed the lowest levels of exposure, followed by BDEs—banned recently. Congeners PCB-138 and PCB-180 were detected in ≥50% of the series, while BDE-47 was detected in near 90% of the pet cats. On the other hand, the highest levels were that of OPFRs, whose pattern of detection was similar to that observed in humans, thus suggesting a potential role of cats as a sentinel species for human exposure to these currently used FRs. Six out of 11 OPFRs determined [2-ethylhexyldiphenyl phosphate, tributylphosphate, triisobutylphosphate, triphenylphosphate, tris (2-chloroethyl) phosphate, and tris (2-chloroisopropyl) phosphate] were detected in 100% of the samples. It will be interesting to perform future studied aimed to elucidating the potential toxicological effects of these highly detected chemicals both, in cats and humans.

Comparative analysis of selected semi-persistent and emerging pollutants in wild-caught fish and aquaculture associated fish using Bogue (Boops boops) as sentinel species

The marine environment acts as a sink for diverse anthropogenic pollutants, although the environmental contamination may be non-uniformly distributed. In recent decades, the aquaculture sector has experienced a steady growth postulating as a good alternative for seafood production. However, a social debate exits about the differential level of pollutants in wild and farmed species. This study was designed to evaluate the level of pollutants in a sentinel species: Bogue (Boops boops) associated and non-associated to fish-farm cages. A total of 82 chemical substances were determined by gas chromatography-mass spectrometry, including persistent (polychlorobiphenyls (PCBs) and organochlorine pesticides (OCPs)), semi-persistent (bromodiphenyl ethers (BDEs) and polycyclic aromatic hydrocarbons (PAHs)), and emerging pollutants (such as organophosphate flame retardants (OPFRs) and UV-filters). In general, aquaculture-associated bogues showed lower levels of semi-persistent and emerging pollutants than wild-caught fish, especially when sums were considered. Thus, sum of BDEs was significantly lower in the aquaculture group (p=0.01). A similar trend was also observed for benzo(a)anthracene, the UV-filter 2-ethylhexyl-p-methoxycinnamate and some OPFRs. In the case of persistent pollutants, the sum of dioxin-like PCBs and sum of DDTs were lower in the group of wild-caught bogues (p=0.034 and p=0.003, respectively) than in aquaculture-associated bogues, as previously described for some aquaculture species. Fish feed appear as an important factor in the uptake of such substances suggesting a diet intervention to reduce their levels in the aquaculture products. Another interesting result is that for almost all chemical substances analyzed, bogues captured near sewage outfalls showed the highest levels of pollutants, pointing out the need of stringent measures for wastewater treatment units discharging in coastal areas. On the light of these results, further research in specific farmed and wild fish species in relation to their dietary value and pollutant's levels seems to be mandatory.

The heartworm (Dirofilaria immitis) seems to be able to metabolize organochlorine pesticides and polychlorinated biphenyls: A case-control study in dogs

It has been described that the co-existence of parasite infection and chemical exposure has various effects on the accumulation of persistent organochlorine pollutants (POPs) in the host. Certain parasites are not only able to accumulate POPs but also seem to have the ability to metabolize certain compounds. We have designed a case-control study aimed to disclose the role of Dirofilaria immitis in the bioavailability of POPs in dogs trying to know whether these parasites store or metabolize the POPs. A total of 40 common POPs (18 polychlorinated biphenyls congeners (PCBs) and 22 organochlorine pesticides were quantified in dog serum. The study included three groups of dogs prospectively recruited in the island of Gran Canaria (Canary Islands, Spain): a) control animals, non-parasitized (serologically tested negative, n=24); b) a group constituted by dogs tested positive for heartworm disease (D. immitis) and negative for other parasites (n=25); and c) the same group of parasitized dogs after the treatment against the parasite (n=25). The presence of D. immitis was strongly associated with lower serum levels of a wide range of pollutant in their hosts (PCB congeners 28, 105, 118, 123, 138, 153, 167 and 180; hexachlorobenzene, lindane, aldrin, dieldrin, and methoxychlor). The serum levels of these substances remained at very low levels after the treatment against the parasite, suggesting that D. immitis do not simply store such compounds, but they probably have some ability to metabolize these pollutants. We encourage the use of the parasite infestation status as a cofactor that needs to be taken into account in studies aimed to evaluate the serum levels of POPs.