Effects of cis-nonachlor, trans-nonachlor and chlordane on the immune system of Sprague-Dawley rats following a 28-day oral (gavage) treatment

Chlordane exposure impairs the growth and behavior of Drosophila

Chlordane, a previously extensively utilized insecticidal pesticide, has since been prohibited, however, owing to its limited degradability, it continues to persist significantly in soil and water reservoirs, subsequently accumulating within plant and animal organisms, representing a substantial threat to human health. Despite extensive research conducted over the past few decades to investigate the toxic effects of chlordane, there remains a notable dearth of studies focusing on its impact on sleep activity. Therefore, in this study, the effects of short-term and long-term exposure to chlordane on the activity and sleep of Drosophila were investigated. When exposed to chlordane at a concentration of 1 μM, Drosophila lost body weight, decreased body size and resulted in lipid metabolism disorders. In addition, chlordane exposure altered the arousal and sleep behaviors of Drosophila. Short-term exposure to chlordane resulted in an increase in night-time sleep duration, while long-term exposure to chlordane resulted in an increase in activity and a decrease in sleep, as evidenced by a decrease in the duration of each sleep session and the appearance of sleep fragmentation. Under conditions of long-term chlordane exposure, reactive oxygen species levels were significantly up-regulated in Drosophila. Our results suggest that long-term chlordane exposure triggers oxidative stress damage in Drosophila, leading to sleep disruption. This study offers novel insights into the harmful impacts of environmental pollutants on human sleep patterns and proposes that mitigating the presence of chlordane in the environment could potentially contribute to the reduction of global sleep disorder prevalence.

POPs in long-finned pilot whales mass stranded in Iceland as a proxy for their physiological condition

Long-finned pilot whales (Globicephala melas) are the most frequently stranded cetaceans in the world; however, the predominant drivers of these events are poorly understood. In this study the levels of persistent organic pollutants from pilot whales stranded in North-east Iceland were quantified and compared to historical data and physical parameters to investigate whether contaminant load may have influenced the physiological state of stranded individuals, how these loads fluctuate with sex and age group, and if this is consistent with the literature. Historical comparison was also carried out to discern how pollutant contamination has changed throughout the past few decades. DDE, transnonachlor and PCB-153 were the top three pollutants respectively. The accumulation of POPs was greater on average in immature individuals than adults, whilst among adults, males had higher concentration than females. Moreover, despite an indication of decreasing POP loads throughout the years, knowledge of harmful thresholds remains exceedingly limited.

Contributing factors common to COVID‑19 and gastrointestinal cancer

The devastating complications of coronavirus disease 2019 (COVID-19) result from the dysfunctional immune response of an individual following the initial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Multiple toxic stressors and behaviors contribute to underlying immune system dysfunction. SARS-CoV-2 exploits the dysfunctional immune system to trigger a chain of events, ultimately leading to COVID-19. The authors have previously identified a number of contributing factors (CFs) common to myriad chronic diseases. Based on these observations, it was hypothesized that there may be a significant overlap between CFs associated with COVID-19 and gastrointestinal cancer (GIC). Thus, in the present study, a streamlined dot-product approach was used initially to identify potential CFs that affect COVID-19 and GIC directly (i.e., the simultaneous occurrence of CFs and disease in the same article). The nascent character of the COVID-19 core literature (~1-year-old) did not allow sufficient time for the direct effects of numerous CFs on COVID-19 to emerge from laboratory experiments and epidemiological studies. Therefore, a literature-related discovery approach was used to augment the COVID-19 core literature-based ‘direct impact’ CFs with discovery-based ‘indirect impact’ CFs [CFs were identified in the non-COVID-19 biomedical literature that had the same biomarker impact pattern (e.g., hyperinflammation, hypercoagulation, hypoxia, etc.) as was shown in the COVID-19 literature]. Approximately 2,250 candidate direct impact CFs in common between GIC and COVID-19 were identified, albeit some being variants of the same concept. As commonality proof of concept, 75 potential CFs that appeared promising were selected, and 63 overlapping COVID-19/GIC potential/candidate CFs were validated with biological plausibility. In total, 42 of the 63 were overlapping direct impact COVID-19/GIC CFs, and the remaining 21 were candidate GIC CFs that overlapped with indirect impact COVID-19 CFs. On the whole, the present study demonstrates that COVID-19 and GIC share a number of common risk/CFs, including behaviors and toxic exposures, that impair immune function. A key component of immune system health is the removal of those factors that contribute to immune system dysfunction in the first place. This requires a paradigm shift from traditional Western medicine, which often focuses on treatment, rather than prevention.

Agricultural Pesticides and Shingles Risk in a Prospective Cohort of Licensed Pesticide Applicators

BACKGROUND

Some pesticides are immunotoxic and have been associated with an increased risk of immune-mediated diseases. The risk of shingles, the clinical reactivation of varicella-zoster virus, increases with aging and immunosuppression; little is known about its associations with pesticides.

OBJECTIVE

We examined the use of agricultural pesticides in relation to incident shingles in a prospective cohort of licensed pesticide applicators.

METHODS

The study sample included 12,820 (97% male) farmers (enrolled in 1993-1997 in North Carolina and Iowa), who were followed for a median of 12 y (interquartile range: 11-13). Shingles was self-reported at enrollment and at follow-up. We evaluated ever-use of 48 agricultural pesticides reported at study enrollment in relation to shingles risk and considered exposure-response for intensity-weighted lifetime days (IWLDs) of use. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazard models, adjusting for state, and allowing estimates to vary by median attained age (60 y).

RESULTS

Incident shingles was reported by 590 participants. Associations were positive (HRs>1.2) for ever- vs. never-use of eight insecticides, three fumigants, two fungicides, and five herbicides, and exposure-response trends were seen across increasing quartiles (Q3 and Q4>Q1) or tertiles (T3 and T2>T1) of IWLDs for four insecticides [permethrin (crops), coumaphos, malathion, and lindane], two fumigants (carbon tetrachloride/carbon disulfide and methyl bromide), and three herbicides [alachlor, trifluralin (<60 years of age) and 2,4-dichlorophenoxyacetic acid]. Shingles was not associated with total years or days per year mixed or applied any pesticides, but in older participants, shingles was associated with a history of a high pesticide exposure event [HR=1.89 (95% CI: 1.45, 2.45)].

CONCLUSIONS

Several specific pesticides were associated with increased risk of shingles in farmers, especially at higher levels of cumulative use. These novel findings, if replicated in other populations, could have broader implications for the potential effects of pesticides on vaccine efficacy and susceptibility to other infections. https://doi.org/10.1289/EHP7797.

Thyroid disrupting pesticides mancozeb and fipronil in mixture caused oxidative damage and genotoxicity in lymphoid organs of mice

The interference in endocrine signaling in particular of hypothyroid-pituitary-thyroid axis during embryonic/neonatal development increases the risk of long-lasting immune dysfunctioning. Anticipating that, environmentally realistic exposure of established thyroid disrupting pesticides of dithiocarbamate group mancozeb and phenylpyrazole fipronil was given to mice as individual and as mixtures (MIX-I/MIX-II) during the critical initiation phase of the immune response from postnatal day (PND) 31 till PND 60 (maturation phase). The direct exposure effect was assessed at PND 61 and the persistent effect was assessed at PND 91. Pronounced oxidative stress/genotoxicity in lymphoid organs at even low dose mixture exposure of pesticides (MIX-I/ MIX-II) continued to suppress the immune system till adulthood; might be due to the synergistic/additive action. The oxidative stress/genotoxicity effect was prevented on T4 supplementation to inhibit immunotoxicity as T4 is an immune enhancer and antioxidants. Oxidative stress/genotoxicity is suggested as a mechanism of thyroid disruption mediated immune suppression.

Prediagnostic serum concentrations of organochlorine pesticides and non-Hodgkin lymphoma: A nested case-control study in the Norwegian Janus Serum Bank Cohort

BACKGROUND

Much of the marked increase in incidence of non-Hodgkin lymphoma (NHL) over the past few decades remains unexplained. Organochlorines, including organochlorine pesticides (OCPs), have been implicated as possible contributors to the increase, but the evidence is inconsistent.

OBJECTIVES

To investigate the relation between pre-diagnostic levels of OCPs and risk of NHL in a case-control study nested within the population-based Janus Serum Bank Cohort in Norway.

METHODS

Prediagnostic concentrations of 11 OCPs or OCP metabolites were measured in baseline blood samples collected between 1972 and 1978 from 190 cases and 190 controls matched on sex, county, age at blood draw, and date of blood draw. We conducted conditional logistic regression to estimate adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) for each quartile of lipid-corrected OCP/metabolite relative to the lowest quartile.

RESULTS

We observed non-significantly elevated ORs across quartiles of β-hexachlorocyclohexane compared to the lowest quartile (OR range: 1.40-1.82) although with no apparent monotonic exposure-response relationship. We also found an inverse association between risk of NHL and o,p'-DDT (OR for Q₄ vs. Q₁ = 0.44, 95% CI: 0.19, 1.01; p-trend = 0.05). In analyses stratified by age at blood collection and duration of follow-up, several other analytes, primarily chlordane-related compounds, showed inverse associations among younger participants or those with longer follow-up time between blood draw and NHL diagnosis.

CONCLUSIONS

We found only limited evidence of positive association between selected OCPs and development of NHL.

Contaminant Exposure Linked to Cellular and Endocrine Biomarkers in Southern California Bottlenose Dolphins

Cetaceans in the Southern California Bight (SCB) are exposed to high levels of halogenated organic contaminants (HOCs), which have previously been linked to impaired reproductive health and immune responses. We used a combination of molecular tools to examine the potential physiological impacts of HOC exposure in two bottlenose dolphin ( Tursiops truncatus) ecotypes in the SCB. We quantified 25 HOCs in the blubber of 22 biopsies collected from males between 2012 and 2016. We then analyzed genome-wide gene expression in skin using RNA-sequencing and measured blubber testosterone to compare HOC exposure with cellular and endocrine biomarkers. We found high levels of HOCs in both ecotypes with significantly higher total polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), tris(4-chlorophenyl)methanol (TCPMOH), and chlordane-related compounds in the coastal ecotype versus the offshore ecotype. We found evidence of PBDE bioaccumulation in both ecotypes, however, the pattern of bioaccumulation or endocrine disruption for other HOCs was different between the ecotypes, suggesting potential endocrine disruption in the coastal ecotype. We also observed correlations between HOCs and gene coexpression networks enriched for xenobiotic metabolism, hormone metabolism, and immune response that could indicate cellular effects from HOC exposure. By integrating measurements of HOC load with both transcriptome profiling and endocrine biomarkers, our approach provides insight into HOC exposure and potential impacts on wild cetacean health in southern California.

Pre-diagnostic serum concentrations of organochlorines and risk of acute myeloid leukemia: A nested case-control study in the Norwegian Janus Serum Bank Cohort

BACKGROUND

Epidemiologic studies suggest an increased risk of leukemia among individuals occupationally exposed to some organochlorine (OC) compounds. Associations between serum OC pesticide and polychlorinated biphenyl (PCB) levels and risk of acute myeloid leukemia (AML), the most common subtype of acute leukemia in adult populations, have not been evaluated prospectively in the general population.

OBJECTIVE

We evaluated the risk of AML in relation to pre-diagnostic serum levels of OC pesticides and PCBs in a case-control study nested within the Janus Serum Bank Cohort.

METHODS

Janus is a large population-based cohort containing biologic samples collected beginning in the early 1970s from ~318,000 individuals in Norway. Serum levels of 11 OC pesticides or their metabolites and 34 PCB congeners were measured in 56 AML cases and 288 controls. Conditional logistic regression was conducted to evaluate associations between lipid-adjusted serum OC levels and risk of AML.

RESULTS

Higher serum levels of total chlordane/heptachlor metabolites were associated with AML risk (3rd vs. 1st tertile odds ratio (OR) = 2.26, 95% confidence interval (CI) = 0.91-5.63; p_trend = 0.11). Significant exposure-response associations were observed for levels of heptachlor epoxide (3rd vs. 1st tertile OR = 2.85, 95% CI = 1.05-7.73; p_trend = 0.02) and dieldrin (3rd vs. 1st tertile OR = 2.71, 95% CI = 1.07-6.83; p_trend = 0.03). No significant exposure-response associations with AML risk were observed for total DDT or individual isomers and derivatives. Higher serum levels of p,p'-DDT showed a non-significant increase in risk, but the exposure-response became attenuated when co-adjusting for heptachlor epoxide or dieldrin levels. Serum PCB levels were not significantly associated with AML risk.

CONCLUSIONS

Our data suggest that higher serum levels of dieldrin and metabolites derived from chlordane/heptachlor are associated with risk of AML in the general Norwegian population, based on samples collected on average ~17 years before diagnosis. Further research in populations with historically high or recent exposure to DDT is warranted to assess the association with AML risk with body burden of specific DDT isomers and derivatives.

Effects of cross-fostering and developmental exposure to mixtures of environmental contaminants on hepatic gene expression in prepubertal 21 days old and adult male Sprague-Dawley rats

The notion that adverse health effects produced by exposure to environmental contaminants (EC) may be modulated by the presence of non-chemical stressors is gaining attention. Previously, our lab demonstrated that cross-fostering (adoption of a litter at birth) acted as a non-chemical stressor that amplified the influence of developmental exposure to EC on the glucocorticoid stress-response in adult rats. Using liver from the same rats, the aim of the current study was to investigate whether cross-fostering might also modulate EC-induced alterations in hepatic gene expression profiles. During pregnancy and nursing, Sprague-Dawley dams were fed cookies laced with corn oil (control, C) or a chemical mixture (M) composed of polychlorinated biphenyls (PCB), organochlorine pesticides (OCP), and methylmercury (MeHg), at 1 mg/kg/day. This mixture simulated the contaminant profile reported in maternal human blood. At birth, some control and M treated litters were cross-fostered to form two additional groups with different biological/nursing mothers (CC and MM). The hepatic transcriptome was analyzed by DNA microarray in male offspring at postnatal days 21 and 78-86. Mixture exposure altered the expression of detoxification and energy metabolism genes in both age groups, but with different sets of genes affected at day 21 and 78-86. Cross-fostering modulated the effects of M on gene expression pattern (MM vs M), as well as expression of energy metabolism genes between control groups (CC vs C). In conclusion, while describing short and long-term effects of developmental exposure to EC on hepatic transcriptomes, these cross-fostering results further support the consideration of non-chemical stressors in EC risk assessments.

Risk Factors Associated with Mortality of Age-0 Smallmouth Bass in the Susquehanna River Basin, Pennsylvania

Evidence of disease and mortalities of young of the year (age-0) Smallmouth Bass Micropterus dolomieu has occurred during the late spring and summer in many parts of the Susquehanna River watershed since 2005. To better understand contributing factors, fish collected from multiple areas throughout the watershed as well as out-of-basin reference populations (Allegheny and Delaware River basins; experimental ponds, Kearneysville, West Virginia) were examined grossly and histologically for abnormalities. Tissue contaminant concentrations were determined from whole-body homogenates, and water contaminant concentrations were estimated using time-integrated passive samplers at selected sites. Observed or isolated pathogens included bacteria, predominantly motile Aeromonas spp. and Flavobacterium columnare; largemouth bass virus, and parasites, including trematode metacercariae, cestodes, and the myxozoan Myxobolus inornatus. Although these pathogens were found in age-0 Smallmouth Bass from multiple sites, no one pathogen was consistently associated with mortality. Chemicals detected in tissue included polychlorinated biphenyl (PCB) congeners, organochlorine, and current-use pesticides. Pyraclostrobin, PCB congeners 170 and 187, cis-chlordane and trans-nonachlor were detected in all Susquehanna watershed samples but rarely in samples from the reference site. The findings support the idea that there is no single cause for disease of age-0 Smallmouth Bass; rather the cumulative effects of co-infections and potential immunomodulation by environmental stressors during a sensitive developmental life stage may lead to mortality. Identifying the most important risk factors will be necessary for more in-depth analyses of individual stressors and better management of the habitat and fish populations.

Association of in utero exposure to organochlorine pesticides with thyroid hormone levels in cord blood of newborns

Organochlorine pesticides (OCPs) had been widely used in agriculture and disease prevention from the 1940s-1960s. Currently, OCPs are raising global concerns due to their associated prevalent contamination and adverse health effects, such as endocrine disruption. Several epidemiological studies have explored the underlying association of OCPs on thyroid hormone (TH) status in adults and newborns, but the results of studies performed on newborns are often inconclusive. This exploratory study was conducted with the purpose of assessing the potential association of the prenatal exposure to OCPs with the concentrations of TH in the cord blood of newborns from China. Cord blood and information on demographic characteristics were collected from 115 newborns between November 2013 and June 2014. The exposure levels of 17 OCPs were measured with a gas chromatography/mass spectrometry, and TH levels including free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) were detected using electrochemiluminescence immunoassay methods. After adjusting for confounding factors (the age of pregnant mothers, education level, monthly household income, parity, and sex of the newborns), we found marginally significant inverse associations of cord plasma measurements of ∑hexachlorcyclohexanes (∑HCHs), 1,1-dichloro-2,2-di(4-chlorophenyl)ethylene (ρ,ρ'-DDE) and methoxychlor with FT4 levels, but not with FT3 and TSH levels. Moreover, higher cord plasma levels of aldrin, dieldrin, ∑dichlorodiphenyltrichloroethanes (∑DDTs), ∑Drins, and ∑OCPs were found to be related to the increase in cord plasma TSH levels after the adjustment for confounders. The results of this exploratory study indicate that in utero exposure to certain OCPs may affect TH status in newborns, and therefore, pose potential effects on early human development. Further research, with larger sample sizes, should be conducted to confirm these findings.

Exposure to organochlorine pesticides and non-Hodgkin lymphoma: a meta-analysis of observational studies

Growing evidence indicates that exposure to organochlorine pesticides (OCPs) could increase non-Hodgkin lymphoma (NHL) risk. However, results from epidemiological studies investigating this association remain controversial. We thus conducted a meta-analysis to quantitatively evaluate the association between OCP exposure and NHL risk. Relevant publications were searched in PubMed, Web of Science, and Embase and identified according to the inclusion criteria. Thirteen studies (6 nested case-control, 1 case-cohort, and 6 case-control) were selected for this meta-analysis. We used odds ratios (ORs) with 95% confidence intervals (CIs) to estimate the relationship between OCPs exposure and NHL risk. The summary OR for included studies was 1.40 (95% CI 1.27 to 1.56). No overall significant heterogeneity in the OR was observed (Ph = 0.253, I(2) = 12.6%). Furthermore, OR estimates in subgroup analyses were discussed, and strong associations were observed for dichlorodiphenyldichloroethylene (DDE, OR = 1.38, 95% CI 1.14 to 1.66), hexachlorocyclohexane (HCH, OR = 1.42, 95% CI 1.08 to 1.87), chlordane (OR = 1.93, 95% CI 1.51 to 2.48), and hexachlorobenzene (HCB, OR = 1.54, 95% CI 1.20 to 1.99). This meta-analysis had suggested that total OCPs of interest was significantly positively associated with NHL risk.

Organochlorine insecticides induce NADPH oxidase-dependent reactive oxygen species in human monocytic cells via phospholipase A2/arachidonic acid

Bioaccumulative organohalogen chemicals, such as organochlorine (OC) insecticides, have been increasingly associated with disease etiology; however, the mechanistic link between chemical exposure and diseases, such as atherosclerosis, cancer, and diabetes, is complex and poorly defined. Systemic oxidative stress stemming from OC exposure might play a vital role in the development of these pathologies. Monocytes are important surveillance cells of the innate immune system that respond to extracellular signals possessing danger-associated molecular patterns by synthesizing oxyradicals, such as superoxide, for the purpose of combating infectious pathogens. We hypothesized that OC chemicals can be toxic to monocytes because of an inappropriate elevation in superoxide-derived reactive oxygen species (ROS) capable of causing cellular oxidative damage. Reactive oxyradicals are generated in monocytes in large part by NADPH oxidase (Nox). The present study was conducted to examine the ability of two chlorinated cyclodiene compounds, trans-nonachlor and dieldrin, as well as p,p'-DDE, a chlorinated alicyclic metabolite of DDT, to stimulate Nox activity in a human monocytic cell line and to elucidate the mechanisms for this activation. Human THP-1 monocytes treated with either trans-nonachlor or dieldrin (0.1-10 μM in the culture medium) exhibited elevated levels of intracellular ROS, as evidenced by complementary methods, including flow cytometry analysis using the probe DCFH-DA and hydroethidine-based fluorometric and UPLC-MS assays. In addition, the induced reactive oxygen flux caused by trans-nonachlor was also observed in two other cell lines, murine J774 macrophages and human HL-60 cells. The central role of Nox in OC-mediated oxidative stress was demonstrated by the attenuated superoxide production in OC-exposed monocytes treated with the Nox inhibitors diphenyleneiodonium and VAS-2870. Moreover, monocytes challenged with OCs exhibited increased phospho-p47(phox) levels and enhanced p47(phox) membrane localization compared to that in vehicle-treated cells. p47(phox) is a cytosolic regulatory subunit of Nox, and its phosphorylation and translocation to the NOX2 catalytic subunit in membranes is a requisite step for Nox assembly and activation. Dieldrin and trans-nonachlor treatments of monocytes also resulted in marked increases in arachidonic acid (AA) and eicosanoid production, which could be abrogated by the phospholipase A2 (PLA2) inhibitor arachidonoyltrifluoromethyl ketone (ATK) but not by calcium-independent PLA2 inhibitor bromoenol lactone. This suggested that cytosolic PLA2 plays a crucial role in the induction of Nox activity by increasing the intracellular pool of AA that activates protein kinase C, which phosphorylates p47(phox). In addition, ATK also blocked OC-induced p47(phox) serine phosphorylation and attenuated ROS levels, which further supports the notion that the AA pool liberated by cytosolic PLA2 is responsible for Nox activation. Together, the results suggest that trans-nonachlor and dieldrin are capable of increasing intracellular superoxide levels via a Nox-dependent mechanism that relies on elevated intracellular AA levels. These findings are significant because chronic activation of monocytes by environmental toxicants might contribute to pathogenic oxidative stress and inflammation.

Potential effects of polychlorinated biphenyls (PCBs) and selected organochlorine pesticides (OCPs) on immune cells and blood biochemistry measures: a cross-sectional assessment of the NHANES 2003-2004 data

BACKGROUND

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are widely distributed in the environment and may have adverse effects on the immune system.

METHODS

Lipid adjusted serum levels of 19 Dioxin Like (DL), 17 Non Dioxin Like (NDL) PCBs, 5 OCPs, and measures of complete blood count and routine biochemistry profile were obtained from the NHANES 2003-2004 cycle. For each of the PCB/OCP variables, individuals were put into four exposure groups and blood markers were compared across these groups.

RESULTS

Serum levels of PCBs and OCPs increased with age. Total white blood cell (WBC) count, red blood cells (RBC), hemoglobin, and hematocrit measures were lowest in the group with the highest serum PCBs. Results for the OCPs varied. For Mirex, WBC declined in the highest exposure; no significant differences were observed for p-p'-DDT or p-p'-DDE; and higher levels of WBC were observed at the highest exposure groups of serum trans-nonachlor and oxychlordane. Liver enzymes (AST, ALT, and GGT) were significantly higher in the highest exposure groups of PCBs/OCPs.

CONCLUSIONS

We observed significant associations between PCB/OCP levels and blood markers in the general population. All of the levels were within normal ranges but the consistency of results is remarkable and may reflect subclinical effects. Largest differences were observed for NDL PCBs. Thus, routine application of toxic equivalency factors, which assume dioxin like mechanisms and aryl hydrocarbon receptor involvement, may not adequately reflect the effects of NDL PCBs in the mixture.

A prospective study of organochlorines in adipose tissue and risk of non‑Hodgkin lymphoma

BACKGROUND

Exposure to organochlorines has been examined as a potential risk factor for non-Hodgkin lymphoma (NHL), with inconsistent results that may be related to limited statistical power or to imprecise exposure measurements.

OBJECTIVE

Our purpose was to examine associations between organochlorine concentrations in prediagnostic adipose tissue samples and the risk of NHL.

METHODS

We conducted a case–cohort study using a prospective Danish cohort of 57,053 persons enrolled between 1993 and 1997. Within the cohort we identified 256 persons diagnosed with NHL in the population-based nationwide Danish Cancer Registry and randomly selected 256 subcohort persons. We measured concentrations of 8 pesticides and 10 polychlorinated biphenyl (PCB) congeners in adipose tissue collected upon enrollment. Associations between the 18 organochlorines and NHL were analyzed in Cox regression models, adjusting for body mass index.

RESULTS

Incidence rate ratios and confidence intervals (CIs) for interquartile range increases in concentrations of dichlorodiphenyltrichlorethane (DDT), cis-nonachlor, and oxychlordane were 1.35 (95% CI: 1.10, 1.66), 1.13 (95% CI: 0.94, 1.36), and 1.11 (95% CI: 0.89, 1.38), respectively, with monotonic dose–response trends for DDT and cis-nonachlor based on categorical models. The relative risk estimates were higher for men than for women. In contrast, no clear association was found between NHL and PCBs.

CONCLUSION

We found a higher risk of NHL in association with higher adipose tissue levels of DDT, cis-nonachlor, and oxychlordane, but no association with PCBs. This is the first study of organochlorines and NHL using prediagnostic adipose tissue samples in the exposure assessment and provides new environmental health evidence that these organochlorines contribute to NHL risk.

Organochlorine exposure, immune gene variation, and risk of non-Hodgkin lymphoma

Organochlorine exposure was linked to non-Hodgkin lymphoma (NHL) risk. To determine whether this relation is modified by immune gene variation, we genotyped 61 polymorphisms in 36 immune genes in 1172 NHL cases and 982 controls from the National Cancer Institute-Surveillance, Epidemiology, and End Results (NCI-SEER) study. We examined 3 exposures with elevated risk in this study: PCB180 (plasma, dust measurements), the toxic equivalency quotient (an integrated functional measure of several organochlorines) in plasma, and alpha-chlordane (dust measurements, self-reported termiticide use). Plasma (100 cases, 100 controls) and dust (682 cases, 513 controls) levels were treated as natural log-transformed continuous variables. Unconditional logistic regression was used to calculate beta coefficients and odds ratios, stratified by genotype. Associations between all 3 exposures and NHL risk were limited to the same genotypes for IFNG (C-1615T) TT and IL4 (5'-UTR, Ex1-168C>T) CC. Associations between PCB180 in plasma and dust and NHL risk were limited to the same genotypes for IL16 (3'-UTR, Ex22+871A>G) AA, IL8 (T-251A) TT, and IL10 (A-1082G) AG/GG. This shows that the relation between organochlorine exposure and NHL risk may be modified by particular variants in immune genes and provides one of the first examples of a potential gene-environment interaction for NHL.

The immunosuppressive effects of 10mg/kg cyclophosphamide in Wistar rats

The purpose of this study is to identify the immunosuppressive effects of cyclophosphamide (a known immunosuppressant) in male Wistar rats which were administered orally for 30 days repeatedly, and to find a proper dose of cyclophosphamide at which the immunosuppressive effects is identified. The dose of cyclophosphamide is 2, 5, 10mg/kg bw, respectively. The results showed that 10mg/kg cyclophosphamide treatment induced decreases in body weight, body weight gain, relative weight of spleen and thymus, antibody plaque-forming cells, delayed-type hypersensitivity reaction, natural killer cell activity, lipopolysaccharide-induced B-cell proliferation, and Concanavalin A-induced T-cell proliferation. The histopathology observation on spleen and thymus revealed as decreased cellularity. But, no significant clinical symptoms of toxicities and stress were observed and no rats died. These results indicated that the immunosuppressive effects of 10mg/kg cyclophosphamide dosed for 30 days orally were identified in male Wistar rats. Based on the results, it is considered that the dose of 10mg/kg of cyclophosphamide orally for 30 days in male Wistar rats could be used as the dose of positive control group for chemicals immunotoxicity assessment tests. This study also proved that the testing procedures and the experimental techniques established in our laboratory for immunotoxicity tests in male Wistar rats are reliable and feasible.

Antinuclear antibodies and bromoxynil exposure in a rural sample

Previous research suggests that farmers may have an increased risk of developing autoimmunity and that exposure to certain pesticides may alter immune function. Little is known, however, about the immunologic effects of farming and pesticide exposures. As part of the Prairie Ecosystem Study, associations between detection of antinuclear antibodies (ANA), an autoimmunity indicator, and exposure to the herbicide bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) were investigated in a cross-sectional study of 208 residents (94 women, 114 men) of a cereal-producing region in Saskatchewan, Canada, during spring herbicide application, 1996. The ANA were assayed in serum by indirect immunofluorescence on HEp-2 cells. Bromoxynil was measured in plasma by gas chromatography/mass spectrometry analysis. Associations were explored between ANA detection and detection of bromoxynil in plasma, self-reported use of bromoxynil and other pesticides, farming exposures, gender, age, body mass index (BMI), and residency. The mean age (SD) of the participants was 50.8 (13.6) yr [women: 49.7 (13.5) yr, men: 51.6 (13.6) yr]. ANA prevalence was 37.5% (women: 39.4%, men: 36%,) at 1:40 serum dilution, 17.3% (women: 20.2%, men: 14.9%) at 1:80, and 10.1% (women: 13.8%, men: 7%) at 1:160. In the multiple-variable Generalized Estimating Equation (GEE) logistic regression analyses, female gender was a positive predictor of ANA detection and gender differences were observed in the relative importance of other study factors. None of the variables examined in the multiple-variable GEE analysis were statistically significant predictors of ANA detection for women. For many of these variables, however, the point estimates for women are similar to those seen in men. For men, with adjustment for age, ANA presence was inversely associated with detection of concentrations of bromoxynil in winter or spring samples and recent occupational use of 2,4-dichlorophenoxyacetic acid, and the positive ANA predictors included having a BMI in the obese (BMI > 30.04 kg/m2) category, recent occupational use of trifluralin or fungicides, and current exposure to oilseed, poultry, or dairy production. The inverse association between ANA detection and bromoxynil exposure observed in farmers in this study is consistent with earlier empirical observations that certain pesticides may suppress immune function. Further research is needed to examine whether these findings are confirmed in other populations and to elucidate the biological mechanisms involved.

Organochlorines and risk of non-Hodgkin lymphoma

Organochlorine chemicals and polychlorinated biphenyls (PCBs) have been suspected as possible risk factors for non-Hodgkin lymphoma (NHL). We investigated PCBs and organochlorine pesticides and risk of NHL in a population-based case-control study in British Columbia, Canada. Congeners of PCBs (including dioxinlike congeners) and pesticides or pesticide metabolites were measured in plasma of 422 pretreatment cases and 460 control subjects. This is so far the largest study to examine organochlorines in plasma to date. Several dioxin-like PCB congeners were associated with increased risk of NHL, including dioxin-like PCB nos. 118 and 156 with odds ratios (OR) for the highest versus lowest quartile between 1.6 and 1.8. Several non-dioxin-like congeners also showed significant associations. The PCB congener with the strongest association was no. 180 with an OR for the highest versus the lowest quartile of 1.83 (95% confidence interval = 1.18-2.84). Six pesticide analytes also showed a significant association with NHL; beta-hexachlorocyclohexane, p,p'-DDE, hexachlorobenzene, mirex, oxychlordane and trans-nonachlor. The strongest association was found for oxychlordane, a metabolite of the pesticide chlordane (highest vs. lowest quartile OR = 2.68, 95% confidence interval = 1.69-4.24). Our results provide further evidence that organochlorines contribute to NHL risk.

Modulating effects of dietary fats on methylmercury toxicity and distribution in rats

Fish consumption is the most important source of human exposure to methylmercury (MeHg). Since fish is also a rich source of n-3 polyunsaturated fatty acids, this study was conducted to examine the effects of dietary fats on MeHg-induced acute toxicity in rats. Weanling male Sprague Dawley rats were administered semi-purified casein-based isocaloric diet containing soy oil, seal oil, docosahexaenoic acid (DHA), fish oil, or lard for 28 days. Rats were then gavaged with 0, 1, or 3 mg MeHg/kg body weight (BW) per day and fed the same diet for 14 consecutive days. On 43rd day of the experiment, rats were sacrificed and blood samples were collected and analyzed for hematology. Liver and spleen were removed, fixed, and examined for pathological changes. Blood, feces, liver, and brain were analyzed for total mercury and/or MeHg contents. Serum samples were analyzed for clinical markers of hepatic injury and immunoglobulin. Total mercury contents in all tissues measured increased with dose. Mercury excretion in feces increased with dose and duration of MeHg treatment. Both diets and MeHg showed significant effects and interacted significantly on many of the toxicological endpoints measured. Many of the effects of MeHg were diet-dependent. For example, in the rats fed the lard diet, 3mg MeHg/kg BW significantly increased relative liver and spleen weight as compared with vehicle control; whereas in rats fed the fish oil, soy oil, seal oil, or DHA, this effect of MeHg was less obvious or absent, suggesting a protective effect of these diets. MeHg at 3mg/kg BW significantly decreased serum albumin level in all except DHA dietary groups, implying a protection by the DHA diet on this parameter. Only in the lard dietary group, did 3mg MeHg/kg BW significantly increase serum bilirubin level, indicating an enhancing effect of this diet on MeHg toxicity. MeHg suppressed the adaptive immune system and stimulated the innate immune system in rats in a diet-dependent fashion. The seal oil diet provided more resistance, while the fish oil diet rendered greater sensitivity to these effects of MeHg on the immune system. These results imply significant modulating effects of dietary fats on MeHg toxicity which may translate into more severe or protective clinical outcomes. Therefore, dietary fats are important factors to be considered in the risk assessment of MeHg exposure.

Residential Insecticide Use and Risk of Non-Hodgkin's Lymphoma

Previous studies have linked non-Hodgkin's lymphoma (NHL) with occupational exposure to insecticides, but residential use is largely unexplored. In this population-based case-control study, we examined NHL risk and use of insecticides in the home and garden. We identified NHL cases, uninfected with HIV, diagnosed between 1998 and 2000 among women and men ages 20 to 74 years in Iowa and the metropolitan areas of Los Angeles, Detroit, and Seattle. Controls were selected using random digit dialing or Medicare files. Computer-assisted personal interviews (1,321 cases and 1,057 controls) elicited data on insecticide use at each home occupied since 1970. Insecticide levels were measured in dust taken from used vacuum cleaner bags (682 cases and 513 controls). We previously reported a positive association with dichlorodiphenyldichloroethylene levels in carpet dust residues. Here, we focus on insecticides that were commonly used after 1970, the time period covered by our questionnaire. People whose homes were treated for termites had elevated NHL risk (odds ratio, 1.3; 95% confidence interval, 1.0-1.6). Risk was modestly, although not significantly, elevated in all but one study center and in all sexes and races. The elevation in risk was restricted to people whose homes were treated before the 1988 chlordane ban. There was a significant trend of increasing risk with increasing levels of alpha-chlordane residues in dust (P(trend) = 0.04) and a marginally significant trend for gamma-chlordane (P(trend) = 0.06). We found no evidence of associations for insects overall, for specific types of insects other than termites, or for elevated residues of other insecticides. We concluded that chlordane treatment of homes for termites may increase residents' NHL risk.

Human health implications of environmental contaminants in Arctic Canada: A review

The objectives of this paper are to: assess the impact of exposure to current levels of environmental contaminants in the Canadian Arctic on human health; identify the data and knowledge gaps that need to be filled by future human health research and monitoring; examine how these issues have changed since our first assessment [Van Oostdam, J., Gilman, A., Dewailly, E., Usher, P., Wheatley, B., Kuhnlein, H. et al., 1999. Human health implications of environmental contaminants in Arctic Canada: a review. Sci Total Environ 230, 1-82]. The primary exposure pathway for contaminants for various organochlorines (OCs) and toxic metals is through the traditional northern diet. Exposures tend to be higher in the eastern than the western Canadian Arctic. In recent dietary surveys among five Inuit regions, mean intakes by 20- to 40-year-old adults in Baffin, Kivalliq and Inuvialuit communities exceeded the provisional tolerable daily intakes (pTDIs) for the OCs, chlordane and toxaphene. The most recent findings in NWT and Nunavut indicate that almost half of the blood samples from Inuit mothers exceeded the level of concern value of 5 microg/L for PCBs, but none exceeded the action level of 100 microg/L. For Dene/Métis and Caucasians of the Northwest Territories exposure to OCs are mostly below this level of concern. Based on the exceedances of the pTDI and of various blood guidelines, mercury and to a lesser extent lead (from the use of lead shot in hunting game) are also concerns among Arctic peoples. The developing foetus is likely to be more sensitive to the effects of OCs and metals than adults, and is the age groups of greatest risk in the Arctic. Studies of infant development in Nunavik have linked deficits in immune function, an increase in childhood respiratory infections and birth weight to prenatal exposure to OCs. Balancing the risks and benefits of a diet of country foods is very difficult. The nutritional benefits of country food and its contribution to the total diet are substantial. Country food contributes significantly more protein, iron and zinc to the diets of consumers than southern/market foods. The increase in obesity, diabetes and cardiovascular disease has been linked to a shift away from a country food diet and a less active lifestyle. These foods are an integral component of good health among Aboriginal peoples. The social, cultural, spiritual, nutritional and economic benefits of these foods must be considered in concert with the risks of exposure to environmental contaminants through their exposure. Consequently, the contamination of country food raises problems which go far beyond the usual confines of public health and cannot be resolved simply by risk-based health advisories or food substitutions alone. All decisions should involve the community and consider many aspects of socio-cultural stability to arrive at a decision that will be the most protective and least detrimental to the communities.

Human erythrocytes are affected by the organochloride insecticide chlordane

Chlordane is a widely used organochlorine insecticide. In order to evaluate its perturbing effect upon the morphology of human erythrocytes it was caused to interact with human red cells and molecular models of cell membranes. These consisted in bilayers of dimyristoylphosphatidylethanolamine (DMPE) and of dimyristoylphosphatidylcholine (DMPC), representative of phospholipid classes located in the inner and outer monolayers of the erythrocyte membrane, respectively. Scanning electron microscopy (SEM) observations indicated that this pesticide induced a significant alteration in the shape of the erythrocytes as they changed their discoid shape to spherocytes. According to the bilayer couple hypothesis, the shape changes induced in erythrocytes by foreign molecules are due to differential expansion of their two monolayers. The fact that chlordane produced spherocytes would indicate that the pesticide was equally located in the outer and the inner moieties of the red cell membrane. This conclusion was supported by the results obtained from X-ray diffraction studies. These showed that the hydrophobic and polar head regions of DMPC bilayers were perturbed when the insecticide was in a 1:10 molar ratio with respect to the lipid. These results were confirmed by the fluorescence experiments performed in DMPC large unilamellar vesicles (LUV). Chlordane produced a sharp decrease in the anisotropy and general polarization parameters in the 0-0.1 mM range, implying an increase in the fluidity at the acyl chain and polar region of DMPC. On the other hand, the bilayer structure of DMPE was perturbed in a fashion similar to that observed by X-ray diffraction in DMPC, a fact that explains the morphological change induced by chlordane to the human erythrocytes.

Toxicity of trans-nonachlor to Sprague-Dawley rats in a 90-day feeding study

The chlordane constituent trans-nonachlor and its metabolite oxychlordane are among the most persistent chlordane-related contaminants and are found in tissues and milk from humans ingesting diets high in Arctic marine mammal fat. Although chlordane is no longer registered in North America, there is a need for toxicological data on chlordane-related contaminants found in food and the environment which are either structurally different or relatively more abundant than the constituents of the original chlordane mixture. Thus, a feeding study was undertaken to provide toxicological data on trans-nonachlor. Male and female Sprague-Dawley rats were exposed to 0, 5, 13 or 50 ppm trans-nonachlor in feed for 90 days and clinical, hematological and histopathological changes were assessed in each rat. Female rats were less able than males to metabolize and eliminate trans-nonachlor and, as a result, accumulated more trans-nonachlor in their adipose tissues. trans-Nonachlor, like technical chlordane and other organochlorines, induced liver microsomal enzymes in a pattern similar to phenobarbital. Endocrine effects included functional and morphological changes in the thyroid and adrenals. In male rats exposure to trans-nonachlor was associated with changes in endpoints indicative of increased oxidative stress, which may be related to both direct action on cellular targets or to secondary effects resulting from cytochrome P450 induction. The results indicate that subchronic trans-nonachlor exposure in rats induced hepatic changes with far-reaching metabolic and endocrine effects. Differences in target organ responses in male and female rats indicate that the sex-related metabolic differences affecting trans-nonachlor bioaccumulation and elimination merit further study.

Does high organochlorine (OC) exposure impair the resistance to infection in polar bears (Ursus maritimus)? Part I: Effect of OCs on the humoral immunity

This study was undertaken to assess if high levels of organochlorines (OCs) are associated with decreased ability to produce antibodies in free-ranging polar bears (Ursus maritimus) and thus affect the humoral immunity. In 1998 and 1999, 26 and 30 polar bears from Svalbard, Norway, and Churchill, Canada, respectively, were recaptured 32-40 d following immunization with inactivated influenza virus, reovirus, and herpes virus and tetanus toxoid. Blood was sampled at immunization and at recapture for determination of plasma levels of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), serum immunoglobulin G (IgG) concentrations, and specific antibodies against influenza virus, reovirus, and herpes virus, tetanus toxoid, and Mannheimia haemolytica. The OCs alone contributed with up to 7% to the variations in the immunological parameters. The combination of sigma PCBs (sum of 12 individual PCB congeners), sigma OCPs (sum of 6 OCPs), and biological factors accounted for 40-60% of the variation in the immunological parameters. Negative associations were found between sigma PCBs and serum immunoglobulin G (IgG) levels and between sigma PCBs and increased antibody titers against influenza virus and reovirus following immunization. In contrast, a positive association was registered between sigma PCBs and increased antibodies against tetanus toxoid. sigma OCPs also contributed significantly to the variations in the immunological responses. OCs did not have the same impact on the antibody production against M. haemolytica. The present study demonstrated that high OC levels may impair the polar bears ability to produce antibodies and thus may produce impaired resistance to infections.

Oral (gavage), in utero and post-natal exposure of Sprague–Dawley rats to low doses of tributyltin chloride

The immunotoxic effects of tributyltin chloride (TBTC) were examined in the offspring of Sprague-Dawley rats exposed in utero from day 8 of gestation, through lactation and post-weaning until pups reached the age of 30 days (male and female), 60 days (female) and 90 days (male). Daily oral (gavage) doses of 0.025, 0.25 and 2.5 mg/kg body weight/day were administered in olive oil 7 days/week. Immunologic endpoints were investigated at the termination of each study. Statistically significant results (P<0.05) included the following: At 30 days, the mean percent and absolute natural killer (NK) cell numbers were increased in male and female rats treated with the high TBTC dose. At 60 days, female rats had increased mean serum IgM levels at the low and high TBTC doses, increased mean percentage CD4(+)8(+) (immature) T lymphocytes at the middle and high doses, a non-linear dose-response increase in NK cell activity at the 50:1 and 100:1 effector:target cell ratios (pairwise comparisons significant at the low dose compared with control), and increased mean numbers of L. monocytogenes colony-forming bacteria on Day 2 post-infection (significant for trend) and Day 3 post infection (pairwise comparisons significant only in the middle dose). The 90-day male rats had decreased mean serum IgA levels at the middle dose group; increased IgM levels at the high dose group, increased IgG levels at the middle and high doses; decreased IgG2(a) in the high dose compared to the control; a dose-related increase in the mean percentage NK cell numbers (pairwise comparisons significant at the high dose compared with the control) and increased mean NK cell activity (pairwise comparisons significant at all dose groups compared with the control). The delayed-type hypersensitivity response to oxazolone was increased in the low and middle doses and decreased in the high dose. Thymus atrophy was observed in the high TBTC dose across all ages. Thus, in utero and post-natal treatment of F1 rats with low levels of TBTC affected some aspects of humoral and cell mediated immunity as well as the number and function of cells which are involved in the host's immunosurveillance mechanisms against tumours and viral infections.

Toxicity of the chlordane metabolite oxychlordane in female rats: clinical and histopathological changes

Due to widespread usage of the pesticide chlordane until the 1980's, this toxic and persistent mixture has accumulated in the food chain. The Arctic acts as a global sink for these and other persistent organic pollutants, which bioaccumulate in the marine and freshwater food chains. As a result, humans consuming diets high in Arctic fish and marine mammal fat can ingest higher levels of chlordane contaminants than humans consuming "southern" diets. The most abundant constituents of the chlordane mixture are trans-chlordane, cis-chlordane, trans-nonachlor, cis-nonachlor and heptachlor; oxychlordane is the major metabolite of the chlordanes and nonachlors. In humans the predominant chlordane-related contaminants detected in breast milk and adipose tissues are trans-nonachlor and oxychlordane. The present studies were undertaken to provide toxicological data on oxychlordane for the purpose of clarifying target organ toxicity and risks to human health associated with ingesting contaminated foods. Female rats were gavaged with oxychlordane at doses ranging from 0.01 to 10 mg/kg body weight/day for up to 28 days. In terms of general toxicity oxychlordane had a steep dose-response curve: 10 mg/kg oxychlordane was acutely toxic and 1 mg/kg oxychlordane caused no measurable effects. Weight loss, reduced feed consumption and thymic atrophy were the hallmarks of acute oxychlordane toxicity. At lower doses rats showed signs of hepatic changes indicative of microsomal enzyme induction. Oxychlordane was more bioaccumulative and was toxic at levels approximately 8 times lower than trans-nonachlor and cis-nonachlor. Thus, ingestion of trans-nonachlor and related chlordane contaminants in foods results in the formation of a metabolite that is more toxic and bioaccumulative than the parent contaminants.