Associations of chronic exposure to a mixture of pesticides and type 2 diabetes mellitus in a Chinese elderly population

Epidemiological studies have related exposure to pesticides to increased risk of diabetes. However, few studies have evaluated the health effects of mixed pesticides exposure, especially in an elderly population. Here, we utilized gas chromatography-tandem mass spectrometry to quantify the levels of 39 pesticides in 4 categories in a Chinese elderly population. Then we used general linear models to explore the association between individual pesticide exposure and type 2 diabetes mellitus (T2DM). Restricted cubic spline (RCS) models were fitted to identify potential non-linearities between those associations. Furthermore, stratified analysis by gender was conducted to explore the gender-specific associations. Finally, we used weighted quantile sum (WQS) regression, quantile-based g computation (qgcomp), and Bayesian kernel machine regression (BKMR) to evaluate the effects of mixed exposure to 39 pesticides. The results showed that exposure to pesticides was associated with high risk of T2DM, with β-Hexachlorocyclohexane (β-BHC) and oxadiazon being the most significant independent contributors, which was pronounced among elderly women. Moreover, the association of β-BHC and oxadiazon with T2DM was linear. These indicated that it is an urgent need to take practical measures to control these harmful pesticides.

Association between persistent organic pollutants in human milk and the infant growth and development throughout the first year postpartum in a cohort from Rio de Janeiro, Brazil

Persistent organic pollutants (POPs) are compounds that are recalcitrant and ubiquitous that bioaccumulate in human milk (HM) and can impact infant growth and development. We explore the association between POP concentration in HM at 2-50 days postpartum and infant growth and development trajectory throughout the first year of life. A cohort of 68 healthy adult Brazilian women and their infants were followed from 28 to 35 gestational weeks to 12 months postpartum. HM samples were collected between 2 and 50 days postpartum, and POP concentrations were analyzed using gas chromatography with mass spectrometry. Concentrations of POPs >limit of quantification (LOQ) were defined as presence, and concentrations ≤LOQ as an absence. Growth z-scores were analyzed according to WHO growth charts and infant development scores according to Age & Stages Questionnaires at 1 (n = 66), 6 (n = 50), and 12 months (n = 45). Linear mixed effects (LME) models were used to investigate the association of POPs in HM with infant growth and development. Benjamini-Hochberg (BH) correction for multiple testing was performed to reduce the false discovery ratio. P < 0.1 was considered for models with the interaction between POPs and time/sex. After BH correction, adjusted LME models with time interaction showed (1) a positive association between the presence of β hexachlorocyclohexane and an increase in head circumference-for-age z-score (β = 0.003, P = 0.095); (2) negative associations between total POPs (β = -0.000002, P = 0.10), total organochlorine pesticides (β = -0.000002, P = 0.10), and dichlorodiphenyldichloroethylene concentrations in HM (β = -0.000002, P = 0.10) and fine motor scores. No statistical difference between the sexes was observed. Postnatal exposure to organochlorine pesticides in HM shows a positive association with the trajectory of head circumference-for-age z-score and a negative association with the trajectories of fine motor skills scores. Future studies on POP variation in HM at different postpartum times and their effect on infant growth and development should be encouraged.

Modeling historical budget for β-Hexachlorocyclohexane (HCH) in the Arctic Ocean: A contrast to α-HCH

The historical annual loading to, removal from, and cumulative burden in the Arctic Ocean for β-hexachlorocyclohexane (β-HCH), an isomer comprising 5-12% of technical HCH, is investigated using a mass balance box model from 1945 to 2020. Over the 76 years, loading occurred predominantly through ocean currents and river inflow (83%) and only a small portion via atmospheric transport (16%). β-HCH started to accumulate in the Arctic Ocean in the late 1940s, reached a peak of 810 t in 1986, and decreased to 87 t in 2020, when its concentrations in the Arctic water and air were ∼30 ng m^-3 and ∼0.02 pg m^-3, respectively. Even though β-HCH and α-HCH (60-70% of technical HCH) are both the isomers of HCHs with almost identical temporal and spatial emission patterns, these two chemicals have shown different major pathways entering the Arctic. Different from α-HCH with the long-range atmospheric transport (LRAT) as its major transport pathway, β-HCH reached the Arctic mainly through long-range oceanic transport (LROT). The much higher tendency of β-HCH to partition into the water, mainly due to its much lower Henry's Law Constant than α-HCH, produced an exceptionally strong pathway divergence with β-HCH favoring slow transport in water and α-HCH favoring rapid transport in air. The concentration and burden of β-HCH in the Arctic Ocean are also predicted for the year 2050 when only 4.4-5.3 t will remain in the Arctic Ocean under the influence of climate change.

Predictors of Beta-Hexachlorocyclohexane blood levels among people living close to a chemical plant and an illegal dumping site

BACKGROUND

Hexachlorocyclohexane is a synthetic chemical with several isomers, including β-Hexachlorocyclohexane (β-HCH). In 2005, a large contamination of crude milk from some bovine farms along the Sacco River (Central Italy) was detected; it was related to the illegal disposal of large quantities of processing waste by a chemical industry of the area. A biomonitoring study, conducted in 2007 on a sample of the residing population, found high values of β-HCH in people living close to the river. These results led to the establishment of a clinical and epidemiological surveillance program on all the exposed population. The aim of the study was to evaluate the determinants of β-HCH blood levels in people living within 1 Km of the Sacco River, focusing on the role of specific foods, body mass index and risk factors not yet identified.

METHODS

The program involved all people living within 1 km of the river. A descriptive analysis of β-HCH blood levels was done in relation to the potential determinants including specific foods. Regression analysis was used to study the association between potential determinants and (natural log) β-HCH haematic concentration. The results were expressed as geometric mean ratios (GMR). To take into account similarities within the families we adjusted for family clustering.

RESULTS

A total of 602 subjects (87.2%) agreed to participate in the surveillance. The β-HCH geometric mean serum concentration was 72 ng/g lipid. The regression analysis showed that being female (GMR: 1.32, 95%CI: 1.14-1.53), elderly (GMR_{> 70yy}: 10.04, 95%CI: 6.65-15.15), obese (GMR: 1.63, 95%CI: 1.28-2.08), eating food of local/own production (GMR 1.47, 95%CI: 1.15-1.88) and using water from private wells (GMR_drink:1.47, 95%CI: 1.00-2.14 and GMR_wash: 1.48, 95%CI: 1.17-1.87) were associated with higher β-HCH values. There was inverse association with breastfeeding (GMR: 0.64, 95%CI: 0.47-0.86). The focus on specific foods showed that the most important factors were eggs and beef.

CONCLUSIONS

The study indicated a greater contamination for older people, and those drinking and washing with water from private wells and consuming locally produced food, especially eggs and beef.

Persistent Environmental Toxicants in Breast Milk and Rapid Infant Growth

BACKGROUND/AIMS

Many environmental toxicants are passed to infants in utero and through breast milk. Exposure to toxicants during the perinatal period can alter growth patterns, impairing growth or increasing obesity risk. Previous studies have focused on only a few toxicants at a time, which may confound results. We investigated levels of 26 toxicants in breast milk and their associations with rapid infant growth, a risk factor for later obesity.

METHODS

We used data from the Norwegian HUMIS study, a multi-center cohort of 2,606 mothers and newborns enrolled between 2002 and 2008. Milk samples collected 1 month after delivery from a subset of 789 women oversampled by overweight were analyzed for toxicants including polychlorinated biphenyls (PCBs), heavy metals, and pesticides. Growth was defined as change in weight-for-age z-score between 0 and 6 months among the HUMIS population, and rapid growth was defined as change in z-score above 0.67. We used a Bayesian variable selection method to determine the exposures that most explained variation in the outcome. Identified toxicants were included in logistic and linear regression models to estimate associations with growth, adjusting for maternal age, smoking, education, pre-pregnancy body mass index (BMI), gestational weight gain, parity, child sex, cumulative breastfeeding, birth weight, gestational age, and preterm status.

RESULTS

Of 789 infants, 19.2% displayed rapid growth. The median maternal age was 29.6 years, and the median pre-pregnancy BMI was 24.0 kg/m2, with 45.3% of mothers overweight or obese. Rapid growers were more likely to be firstborn. Hexachlorobenzene, β-hexachlorocyclohexane (β-HCH), and PCB-74 were identified in the variable selection method. An interquartile range (IQR) increase in β-HCH exposure was associated with a lower odds of rapid growth (OR 0.63, 95% CI 0.42-0.94). Newborns exposed to high levels of β-HCH showed reduced infant growth (β = -0.03, 95% CI -0.05 to -0.01 for IQR increase in breast milk concentration). No other significant associations were found.

CONCLUSIONS

Our results suggest that early life β-HCH exposure may be linked to slowed growth. Further research is warranted on the potential mechanism behind this association and the longer-term metabolic effects of perinatal β-HCH exposure.

Stepwise enhancement of catalytic performance of haloalkane dehalogenase LinB towards β-hexachlorocyclohexane

Two haloalkane dehalogenases, LinB_UT and LinB_MI, each with 296 amino acid residues, exhibit only seven amino acid residue differences between them, but LinB_MI’s catalytic performance towards β-hexachlorocyclohexane (β-HCH) is considerably higher than LinB_UT’s. To elucidate the molecular basis governing this difference, intermediate mutants between LinB_UT and LinB_MI were constructed and kinetically characterized. The activities of LinB_UT-based mutants gradually increased by cumulative mutations into LinB_UT, and the effects of the individual amino acid substitutions depended on combination with other mutations. These results indicated that LinB_UT’s β-HCH degradation activity can be enhanced in a stepwise manner by the accumulation of point mutations.

Prenatal exposure to organochlorine pesticides and infant birth weight in China

In utero exposure to organochlorine pesticides (OCPs) is thought to be potentially harmful to fetal development. We aimed to investigate the associations of maternal and cord serum OCPs levels with infant birth weight in China. In this study, we measured serum levels of 18 OCPs in 81 mother-infant pairs, including DDT, hexachlorocyclohexanes (BHC), hexachlorobenzene (HCB), heptachlors, chlordanes, endosulfan-I, and mirex using a high-resolution-gas-chromatography with high-resolution-mass-spectrometry method. We found that p,p'-DDE and β-BHC had the highest detection rate in both maternal and cord blood serum (97.2% and 96.7%, respectively), followed by HCB (93.0%, 51.7%), p,p'-DDT (88.7%, 36.7%), and p,p'-DDD (83.1%, 60.0%). Among all OCPs, the concentration of p,p'-DDE was the highest (mothers geometric mean (GM): 203.54ngg(-1), newborns GM: 116.14ngg(-1)), followed by HCB (70.62ngg(-1), 65.16ngg(-1)), and β-BHC (67.67ngg(-1), 33.39ngg(-1)). Multiple linear regression analyses showed that each 1ngg(-1) increment of cord serum p,p'-DDE, total DDT, and β-BHC was associated with a 0.10g, 0.10g, and 0.92g decrease in infant birth weight, respectively, and as the cord serum concentrations of p,p'-DDT, p,p'-DDD, HCB and mirex increased, the infant birth weight was also decreased, although the associations were not statistically significant due to the relatively small sample size. These results suggest that p,p'-DDE, β-BHC, and HCB were the predominant OCPs in the serum of Chinese pregnant women and cord blood of their newborns. Prenatal exposure to DDT, β-BHC, HCB, and mirex were associated with a decrease in birth weight, but these results need validation in larger sample-sized studies.

Serum organochlorine pesticide levels in patients with metabolic syndrome

INTRODUCTION

Organochlorine pesticides (OCPs) are endocrinal disruptors that tend to accumulate in adipose tissue and have been found to be associated with Metabolic Syndrome (MS).

AIM AND OBJECTIVES

1. To measure serum OCP levels in patients of MS and control subjects, 2. To identify differences, if any, in serum OCP levels, in patients with MS and control subjects.

MATERIALS AND METHODS

Cross-sectional study was conducted in the Departments of Medicine and Biochemistry at University College of Medical Sciences (UCMS) and Guru Teg Bahadur Hospital (GTBH), Delhi. Nine OCPs [α-HCH (Hexachlorocyclohexane), β-HCH, g-HCH, α-endosulfan, β-endosulfan, aldrin, dieldrin, p, p'-DDT (Dichloro-diphenyl-trichloro-ethane), and p, p'-DDE (Dichloro-diphenyl-dichloro-ethylene)] were studied. Fifty subjects ≥18 years with MS (study group) and 50 age and sex-matched controls were included in the study.

EXCLUSION CRITERIA

(1) Persons having chronic occupational exposure to OCPs such as workers of pesticide factories, (2) Recent exposure to OCPs within 4 weeks.

RESULTS

Levels of all nine OCPs were higher in cases as compared to controls. However, only the mean value of β-HCH in cases (8.40 ± 8.64 ng/ml) was significantly (P < 0.001) higher as compared to controls (2.58 ± 2.34 ng/ml). After adjustment of confounding factors like age, sex, smoking, alcohol, and body mass index (BMI), only β-HCH and aldrin levels were positively and significantly associated with the risk of having MS. Adjusted Odds Ratio (OR) was 1.34 [CI = 1.14-1.57 (P < 0.001)] and 1.23 [CI = 1.01-1.50 (P = 0.045)], respectively.

CONCLUSION

There was a significant association of β- HCH and aldrin levels with MS.