Inhibition of interleukin-2-stimulated enhancement of human natural killer (NK) cell activity by carbaryl, an anticholinesterase insecticide

Pesticide Poisoning and the Use of Personal Protective Equipment (PPE) in Indonesian Farmers

This study aimed to investigate the poisoning symptoms occurring in pesticide-exposed farmers. This study was conducted in a red onion farming center area in Wanasari Subdistrict, Brebes, Indonesia, from May to June 2018. This study was designed as the descriptive study. The significance value of p < 0.005 showed that the variable was correlated with the health problems, including excessive fatigue (p value = 0.041), excessive saliva (p value = 0.006), hard breathing (p value = 0.021), frequent urination (p value = 0.047), blurred vision (p value = 0.059), dizziness (p value = 0.032), and finger pain (p value = 0.007). The significance value (p < 0.005) of 0.000 showed that the use of personal protective equipment was correlated with the health problems. Based on the odds ratio value of 1.137, 95% confidence interval = 0.042-0.444 meant that the personal protective equipment was a risk factor of health problems. The results showed that 89.2% of the farmers who used the personal protective equipment were categorized in the healthy group.

Pesticide Exposure and Risk of Rheumatoid Arthritis among Licensed Male Pesticide Applicators in the Agricultural Health Study

BACKGROUND

The occupation of farming has been associated with rheumatoid arthritis (RA); pesticides may account for this association, but there are few studies.

OBJECTIVES

We investigated associations between RA and use of pesticides in the Agricultural Health Study.

METHODS

The study sample was drawn from male pesticide applicators enrolled in 1993–1997 who provided questionnaire data at baseline and at least once during follow-up (over a median 18 y; interquartile range 16–19). Incident RA cases (n=220), confirmed by physicians or by self-reported use of disease-modifying antirheumatic drugs, were compared with noncases (n=26,134) who did not report RA. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression, adjusting for enrollment age, state, smoking pack-years, and education. We evaluated the association of RA with the use of 46 pesticides and across 4 levels (never use and tertiles) of lifetime days of use for 16 pesticides with OR≥1.2 for ever use.

RESULTS

Incident RA was associated with ever use of fonofos (OR = 1.70; 95% CI: 1.22, 2.37), carbaryl (OR = 1.51; 95% CI: 1.03, 2.23), and chlorimuron ethyl (OR = 1.45; 95% CI: 1.01, 2.07) compared with never use. Statistically significant exposure–response trends in association with RA were observed for lifetime days of use of atrazine [OR_tertile3= 1.62 (95% CI: 1.09, 2.40); p_trend=0.01] and toxaphene [OR_tertile3= 2.42 (95% CI: 1.03, 5.68); p_trend=0.02]. Exposure–response was nonlinear for fonofos [OR_tertile1= 2.27 (95% CI: 1.44, 3.57); OR_tertile2= 0.98 (95% CI: 0.54, 1.80); OR_tertile3= 2.10 (95% CI: 1.32, 3.36); p_trend=0.005] and suggestive for carbaryl (p_trend=0.053).

CONCLUSIONS

Our results provide novel evidence of associations between exposure to some pesticides and RA in male farmers. https://doi.org/10.1289/EHP1013.

Pyridostigmine Bromide (PYR) Alters Immune Function in B6C3F1 Mice

Pyridostigmine bromide (PYR) is an anticholinesterase drug indicated for the treatment of myasthenia gravis and neuromuscular blockade reversal. It acts as a reversible cholinesterase inhibitor and was used as a pretreatment for soldiers during Operation Desert Storm to protect against possible nerve gas attacks. Since that time, PYR has been implicated as a possible causative agent contributing to Gulf War Illness. PYR's mechanism of action has been well-delineated with regards to its effects on the nervous system, yet little is known regarding potential effects on immunological function. To evaluate the effects of PYR on immunological function, adult female B6C3F1 mice were gavaged daily for 14 days with PYR (0, 1, 5, 10, or 20 mg/kg/day). Immune parameters assessed were lymphoproliferation, natural killer cell activity, the SRBC-specific antibody plaque-forming cell (PFC) response, thymus and spleen weight and cellularity, and thymic and splenic CD4/CD8 lymphocyte subpopulations. Exposure to PYR did not alter splenic and thymus weight or splenic cellularity. However, 20 mg PYR/kg/day decreased thymic cellularity with decreases in both CD4+/CD8+ (20 mg/kg/day) and CD4-/CD8- (10 and 20 mg/kg/day) cell types. Functional immune assays indicated that lymphocyte proliferative responses and natural killer cell activity were normal; whereas exposure to PYR significantly decreased primary IgM antibody responses to a T-cell dependent antigen at the 1, 5, 10 and 20 mg/kg treatment levels for 14 days. This is the first study to examine the immunotoxicological effects of PYR and demonstrate that this compound selectively suppresses humoral antibody responses.

Effects of pesticide exposure on serum immunoglobulin and complement levels

Serum immunoglobulins (IgG, IgA and IgM), C3 and C4 complement protein levels were examined in the male workers of the municipality who routinely applied pesticides for at least one year, and compared to healthy male controls in order to determine whether immune alterations were evident in the pesticide-exposed workers. Pyrethroids were the most commonly used pesticides for the last 3 years. Serum immunoglobulins and complement levels were measured by turbidimetry. Serum IgG, IgA, IgM and C3 complement levels were found to be unchanged when compared to controls whereas a significant decrease was observed in serum C4 complement levels of the workers.

A preliminary study of immunologic and hematologic profiles of peripheral blood from Nebraska farmers who apply pesticides to their fields

OBJECTIVE

Laboratory studies have documented a wide range of pesticide-induced changes in the hematopoietic and lymphoreticular systems. Some of these are expressed as altered serum values, blood cell counts, and leucocyte functions. The goal of the present study was to determine whether these alterations were evident in peripheral blood of Nebraska farmers who applied pesticides to their fields.

METHODS

An invitation to participate was mailed to 100 residents (70 farmers; 30 controls) of Butler County, Nebraska. All respondents (51 farmers and 21 controls) were enrolled and surveyed by written questionnaire for health status and pesticide use. Our analysis included 45 farmers and 18 controls. The farmers were divided into a high (n = 23) and a low (n = 22) pesticide use group. Statistical correlations of ten blood values with both pesticide use and age were evaluated, since pesticide use correlated with age.

RESULTS

Four of the ten blood values correlated with pesticide use and age (Spearman Rho). In a multiple regression model, pesticide use (not age) proved to be a predictor of red blood cell count and hematocrit. In the same model, pesticide use was not a predictor of mean red cell volume or candida antigen-induced T-lymphocyte proliferation. Serum complement activity did not correlate with pesticide use among the farmers (n = 45) but was significantly reduced (ANOVA) in the high pesticide use group, compared to controls.

CONCLUSIONS

A preliminary study of blood values in a small cohort of Nebraska farmers found no pesticide-associated effects on 1) leucocyte count, 2) antigen- and mitogen-stimulated T-cell proliferation, 3) mitogen-stimulated B-cell proliferation, and 4) concentrations of serum IgG and IgM. The study found small but statistically significant pesticide-associated effects on red blood cells and serum complement.

Poisons and fever

1. Dysfunction of the thermoregulatory system is one of many pathologies documented in experimental animals and humans exposed to toxic chemicals. The mechanism of action responsible for many types of poison-induced fevers is not understood. Some elevations in body temperature are attributed to the peripheral actions of some poisons that stimulate metabolic rate and cause a forced hyperthermia. Exposure to organophosphate (OP) pesticides and certain metal fumes appears to cause a prolonged, regulated elevation in body temperature (Tb). 2. Activation of cyclo-oxygenase (COX) and the production of prostaglandin (PG)E2 in central nervous system (CNS) thermoregulatory centres is required to elicit a fever. Activating the COX-PGE2 pathway by a poison may occur by one of three mechanisms: (i) induction of cell-mediated immune responses and the subsequent release of cytokines; (ii) induction of lipid peroxidation in the CNS; and (iii) direct neurochemical activation. 3. Radiotelemetric monitoring of core temperature in unstressed rodents has led to an experimental animal model of poison-induced fever. Rats administered the OP agents chlorpyrifos and diisopropyl fluorophosphate display an initial hypothermic response lasting approximately 24 h, followed by an elevation in diurnal core temperature for 24-72 h after exposure. The hyperthermia is apparently a result of the activation of the COX-PGE2 pathway because it is blocked by the anti-pyretic sodium salicylate. Overall, the delayed hyperthermia resulting from OP exposure involves activation of thermoregulatory pathways that may be similar to infection-mediated fever.