Effects of pesticide exposure on the human immune system.

Epidemiological evidence from Western countries indicates that the prevalence of diseases associated with alterations in the immune response, such as asthma, certain autoimmune diseases and cancer, are increasing to such an extent that it cannot be attributed to improved diagnostics alone. There is some concern that this trend could be, at least, partially attributable to new or modified patterns of exposures to chemicals, including pesticides. The purpose of this article is to review the evidence on pesticide immunotoxicity in humans. Overall, the available data are inadequate to draw firm conclusions on the immunotoxic risk associated with pesticide exposure. The available studies on the effects of pesticides on the human immune system have several limitations, including limited data on exposure levels, heterogeneity of the applied methods, and difficulties in assessing the prognostic significance of observed slight changes and in the interpretation of the reported findings. Further studies are needed and preferably as prospective studies, comparing pre- and post-exposure data in the same group of subjects and including an appropriate non-exposed control group. More knowledge is required regarding the prognostic significance of the small changes observed.

Association of pesticide exposure, vaccination response, and interleukin-1 gene polymorphisms.

We performed a cross-sectional study involving workers from four European countries in which exposure to pesticides and immune parameters were evaluated over a short period of time. The total study population consisted of 238 workers occupationally exposed to pesticides and 198 nonoccupationally exposed workers. The study showed that pesticide exposure at levels encountered by workers under different conditions in Europe did not affect the ability of the immune system to respond to vaccination. We could, however, identify individuals within the group of pesticide exposed workers who were genetically characterized by the 2.2 IL-1alpha polymorphism and who showed a lower antibody response, pointing out the importance of the understanding of genetic variability and the interaction between genetic and environmental factors in the identification of high-risk individuals, which may eventually lead to preventive measures.

Biological monitoring and questionnaire for assessing exposure to ethylenebisdithiocarbamates in a multicenter European field study.

This study deals with pesticide exposure profile in some European countries with a specific focus on ethylenebisdithiocarbamates (EBDC). In all, 55 Bulgarian greenhouse workers, 51 Finnish potato farmers, 48 Italian vineyard workers, 42 Dutch floriculture farmers, and 52 Bulgarian zineb producers entered the study. Each group was matched with a group of not occupationally exposed subjects. Exposure data were gained through self-administered questionnaires and measuring ethylenethiourea (ETU) in two spot urine samples collected, respectively, before the beginning of seasonal exposure (T0), and after 30 days, at the end of the exposure period (T30). Controls underwent a similar protocol. Study agriculture workers were involved in mixing and loading pesticides, application of pesticide mixture with mechanical or manual equipments, re-entry activities, and cleaning equipments. Chemical workers were involved in synthesis, quality controls, and packing activities. The number of pesticides to whom these subjects were exposed varied from one (zineb production) to eight (potato farmers). The use of personal protective devices was variegate and regarded both aerial and dermal penetration routes. EBDC exposure, assessed by T30 urinary ETU, was found to follow the order: greenhouse workers, zineb producers, vineyard workers, potato farmers, floriculture farmers with median levels of 49.6, 23.0, 11.8, 7.5, and 0.9 microg/g creatinine; the last group having ETU at the same level of controls (approximately 0.5 microg/g creatinine). Among agriculture workers, pesticide application, especially using manual equipment, seems to be the major determinant in explaining internal dose. Although the analysis of self-administered questionnaires evidenced difficulties especially related to lack and/or poor quality of reported data, biological monitoring confirms to be a powerful tool in assessing pesticide exposure.

Immune effects and exposure to ethylenebisdithiocarbamate pesticides in re-entry workers in the Netherlands.

Ethylenebisdithiocarbamates are widely used as fungicides in agriculture. Although EBDC's have a low acute toxicity, they are suspected to have immune effects at low doses. However, little human studies on these effects have been published. In the Netherlands, a study was conducted among pesticide exposed workers aimed at evaluating the short-term and long-term immune effects of exposure and the relation between ethylenebisdithiocarbamate and immune effects. Forty-one re-entry workers and 40 nonexposed controls were medically examined; furthermore, immune parameters were determined in blood, and all participants filled in a questionnaire regarding exposure and outcome parameters. The level of ethylenethiourea in urine was determined as indicator of exposure. No relevant adverse immune effects were found in the pesticide exposed workers compared with the nonexposed controls. Also no exposure response relationship between immune effects and ethylenebisdithiocarbamate in urine was found. This finding might be due to very low exposure levels of the re-entry work but might also be due to a lack of immunotoxicity of ethylenebisdithiocarbamate at normal exposure levels.

Toxicological evaluation of the immune function of pesticide workers, a European wide assessment.

In this study, the prolonged low-dose exposure of mixtures of pesticides has been examined on hematological parameters and components of the immune defense in occupationally exposed humans. This investigation was carried out in five field studies in: the Netherlands (flower bulb growers, mainly re-entry workers), Italy (vineyard workers), Finland (potato farmers), and Bulgaria (workers from a zineb factory and greenhouse workers). Immunotoxicity was studied by measuring hematological parameters, complement, immunoglobulins, lymphocyte subpopulations, natural killer cells, autoimmunity, and antibody responses to hepatitis B vaccination. The total study population consisted of 248 pesticide-exposed and 231 non-occupationally exposed workers. As a surrogate measure of pesticide exposure the urinary excretion of ethylenethiourea (ETU), the main metabolite ethylenebisdithiocarbamates was measured. A significantly higher level of ETU in occupationally exposed subjects compared with controls (2.7 +/- 8.1 microg/g vs 0.5 +/- 3.7 microg/g creatinine) was found. Statistically significant differences, albeit very low, were found for complement C3 and C4 and the immunoglobulin classes IgG4 and IgA. For complement and IgG4, the levels were slightly increased and the level of IgA was decreased. In the lymphocyte populations, the CD8 subpopulation was increased. No effects were found on autoimmune antibodies and antibody response to hepatitis vaccination. In conclusion, pesticide exposure under various work place conditions in Europe was associated only with some subtle effects on the immune system, which may suggest that occupational exposure to pesticides does not influence the immunologic system in a clinically significant fashion, and does not pose a significant health risk to the exposed subjects.

Occupational exposure to ethylenebisdithiocarbamates in agriculture and allergy: results from the EUROPIT field study.

This epidemiological study was carried out to evaluate the possible association between occupational exposure to ethylenebisdithiocarbamates (EDBC) and allergy. The study was conducted in four countries in the European Union: The Netherlands, Finland, Italy and Bulgaria. A total of 248 workers exposed to EDBC and 231 non-occupationally exposed subjects entered the study. Exposure to EDBC was measured as urinary ethylenethiourea (ETU) in urinary samples collected at baseline and after 30 days of exposure. Several effect parameters were evaluated including questionnaire data on allergy, Phadiatop, a general allergy test, and specific IgE parameters. These data were also collected at baseline and after 30 days of exposure. Cross-sectional as well as longitudinal comparisons were made, adjusted for potential confounding factors. No association was found between exposure status, EDBC levels and allergic contact dermatitis, allergic rhinitis, food allergy or atopy as measured by the Phadiatop. The prevalence of skin irritation was elevated in the Dutch field study only and is more likely a result of plant contact rather than EDBC exposure. Occupational exposure to sunlight was noted to have a protective effect on atopy in terms of IgE positivity. We conclude that the EDBC exposure levels experienced in our field study are not associated with increased prevalence of allergic symptoms or allergy.

Asthmatic symptoms after exposure to ethylenebisdithiocarbamates and other pesticides in the Europit field studies.

We conducted a multicenter prospective study to assess the effects of occupational exposure to ethylenebisdithiocarbamate fungicides and/or other pesticides on self-reported asthma and asthmatic symptoms. This multicenter study was conducted among 248 workers exposed to pesticides and 231 non-exposed workers from five field studies. The five field studies were carried out in The Netherlands, Italy, Finland, and two studies in Bulgaria. Subjects constituting this cohort completed a self-administered questionnaire at baseline (before the start of exposure). Ethylenethiourea in urine was determined to assess exposure to ethylenebisdithiocarbamates. In multivariate analyses adjusted for all potential confounders (age, education, residence, smoking, gender, and field study), we found inverse associations, all not statistically significant, between occupational exposure to pesticides and asthma diagnosis (OR 0.41; 95% CI 0.15-1.11), complains of chest tightness (OR 0.60; 95% CI 0.36-1.02), wheeze (OR 0.56; 95% CI 0.32-0.98), asthma attack (OR 0.52; 95% CI 0.12-2.25), and asthma medication (OR 0.79; 95% CI 0.25-2.53). Furthermore, we reported null associations for multivariate analysis using ethylenethiourea as determinant for exposure. Although exposure to pesticides remains a potential health risk, our results do not suggest an association between exposure to ethylenebisdithiocarbamates and/or other pesticides used in our study on asthma and asthmatic symptoms.

The dose response principle from philosophy to modern toxicology: The impact of ancient philosophy and medicine in modern toxicology science.

Since ancient times the concept of dose response, from a toxicological perspective, has been a matter of concern. Already by the 8th century BC and over the years, many enlightened people have attempted to interpret this phenomenon, observing and coming across its results and practical implementation through exposure to chemical substances, either from natural or synthetic sources. Nowadays, the environmental exposure of human populations to chemicals in terms of quantity and quality might differ. Nevertheless, dose response still remains an issue joining hands with scientific and technological progress. The aim of the present review is not only to briefly recount the history of the dose response concept, from ancient time theories to novel approaches, but also to draw the outline of challenges and requirements toxicology science needs to fulfill.

Simulating real-life exposures to uncover possible risks to human health: A proposed consensus for a novel methodological approach.

In real life, consumers are exposed to complex mixtures of chemicals via food, water and commercial products consumption. Since risk assessment usually focuses on individual compounds, the current regulatory approach doesn't assess the overall risk of chemicals present in a mixture. This study will evaluate the cumulative toxicity of mixtures of different classes of pesticides and mixtures of different classes of pesticides together with food additives (FAs) and common consumer product chemicals using realistic doses after long-term exposure. Groups of Sprague Dawley (CD-SD) rats (20 males and 20 females) will be treated with mixtures of pesticides or mixtures of pesticides together with FAs and common consumer product chemicals in 0.0, 0.25 × acceptable daily intake (ADI)/tolerable daily intake (TDI), ADI/TDI and 5 × ADI/TDI doses for 104 weeks. All animals will be examined every day for signs of morbidity and mortality. Clinical chemistry hematological parameters, serum hormone levels, biomarkers of oxidative stress, cardiotoxicity, genotoxicity, urinalysis and echocardiographic tests will be assessed periodically at 6 month intervals. At 3-month intervals, ophthalmological examination, test for sensory reactivity to different types of stimuli, together with assessment of learning abilities and memory performance of the adult and ageing animals will be conducted. After 24 months, animals will be necropsied, and internal organs will be histopathologically examined. If the hypothesis of an increased risk or a new hazard not currently identified from cumulative exposure to multiple chemicals was observed, this will provide further information to public authorities and research communities supporting the need of replacing current single-compound risk assessment by a more robust cumulative risk assessment paradigm.

Free L-tryptophan plasma levels in antisocial violent offenders.

RATIONALE: Several studies have shown that impulsive violent behavior is associated with reduced serotonin metabolism in the brain, but no data exist on possible alterations of the serotonin precursor (free L-tryptophan) levels among violent offenders. OBJECTIVES: To study free L-tryptophan and kynurenine plasma levels among antisocial violent offenders. METHODS: Free L-tryptophan and competing amino acid (CAA) plasma levels were measured among 19 male impulsive antisocial violent offenders and 19 age-matched healthy male controls. RESULTS: Mean free L-tryptophan/(CAA) plasma levels were 160% (95% CI 116%-204%) higher among offenders than controls (P=0.000). Seventeen of the 19 offenders (89.5%) had values of more than 2 SD above the mean value of controls. The levels of kynurenine, the major metabolite of tryptophan, were slightly increased in offenders. CONCLUSION: Free plasma L-tryptophan/CAA levels were markedly increased among antisocial violent offenders indicating a disturbed tryptophan metabolism.

Urinary NAG and GAG as biomarkers of renal effects in exposure to 2-alkoxyalcohols and their acetates.

Many sensitive biomarkers are available for the surveillance of the early health effects of chemicals on humans. This study was conducted to evaluate the usefulness of glycosaminoglycans (GAG) as biomarkers of early kidney effects in exposure to 2-alkoxyethanols and their acetates. GAG were compared with effects on the urinary beta-N-acetylglycosaminidase activity (NAG). According to the results of the present study, the excretion rate of GAG was higher among women than men. On the other hand, the excretion rate of GAG was lower among exposed subjects than among the controls, and the level was decreased at the tested levels of exposure. The NAG activity was higher in most of the exposed groups than in the controls. The data indicated that an appropriate urinary limit value for ethoxyacetic acid was 30 mmol/mol creatinine in postshift samples and that this value corresponded to an 8-hour exposure level of 2 cm3/m3 2-ethoxyethylacetate. Urinary butoxyacetic acid excretion of 60 mmol/mol creatinine corresponded to the inhalation exposure level of 5 cm3/m3 2-butoxyethanol and its acetate in postshift samples.

Evaluation of sensory irritation of delta3-carene and turpentine, and acceptable levels of monoterpenes in occupational and indoor environment.

The standard mouse bioassay was used for obtaining the RD50 (i.e., the concentration that causes a 50% decrease in respiratory frequency) and for estimating the irritation properties of d-delta3-carene (i.e., (+)-delta3-carene) and commercial turpentine. The chemicals studied possess mainly sensory irritation properties similar to the previously studied monoterpenes, pinenes. The irritation potency of d-delta3-carene (RD50 = 1345 ppm) was almost equal to that of d-pinenes. Thus, d-delta3-carene was about four times more potent as a sensory irritant than I-beta-pinene, whereas the difference with I-alpha-pinene was more marked; as a sensory irritant, I-alpha-pinene is almost inactive. Based on sensory irritation potency and physicochemical and structural properties of pinenes and delta3-carene, the potency of a closely related monoterpene, limonene, is discussed. For commercial turpentine, a mixture of monoterpenes (mainly d-delta3-carene, I-beta-pinene, alpha-pinenes, and limonenes), the RD50 (1173 ppm) was the same order of magnitude as those of d-pinenes and d-delta3-carene. Apparently, d-monoterpenes are responsible for the sensory irritation caused by turpentine. In the wood industry and in the indoor air of nonindustrial environments, monoterpenes are thought to be one of the causative agents for irritation symptoms. The occupational exposure limit (OEL) of turpentine (100 ppm in Finland and the United States) is also used for individual monoterpenes, excluding limonene. Using results from this and our previous study, proposed OELs and recommended indoor levels (RILs) for selected monoterpenes and turpentine were determined based on their RD50 values. According to our studies, the present OEL of turpentine (100 ppm; 560 mg/m3) in Finland and in the United States seems to be suitable only for I-pinenes. For d-monoterpenes and turpentine, an OEL about three times lower is suggested. Our results show that recommended indoor levels (RILs) for monoterpenes are high compared to the concentrations measured indoors in nonindustrial environments. Thus, it is very unlikely that monoterpenes alone can cause irritation symptoms in homes or offices under normal conditions.

The effects of wood dusts on the redox status and cell death in mouse macrophages (RAW 264.7) and human leukocytes in vitro.

Wood dusts are classified as carcinogenic to humans and also produce other toxic, allergic, and acute effects in woodworkers. However, little is known about causative agents in wood dusts and their mechanisms of action. The effects of different tree species and particle size for biological activity were studied. The differences in the production of reactive oxygen species (ROS) and cell death (necrotic and apoptotic) between mouse macrophage (RAW 264.7) cells and human polymorphonuclear leukocytes (PMNL) for pine, birch, and beech dust exposures were investigated in vitro. The pine and birch dust exposure (1-100 microg/ml) produced concentration-dependent ROS production in both the cells, which was one order of magnitude higher with pine dust. The ROS production was faster in human PNML than murine RAW cells. The higher concentrations (500 and/or 1000 microg/ml) decreased ROS formation. With pine and birch dust exposure, this was probably due to the necrotic cell death. The pine dust concentrations of 500 and 1000 microg/ml were cytotoxic to human PMNL. The beech dust exposure activated the ROS production and decreased the cell viability only at the highest concentrations, being least potent of the three dusts. A sign of the apoptotic cell death in the murine RAW cells was observed at the pine dust concentration of 100 microg/ml. The exposure to the birch and beech dusts with a smaller particle size (<5 microm) produced greater ROS production than exposure to the corresponding dust with a wide range of particle sizes. However, changing the particle size did not affect the cell viability. The results indicate that the type of wood dust (tree species and possibly particle size) has a significant impact on the function and viability of phagocytic cells.

Reactions of hydrated formaldehyde in nasal mucus.

Formaldehyde is a well known toxic air impurity affecting the upper respiratory tract. It rapidly forms methylene glycol in water. Reactions of the hydrated formaldehyde with nasal mucus were studied by C-13 NMR spectroscopy. In the NMR spectra methylene glycol dominated and only minor signals from possible reactions were observed. This finding suggests that nasal mucus effectively protects nasal epithelium against formaldehyde.

Urinary biochemistry in occupational exposure to glycol ethers.

Glycol ethers and glycol ether acetates are dehydrogenated to alkoxyacetic acid congeners which may serve as biological indicators of exposure. The ethereal bond may also be cut in an oxidation reaction catalyzed by the mixed function oxidase. In case of ethylene glycol, the eventual endproduct is oxalic acid. Urinary oxalic acid and alkoxyacetic acid excretion together was found to relate to the decrease of the succinate dehydrogenase activity (SDH) as an indicator of renal mitochondrial effects. The excretion of ammonia by exposed workers was doubled as compared to controls. The excretion of chloride was found to be smaller in the exposed than in controls. The excretion of calcium and glycosaminoglycans (GAG) among exposed workers were similar compared to controls.

Exposure to airborne microorganisms and volatile organic compounds in different types of waste handling.

Occupational exposure of workers to airborne microorganisms and volatile organic compounds (VOC) in different types of waste treatment situations was examined during summer time. Microorganisms were collected as stationary samples using a six-stage Andersen impactor, while for VOCs both personal and stationary sampling was conducted. The exposure at the waste handling facility was considerably greater than at landfill sites or in waste collection. The concentrations of viable fungi were maximally 10(5) cfu/m3, and the concentrations of both total culturable bacteria and Gram-negative bacteria exceeded the proposed occupational exposure limit values (OELV), being 10(4) and 10(3) cfu/m3, respectively. Exposure to VOCs in the waste handling facility was three times higher than at the landfill sites, being at highest 3000 microg/m3, considered to be the limit for discomfort. The use of personal protective equipment at work, thorough hand washing and changing clothes after the work shift are strongly recommended in the waste handling facility and the landfill sites.

CYP enzymes catalyze the formation of a terminal olefin from 2-ethylhexanoic acid in rat and human liver.

1. The metabolism of 2-ethylhexanoic acid (2-EHA) was studied in rat, mouse and human liver microsomes in vitro. The metabolites of 2-EHA were identified as methylated derivatives by gas chromatography-mass spectrometry. 2. 2-Ethyl-1,6-hexanedioic acid was the main metabolite produced in rat, mouse and human liver microsomes. Unsaturated 2-ethyl-5-hexenoic acid, a terminal olefin, was produced only in human liver microsomes and phenobarbital-induced rat liver microsomes. The cytochrome P450 (CYP) inhibitors metyrapone, SKF 525A, triacetyloleandomycin (TAO), quinidine and the cytochrome P450 reductase antibody abolished its formation both in rat and human microsomes. 3. The metabolites were analyzed also in vivo in urine of 2-EHA-exposed rats and in urine of sawmill workers exposed occupationally to 2-EHA. Both rat and human urine contained 2-ethyl-1,6-hexanedioic acid as the main metabolite and also 2-ethyl-5-hexenoic acid. Metyrapone, SKF 525A and TAO all decreased drastically the formation of 2-ethyl-5-hexenoic acid in the rat. 4. The data indicate that (1) several CYP families (CYP2A, CYP2B, CYP2D and CYP3A) could be responsible for the hepatic metabolism of 2-EHA, (2) the same metabolites were formed in rats and man and (3) an unsaturated terminal olefin, 2-ethyl-5-hexenoic acid is formed in the liver.

Qualitative identification of volatile metabolites from two fungi and three bacteria species cultivated on two media.

Two fungal species, Aspergillus fumigatus and Penicillium brevicompactum and three bacteria, Klebsiella pneumoniae, Enterobacter agglomerans and Streptomyces albus were cultivated on two media, malt extract agar and dichloran glycerol agar. The volatile metabolite samples from the cultures were adsorbed on Tenax TA and analyzed qualitatively by thermal desorption gas chromatography and with a mass selective detector. Various hydrocarbons, alcohols, ketones, esters and terpenes were identified. The production was highly dependent on both the medium and the microbial species. 2-Methyl-1-propanol, 2-methyl-1-butanol and 3-methyl-1-butanol were the most commonly produced substances. The bacterial species did not produce any hydrocarbons that were characteristic to the fungi (e.g. methyl-1,3-pentadiene, 1-octene and 1,3-octadiene or 8-carbon alcohols 1-octen-3-ol and 3-octanol). Instead, K. pneumoniae and E. agglomerans produced 3-hydroxy-2-butanone and 1-hydroxy-2-propanone, which were not produced by the fungi. Geosmin and a large number of sesquiterpenes were produced by S. albus.

Hair nicotine/cotinine concentrations as a method of monitoring exposure to tobacco smoke among infants and adults.

In this pilot study, we examined the validity and usefulness of hair nicotine-cotinine evaluation as a biomarker of monitoring exposure to tobacco. Head hair samples were collected from 22 infants (<2 years of age) and 44 adults with different exposures to tobacco (through either active or passive smoking) and analyzed by liquid chromatography-mass spectrometry (LC-MS) for nicotine and cotinine. Hair samples were divided into three groups, infants, passive smoker adults and active smoker adults, and into eight subgroups according to the degree of exposure. The limit of quantification (LOQ) was 0.1 ng/mg for nicotine and 0.05 ng/mg for cotinine. Mean recovery was 69.15% for nicotine and 72.08% for cotinine. The within- and between-day precision for cotinine and nicotine was calculated at different concentrations. Moreover, hair nicotine and cotinine concentrations were highly correlated among adult active smokers (R (2) = 0.710, p < 0.001), among adult nonsmokers exposed to secondhand smoke (SHS; R (2) = 0.729, p < 0.001) and among infants (R (2) = 0.538, p = 0.01). Among the infants exposed to SHS from both parents the noted correlations were even stronger (R (2) = 0.835, p = 0.02). The above results identify the use of hair samples as an effective method for assessing exposure to tobacco, with a high association between nicotine and cotinine especially among infants heavily exposed to SHS.