Risk assessment and management of occupational exposure to pesticides in agriculture.

Nearly 50% of the world labour force is employed in agriculture. Over the last 50 years, agriculture has deeply changed with a massive utilisation of pesticides and fertilisers to enhance crop protection and production, food quality and food preservation. Pesticides are also increasingly employed for public health purposes and for domestic use. Pesticide are unique chemicals as they are intrinsically toxic for several biological targets, are deliberately spread into the environment, and their toxicity has a limited species selectivity. Pesticide toxicity depends on the compound family and is generally greater for the older compounds; in humans, they are responsible for acute poisonings as well as for long term health effects, including cancer and adverse effects on reproduction. Due to their intrinsic toxicity, in most countries a specific and complex legislation prescribes a thorough risk assessment process for pesticides prior to their entrance to the market (pre-marketing risk assessment). The post-marketing risk assessment takes place during the use of pesticides and aims at assessing the risk for exposed operators. The results of the risk assessment are the base for the health surveillance of exposed workers. Occupational exposure to pesticides in agriculture concerns product distributors, mixers and loaders, applicators, bystanders, and rural workers re-entering the fields shortly after treatment. Assessing and managing the occupational health risks posed by the use of pesticides in agriculture is a complex but essential task for occupational health specialists and toxicologists. In spite of the economic and social importance of agriculture, the health protection of agricultural workforce has been overlooked for too many years, causing an heavy tribute paid in terms of avoidable diseases, human sufferance, and economic losses. Particularly in the developing countries, where agricultural work is one of the predominant job, a sustainable model of development calls for more attention to occupational risks in agriculture. The experience of many countries has shown that prevention of health risk caused by pesticides is technically feasible and economically rewarding for the individuals and the whole community. A proper risk assessment and management of pesticide use is an essential component of this preventative

Low level exposure to chemicals and immune system.

Industrialized countries are facing an increase of diseases attributable to an alteration of the immune system function, and concern is growing that this trend could be at least partially attributable to new and modified patterns of exposure to chemicals. Among chemicals matter of concern, pesticides can be included. The Authors have reviewed the existing evidence of pesticide immunotoxicity in humans, showing that existing data are inadequate to raise conclusions on the immunotoxic risk related to these compounds. The limits of existing studies are: poor knowledge on exposure levels, heterogeneity of the approach, and difficulty in giving a prognostic significance to the slight changes often observed. To overcome these limits, the Authors have proposed a tier approach, based on three steps: the first, addressed at pointing out a possible immunomodulation; the second, at refining the results and the third one, when needed, to finalize the study and to point out concordance with previous results. Studies should preferably be carried out through comparison of pre- and post-exposure findings in the same groups of subjects to be examined immediately after the end of the exposure. A simplification of the first step approach can be used by the occupational health physician and the occupational toxicologist. Conclusions on the prognostic significance of the slight changes often observed will be reached only by validating the hypothesis generated by field studies with an epidemiological approach. In this field, the most useful option is represented by longitudinal perspective studies.

Influence of sex, age, and smoking habits on the urinary excretion of D-glucaric acid.

Reference values for urinary D-glucaric acid and the influence of sex, age and smoking habits were evaluated with a low-pH enzymatic method. D-Glucaric acid measured on spot urine samples from 573 healthy subjects gave mean concentrations (mumol/1) and D-glucaric acid/creatinine ratios (mmol/mol creatinine) of 56.1 (+/- 22.9) and 3.05 (+/- 0.99) for males and 53.3 (+/- 20.9) and 3.35 (+/- 0.95) for females. No difference between morning and evening was observed for urinary D-glucaric acid/1 values, but D-glucaric acid/creatinine was higher in the evening samples for both sexes. There was a negative correlation between D-glucaric acid/1 values and age in males but not in females: the decrease of D-glucaric acid concentration was, however, quantitatively very small. Smoking produced a significant increase in D-glucaric acid concentration and in the D-glucaric acid/creatinine ratio for males and also partially for females.

Low-pH method for the enzymatic assay of D-glucaric acid in urine.

The enzymatic methods for measuring D-glucaric acid in urine are based on the conversion of D-glucaric acid into its 1,4-lactone and measurement of inhibition of 1,4-lactone against beta-glucuronidase at pH 5.0. All the enzymatic methods described suffer from the disadvantage of a procedure that is complicated and inherently inaccurate, because the nature of glucaric acid/1,4-lactone equilibrium has not been properly considered in the development of such methods. After elucidating the factors influencing glucaric acid/1,4 lactone equilibrium in more detail, a low-pH enzymatic method has been developed in which the 1,4-lactone is formed in the urine sample by acid boiling at pH 3.8 and assayed at the same pH using beta-glucuronidase from Limpets. This procedure allows the acid/lactone equilibrium to remain stable during both the lactonization step and the enzymatic assay. The coefficient of variation for the proposed method (within-run and between-day precision) was from 4.2 to 8.7. The analytical recovery varied from 92-108%.

Health effects in man from long-term exposure to pesticides. A review of the 1975-1991 literature.

The scientific literature published over the period 1975-1991 on long-term health effects from prolonged exposure to pesticides has been reviewed, in order to document the state-of-knowledge on the mortality and morbidity of groups of the population exposed to pesticides. Specific aims of the review were to identify (1) which groups of the population have been more broadly surveyed, (2) which adverse effects have been consistently associated with specific pesticide exposures, (3) which are the pesticides of concern and (4) which health effects would require special attention in future research. The literature on acute effects and animal toxicology studies have not been considered at all in this monograph. In the period of interest, 440 papers have been published. Apart from 97 reviews and a small number of case reports, approximately half of the original investigations were of the case-control design (n = 108), while the remaining papers reported results from proportionate mortality (n = 10), cohort (n = 66) or cross-sectional studies (n = 51), carried out on pesticide applicators (n = 48), agricultural workers (n = 26) or people employed in the pesticide manufacturing industry (n = 50). Most of the case-control studies related to cases of cancer from various sites, especially myelolymphoproliferative disorders (MLP) and soft-tissue sarcomas (STS). When compared to the general population total mortality has been found to be consistently lower among pesticide manufacturers as well as among other groups of workers. This observation has been mostly attributed to the 'healthy worker effect' or, in the case of agricultural workers, to the healthier lifestyle of farm families. With the exception of deaths by accidental causes, non-cancer causes of death (mainly represented by cardiovascular diseases), were generally found to be less frequent than expected among manufacturers or users of pesticides, in particular among farmers. No consistent evidence of a global cancer mortality different from that of the general population has been reported among pesticide manufacturers or applicators. On the other hand, the papers examined have been strikingly consistent in reporting a low overall cancer risk among agricultural workers; life-style, clean air, low prevalence of smoking have been hypothesized so as to explain this observation. Numerous studies considered the possible link between exposure to phenoxyherbicides and occurrence of certain types of cancer, especially STS and MLP disorders.(ABSTRACT TRUNCATED AT 400 WORDS)

Biological Monitoring of Pesticide Exposure: a review. Introduction.

Pesticides are used worldwide in agriculture, industry, public health and for domestic applications: as a consequence, a great part of the population may be exposed to these compounds. In spite of this extensive use, knowledge on the health risks associated with prolonged exposure is rather poor, and major uncertainties still exist. Epidemiological observations in man have so far produced little conclusive information, mainly because of weaknesses in exposure assessment. Therefore, information on the type and levels of exposure is fundamental in order to better understand and characterize risk to human health. Exposure assessment can be carried out via measurement of environmental concentrations, as well as via determination of the chemical or its metabolites in body tissues (biological monitoring). Besides indices of internal dose, biological monitoring also includes measurements of early effects attributable to interaction between the chemical agent and the human body. Biological monitoring has the advantage, over environmental monitoring, of determining the dose actually absorbed via any possible route: differences in absorption can be taken into account. whether they are due to biological variability or to use of protective equipment. When, in some cases, a combination of occupational and non-occupational exposure occurs, this also can be taken into consideration by biological monitoring. Few reference documents have been published on biological monitoring of pesticides. For this reason, the Office of Occupational Health of the World Health Organization gave ICPS a mandate to prepare a monograph specifically addressed to reviewing methods for biological monitoring of pesticide exposure. This review is based on more than 300 studies published over the period 1980-1999. For the most representative chemical classes, the available biological exposure indices are reported. Both indices of internal dose and. when available, of early effects are discussed. The reported tests were used to monitor exposure of pesticide applicators in agriculture and public health, manufacturing and formulating workers. subjects poisoned after accidental exposure or attempted suicide, volunteers involved in pharmacokinetic studies, as well as sub-groups of the general population exposed to environmentally persistent pesticides. Single chapters deal with organophosphorus insecticides, carbamate pesticides, dithiocarbamates, phenoxyacids, quaternary ammonium compounds. coumarin rodenticides, synthetic pyrethroids, organochlorine pesticides, chlorotriazines, and pentachlorophenol.

Neurobehavioral effects of pesticides: state of the art.

The authors have reviewed the literature on neurobehavioral toxicity of pesticides to assess the status of knowledge on this matter. Some data suggest that exposure to DDT and fumigants may be associated with permanent decline in neurobehavioral functioning and increase in psychiatric symptoms, but, due to the limited number of studies available and the scarce knowledge on exposure levels, no firm conclusion can be drawn. Data on subjects acutely poisoned with organophosphorous compounds suggest that an impairment in neurobehavioral performance and, in some cases, emotional status may be observed as a long-term sequela, but the possibility still remains that these effects were only an aspecific expression of damage and not of direct neurotoxicity. Studies carried out on subjects chronically exposed to organophosphates, but never acutely poisoned, do not provide univocal results but the slight changes consistently observed in sheep dippers suggest the need of focusing on activities characterized by relatively higher exposure levels. In general, the main limits of existing knowledge are the variability of the testing methods used, which makes it difficult to compare the results of single studies, and the scarce knowledge on exposure levels. A promising approach may be the conduction of prospective longitudinal or cohort studies, where exposure and dose assessment can be more easily controlled, or the evaluation of cohorts of workers a priori selected for the availability of environmental and biological monitoring data. The follow up of the populations under study may give an answer at the problem of the prognostic significance of the observed changes. Also the protocols used to assess neurobehavioral functioning need to be standardized.

Effect of the progestagen Promegestone (R-5020) on mRNA of the oestrone sulphatase in the MCF-7 human mammary cancer cells.

Using reverse transcriptase polymerase chain reaction amplification it was possible to detect the presence of oestrogen sulphatase mRNA in different hormone-dependent (MCF-7, T-47D) and hormone-independent (MDA-MB-231, MDA-MB-468) mammary cancer cell lines. The expression of this mRNA is significantly higher in T-47D and MDA-MB-231 than in the other cell lines, and a correlation of this expression with the enzymatic activities was observed. The progestagen Promegestone (R-5020) can significantly decrease the mRNA of the sulphatase in MCF-7 cells. As this progestagen can also inhibit the enzyme itself in the same mammary cancer cell line, it is suggested that for the decrease in the sulphatase activity not only the effect on the enzyme, but also the effect on transcriptional factor(s) which express this enzyme are involved. The present data not only contribute to the knowledge of the mechanism of the sulphatase activity, but also can open new possibilities in breast cancer treatment.

Risk assessment and management of occupational exposure to pesticides.

Occupational exposure to pesticides in agriculture and public health applications may cause acute and long-term health effects. Prevention of adverse effects in the users requires actions to be undertaken in the pre-marketing and post-marketing phase of these products. The pre-marketing preventive actions are primary responsibility of industry and the public administration. Admission of pesticide use (registration) is carried out by considering the toxicological properties of each pesticide (hazard identification), determining the dose-response relationship (NOEL identification), assessing or predicting the exposure level in the various scenarios of their use, and characterising the risk. The decision about admission takes into consideration the balance between risks and benefits. The post-marketing preventive activities consist of the promotion of a proper risk management at the workplace. Such a management includes the risk assessment of the specific conditions of use, the adoption of proper work practices, and the health surveillance of the workers. Each country should develop an adequate National Plan for Prevention of Pesticide Risk which allocates different roles and tasks at the central, regional and local level.

The WHO-UNDP epidemiological study on the health effects of exposure to organophosphorus pesticides.

A multinational epidemiological study on the neurotoxic effects of long-term, low-level exposure to organophosphorus pesticides (OPs) is being supported in ten European countries by the United Nations Development Programme (UNDP) jointly with the World Health Organization (WHO) Regional Office for Europe. The protocol developed for the study is directed at the assessment of OP exposure and absorption, abnormal neurological findings, and behavioral changes in both agricultural and industrial workers. The biological monitoring tests adopted in the study have been standardized and submitted to quality assurance programmes.

Immune parameters in biological monitoring of pesticide exposure: current knowledge and perspectives.

Exposure to pesticides can cause a number of effects on the immune system, varying from a slight modulation of immune functions to the development of clinical immune diseases. The aim of this study has been reviewing published data on immune effects of pesticides in humans, with particular attention for effects observed in absence of any other change, and to the possibility of identifying a dose effect relationship. Some evidence of immunotoxic effects in man involve organophosphorus compounds, some organochlorine insecticides (OC), some carbamates, some phenoxy herbicides, dithiocarbamates, and pentachlorophenol (PCP). The alterations are usually observed in absence of any other change; in some cases, data suggest the presence of a dose effect relationship. The prognostic significance of the observed changes is still unclear. The Authors propose a tier approach to assess immune effects in humans.

Biological monitoring of human exposure to atrazine.

Atrazine exposure was evaluated in six manufacturing workers by personal and biological monitoring. Total atrazine exposure varied from 10 to 700 mumol per workshift and total urinary atrazine excretion accounted for 1-2% of the external dose. The spectrum of the urinary atrazine metabolites comprises bi-dealkylated (80%), deisopropylated (10%), deethylated (8%) and unmodified atrazine (2%). The metabolites are eliminated in urine in slightly longer than 24 h: 50% of the amount is excreted in the first 8 h following the workshift.

Ethylenethiourea in urine as an indicator of exposure to mancozeb in vineyard workers.

In the present study, the personal exposure to mancozeb and/or ethilenethiourea (ETU) in 13 Italian vineyard workers and in 13 subjects without occupational exposure to pesticides was investigated. With this aim, the level of ETU in urine and the dermal exposure to mancozeb were determined. Baseline urinary ETU results were lower than the analytical limit of detection for all controls (<0.5 microg/g creatinine) and for ten workers (median <0.5, range <0.5-3.4 microg/g creatinine). In workers, urinary ETU was significantly increased at the end of shift (2.5, <0.5-95.2 microg/g creatinine) compared with baseline levels. End-shift urinary ETU was higher in operators using open tractors (n=7) than in those using closed tractors (n=5) (16.2 vs. 2.4 microg/g creatinine), but the difference was not significant (P=0.073). End-shift urinary ETU was positively correlated with dermal exposure to mancozeb determined both over the clothes and on the skin (Spearman's rho=0.770 and 0.702, P=0.009 and 0.024, respectively). Wine consumption positively influenced the excretion of ETU.

Chlormadinone acetate versus micronized progesterone in the sequential combined hormone replacement therapy of the menopause.

OBJECTIVE: The efficacy and safety of chlormadinone acetate (CA) versus micronized progesterone (P) were assessed in non-hysterectomized postmenopausal women. MATERIALS AND METHODS: This was a multicenter, randomized, parallel group study with a 6-month double-blind period followed by a 12-month open period. Patients were randomized to receive every month during 18 months percutaneous 17 beta-estradiol (E(2)) 1.5 mg/day from Day 1 to 24 of treatment cycle, combined from Day 11 to 24 to either CA 10 mg/day (n=167) or P 200 mg/day (n=169). Endometrial biopsy (EB, main analysis criterion) was performed at baseline, and at Day 18-24 of the 6th and 18th cycles. RESULTS: At Month 6, EB did not evidence any hyperplasia. EB were inadequate for assessment in 24.5% and 47.5% of patients in the CA and MP groups, respectively. CA was found to be as protective as P (96.3% and 92.0% of success). However, the hormonal status of the endometrium differed (P<0.001): a secretory endometrium was found in 81.5% of the CA patients, compared to 50.7% in the P group. These transformations resulted in predictable, cyclic bleeding in 94.5% of the CA patients, compared to only 62.3% of the P patients (P=0.0001). Unscheduled bleeding, spotting and/or metrorrhagia, were more frequent under P than under CA (17.9% and 13.7%, respectively). The beneficial effects on hot flushes were more important in the CA group than in the P (P<0.001). At Month 18, the biopsy and clinical results were similar to those obtained at Month 6. The safety profile, particularly the lipid one, was similar in both groups, except for drowsiness and dizziness, which were significantly more frequent under P than under CA. CONCLUSION: The progestative effects of CA on the endometrium and on menopause-related symptoms were at least as good as those of P. Moreover, CA resulted more often than P in secretory effects, and in satisfying bleeding patterns.

Comparative endometrial histology in postmenopausal women with sequential hormone replacement therapy of estradiol and, either chlormadinone acetate or micronized progesterone.

OBJECTIVES: To determine the endometrial response in postmenopausal women treated with a sequential hormone replacement therapy (HRT) of estradiol and, either chlormadinone acetate (CA) or micronized progesterone (MP). METHODS: Three hundred and thirty-six postmenopausal women with a normal endometrium were randomized in the double-blind study. All patients received percutaneous estradiol 1.5 mg/day from day 1 to day 24 and either CA 10 mg/day or oral MP 200 mg/day from day 10 to day 24. The total duration of treatment was 18 months. Endometrial biopsies were performed before treatment and between day 18 and day 24 of the 18th month of HRT. RESULTS: Of the 336 patients selected, 317 had a biopsy at inclusion. Of them, 244 patients (124 in the CA group and 120 in the P group) were suitable for evaluation for analysis at the 18th month. Insufficient sampling occurred in 33.9% in the CA group and 60% in the MP group (probably atrophic). No case of hyperplasia could be reported in both groups. The endometrium was atrophic in 19.5 versus 27.1%, proliferative in 3.7 versus 8.3% and secretory in 76.8 versus 62.5% in CA and MP groups, respectively. It was possible to see histological differences induced by the two progestins. The CA endometria showed fewer glands lined by a cubo-cylindrical epithelium, with an edematous stroma, compared to the MP endometria which had more glands lined by a cylindrical epithelium, stroma being poorly edematous. These figures varied in intensity due to the length of progestative impregnation, predecidualization occurring later in the CA group, with distended capillaries. CONCLUSIONS: These results show that CA 10 mg/day is a powerful progestin compared to MP 200 mg/day, on weakly estradiol-primed endometria, giving a molecule-specific histological aspect with a good endometrial safety.

Biological indicators of neurotoxicity in central and peripheral toxic neuropathies.

This article reviews the biological indicators available for monitoring human neurotoxicity by exogenous chemicals with reference to the phases in which the neurotoxic process takes place, namely delivery, receptor-linkage, and toxicodynamic phase. Among the delivery phase tests, indicators are available for metals (lead, mercury) and some organic substances (CS2, n-hexane, DDT, etc.), but a correlation between neurotoxic effects and these indices is rather loose or not yet proved. The receptor-phase tests comprise well known enzymes, such as cholinesterase, less known but promising indicators, such as neuropathy target esterase (NTE), and new tools under study, such as acrylamide-hemoglobin adducts or 2,5-hexanedione-protein adducts. The toxicodynamic phase tests, which mainly consist of measuring substances released from the nervous system, have provided so far rather poor results, but more specific techniques of measurement (monoclonal antibodies) could offer new possibilities in the future.

A clinical, neurophysiological and behavioral study of female workers exposed to 1,1,1-trichloroethane.

Twenty-two female subjects working in a factory in which 1,1,1-trichloroethane was the only solvent used were investigated by means of clinical, neurophysiological and psychometric methods so that the neurotoxicity of the solvent could be evaluated. On the basis of the ambient air concentrations of 1,1,1-trichloroethane ranging from 110 to 990 ppm, the workers were divided into three risk groups and compared with a reference group. No significant difference was observed between the exposed and unexposed females with respect to clinical features, maximal motor conduction velocity, conduction velocity of slow fibers, and psychometric data. The most frequent complaints of the workers were of the "neurotic" type with a slightly higher, but not significant, difference in the exposed group. The results obtained favor the absence of a manifest neurotoxic effect of 1,1,1-trichloroethane under the specific work conditions of the investigation; generally unfavorable work conditions seem to have played a prominent role in the genesis of the neurotic complaints. The importance of a global methodological approach in the study of work-related risks, particularly in neurological and psychological surveys, is stressed.

Allergens in indoor air: environmental assessment and health effects.

It has been suggested that the increase in morbidity and mortality for asthma and allergies, may also be due to an increase in exposure to allergens in the modern indoor environment. Indoor allergen exposure is recognised as the most important risk factor for asthma in children. House dust mites, pets, insects, plants, moulds and chemical agents in the indoor environment are important causes of allergic diseases. House dust mites and their debris and excrements that contain the allergens are normally found in the home in beds, mattresses, pillows, carpets and furniture stuffing, but they have also been found in office environments. Domestic animals such as cats, dogs, birds and rodents may cause allergic asthma and rhinoconjunctivitis. The exposure usually occurs in homes, but also in schools and kindergartens where domestic animals are kept as pets or for education; moreover, cat and dog owners can bring allergens to public areas in their clothes. Allergy to natural rubber latex has become an important occupational health concern in recent years, particularly among healthcare workers; when powdered gloves are worn or changed, latex particles get into the air and workers are exposed to latex aerosolised antigens. To assess the environmental risk to allergen exposure or to verify if there is a causal relationship between the immunologic findings in a patient and his/her environmental exposure, sampling from the suspected environment may be necessary.

The speciation of the chemical forms of arsenic in the biological monitoring of exposure to inorganic arsenic.

Total As content may be determined in blood and urine by means of an AAS method that involves reduction of As to its volatile hydride and ashing at 600 degrees C with MgO and Mg (NO3)2. Separation of inorganic As (InAs), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMAA) by ion-exchange chromatography, followed by direct AAS analysis, allows the determination of each As species in the urine. In a reference population of 148 subjects with only normal environmental exposure to As, total As concentration in the urine averages 17.2 +/- 11.1 micrograms/l. Urinary As consists of 10% each of InAs, MMAA and DMAA, the remaining 70% consisting of other forms of organic As. Blood As concentration averages 5.1 +/- 6.9 micrograms/l and correlates significantly with the urinary concentration of InAs and the sum of its metabolites (InAs + MMAA + DMAA). Inorganic arsenic undergoes methylation in the organism. After ingestion of high quantities of As2O3, the time course of excretion of its metabolites indicates that As methylation occurs by a saturable mechanism. In workers exposed to As2O3, InAs, MMAA and DMAA are the only chemical forms of As excreted in the urine that are relevant to a study of occupational exposure. Blood As concentration is proportional to exposure and correlates only with urinary DMAA excretion; DMAA seems to be the most appropriate single indicator of exposure. At high levels of exposure (total As excretion above 200 micrograms/l), As accumulates in the organism and DMAA excretion reflects its accumulation. At low levels of exposure (total As excretion below 50 micrograms/l) a short-term accumulation does not occur and the best biological indicator of exposure is InAs excretion. Seafood ingestion brings about a marked increase in urinary excretion of total As that lasts for 24-48 h and is not accompanied by any increase in InAs, MMAA or DMAA excretion. Organic As from seafood does not mix with the pool of inorganic As in the organism and may be separately detected in urine. In the biological monitoring of human exposure to As, particularly in the case of high urinary values, the speciation of the chemical forms of As in urine is necessary in order to establish with certainty the source, industrial or alimentary, of exposure.

Toxicological and immune findings in workers exposed to pentachlorophenol (PCP).

Pentachlorophenol (PCP) is a pesticide used worldwide in industrial and domestic applications. Data available on the effects of technical-grade PCP on the immune system are insufficient and equivocal; some data indicate inhibitory effects, whereas others suggest stimulating effects. This study was performed to evaluate toxicological and immune findings in 32 subjects who had prolonged exposure to PCP in a wood factory and in 37 controls. PCP concentrations were determined in plasma and urine of all subjects. Lymphocyte subsets of CD3-, CD4-, and CD8-positive cells were evaluated, and the proliferative response of peripheral blood mononuclear cells (PBM) to mitogens was assessed. The results suggested the absence of major laboratory and clinical signs of PCP-dependent immune deficiency. A weak effect of long-term exposure to PCP on the functional immune response could not be ruled out because of the finding of a decreased response to 5% PHA in the high-exposure group. A weak effect against hepatocyte membrane was evidenced by the finding of raised serum concentration of glycocholic, taurodeoxycholic, and glycochenodeoxycholic acids in subjects directly exposed to PCP for more than 10 y.