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.

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

[Indoor air quality and occupational health, past and present]

The expression "indoor pollution" of residential, office and public buildings appeared for the first time in western societies toward the end of the '60s to indicate a complex phenomenon as important to public health as that of the "outdoor air pollution" or even more so. The demonstration of the toxic effects of passive smoking, radon, and other chemical and biological pollutants present in office and residential environments has prompted a wide spectrum of research into health risks, has led to position-taking by national and international authorities, and has given rise to a new scientific multi-disciplinary field of research, with respective international associations, scientific journals, and international conferences attended by thousands of participants. In Italy, since 1988, several scientific conferences have been organised and these have led to institutional initiatives such as the Commission set up in 1990 by the Italian Environment Ministry and the Commission set up in 1998 by the Italian Ministry of Health. The latter produced a Prevention Plan for Health Protection and Promotion in Indoor Environments which, for the first time, tackles indoor air pollution in a systematic way and provides an overall picture of the health and economic impact of the main illnesses related to indoor pollution on society. Decree 626/94 has also been affected, in some way, by these new scientific findings and in art. 33 has produced an update of the old art. 9 of the Decree 303/56. The attention to the subject of indoor air quality, in addition to that of offices and commercial buildings, has turned in more recent years to special environments such as schools and hospitals, resulting in the production of important publications. The modern frontier of research on indoor and outdoor air hazards is represented by fine air particulate matter. A large number of worldwide epidemiological studies have revealed that the daily variation in fine and ultra-fine particle air concentration in urban areas is associated with the simultaneous daily variation in the morbidity and mortality of the general population. The particle-linked increase in mortality has been attributed to respiratory and cardiovascular toxic effects, but the mechanisms by which urban air particles (indoor and outdoor) induce worsening of respiratory and cardio-vascular diseases are so far unknown and are the subject of intense investigation. Workers employed in the tertiary sector (offices, trade, banking, hospitals, schools, etc.) now account for 80% of the Italian labour force and the occupational physician is increasingly requested to assess the risk and monitor the health status of tertiary sector workers. These working environments are believed to be healthy and lacking in specific health risk factors, but such a belief is often only the result of the limited knowledge that employers, workers and the physicians themselves have about these environments and the results of international research studies over the last forty years. This issue is surely at the centre of the interest of our discipline and of public health throughout the developed western world and represents an ongoing challenge for the occupational physician, with new research topics and new problems to deal with. Recent issues include SARS and the defence of buildings and the air of working environments against terrorism attacks, such as the use of anthrax dust.

[Biological monitoring and risk assessment]

Risk assessment in occupational medicine is the part of risk analysis where physicians also contribute. A risk is the probability of an adverse health effect and derives from the hazard posed by a given chemical and from exposure characteristics. Due to the complexity of this process, models are used in occupational medicine, where risk factors are identified and exposure estimated, combined with an understanding of the severity of possible effects. Theoretically, the advantages of biological monitoring are obvious. However, the paucity of available data on biological monitoring limits its uses. Moreover, the utilization of data on biological monitoring requires evaluation of their significance. Examples are discussed to highlight advantages and limitations of biological monitoring data in both hazard and risk assessments. They include exposure to polycyclic aromatic hydrocarbons, benzene, other carcinogens, paraquat and polychlorinated biphenyls.

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.

[Risk profiles in agriculture: activities in the region of Lombardy]

Agriculture represents a very complex scenario that needs proper tools. To this aim, in the frame of Special Project "La Prevenzione nell'impiego di Antiparassitari in Agricoltura" promoted by the Region of Lombardy, profiles of exposure and/or risk have been identified as valid approach able to define particular conditions of exposure and risk for the operator in particular settings. The evaluation necessarily needs to identify the most important parameters affecting exposure and their extent on magnitude of exposure. Therefore, field studies should be further performed in order to confirm and improve the profile. The identification of profiles of exposure and risk is an activity still in progress that need to be carefully set up and standardised. The team involved in the study identified priorities deserving much attention in Lombardy, and planned a three years programme aimed at define the profile of exposure and risk in viticulture, maize crop, rice growing, nursery gardening, horticulture in greenhouses, maintenance of gardens, and poplar growing.

[Definition of acceptable operator exposure levels (AOELs) to pesticides]

A guidance document entitled "Recommended method for the establishment of Acceptable Operator Exposure Levels" has been prepared within the EU 5th Framework program. The paper describes the main outcomes of the project and the issues that apply particularly to agricultural workers and bystanders and the difficulties in developing an agreed uniform approach. The scientific basis of the process is discussed, to be used by the European Commission and Member States when making decision about the inclusion of an active substance in Annex 1 of Directive 91/414/EEC.

[Epidemiologic research on asbestos related disease in ENEL SpA electricity production plant maintenance]

Since many years research programs have been set up to study the relationship between asbestos occupational exposure and development of asbestos-related lung diseases in electricity production plants workers. In the year 2000 a new study of asbestos-related lung abnormalities prevalence in italian geothermal and idrothermal power plant maintenance workers was planned. The cohort comprised 3891 subjects. To meet the criteria, only workers in service for at least six months before 1990 and still in service at power plants in May 2000 were included in the study; chest X-rays were taken and made anonymous. Independent reading of X-rays was made by two groups of specialists, and a third reading of selected discordant readings X-rays was made by another group of specialists. A further diagnostic protocol (including HRCT) was planned when two out of three readings showed the presence of asbestos related lung abnormalities. The analysis was made on 3063 subjects (78.7% of the cohort). The number of asbestos-related abnormalities in two out of three X-ray readings was 122 (4%). The further diagnostic protocol, that included occupational and pathological anamnesis and HRCT, confirmed an asbestos-related occupational lung abnormalities in 41 cases (1.3% out of 3063 subjects). The prevalence of asbestos-related lung abnormalities among 3063 power plant maintenance workers was 1.3%. If all the cases of lung abnormalities so far detected (data are still provisional) had developed only in the power plant environment, and not in previous working activities, the prevalence of lung abnormalities would be extremely low. These data support the evidence of limited exposure levels to asbestos in this working environment And bears witness to the success of preventive measures to control this specific risk.

[Occupational exposure to fungicides in floriculture in Ecuador]

Floriculture represents one of the major sources of income in the Ecuadorian Andean Region that can be carried out either in open fields as in greenhouses by using chemical compounds, growing hormones and xenobiotics. Among pesticides, ethylenbisdithiocarbamate (EBDTCs) fungicides represent the most extensively used. The aim of the study was the assessment of exposure to EBDTCs in Ecuadorian floricultural workers by the determination of the urinary excretion of the main metabolite of these compounds, ethylenethiourea (ETU). For this purpose, thirty-six floriculture workers and 7 unexposed healthy subjects were recruited for the study. Median level of ETU excretion in agricultural workers before the work shift was 3.2 micrograms/g creatinine, ranging from 0.4 to 34.5 micrograms/g creatinine. After pesticide application, urinary ETU increased to 6.2 micrograms/g creatinine (1.5-26.5) microgram/g creatinine. Urinary ETU resulted significantly higher in overall workers, taken as pre- and post-shift samples, when compared to controls (0.7, 0.4-2.1 micrograms/g creatinine, p < 0.01). According to jobs, applicators showed the highest levels of ETU excretion whereas growing, post-harvesting and maintenance workers showed similar levels of exposure. Higher level ETU excretion was observed in greenhouse compared to open field workers.

[From industrial hygiene and toxicology to environmental hygiene and toxicology: problems and prospects]

BACKGROUND

Low-dose exposures to mixtures of substances have received increasing interest and they involve many different occupational and environmental situations. The presence in the population (working and general) of groups of susceptible individuals is an important public health issue that poses new challenges to science and society.

OBJECTIVES

To discuss the evolution from traditional occupational hygiene and toxicology to the new environmental (general and occupational) hygiene and toxicology.

RESULTS

Environmental hygiene and toxicology have remarkably improved analytical tools available to solve most of the analytical issues posed by the present exposure scenario. Biomarkers of low-dose exposure, early effects and individual susceptibility are being intensively investigated.

CONCLUSIONS

The challenge in this field for the coming years appears to be not the analytical but the medical and ethical implications.

Periportal fibrosis and other liver ultrasonography findings in vinyl chloride workers

AIMS

To investigate the presence of liver lesions and their relation with vinyl chloride monomer (VCM) exposure or other personal risk factors, in workers involved in the production of VCM and polyvinyl chloride (PVC).

METHODS

A liver ultrasonography examination was conducted in 757 workers, some of whom had long standing service in the production of VCM and PVC. The study involved: assessment of individual past and present VCM exposure of each worker; collection of past personal health history, lifestyle and personal data; routine liver function tests; and liver ultrasonography.

RESULTS

No cases of liver malignancies were detected. Angiomas and liver cysts were found with a frequency of occurrence within the expected range of the general population. The main findings consisted of hepatomegaly (34.7%), steatosis (31.8%), and periportal fibrosis (16.0%). A logistic regression analysis indicated that hepatomegaly and steatosis were associated with obesity and lipid metabolism disturbances and not with VCM exposure. Periportal fibrosis, in addition to constitutional or dietary factors, was shown to be associated with VCM exposure, but only when maximum exposure in the subject's history had been at least 200 ppm as a yearly average; no effects were observed at 50 ppm or below.

CONCLUSIONS

Workers exposed to 200 ppm VCM for at least one year have a fourfold increased risk of developing periportal liver fibrosis. Liver ultrasonography is a suitable and important diagnostic test for the medical surveillance of vinyl chloride workers.

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.

[Adaptation of the TriTEST TM for the investigation of blood samples for a multicenter study taken to a single laboratory]

BACKGROUND

Immunotoxicological studies in humans are usually carried out via the determination of some selected immune parameters in subjects occupationally and/or environmentally exposed to immunotoxic substance. One of the most often measured parameters is the determination of lymphocyte subsets, which needs to be carried out in a very short time (a few hours) after blood collection. This is the major problem limiting the determination of lymphocyte subpopulations in field studies, where samples are usually collected directly at the workplace, and very often at the end of the workshift. Unfortunately, these collection modalities significantly prolong the time between collection and analysis. The problem is more evident in multicentric studies, where a further problem is represented by the time needed to send samples to the laboratory.

OBJECTIVE

Since an immune evaluation was planned, including the determination of lymphocyte subpopulations CD4 (T-helper), CD8 (T-suppressor cytotoxic) and CD16/CD56 (natural killer) in the project "Assessing health effects in man from exposure to low doses of inorganic mercury in environmental and occupational settings", a method was developed for performing cytofluorimetric analysis in "field studies".

METHODS

The method is based on commercially-available kits, and involves in loco treatment. Whole blood is labeled with monoclonal antibodies, and fixed samples immediately after collection. After the treatment, the samples are ready for flow cytometric analysis, which may be performed after a two-day period from sample collection.

RESULTS AND CONCLUSION

The method described is adequate for immunotoxicity testing in field studies because it prolongs the maximum latency time from collection and cytofluorimetric analysis up to 48 hours. A second interesting characteristic of the method is the possibility of using whole blood, without any need of either complex manipulations or particular equipment.

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.

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.

[Evaluation to the exposure to polycyclic aromatic hydrocarbons, benzene, toluene and xylenes in workers in a power plant fueled with heavy oil]

Occupational exposure to polycyclic aromatic hydrocarbons (PAHs) has been demonstrated in many industrial sectors. However, up to date there are few studies in the literature on PAH exposure in thermoelectric power plants. The study was aimed at the evaluation of personal exposure to PAHs in workers of a power plant fueled with heavy oil. Exposure to polycyclic aromatic hydrocarbons (PAHs) and to benzene, toluene and xylenes (BTX) was evaluated on power plant workers exposed to heavy fuel oil; the control group consisted of office workers of the same power plant. Altogether 39 subjects were studied, for a total of 84 days of monitoring. Personal environmental exposure, cutaneous exposure and urinary concentrations of 1-hydroxypyrene (1-OHP), trans,trans-muconic acid (TTMA) and nicotine were measured. Personal environmental exposure to PAHs was very low; only maintenance workers showed exposure to total carcinogenic PAHs significantly higher than controls (median levels 3.05 and 0.88 ng/m3 respectively). All workers showed very low levels of dermal exposure to PAHs (less than 1 ng). The median 1-OHP urinary concentrations were 0.16, 0.11 and 0.08 mumol/mol creatinine in the groups of exposed workers and 0.08 mumol/mol creatinine in the control group. Neither the exposed workers nor the controls showed a significant increase in 1-OHP urinary concentrations across the shift. The regression analysis showed a significant effect of cigarette smoking on urinary 1-OHP, while no association was observed between occupational exposure and diet. Personal environmental exposure levels to BTX were very low. TTMA urinary concentrations of the exposed subjects were similar to those of the controls. No significant increase in the TTMA urinary concentrations was observed across the shift and, as expected, smokers showed higher values than non-smokers. The study did not show a measurable intake of PAHs and BTX in power plant workers that could be ascribed to occupational exposure, thus confirming the efficacy of the protective measures in force.

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.

Assessment through environmental and biological measurements of total daily exposure to volatile organic compounds of office workers in Milan, Italy

Personal exposure to total volatile organic compounds (TVOCs), benzene and toluene of 100 Milan office workers was assessed through personal air monitoring at home, in the office, and during commuting. Biological monitoring was performed by measuring blood benzene and toluene concentrations together with urinary trans-trans-muconic acid (t,t-MA) and cotinine at the end of the monitoring period. The geometric means of the total 24-h personal exposure were 514 micrograms/m3 for TVOCs, 21.2 micrograms/m3 for benzene and 35.2 micrograms/m3 for toluene. Daily exposure to the volatile organic compounds was almost totally determined by indoor exposure at home and in the office, with a minor contribution in the transport means. An important factor determining exposure to benzene was found to be tobacco smoke, both for active smokers and for non-smokers exposed to environmental tobacco smoke (ETS). All the mean levels of the biological indicators were significantly higher in active smokers than in non-smoking subjects non-exposed to ETS; urine cotinine and t,t-MA levels were also significantly higher in non-smokers exposed to ETS than in non-smokers non-exposed to ETS.

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.

Health risk assessment for inhalation exposure to arsenic

Health risk assessment was used as the formal process to estimate the likelihood and magnitude of the health effects occurring in humans as a result of environmental and occupational exposure to polluting agents. This study was focused at estimating the human health risk of the general and working population living in the region polluted by arsenic for more than 40 years, from combustion of coal with high arsenic content in the power plant. The exposure to arsenic from inhalation was under investigation. A study period of 40 years (1973-1993) was chosen. The study period was defined taking into account, besides the availability of data, the temporal patterns of the technological processes and the trends over time of environmental concentrations. The results from the arsenic risk assessment study were used for the evaluation of the health risk for different population groups in the polluted areas and for different professions of workers exposed to As in a power plant. The results are applicable for the evaluation of risk in real conditions, for health surveillance and for remedial changes and a potential suggestion on technological improvement.

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.

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.

Mortality among workers in the geothermal power plants at Larderello, Italy

BACKGROUND

Since the early 1990s various European electricity companies have set up a research program, named EURELEX, devoted to the development of a comprehensive and validated title-occupation--job-exposure matrix (i.e., an instrument to assess exposures from occupations and jobs), in order to estimate and quantify past exposure to a number of potentially carcinogenic agents plus a few selected other toxic substances. The EURELEX program was first applied in Italy to a cohort of geothermal workers in Larderello, Tuscany.

METHODS

The cohort mortality study comprised 4,237 men who had worked at the geothermal power plant between 1950 and 1990. Vital status and death certificates were obtained from registration offices in the municipality of birth or death. Particular attention was paid to neoplastic effects of exposure to asbestos, largely used in the past for pipeline insulating purposes. The matrix allowed the workers to be subdivided into several categories according to estimated absestos exposure. Smoking information was not available.

RESULTS

No excess mortality was found for all causes and total cancer mortality. A small excess of pleural cancer (2 obs. vs. 1.4 exp.) was not statistically significant. The effect of other agents included in the matrix was also examined: the small excess of leukemia among those exposed to solvents prior to 1963 (year of benzene ban in Italy) did not reach the level of statistical significance. No cases of leukemia were found among the workers presumed to have been exposed to important ELF electromagnetic fields.

CONCLUSION

The study provides reassuring information on a large cohort of a unique geothermal power plant since no significant excess mortality for asbestos related cancers was observed. Furthermore, it represents a useful application and validation of a comprehensive job-exposure matrix for the electric industry in Europe.

Risk assessment and health surveillance of pesticide workers

Occupational health has two main objectives: the protection of workers from health hazards associated with the working environment, and the promotion of workers' health. Fundamental aspects of health protection are health risk management, information and training, first aid and medical treatment. Risk management comprises risk characterization, and exposure assessment. Integrating information on the identified hazards and exposure levels, and assessing the likelihood and severity of health effects performs risk characterization. Health surveillance includes medical surveillance and biological monitoring. The physician in charge of the occupational health programme, taking into account the results of the risk assessment process should determine frequency and contents of periodical medical examinations. Pre-employment medical examinations should be carried out in order to determine the physical ability to do the job the candidate is recruited for. Periodical medical examinations are aimed at detecting, in an early and reversible phase, any adverse effect attributable to exposure. A worker should undergo a broad medical examination when returning to work after a significant illness. Records of occupational health programmes should be filed and kept for at least 30 years.

Immunomodulatory effects of occupational exposure to mancozeb

The effects of occupational exposure to ethylene-bis-dithiocarbamate of manganese and zinc on the immune system were evaluated in a group of mancozeb-exposed manufacturers and controls. The immune system tests revealed the following: (a) lymphocyte proliferative responses triggered by different activators and mitogen-induced IL-2 production were higher in exposed subjects than in controls; (b) production of monocyte/macrophage-derived IL-1 and polyclonal IgG and IgM, by beta-lymphocytes, did not differ between exposed subjects and controls; (c) percentages and absolute numbers of total T-cells, T-helper cells, T-suppressor/cytotoxic cells, activated T-cells, total beta-cells, and natural killer cells were similar in exposed subjects and controls; (d) serum immunoglobulin classes and complement fractions were within the range of normality; and (e) rheumatoid factor and non-organ-specific serum autoantibodies were absent in exposed and control subjects. An increase in T-cell functional response was found in the exposed group, suggesting a slight immunomodulator effect of mancozeb in conditions of low-level, prolonged occupational exposure.

Impact of pesticides to groundwater resources in an alluvial plain using a geographical information system

A methodology to evaluate the impact of pesticides to drinking water resources in an agricultural region has been applied in an Italian alluvial plain using a Geographical Information System (GIS). With this technology it is possible to store, process and represent geographical data and update them according to the environmental characteristics. The studied area, covering a surface of 500 km2, is located immediately south of Milan, in the alluvial plain of the Po river. The DRASTIC model (1) has been utilized in order to evaluate the intrinsic vulnerability of aquifers, DRASTIC is a quantitative method proposed by EPA to identify pollution potential especially referred to pesticides in USA. The application of this model, combined with data of land use has provided maps identifying areas at risk for groundwater pollution. Information derived from risk maps is of primary importance in territorial planning such as: selection of areas to be monitored, identification of areas to be protected, correct management of agricultural practices and use of pesticides. These maps should provide an useful instrument for agricultural and territorial management.

[Paraquat-induced acute dermatitis in a child after playing with a discarded container]

The improper use of pesticide waste containers is a significant risk in rural areas, especially where appropriate systems of draining off refuse are lacking. A case is reported of an eight-year-old child who had played with the abandoned Paraquat container. After contamination with the pesticide she showed several II degree caustic lesions on both thighs and knees, associated with a mild erythemato-desquamative cheilitis and a "strawberry tongue". Common laboratory findings did not reveal any kidney, liver and/or red/white cell alterations and the chest X-ray was normal even several months after the accident. No physical consequences ensued, except for hyperchromic pigmentation on the legs. Where empty pesticide containers are not properly collected, they can represent a risk of pesticide exposure for the general population. They can also be a potential source of pollution for superficial water and soil. In the district where the accident was reported it was estimated that empty containers made up 7% of the weight of the 146,330 kg of pesticides sold to local farmers in 1993, of which about 10,400 kg was burned, buried and dispersed in the soil. Within the framework of a global pesticide prevention programme launched by the Regional Government of Lombardy, local health authorities, with the contribution of farmers, are carrying out a project for the proper collection of empty pesticide containers.

Programmes and activities of the International Centre for Pesticide Safety

The International Centre for Pesticide Safety (ICPS) is a research unit of the National Health Service created by the Government of the Region of Lombardy at the proposal of the World Health Organization-Regional Office for Europe, in cooperation with the University of Milan, and in agreement with the Italian Ministry of Health. ICPS operates in the following areas of activity: information and documentation on pesticide toxicity to man and environment, epidemiological, toxicological and clinical research on effects of pesticides in man; training and education of personnel in public health, assessment of environmental and health impact of pesticides by means of Geographical Information Systems, laboratory research for development and standardisation of methods for residue measurement in environmental and biological media. ICPS is also a centre of international meetings and continuing education courses. A number of projects carried out or underway at ICPS are briefly described in this paper.

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.

[The role of biotransformation in assessing the toxicological risk from pesticides]

Pesticides are an extremely heterogeneous group of chemical compound with varying toxicity. The biotransformation and degradation mechanisms are essential factors in the regulation of their toxic effects and of their persistence in the environment and biological tissues. Knowledge of metabolism and measurement of metabolites are fundamental to evaluate the risk from residues in food and water and to assess the toxicological risk for subjects occupationally exposed to pesticides.

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.

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)

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.

[The efficacy of personal prevention measures in controlling the exposure to metals of welders]

Biological monitoring of welders employed in a power plant showed urinary nickel levels largely exceeding the reference values (Ni-U welders mean = 43.2, S.D. = 22.1 micrograms/24 h; Ni-U reference values mean = 2.7, S.D. = 1.4 micrograms/24 h). Subsequently urinary excretion levels of other metals (Cr, Zn, Fe, Mn, Cu, Al, Pb) were measured for a more complete assessment of occupational exposure of these subjects; only aluminum and lead were found to slightly exceed the reference values and correlate with urinary nickel levels. As a consequence of these results, some adjustments in personal prevention measures were introduced at the workplace; the subsequent biological monitoring checks showed a progressive reduction in urinary nickel excretion levels over time in all welders.

The International Centre for Pesticide Safety

The International Centre for Pesticide Safety (ICPS) was inaugurated in March 1990. Coordinated by the World Health Organization (WHO) and in collaboration with research and university institutions, the Centre operates in the following areas of activity: information and documentation on pesticide toxicity; epidemiological, toxicological and clinical research; training and education; laboratory research. ICPS is also a centre of meetings and courses on permanent education. This paper reports on the activities carried out so far and on the future programmes of ICPS.

[Enclosed environments and health]

Problems related to Indoor Air Quality are subject of study since about twenty years. New architectural criteria, new building materials and increasing demands of energy saving have progressively changed residences, offices and all non-industrial indoor environments. This paper present a review of the IAQ-related issues from sources characterization, to pollutant assessment and definition of effects on human health.

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.

Studies of transformer repair workers exposed to PCBs: I. Study design, PCB concentrations, questionnaire, and clinical examination results

A cross-sectional study compared 55 transformer repairmen, 38 currently, and 17 previously exposed to polychlorinated biphenyls (PCBs) with 56 non-exposed subjects. PCBs exposures occurred from air and contaminated surfaces, predominantly from Aroclor 1260 with some exposure to Aroclor 1242. Each worker underwent: a questionnaire; standardized medical examination; delayed hypersensitivity testing; and determination of serum and adipose tissue lipid total PCB concentrations. Adipose and serum [PCBs] were significantly higher in the currently exposed, but previously exposed workers did not differ significantly from comparison subjects. No subjects had a classical syndrome of PCB poisoning. A number of neurobehavioral and irritant symptoms were significantly more prevalent in the exposed group, but were probably not related to PCBs. Comedones were more frequent in the exposed group, but no evidence of classical chloracne was noted. Cutaneous delayed hypersensitivity responses to mumps and to trichophyton antigens did not differ between the groups. The association of PCBs with job functions were explored.

Studies of transformer repair workers exposed to PCBs: II. Results of clinical laboratory investigations

Thirty-eight transformer repairmen currently exposed to polychlorinated biphenyls (PCBs), 17 former transformer repairmen, and 56 comparison workers not known to be exposed to PCBs were studied. Measurements were made of serum liver function tests, gamma-glutamyl transpeptidase (GGT), lipid profile, thyroid function tests, and other serum biochemistry; hemoglobin; white cell count; 24-hour excretion of delta-aminolevulinic acid, porphyrins, 17-hydroxycorticosteriods and 17-ketosteroids; sperm count; spirometry; and antipyrine half-life to evaluate microsomal mixed function oxidase induction. The total exposed group differed significantly from the comparison group in albumin, LDH, T4, T4-RT3 index, and actual/predicted FEV1. Significant differences among all three exposure groups were seen for albumin, T4, T4-RT3 index, and 17-hydroxycorticosteroid excretion. Differences in FEV1 were attributable to smoking. Significant correlations between serum PCBs and serum lipids were removed by adjustment for confounding variables. After adjustment for confounding variables, there was a statistically significant positive correlation between serum PCBs and GGT and a negative correlation between adipose PCBs and 17-hydroxycorticosteroid excretion. These may reflect subtle metabolic effects of PCBs.