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Non-occupational exposures to pesticides for residents of two U.S. cities.

The Non-Occupational Pesticide Exposure Study, funded by the U.S. Environmental Protection Agency, was designed to assess total human exposures to 32 pesticides and pesticide degradation products in the non-occupational environment; however, the study focused primarily on inhalation exposures. Two sites--Jacksonville, Florida (USA) and Springfield/Chicopee, Massachusetts (USA)--were studied during three seasons: Summer 1986 (Jacksonville only), Spring 1987, and Winter 1988. Probability samples of 49 to 72 persons participated in individual site/seasons. The primary environmental monitoring consisted of 24-hr indoor, personal, and outdoor air samples analyzed by gas chromatography/mass spectrometry and gas chromatography/electron capture detection. Indoor and personal air concentrations tended to be higher in Jacksonville than in Springfield/Chicopee. Concentrations tended to be highest in summer, lower in spring, and lowest in winter. Indoor and personal air concentrations were generally comparable and were usually much higher than outdoor air concentrations. Inhalation exposure exceeded dietary exposure for cyclodiene termiticides and for pesticides used mainly in the home. Dietary exposures were greater for many of the other pesticides. Inhalation risks were uncertain for termiticides (depending on rates of degradation) but were negligible for other pesticides. The data were insufficient to support risk assessments for food, dermal contact, or house dust exposures.

Adolescent↗

Organochlorine pesticide accumulation and genotoxicity in Mexican free-tailed bats from Oklahoma and New Mexico.

The summer population of Mexican free-tailed bats (Tadarida brasiliensis) at Carlsbad Caverns, New Mexico, declined from an estimated 8.7 million in 1936 to 200,000 in 1974; thereafter, it increased to approximately 700,000 in 1991. This decline has been attributed primarily to organochlorine (OC) pesticide contamination and habitat disturbance. Similar declines have been observed in other populations of this species. This study examined the potential genotoxic effects of OC pesticide contamination on two populations of T. brasiliensis. Pesticide accumulation, frequencies of chromosomal aberrancy, and nuclear DNA content variation in spleen and testicular tissues were examined in specimens collected from Carlsbad Caverns and Vickery Cave, a maternity colony in northwestern Oklahoma, during the summers of 1990 and 1991. Pesticide residues in brain and carcass tissues were identified and quantified by electron capture gas chromatography. Genotoxicity was examined with the standard bone marrow chromosomal aberration assay and flow cytometry. Statistical relationships among pesticide content, observed chromosomal aberrancy, and nuclear DNA content variation were examined. Both populations demonstrated significant levels of DDE contamination; however, the Carlsbad Caverns population showed consistently higher pesticide loads. Males also demonstrated higher levels than females. No statistical differences in chromosomal aberrancy or nuclear DNA content variation were observed among sexes, sites, or collected periods. Positive correlations were detected between brain and carcass DDE concentrations for all bats examined. A significant negative relationship was found between brain DDE concentration and coefficients of variation in spleen DNA content only for males.

Analysis of Variance↗

Laundering as decontamination of apparel fabrics: residues of pesticides from six chemical classes.

Research on reducing the level of pesticide residue on a textile substrate has examined many variables under many different conditions. This study controlled fiber type and the use of prewash product in an examination of residue levels for a number of pesticides in different pesticide classes. For all pesticides examined, the use of prewash lowered pesticide residues regardless of fiber type. Differences in pesticide residue level attributable to fiber type were not consistent.

Clothing↗

Use and fate of pesticides in the Amazon State, Brazil: risk to human health and the environment.

During the last 30 years, the increase of the human population in the Amazon introduced the need for additional food production and caused the state government to implement programs to increase and improve agricultural production. The production of nontraditional crops introduced several problems unknown to traditional farmers, since they are not well adapted to tropical conditions. Their susceptibility to insects, fungi and other plagues, and the competition with native vegetation forced farmers to use pesticides intensively. Amazonian farmers were not adequately prepared for the use of this new technology; they ignored the risk of pesticides to human health and the environment. Using the region of the state capital Manaus as an example, the characteristics of the pesticide use are described (e.g. the increased use and the lack of personal protective equipment, as well as the legal situation). In detail, the registration status of pesticides used in the State of Amazonas and the state of their registration in the European Union is compared. Finally, it is concluded that the use and the fate of pesticides in the Amazon region has to be monitored. Data of the effects on humans and on the environment have to be collected from the literature or have to be produced in standardized tests, so that an environmental risk assessment becomes possible. Training and information programs are urgently needed in order to build up environmentally sustainable agriculture. Finally, the enforcement of Brazilian laws concerning pesticide registration has to be improved.

Agriculture↗

Assessment of DNA damage in workers occupationally exposed to pesticide mixtures by the alkaline comet assay.

The potential genetic hazard of pesticides to human beings is of great concern in occupational and environmental settings because of the widespread use of these chemicals for domestic and industrial applications. Various studies have revealed a significantly elevated risk for particular tumours in humans exposed to some pesticides. Results from the biological monitoring or cytogenetic methods for the detection of health risks to pesticides have given both positive and negative results of mutagenicity. In this study DNA damage in peripheral lymphocytes of 33 pesticide-exposed workers employed in the municipality of Ankara (Turkey) for at least 1 year was examined by alkaline single-cell gel electrophoresis, the 'comet' technique. Results were compared with those from 33 controls of comparable age, sex and smoking habits, which were not occupationally exposed to pesticides. Work characteristics of the exposed workers and the use of personnel protective measures were also investigated. The DNA damage observed in lymphocytes of the workers was significantly higher than that in the controls ( P<0.001). The observed DNA damage was found to be significantly lower ( P<0.001) in workers applying some of the necessary individual safety protections during their work. Cigarette smoking was not related to increases in DNA damage; also, no significant association was found between the duration of occupational exposure to pesticides and the degree of DNA damage.

Adult↗

The use of dogs as second species in regulatory testing of pesticides. Part II: Subacute, subchronic and chronic studies in the dog.

Data on 172 pesticides (fungicides, herbicides, insecticides and other pesticides) submitted for regulatory purposes during the past 40 years to the German Federal Institute for the Health Protection of Consumers and Veterinary Medicine (BgVV) were analysed to determine whether chronic studies in dogs (52/104 weeks) provide essential additional specific toxicological compared with subchronic (13 weeks) or subacute (4 weeks) studies in the same species. Comparison of the lowest observed effect levels (LOELs) in dogs revealed no significant differences between subchronic and chronic studies but a significant difference between subacute studies and subchronic or chronic studies. Moreover, there was a significant correlation between the LOELs determined in subchronic studies and those determined in chronic studies in dogs (r = 0.78-0.84). The distribution of target organ toxicity determined in chronic studies in dogs was not significantly different from the distribution determined in subchronic studies, except for effects on the spleen in studies on herbicides which were only observed in chronic studies and in combined subchronic/chronic studies, but never in subchronic studies. Organ-specific effects that were observed in chronic studies but not in subchronic studies were found in 30 of 55 studies on fungicides, in 25 of 44 on herbicides, in 17 of 38 on insecticides and in 10 of 16 on other pesticides. Compared with 26-week studies, additional organ-specific toxic effects were found in three of five, in three of four, in one of three and in one of one 52/104-week studies on fungicides, of herbicides, of insecticides and other pesticides, respectively. The organ-specific effects that were seen only in the chronic dog studies were evaluated according to their severity, e.g. significant damage to organs versus changes in enzyme activities that do not affect organ function or histology. Such effects were not considered to be specific for dogs in chronic studies if similar effects were also found in chronic studies in rodents (rat or mouse). In 15 of 141 studies in dogs serious side effects were observed in chronic studies that were not observed in subchronic studies. Furthermore, for 9 of 172 pesticides significant new effects were seen in 52/104-week studies when compared with 4- or 13-week studies and in 7 of 141 52/104-week studies when compared with 13-week studies. Analysis of the severity of organ-specific toxic effects of pesticides revealed that chronic long-term studies (52/104 weeks) in dogs do not provide specific additional information to 26-week studies in the same species.

Animals↗

Determination of pesticides by solid phase extraction followed by gas chromatography with nitrogen-phosphorous detection in natural water and comparison with solvent drop microextraction.

The European Union specifies that drinking water can contain pesticide residues at concentrations of up to 0.1 microg/L each and 0.5 microg/L in total, and that 1-3 microg/L of pesticides can be present in surface water, but the general idea is to keep discharges, emissions and losses of priority hazardous substances close to zero for synthetic substances. Therefore, in order to monitor pesticide levels in water, analytical methods with low quantification limits are required. The method proposed here is based on solid phase extraction (SPE) followed by gas chromatography with a nitrogen-phosphorous detector (GC-NPD). During method development, six organophosphate pesticides (azinphos-ethyl, chlorfenvinphos, chlorpyriphos, ethoprophos, fenamiphos and malathion) and two organonitrogen pesticides (alachlor and deltamethrin) were considered as target analytes. Elution conditions that could influence the efficiency of the SPE were studied. The optimized methodology exhibited good linearity, with determination coefficients of better than 0.996. The analytical recovery for the target analytes ranged from 70 to 100%, while the within-day precision was 4.0-11.5%. The data also showed that the nature of the aqueous matrice (ultrapure, surface or drinking water) had no significant effect on the recovery. The quantification limits for the analytes were found to be 0.01-0.13 microg/L (except for deltamethrin, which was 1.0 microg/L). The present methodology is easy, rapid and gives better sensitivity than solvent drop microextraction for the determination of organonitrogen and organophosphate pesticides in drinking water at levels associated with the legislation.

Chromatography, Gas↗

Determination of pesticides and some metabolites in different kinds of milk by solid-phase microextraction and low-pressure gas chromatography-tandem mass spectrometry.

A new analytical method is proposed to determine more than 40 multiclass pesticides in different kinds of processed (whole, skimmed and powdered) and unprocessed (goat and human) milk samples using solid-phase microextraction (SPME). A comparative study between headspace (HS) and direct immersion (DI) was carried out. The effect of milk dilution and the use of acid to reduce the influence of the matrix in DI-SPME mode were also evaluated. DI of the SPME fiber into previously diluted and acidified milk samples achieved the best sensitivity results. Pesticides were determined using low-pressure gas chromatography-tandem mass spectrometry (LP-GC-MS/MS). Both of the selected techniques have been shown to be effective at reduce fat interference and can determine analytes present at very low concentrations (limits of quantification between 0.02 and 1.00 microg L(-1)). Performance characteristics such as linearity, recovery, precision, and lower limits, together with an estimation of the measurement uncertainty using validation data, are presented for each pesticide. All of the pesticides presented recovery rates of between 81 and 110% and precision values lower than 12% (expressed as the relative standard deviation). The overall uncertainty of the method was estimated at three different concentrations (10, 25 and 50 microg L(-1)) and was lower than 25.5% in all cases. The proposed analytical methodology was applied to the analysis of target pesticides in 35 samples: 15 commercial, 3 human and 17 goat milk samples. The metabolite p,p'-DDE was the compound most frequently found in both the breast and goat milk samples, at concentration levels < 20 microg L(-1). However, pesticide residues were not found in any of the other 15 commercial milk samples (skimmed, powdered and whole milk) analyzed.

Animals↗

Behaviour of semipermeable membrane devices in neutral pesticide uptake from waters.

The application of semipermeable membrane devices (SPMDs) has been evaluated as a passive sampler for the collection of multiresidue pesticides in continental waters. Seven chlorinated, five organophosphorus, six carbamate, nine pyrethroid and ten other pesticides were tested in order to estimate which compounds can be retained with these devices. The effect of water parameters, such as temperature, pH, ionic strength and organic matter content, were evaluated for their effect on the retention of the pesticides by the SPMDs. Studies of uptake from water were performed in a glass beaker containing 2 L distilled water spiked with 50 ng L-1 of each pesticide investigated. A SPMD was put in the beaker, under turbulent conditions, and analysed after 2 days' extraction. The contents of each SPMD were microwave-assisted-extracted twice with 30 mL hexane-acetone, to 90 degrees C for 10 min, and this was followed by a cleanup based on acetonitrile partitioning and solid-phase extraction. Gas chromatography with tandem mass spectrometry detection was employed for determination of pesticides, and provided low limits of detection from 0.5 to 7 ng per SPMD. Higher absorption rates were observed for pyrethroid, organophosphorus and chlorinated compounds than for carbamates. Pesticide uptake rates were independent of the water composition and decreased at low temperature.

Hydrogen-Ion Concentration↗

A natural matrix (pureed tomato) candidate reference material containing residue concentrations of pesticide chemicals.

NARL (the Australian National Analytical Reference Laboratory) is preparing a pureed tomato reference material spiked with residue concentrations of a range of pesticide chemicals relevant to the Australian horticultural industry. Traceable certified pesticide concentration values will be established using both isotope dilution mass spectrometry primary methods (developed within NARL) and measurements carried out by a number of experienced laboratories. As far as we are aware, there is no other similar CRM available anywhere in the world. The need for such a material is evident from the results of interlaboratory proficiency studies conducted by NARL among Australian and Asia-Pacific residue testing laboratories. Many participants are experiencing difficulties with the analysis of pesticide residues in fruit and vegetables at concentrations of regulatory significance. Chemicals such as methamidophos (an organophosphorus pesticide widely used on tomato crops) are causing particular problems. In a pilot study, a number of units of control (unspiked tomato) and the candidate reference material were prepared and packaged into lacquered steel cans which were sealed and sterilised by immersion in boiling water. Accelerated stability testing of the packaged material was conducted using isochronous measurement. All of the pesticides showed some degree of degradation after 4 weeks of storage at 50 degrees C, and after 168 days of storage at room temperature. However, all appeared to be stable after 168 days of freezer storage. Homogeneity testing involved duplicate test portions taken from every 50th unit of reference material. An experimental protocol was devised with the aim of minimising the analytical variability and assuring the quality of the data generated. There is some degree of inhomogeneity in the prepared material and a small fill trend is also indicated. Potential improvements to the spiking and preparation procedure have been identified and it is planned to prepare a second batch of both control and spiked material for further homogeneity trials and for certification of the pesticide concentrations.

Cold Temperature↗

Direct and indirect exogenous contamination by pesticides of rice-farming soils in a Mediterranean wetland.

It is known that the sources of soil contamination can be endogenous or exogenous and that exogenous contamination may be direct or indirect. In this work, an environmental pesticide fate study was conducted in soil profiles collected from 23 rice field sites in an important Mediterranean wetland (Albufera Natural Park, Valencia, Spain) from April 1996 to November 1997. Temporal and spatial distribution of 44 pesticide residues in an alluvial Mediterranean soil (gleyic-calcaric Fluvisol, Fluvaquent) were monitored. During this period, the levels of pesticide residues in different soil horizons (Ap1 0-12 cm, Ap2 12-30 cm, ApCg 30-50 cm, C1gr 50-76 cm, and C2r 76-100 cm) were investigated. In addition, information was collected on agricultural pesticide application practices and soil characteristics. Distribution throughout the soil profile showed that pesticide concentrations were always higher in the topsoil (Ap1 horizon), in the autumn season, and in the border with citrus-vegetable orchard soils (calcaric Fluvisol, Xerofluvent). Chlorpyrifos (organophosphorus), endosulfan (organochlorine), and pyridaphenthion (organophosphorus) insecticides were, respectively, the most detected of all the pesticides investigated. These results were associated with processes, such as nonleaching, transport by movement into surface waters, retention, volatilization, and chemical and biological degradation in the topsoil, as well as with direct and indirect exogenous contamination sources.

Agriculture↗

Comparative sublethal toxicity of nine pesticides on olfactory learning performances of the honeybee Apis mellifera.

Using a conditioned proboscis extension response (PER) assay, honeybees (Apis mellifera L.) can be trained to associate an odor stimulus with a sucrose reward. Previous studies have shown that observations of conditioned PER were of interest for assessing the behavioral effects of pesticides on the honeybee. In the present study, the effects of sublethal concentrations of nine pesticides on learning performances of worker bees subjected to the PER assay were estimated and compared. Pesticides were tested at three concentrations. The highest concentration of each pesticide corresponded to the median lethal dose value (48-h oral LD50), received per bee and per day, divided by 20. Reduced learning performances were observed for bees surviving treatment with fipronil, deltamethrin, endosulfan, and prochloraz. A lack of behavioral effects after treatment with lambda-cyalothrin, cypermethrin, tau-fluvalinate, triazamate, and dimethoate was recorded. No-observed-effect concentrations (NOECs) for the conditioned PER were derived for the studied pesticides. Our study shows that the PER assay can be used for estimating sublethal effects of pesticides on bees. Furthermore, comparisons of sensitivity as well as the estimation of NOECs, useful for regulatory purposes, are possible.

Animals↗

Risk assessment as a management tool used to assess the effect of pesticide use in an irrigation system, situated in a semi-desert region.

A preliminary study undertaken by the CSIR in July 1993 on the health effects of aerial crop spraying of pesticides in the Vaalharts irrigation area in South Africa indicated that potential health risks could exist for the inhabitants of this area. An extensive scientific health risk assessment and epidemiological study to determine the actual health risks, is very expensive and requires medical and financial justification. The aim of this study was to develop a theoretical health risk model, which could be used as a predictive tool to determine as accurately as possible from the data available if a complete scientific health risk assessment study is justified. The actual amounts of pesticides sold in the Vaalharts area by two major pesticide manufacturers were used to perform a theoretical health risk assessment. The risks were assessed by making use of RISK*ASSISTANT, a computer modeling system and chemical database. The United States Environmental Protection Agency's (EPA) health risk model was applied to the data to identify the hazards, assess the exposures and dose response, and characterize the risks. Three exposure scenarios, namely, the ingestion of food and water and the inhalation of air were evaluated. The method used to calculate the risks varied according to the type of health hazard and the results were characterized accordingly. The acute health effects due to exposure to pesticides are well known and the risks are easy to determine. However, the risks associated with chronic health hazards were more difficult to calculate. For this reason a ranking model was developed which made use ofa point scoring system. This model highlights those pesticides which have the greatest possibility of causing chronic health effects. From the results it can be concluded that very large amounts of pesticides are used in the Vaalharts area and that the community might be at risk to chronic health effects. Although the theoretical health risk assessment model was successfully used in this study, its effectiveness as a predictive tool still has to be proven by a complete scientific study.

Air Pollution↗

Prostate cancer among pesticide applicators: a meta-analysis.

OBJECTIVES: To analyse data from peer-reviewed, case-referent and cohort studies, studying the occurrence of prostate cancer in pesticide applicators and in some other, related, occupational categories, in order to determine a possible relationship of cancer of the prostate with pesticide exposure; to calculate a meta-rate ratio and to compare it with the meta-rate ratios obtained in a previous meta-analysis performed over a shorter time (1995-2001) in a broader exposure category, including many pesticide-related agricultural and non-agricultural occupations. METHODS: Medline was searched for the years between 1966 and 2003, and relevant studies were identified from 1986 on. We conducted a meta-analysis of 22 studies complying with the inclusion criteria in order to pool their relative risk (RR) estimates. Studies were summarised and assessed for homogeneity and publication bias. RESULTS: The meta-rate ratio, based on 22 estimates of RR, is 1.24 [95% confidence interval (95% CI) 1.06-1.45]. This pooled risk estimate for the occupational categories selected is higher than the one previously calculated for farmers in general over a shorter period of publication. Substantial heterogeneity of rate ratios exists between the different studies. The major source of heterogeneity identified is geographic location. Increased meta-rate ratios are observed for studies derived from North America as well as from Europe, the meta-rate ratios from Europe being lower than those from North America. There is no obvious indication of publication bias. CONCLUSION: The increased meta-rate ratio for prostate cancer in agricultural pesticide applications provides additional evidence for a possible relationship between pesticide exposure and prostate cancer. The homogeneity observed between the individual rate ratios, after we had regrouped the data according to geographic location, tends to increase the consistency of the association. However, the data available from the individual studies do not provide sufficient exposure information for firm conclusions to be drawn about pesticide exposure as the cause of prostate cancer, independently from other factors.

Agricultural Workers' Diseases↗

Thyroid function in nestling tree swallows and eastern bluebirds exposed to non-persistent pesticides and p, p'-DDE in apple orchards of southern Ontario, Canada.

This study examined the associated effects of pesticides and persistent residues of p,p'-DDE on thyroid function in 16-day-old tree swallows (Tachycineta bicolor) and 12-day-old eastern bluebirds (Sialia sialis). Apple orchards sprayed with pesticides in current use and reference sites were chosen for study in southern Ontario, Canada, during 2000-2001. We assessed thyroid hormone concentrations (plasma and muscle thyroxine [T4], and triiodothyronine [T3]) and the response to a challenge with thyroid stimulating hormone (TSH) as well as parameters of thyroid histology. Individual nests were exposed to as many as seven individual pesticide applications and up to five pesticide mixtures. Concentrations of p,p'-DDE in eggs from both species were highest in orchard sites, and ranged from 0.05 to 5.44 mg/kg wet weight for tree swallows, and from 0.17 to 95.4 mg/kg for eastern bluebirds. In 2000, tree swallows from sprayed orchards had elevated plasma T4 concentrations, and thyroid glands with collapsed follicles, hypertrophic epithelia, and higher follicular epithelial cells relative to chicks from reference sites. Plasma T4 concentration was positively correlated with the total number of pesticide mixtures applied during egg incubation through chick rearing. In 2001, basal plasma T3 concentration in tree swallow chicks did not differ between orchard and reference sites, though there were differences among orchards; T3 was positively correlated with total number of individual sprays applied during egg incubation through chick rearing. Tree swallows challenged with TSH showed no significant difference in thyroid hormone concentration or follicular epithelial cell height between exposure groups; however, a significantly greater proportion of chicks from reference sites were found to have thyroids with focal or diffuse hypertrophic epithelia relative to orchard chicks. In 2001, bluebirds from sprayed orchards had significantly higher T3 concentrations in response to TSH challenge; this response was positively correlated with the total number of pesticides applied during egg incubation through chick rearing.

Animals↗

Chronic bronchitis and pesticide exposure: a case-control study in Lebanon.

OBJECTIVE: Pesticides are widely used toxics. The objective of the study is to evaluate the odds of exposure to pesticides in chronic bronchitis patients. METHODS: Using the American Thoracic Society standardized questionnaire confirmed by medical diagnosis of chronic bronchitis, a case-control study was performed in Lebanon. Pesticide exposure was estimated and between groups comparison was made. RESULTS: The study involved 262 controls and 110 chronic bronchitis outpatient subjects from 10 medical centers. Any exposure to pesticides was associated to chronic bronchitis (OR = 2.46 [1.53-3.94]; p < 10(-4)). Occupational use presented the highest association (15.92 [3.50-72.41]; p < 10(-4)), followed by regional exposure (3.70 [2.05-6.70]; p < 10(-4)). Results were confirmed by multivariate and subgroup analysis. CONCLUSION: Pesticide exposure was associated with chronic bronchitis in Lebanese adults. Pesticides toxicological effects may explain chronic respiratory effects associations found with all exposure types.

Adult↗

Pesticides: the good and the bad.

Pesticides have been used for many years. In earlier times they were a protection against fungi and insect pests. The great increase in the use of pesticides occurred with the development of new organic chemicals following World Wars I and II. In addition to chemicals for the control of fungi and insects, new developments were nematocides, herbicides, rodenticides, avicides, defoliants, wood preservatives, etc. The use of chemicals helped increase productivity, but caused great concern about their effect on human health and safety. On the other hand, chemicals did help tremendously from the standpoint of protecting against diseases that were carried by insects, especially mosquitoes. Adverse publicity has caused great concern about pesticides and this is especially so since our society has undergone great changes from an agricultural society to an industrial society and finally to a communications society. Unfortunately, publicity relating to the use of pesticides has seldom been balanced from the standpoint of the good and the bad. In fact, the communications media has and does usually stress the potential adverse effects of pesticides without reference to the good. This has caused concern on the part of advocates and the average person to the extent that it has placed heavy constraints on agriculture. There is a need for the dissemination of balanced information on the good as well as the bad of pesticides.

Agricultural Workers' Diseases↗

Status of the toxicity reports of pesticides for their registration in Finland.

Recently, attention has centered on the validity of toxicity reports for the registration of pesticides. In Finland, a study was conducted to evaluate the validity of the toxicity reports of pesticides done in U. S. laboratories. Twenty-seven pesticide formulations of the 230 on the market in Finland were selected for the study. The material contained 61 toxicity reports of 16 pesticide formulations done in U. S. laboratories considered questionable, 64 reports from U. S. laboratories considered reliable, and 142 reports originating from European laboratories, totally 267 reports. These reports were divided into valid according to the Organization for Economic Cooperation and Development (OECD) guidelines, and included those with minor discrepancies but in compliance with the good laboratory practice at the time of the study (group I), and and invalid according to the OECD guidelines (group II). After a closer evaluation of the 125 U. S. reports, 85 reports were considered valid and 40 invalid. As a function of time, the proportion of valid studies of all studies on pesticides for the registration purposes in Finland increased during 1961-1981 from 47 to 93%, being 100% at the present time. The lack of information of pesticide formulations registered earlier creates a problem to be solved in the future in Finland, rather than the lack of the validity of toxicity reports.

Animals↗