Assuring the quality of data in the pesticide residue laboratory

Abstract

The importance of quality control procedures to the collection of pesticide residue data is discussed. The equipment requirements of an adequate, safe pesticide residue laboratory are presented. Equipment maintenance, personnel training, and preservation of samples is also reviewed. Appropriate objectives for an intra‐laboratory quality control program are outlined.     

Measurements of surface contamination of spray equipment with pesticides after various methods of application

Abstract

A traditional method to determine operator dermal exposure is to quantify the amount of pesticide coming into contact with specific body regions and then to integrate the deposition density values with the total body surface. It is known that extremely high deposition values may occur in the hand region; however, the source of contamination is generally assumed to be direct splash or contact with the pesticide container. One of the parameters affecting operator/pilot exposure could be the transfer of pesticide residue, particularly in the case of pesticides with a longer half‐life, from contaminated surfaces of spray equipment by direct contact over extended periods. If the rate of skin absorption of pesticide is readily known, the expected values of daily dose for an operator or pilot may significantly rise due to the extended contact period. This study produced field data on the surface contamination of spray equipment used for ground and aerial applications. If field data on precise work practice (time‐motion) observations are incorporated, it may be possible to estimate the potential exposure of operator/pilot due to hand contact with contaminated surfaces.     

The greenhouse work environment: a modifier of occupational pesticide exposure?

Abstract

Greenhouses are enclosed structures which have various characteristics that enhance crop productivity, but the implications for workers’ pesticide exposure and uptake are not well understood. A narrative literature review was conducted to explore the mechanism/s of interactions between greenhouse characteristics and occupational pesticide exposure. Using a “work”, “worker” and “workplace” conceptual framework, the greenhouse environment (hot and humid microclimate, limited space and dense crop arrangements) combines with work characteristics (high work and pesticide use intensity, multi-tasking, predominantly manual spraying techniques and quick reentry to treated farms) to potentially increase occupational pesticide exposure, compared with open field farming. Greenhouse environments, are variable but have been shown to influence pesticide availability, route, pathways and frequency of exposure, deposition and distribution on a worker’s body as well as use and performance of exposure control methods. Training programs can emphasize the differences in exposure potential between greenhouse and open field farming. Development of tailored guidelines for exposure control strategies to better suit the level of uniqueness of greenhouse agriculture seems warranted.     

The role of toxicology in the evaluation of new agrochemicals

Abstract

The use of agrochemicals like crop protecting agents, veterinary disinfectants, and wood preservatives may result in (un)intentional exposure of the environment, animals and man. This paper deals with current testing strategies to assess the potential health risks for humans exposed to these chemicals during production or application or via consumption of foods containing pesticide residues.

Principles and procedures for safety assessment of pesticide residues in food as developed by WHO/FAO are described. Different types of toxicity studies in mammalian test animal species are discussed and a strategy is outlined in order to characterize the toxicity profile of a compound and the relationship between applied doses and adverse effects. Safety testing of agrochemicals should be carried out in relation to its intended use, and in particular attention will be paid to toxicity testing of residues of pesticides in food. Extrapolation of results from animal studies to humans and the use of safety factors is discussed.

Besides the use of animal protocol studies for safety testing of agrochemicals, the potential use of in‐vitro models derived from organs and tissues of animals is discussed. Data on the in‐vitro metabolism of thiabendazole, aldicarb and alachlor are discussed in order to demonstrate that such data may complement or partly substitute whole animal experimentation.

Principles and procedures for safety testing of residues of agrochemicals in food as applied during the last three decades, constitute a ‘safety‐first’ approach, providing sufficient safety margins for the consumer of foods which may contain low levels of residues of agrochemicals.     

Mutagenicity evaluation of chemical pesticides

Abstract

Over the last few decades, the use of chemical pesticides has increased dramatically in the U.S. This relatively sudden increase greatly concerns the U.S. Environmental Protection Agency (EPA), since it has the responsibility for ensuring the safety of all pesticides used in the U.S. In response to this concern, EPA has established a review program, the Rebuttable Presumption Against Registration (RPAR), for periodically reassessing the mutagenic and carcinogenic potential of pesticide compounds.

This paper presents a review and evaluation of the data reported in the literature on six chemical pesticides suspect for mutagenic potential. The pesticide chemicals discussed are maleic hydrazide; rotenone; monuron; diallate; triallate, and benomyl.     

National short-term dietary exposure assessment of a selected group of pesticides in Argentina

ABSTRACT

An evaluation of acute dietary exposure to pesticide residues, applying deterministic and stochastic methods, was performed for a selected group of pesticides in two representative age groups from Argentina. Thus, 28 active ingredients (a.i.) and 75 food items were evaluated for the group of 2–5-year-old children, while 9 a.i. and 59 food items were considered for the 10–49-year-old women group. A deterministic assessment was conducting following the Food and Agriculture Organization (FAO) and World Health Organization (WHO) procedure but using the national maximum residue limits (MRLs) as pesticide residue concentration data, while in the stochastic approach, a theoretical distribution modeled with the available information was used. Food consumption data were obtained from the 2004–2005 comprehensive national nutrition and health survey. The risk was estimated by comparing the short-term dietary exposure with the acute reference dose (ARfD) values for each pesticide-food combination evaluated. In the deterministic assessment, 173 (39.1%) and 40 (31.3%) combinations exceeded the ARfD thresholds for the 2–5-year-old children and 10–49-year-old women groups, respectively. This conservative study generated relevant information as a first stage of acute dietary risk assessment in Argentina.     

Pesticide decontamination from fabric by laundering and simulated weathering1

Abstract

This laboratory study investigated the effectiveness of selected detergents and the phenomenon of simulated environmental conditions (weathering) on the removal of a commercial‐grade mixture of parathion and methyl parathion from a three‐layer laminated fabric. The weathering treatment consisted of exposure and non‐exposure to simulated environmental conditions of heat, light, and humidity. Contaminated fabric samples were laundered in one of three detergents containing an anionic, a nonionic, and a combined anionic and nonionic surfactant. The test fabric, a three‐layer fabric containing an impermeable microporous film laminated between two layers of nylon, was pipette‐contaminated with 400 microliters of field strength pesticide solution and allowed to dry. Half of the contaminated samples were weathered in an Atlas Fade‐Ometer. All of the contaminated samples were subsequently laundered in a Launder‐Ometer. Percent of pesticide residue was determined by gas chromatography. Weathering did significantly reduce both parathion and methyl parathion residues remaining in the test fabric. No statistically significant difference was found among the three detergents. High amounts of both parathion and methyl parathion remained in the test fabric after weathering and laundry treatments. Before the test fabric can be recommended for use in protective garments further research is needed to develop more effective decontamination procedures.     

Exposure assessment of pesticides in a shallow groundwater of the Tagus vulnerable zone (Portugal): a multivariate statistical approach (JCA)

Purpose

To assess groundwater exposure to pesticides, in agricultural areas of ??Ribatejo?? region (Portugal), and the influence of some key factors in that exposure, field, laboratory and modelling studies were carried out.

Methods

The study was performed in maize, potato, sugar beet, tomato and vegetables agricultural areas, located in a shallow aquifer, with pesticides use and, in most cases, with irrigation practices. Pesticides used in the studied agricultural areas and having leaching potential were selected, being considered also other pesticides included in priority lists, defined in Europe. Evaluation of groundwater exposure to pesticides was carried out by successively: (1) groundwater sampling in seven campaigns over the period 2004?C2006; (2) pesticide analysis [including isolation and concentration from the groundwater samples and further determination by gas chromatography?Cmass spectrometry (GC?CMS) of 14 herbicides, four insecticides and two metabolites]; and (3) analysis and discussion of the results by applying joint correspondence analysis (JCA).

Results

From the 20 pesticides and metabolites selected for the study, 11 were found in groundwater. Pesticides and metabolites most frequently detected were atrazine, alachlor, metolachlor, desethylatrazine, ethofumesate, ??-endosulfan, metribuzine, lindane and ??-endosulfan. The results showed that groundwater exposure to pesticides is influenced by local factors??either environmental or agricultural, as precipitation, soil, geology, crops and irrigation practices. Spring and autumn were more associated with the detection of pesticides being more likely to observe mixtures of these compounds in a groundwater sample in these transition seasons.

Conclusions

This work evidences the importance of models, which evaluate pesticides environmental behaviour, namely their water contamination potential (as Mackay multicompartimental fugacity model) and, specially, groundwater contamination potential (as GUS and Bacci and Gaggi leaching indices), in pesticide selection. Moreover, it reveals the importance to adapt proper statistical methods according to level of left-censored data. Using JCA was still possible to establish relations between pesticides and their temporal trend in a case study where there were more than 80% of data censored. This study will contribute to the Tagus river basin management plan with information on the patterns of pesticide occurrence in the alluvial aquifer system.     

Predicting Particulate (PM10) Personal Exposure Distributions Using a Random Component Superposition Statistical Model

ABSTRACT

This paper presents a new statistical model designed to extend our understanding from prior personal exposure field measurements of urban populations to other cities where ambient monitoring data, but no personal exposure measurements, exist. The model partitions personal exposure into two distinct components: ambient concentration and nonambient concentration. It is assumed the ambient and nonambient concentration components are uncorrelated and add together; therefore, the model is called a random component superposition (RCS) model. The 24-hr ambient outdoor concentration is multiplied by a dimensionless “attenuation factor” between 0 and 1 to account for deposition of particles as the ambient air infiltrates indoors. The RCS model is applied to field PM₁₀ measurement data from three large-scale personal exposure field studies: THEES (Total Human Environmental Exposure Study) in Phillipsburg, NJ; PTEAM (Particle Total Exposure Assessment Methodology) in Riverside, CA; and the Ethyl Corporation study in Toronto, Canada. Because indoor sources and activities (smoking, cooking, cleaning, the personal cloud, etc.) may be similar in similar populations, it was hypothesized that the statistical distribution of nonambient personal exposure is invariant across cities.     

Measurements of surface contamination of spray equipment with pesticides after various methods of application

A traditional method to determine operator dermal exposure is to quantify the amount of pesticide coming into contact with specific body regions and then to integrate the deposition density values with the total body surface. It is known that extremely high deposition values may occur in the hand region; however, the source of contamination is generally assumed to be direct splash or contact with the pesticide container. One of the parameters affecting operator/pilot exposure could be the transfer of pesticide residue, particularly in the case of pesticides with a longer half-life, from contaminated surfaces of spray equipment by direct contact over extended periods. If the rate of skin absorption of pesticide is readily known, the expected values of daily dose for an operator or pilot may significantly rise due to the extended contact period. This study produced field data on the surface contamination of spray equipment used for ground and aerial applications. If field data on precise work practice (time-motion) observations are incorporated, it may be possible to estimate the potential exposure of operator/pilot due to hand contact with contaminated surfaces.     

Inhibition, recovery and oxime-induced reactivation of muscle esterases following chlorpyrifos exposure in the earthworm Lumbricus terrestris

Assessment of wildlife exposure to organophosphorus (OP) pesticides generally involves the measurement of cholinesterase (ChE) inhibition, and complementary biomarkers (or related endpoints) are rarely included. Herein, we investigated the time course inhibition and recovery of ChE and carboxylesterase (CE) activities in the earthworm Lumbricus terrestris exposed to chlorpyrifos, and the ability of oximes to reactivate the phosphorylated ChE activity. Results indicated that these esterase activities are a suitable multibiomarker scheme for monitoring OP exposure due to their high sensitivity to OP inhibition and slow recovery to full activity levels following pesticide exposure. Moreover, oximes reactivated the inhibited ChE activity of the earthworms exposed to 12 and 48 mg kg⁻¹ chlorpyrifos during the first week following pesticide exposure. This methodology is useful for providing evidence for OP-mediated ChE inhibition in individuals with a short history of OP exposure (≤1 week); resulting a valuable approach for assessing multiple OP exposure episodes in the field.     

A Protocol to Select High Quality Datasets of Ecotoxicity Values for Pesticides

Abstract

The key to any QSAR model is the underlying dataset. In order to construct a reliable dataset to develop a QSAR model for pesticide toxicity, we have derived a protocol to critically evaluate the quality of the underlying data. In developing an appropriate protocol that would enable data to be selected in constructing a QSAR, we concentrated on one toxicity end point, the 96 h LC50 from the acute rainbow trout study. This end point is key in pesticide regulation carried out under 91/414/EEC. The dataset used for this exercise was from the US EPA-OPP database.     

PeLM: Modeling of Pesticide-Losses Through Runoff and Sediment Transport

Abstract

A GIS-aided pesticide loss model (PeLM) was developed to simulate pesticide losses through surface runoff and sediment transport in watershed systems. The PeLM could tackle the movement of eroded soil along with surface runoff as well as the pesticide losses in adsorbed and dissolved phases. The contributions of different soil types in the sediment were also examined. The model was applied to the Kintore Creek Watershed of southern Ontario, Canada. The simulation results were verified through observed data, indicating a correlation level of 0.89–0.98. The results also showed that clay particles usually held the largest share of contributions to pesticide losses through soil erosion. This study is significant in the efforts for modeling nonpoint source pollution in watershed systems. It provides useful information and support for the related decisions of watershed management.     

Statute and legislative history of the federal insecticide,fungicide, and rodenticide act and its impact on agriculture

Abstract

This report discusses the responsibilities of government for the legislation of pesticides, and describes the impact of various statutes on the use of pesticides in agriculture. Governmental responsibilities for management of the economy, education, and enactment of laws and regulations are discussed, and the history of U.S. legislation of pesticides and related substances is presented. Finally, the impact of pesticide regulation on international trade is considered.     

Metabolic effects of diazinon on the European eel

Abstract

Eels were exposed to a sublethal diazinon concentration of 0.042 mg/L for exposure times of 6, 24, 48, 72 and 96 hours. Biochemical analyses of blood composition, such as plasma glucose, total plasma cholesterol and triglycerides, plasma lactate, plasma urea and uric acid, showed significant differences between treated and control animals. Plasma glucose and lactate increased after 6 hours exposure to the insecticide. Plasma cholesterol and triglycerides content decreased during 96 hours treatment. Urea levels increased at 72 hours while uric acid content decreased significantly at 24, 72 and 96 hours exposure to the pesticide.

The observed effects of diazinon on eel metabolism suggested that the treated fish was faced with a serious metabolic crisis, and the fish looked for alternative methods of metabolism to overcome the toxic stress.     

Pesticide transport via sub-surface drains in Europe

Transport of pesticides from point of application via sub-surface drains can contribute significantly to contamination of surface waters. Results of 23 field drainage experiments undertaken at sites across Europe were collated and analysed by residual maximum likelihood. Both maximum concentration of pesticide in drainflow (n = 167) and seasonal loss of pesticide to drains (n = 97) were significantly related to strength of pesticide sorption to soil, half-life of the pesticide in soil, the interval between application and first drainflow and the clay content of the soil. The statistical models accounted for 71% of the variability in both maximum concentration and seasonal load. Next, the dataset was used to evaluate the current methodology for assessment of aquatic exposure used in pesticide registration in Europe. Simulations for seven compounds with contrasting properties showed a good correspondence with field measurements. Finally, the review examines management approaches to reduce pesticide transport via sub-surface drains. Despite a large amount of work in this area, there are few dependable mitigation options other than to change application rate or timing or to restrict use of a compound in the most vulnerable situations.     

Options for cleanup and disposal of pesticide wastes generated on a small‐scale

Abstract

Many processes have been investigated to dispose of obsolete pesticide stocks and clean up wastewater and contaminated soil. The processes vary in their stages of development and commercial utility. With the exception of incineration, no single process may be amenable to all pesticide waste. Thus, any chosen process must consider first the chemical constituents needing remediation, their concentration, and desired or regulated cleanup objectives. Incineration seems too impractical and expensive to clean up routinely generated wastewater and contaminated soil, but it may currently be the only practical option for obsolete stocks . Practical remediation processes for wastewater and contaminated soil produced by small waste generators are discussed. Cleanup should be viewed as an integration of physical, chemical, and biological technologies.     

Bioaccumulation Kinetics and Bioconcentration Factor of Chlorinated Pesticides in Tissues of Puntius ticto (Ham.)

Abstract

Bioaccumulation kinetics and bioconcentration factor (BCF) of chlorinated pesticides like Aldrin, Dieldrin, Benzene hexachloride (BHC), and Dichloro-diphenyl-dichloro-ethane (DDT) in fish tissues of Puntius ticto was studied in detail in a continuous fed system. The bioconcentration process is summarized by using a first order uptake model and the steady-state BCF is calculated based on the 30 days exposure. Rate of bioaccumulation of DDT was maximum of 4.6432 µg g^?1 wet weight per day in liver tissue whereas it was minimum of 0.0002 µg g^?1 wet weight per day in case of Dieldrin in the muscle tissue among the pesticides. It was observed that DDT showed maximum BCF of 89,010 in case of liver tissue of the fish exposed to 30 days. The regression coefficient (r ²) between pesticide concentration and exposure time varied between 0.6212 and 0.9817 indicating high correlation. Based on actual calculated BCF values, the octanol–water partition coefficient (K _ow) values were predicted. In order to prove the hydrophobic property of chlorinated compounds and its affinity towards lipid, the K _ow is predicted. Results showed that pesticide burden differ from tissue to tissue and can be correlated to the lipid content, size, exposure time, and species.     

Estimating Separately Personal Exposure to Ambient and Nonambient Particulate Matter for Epidemiology and Risk Assessment: Why and How

ABSTRACT

This paper discusses the legal and scientific reasons for separating personal exposure to PM into ambient and nonambient components. It then demonstrates by several examples how well-established models and data typically obtained in exposure field studies can be used to estimate both individual and community average exposure to ambient-generated PM (ambient PM outdoors plus ambient PM that has infiltrated indoors), indoor-generated PM, and personal activity PM. Ambient concentrations are not highly correlated with personal exposure to nonambient PM or total PM but are highly correlated with personal exposure to ambient-generated PM. Therefore, ambient concentrations may be used in epidemiology as an appropriate surrogate for personal exposure to ambient-generated PM. Suggestions are offered as to how exposure to ambient-generated PM may be obtained and used in epidemiology and risk assessment.     

A monitoring study of workers handling pesticides in warehouses and godowns

Abstract

Monitoring observations made on 60 operators involved in pesticide application work in godowns and warehouses and 60 matched control workers are reported. Occupational exposure history and medical history are noted. Biochemical investigations, plasma and RBC cholinesterase estimations are included along with medical examination of the workers. Workers were found to be mostly exposed to Celphos, DDVP, Malathion, Pyrethrum, etc, and the use of protective devices were very limited. Cases of significant reduction in plasma and RBC cholinesterase activity were found. Frequency of symptoms like dizziness, headache, lachrymation, burning sensation in eyes, nausea and anorexia, etc, were much more in the exposed workers. No cases of clinical poisoning attributable to occupational exposure to pesticides were reported by the workers.