Analytical method development for 18 pesticides in house dust and settled residues using SEC, SPE, TMS methylation, and GC-MS

Passive monitoring techniques to evaluate environmental pesticide exposure: Results from the Infant's Environmental Health study (ISA)

BACKGROUND

Pesticides used in agriculture may expose populations living nearby. Costa Rica is a major banana-exporting country, its production depends on extensive pesticide use.

OBJECTIVES

To evaluate environmental pesticide exposure, we measured levels of current-use pesticides in air and dust from 12 schools in Matina County, Costa Rica, with passive sampling methods.

METHODS

We selected ten proximal and two non-proximal schools and placed polyurethane foam passive air samplers outdoors at each school, during four consecutive periods. At three of these schools, we also placed an active air sampler during the first 24 h of each sampling period. We collected passive dust samples by placing a glass Petri Dish at the inside of each school. We subsequently performed a chemical analysis of 18 pesticides, using gas chromatography with mass detector.

RESULTS

With passive air samplers we detected ten different pesticides: two insecticides, two nematicides, and six fungicides, of which nine reported to be used on banana plantations. More than half of the samples contained at least five pesticides. Chlorpyrifos was detected most-frequently, in 98% of samples, followed by the nematicides etoprophos and the fungicide pyrimethanil that were both detected in 81% of samples. Chlorpyrifos concentrations were five times higher in proximal as compared to non-proximal schools: mean = 18.2 ng/m3 (range = 6.1-36.1) and mean = 3.5 ng/m3 (range= <0.5-11.4) and varied more between schools than in time (intra-class correlation coefficient = 0.80). In general, results from passive and active samplers showed similar exposure patterns; yet median concentrations tended to be higher in passive samplers. In dust samples, mostly fungicides were detected; chlorothalonil was detected most frequently, in 50% of samples.

DISCUSSION

Passive air sampling is a promising technique to characterize environmental exposure to current-use pesticides; more studies are needed to characterize the sampling rates, reproducibility and optimum sampling times for passive samplers. School environments near banana plantations are contaminated with multiple pesticides that include insecticides, nematicides, and fungicides, which is of concern.

Trends in long term exposure to propoxur and pyrethroids in young children in the Philippines

BACKGROUND/AIM

Pesticides are neurotoxic and can adversely affect children's neurobehavioral outcome. Ongoing pesticide exposure has to be monitored in the study of long term outcome of pesticide adverse effects since changes in the type and amount of exposure can influence outcome. The aim of this paper is to describe the trend in long term pesticide exposure in children through the analysis of pesticides in their hair.

PATIENTS AND METHODS

As part of an NIH study on the long term effects of pesticide exposure in young children, ongoing exposure to pesticides was determined by the analysis of children's hair for propoxur and pyrethroids by gas chromatography/mass spectrometry at 2, 4 and 6 years of age.

RESULTS

There were significant changes in the prevalence and concentration of propoxur and pyrethroids in children's hair at 2, 4 and 6 years of age. At ages 2 and 4 years, the prevalence of propoxur exposure increased from 12.4% to 24.1% (p<0.001) but dramatically decreased to 1.7% at 6 years (p<0.001). For bioallethrin, the prevalence of exposure steadily increased from 2 years (0.7%, p<0.001) to 4 years (12.4%, p<0.001) and to 6 years (18.4% p<0.001). Exposure to transfluthrin significantly increased from 4 years (1.0%) to 6 years (9.2%, p<0.001). There were also significantly higher median concentrations of bioallethrin at 2 compared to 4 years and for propoxur at 2 years compared to 6 years. Between 4 and 6 years, there was a higher median concentration of propoxur at 4 compared to 6 years and for transfluthrin and bioallethrin, at 6 compared to 4 years.

CONCLUSION

Changes in the prevalence and concentration of exposure to propoxur and pyrethroids in children at 2, 4 and 6 years of age are related to the progress in ambulation of young children and to changes in the formulation of home spray pesticides. Thus, periodic monitoring of pesticide exposure is necessary when studying the long term effects of pesticide exposure in the neurodevelopment of young children.

Analysis of House Dust and Children's Hair for Pesticides: A Comparison of Markers of Ongoing Pesticide Exposure in Children

BACKGROUND/AIM

The long term study of the adverse effects of pesticides on child neuro development requires monitoring not only of initial, but ongoing pesticide exposure. Our aim was to compare house dust and children's hair as environmental and biological markers of ongoing pesticide exposure in children.

DESIGN/METHODS

In a continuing NIH study on the adverse effects of prenatal pesticide exposure on child neurodevelopment, ongoing pesticide exposure after birth was measured in swept house dust and hair in the children at 4 years of age for propoxur and pyrethroids (transfluthrin, bioallethrin, cyfluthrin and cypermethrin) by gas chromatography/mass spectrometry. The prevalence and concentration of pesticides in the two matrices were compared.

RESULTS

Prevalence of propoxur was higher in hair compared to house dust (p<0.001) whereas prevalence of the pyrethroids was higher (p<0.001) in house dust. The overall concentrations of the pyrethroids were also higher (p<0.007) in house dust compared to hair. There was a significant (p<0.001) correlation between dust and hair for bioallethrin and cypermethrin.

CONCLUSIONS

Ongoing exposure of children to environmental pesticides is sensitively detected by analysis of children's hair and house dust. However, prevalence of propoxur was higher in hair compared to swept house dust, but the opposite was found for the pyrethroids. Thus, both matrices should be analyzed. There was a significant (p<0.001) correlation between house dust and hair for bioallethrin and cypermethrin.

Development of a high-throughput method for the determination of organochlorinated compounds, nitromusks and pyrethroid insecticides in indoor dust

Investigation of chemical exposure inside the homes and offices where people spend the majority of their lives has only recently begun. These chemicals are degraded much more slowly than outdoor because they are more protected from sunlight, severe environmental conditions and microbial activity. Hence, indoor dust has been recognized as an important exposure pathway for organic contaminants. Pyrethroids are synthetic insecticides widely used in domestic environment for numerous applications and also in agriculture. Chlorobenzenes are a family of compounds used as intermediates in the production of a wide range of household consumer products. Nitromusks are a kind of synthetic musks used in the production of cleaning agents, detergents, and personal care products. A high-throughput method for the determination of these compounds in indoor dust samples has been developed. Microwave-assisted solvent extraction was used as the extraction technique whereas quantification of compounds was carried out by gas chromatography with micro-electron-capture detection. Several cleanup procedures were tested and finally a non-classical "on batch" procedure was selected, which allows increasing the throughput of the analysis while decreasing sample manipulation. Extraction conditions were optimized using a multifactorial experimental design approach. Quantitative recovery (84-103%) was achieved for all compounds and method precision was satisfactory. Limits of detection ranged from 0.22 ng g(-1) for lindane to 40 ng g(-1) for 1,4-dichlorobenzene. Standard reference material SRM 2585 was analyzed and the obtained values were in good agreement with the reported reference values for organochlorinated compounds and nitromusks. Pyrethroids and polychlorobenzenes have been analyzed for the first time in this reference material and some of them have been found. In addition, real samples collected in houses of north-western Spain have been analyzed by the proposed method and 17 of the 22 target compounds have been detected in the samples.

Distribution of pesticide residues within homes in central New York State

Residues for 17 pesticides were analyzed in 41 households in central New York State that represented farm, rural, and urban houses. Samples were taken in both summer and winter of 2000-2001 from the same households from four locations; family room carpet; adjacent smooth floor; flat tabletop surface; and settled dust collected in a Petri dish on a tabletop. Pesticide residues were analyzed to identity factors that influence both the transport into and the redistribution of pesticides in the indoor environment. Differences were observed between the various pesticides and pesticide classifications relative to location within and between households as well as by season. Variations in the pesticide residues were related to a number of factors. Higher residues were observed in the farm households, particularly in summer, with the highest amount observed for chloropyrifos in carpet (33 microg/m2). For many pesticides, the frequency of detection and the amount of residues were higher in summer, which relates to usage patterns in agriculture and horticulture; however, larger amounts of insecticides such as mecoprop, resmethrin, and tetramethrin were found on flat surfaces in winter, indicating household use and possible redistribution within the home. Distribution patterns suggest that routines within a household may cause high variation in residues; these practices include indoor pets and treatment for fleas and ticks, use of termiticides, and fastidiousness of occupants. Frequency of pesticide detection was highest in carpet for both summer and winter for all households, indicating that carpets hold pesticides over time. Adsorbent fibrous materials such as textiles hold pesticides by macro- and micro-occlusion in their complex structures. Amounts of pesticide residue were higher in carpets than on smooth floors, particularly for rural farm households where the farmer was a certified pesticide applicator. The maximum amount of pesticide residue on a smooth floor surface was 13.6 microg/m2 malathion while the maxima on wiped surfaces and in settled dust were 1.8 microg/m2 2, 4 D and 3 microg/m2 pendimethalin, respectively. Physical properties of individual pesticides such as vapor pressure influenced the distribution of the pesticide within the households. Evidence of volatilization of pesticides and redeposition on surfaces was observed, indicating that this is a mechanism for contamination of surfaces in addition to adsorption on airborne particles and tracking. High residues in winter are evidence that closure of households in winter that reduces ventilation results in redistribution of pesticides within households.

Derivatization in mass spectrometry-3. Alkylation (arylation)

The review is devoted to alkylation (arylation) as a widely employed derivatization procedure for the protection of OH (carboxylic acids, phosphoric acids, sulfonic acids, alcohols, polyols, phenols, enols), SH (thiols) and NH (amines, amides) groups in order to increase volatility, to improve the chromatographic properties and, if possible, mass spectral properties of derivatives. Chemical aspects of derivatization and various alkylation (arylation) reagents and reaction procedures are described. Specific mass spectral (electron ionization, chemical ionization) features of derivatives helpful in identification, structure elucidation, profiling and quantitative determination of the above-mentioned polar compounds by coupled gas chromatography or high-performance liquid chromatography are discussed. Some common analytical applications of the procedures in organic chemistry, clinical chemistry, environmental chemistry etc. are briefly summarized.

Mass spectrometric detection in chromatography. Trends and perspectives

The newest results in the use of miscellaneous mass spectrometric detection methods in various chromatographic techniques are compiled and critically evaluated. Examples of application in clinical chemistry, health care, and in the analysis of pharmaceuticals, environmental pollutants, foods and food products are given. The benefits and drawbacks of MS detection are discussed, and future trends are briefly discussed.