Pesticides aging

Pesticides Ageing VDUs Eluorescent lights Plant, timber and fabric treatments... 

With the typical dimethoxy and dicthoxy structure of pesticides, aging rates arc such that the phenomenon only becomes a problem when treatment is delayed and/or exposure prolonged. It i.s commonly, but erroneously, believed that 1 day after intoxication with an OF insecticide virtually all the phosphorylaicd enzyme will be in the t cd fonn so that oxime therapy will be ineffective after this time. However, this interpretation derives from in vitro. studies in which AChE is rapidly inhibited and is maintained fully inhibited thereafter by the pre.scncc of an excess of inhibitor and in the absence of oxime throughout the experiment. Such experiments do not represent the case in 1 ivo and should not be used as a reason to abandon the use of oxime therapy after 24 hr. 

We now have much better tools for assessing specificity than we had at the beginning of the pesticide age. Gas and thin layer chromatography can usually detect the presence of mixtures. They do not work so well the other way—proving the identity of a pure compound. For this you have to apply the instruments which work on the whole molecule, or appreciable or critical fractions of the molecule, such as infrared spectroscopy, nuclear magnetic resonance, or best of all, mass spectrometry. But there are always footnotes or reservations to the best of techniques. In this case, for unequivocal identification, apply the techniques only to pure samples only a small amount is needed, but it must be pure ... 

Sorption. Most organics are sorbed to a very small degree on the biofloc, ie, < 2 percent. Exceptions are the nondegradable pesticide Lindane, other pesticides, and PCBs. Heavy metals will complex with the ceU wall and precipitate within the floe. Metal accumulation will increase with increasing sludge age. 

In a case-control study of pesticide factory workers in Brazil exposed to methyl parathion and formulating solvents, the incidence of chromosomal aberrations in lymphocytes was investigated (De Cassia Stocco et al. 1982). Though dichlorodiphenyltrichloroethane (DDT) was coformulated with methyl parathion, blood DDT levels in the methyl parathion-examined workers and "nonexposed" workers were not significantly different. These workers were presumably exposed to methyl parathion via both inhalation and dermal routes however, a dose level was not reported. The exposed workers showed blood cholinesterase depressions between 50 and 75%. However, the baseline blood cholinesterase levels in nonexposed workers were not reported. No increases in the percentage of lymphocytes with chromosome breaks were found in 15 of these workers who were exposed to methyl parathion from 1 week to up to 7 years as compared with controls. The controls consisted of 13 men who had not been occupationally exposed to any chemical and were of comparable age and socioeconomic level. This study is limited because of concomitant exposure to formulating solvents, the recent history of exposure for the workers was not reported, the selection of the control group was not described adequately, and the sample size was limited. 

The controls were patients who had undergone appendicitis or hernia surgery, and were matched for sex, age, and socioeconomic status with a larger set of 31 pesticide poisoning eases, of whieh the methyl parathion eases were a subset. Limitations of this study include the small number of methyl parathion eases, and the use of appendieitis and other surgery patients as eontrols. 

Pope CN, Liu J. 1997. Age-related differences in sensitivity to organophosphorus pesticides. Environ Toxicol Pharmacol 4 309-314. 

Validation of true extraction efficiency normally requires the identification and quantitation of field-applied radiolabeled analyte(s), including resulting metabolites and all other degradation products. The manufacturer of a new pesticide has to perform such experiments and is able to determine the extraction efficiency of aged residues. Without any identification of residue components the calculation of the ratio between extracted radioactivity and total radioactivity inside the sample before extraction gives a first impression of the extraction efficiency of solvents. At best, this ratio is nearly 1 (i.e., a traceability of about 100%) and no further information is required. Such an efficient extraction solvent may serve as a reference solvent for any comparison with other extraction procedures. 

One more example of acute polychlorpinen poisoning occurred in the Ukraine around 1969-70, when 27 women aged 26-49 were sent out to sow collective farm fields three days after the fields had been treated with polychlorpinen. A warm rain washed the pesticide from the soil, and the pesticide evaporated intensively. All the women showed symptoms of acute poisoning 20-40 minutes later eight lost consciousness, and nine had fits. The poisoned women spent from 3-25 days in the regional hospital, after which they all went to the VNIIGINTOKS clinic with disruptions of the neural and cardio-vascular systems, as well as of the digestive tract over the next 9-13 months [43]. 

Blood was studied in a group of virtually healthy adolescents aged 14-17 from two localities in the Ukraine, where pesticide exposure differed by a factor of three, though the pesticide content in food products, drinking water, air and soil in the experimental zone was not higher than public health standards permitted. In Azerbaijan there was a difference of 100 times in the amounts of pesticides used in the experimental and control localities, while the pesticide contamination of elements of the environment and food products in the experimental zone was 2-50 times higher than acceptable levels [A97]. Table 3.6 shows the results. 

In rural regions with maximal pesticide exposure, children more often suffer the following illnesses before the age of 14 [A109] iron-deficit anemias (10 times more often in Turkmenia, 4 times in Armenia, 2.5 times in Azerbaijan, 2 times in Uzbekistan, and 1.4 times in Moldavia) active tuberculosis (2 times in Moldavia, 2.3 times in Kirgizia, 1.6 times in Armenia and Azerbaijan) viral hepatitis (23.7 times in Turkmenia, 2.4 times in Armenia, 2 times in Azerbaijan, 1.2 times in Kirgizia) and acute upper respiratory tract infections (21 times in Turkmenia, 1.4 times in Kirgizia). 

The indicator for infant mortality in children up to one year of age in Armenia turned out to be significantly higher in those regions that actively used pesticides than in those where pesticides were less actively employed [A99]. 

Pesticides have a statistically reliable effect on children in zones where OCPs are intensively used (in the Salyansk region of Azerbaijan, the amount of OCPs introduced into humans exceeded public health standards by up to 7.7 times). Primary illness of the endocrine system increased 3.1 times in children up to age 15 (over a five year observation period) in disruptions in diet and metabolism, the nervous system, and the sensory and respiratory organs in increased frequency of illness (over five years) in children up to age 15 (an overall increase by 3.6 times, and by class of illness, from 2.2-7.6 times) in the prevalence of pathological disruptions according to data from medical examinations of children from 8-14 years (an overall increase by 2.3 times, and by class of illness by 2.0-8.4 times) in... 

In 1971-75, the health of a group of 2473 children aged 1-14 was studied in several farms of the Khorezm Oblast (Uzbekistan), where HCH, phosalone and DEF were used to grow cotton. Overall illnesses among children in the region where the air was contaminated with pesticides were three times higher than in the control region [A85]. 

In 1970-75, the health of 2972 children aged 1-14 was studied in the Fergana Oblast, where OPPs were widely used. Overall illnesses among children were 2.4 times higher than in the control region of the Tashkent Oblast, where pesticides were virtually unused. Moreover, children aged 4-7 years were the most sensitive to air contamination. The OPP formothion,... 

Table 3.10. Average annual number of illnesses (per 10,000) established for the first time in children up to age 14 in rural regions of the USSR in 1980-84 in territories with differing pesticide exposure [3]...

A report entitled Chemical Trespass was issued in May 2004 by the Pesticide Action Network (Schafer et al., 2006). It contained detailed analysis of 2000/01 National Health and Nutrition Examination Survey (NHANES) OP urinary metabolite data and used published methods to estimate exposure levels to parent compounds from creatinine corrected urinary metabolite levels. They focused on chlorpyrifos and its metabolite 3,4,6-trichloro-2-pyridinol (TCP), and found that chlorpyrifos exposures for children ages 6-11 and 12-19 exceeded EPA s chronic population-adjusted dose (cPAD) by surprisingly wide margins. Geometric mean TCP levels were 3 to 4.6 times higher than the EPA-estimated safe dose, as shown in Fig. 14.2. The more heavily exposed children received daily doses more than ten times the safe level. 

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