Persistent organochlorine pesticide levels in bovine fat from Mexico.

Organochlorine pesticides have been used in Mexico in agriculture as a seed dresser, in sanitation, in malaria control programmes and in livestock to combat ectoparasites. The pesticides applied drift to areas where cattle graze and plants grow. Because of their chemical stability, they accumulate in the lipid-rich tissues of the body. In the body, they circulate throughout all compartments and accumulate in adipose fat. The aim was to monitor the organochlorine pesticide levels in bovine muscle fat and kidney fat from cows living in an endemic malaria zone, where the environmental contamination can be suspected as being higher. Two hundred samples (100 muscle fat, 100 kidney fat) were analysed by gas chromatography. From the pesticides, only hexachlorobenzene (HCB), beta-hexachlorocyclohexane (HCH), gamma-HCH, pp'-1.1.1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT), op'-DDT and pp'-DDE, were detected frequently and at levels above the detection limits. The HCB mean level was low at 0.009 mg kg(-1) on a fat basis. From the HCH isomers, beta-HCH mean concentration was 0.039 mg kg(-1) and gamma-HCH was 0.025 mg kg(-1) on a fat basis. Among DDTs, pp'-DDT was the major constituent (0.032 mg kg(-1) on a fat basis) followed by pp'-DDE (0.025 mg kg(-1) on a fat basis) and op'-DDT (0.023 mg kg(-1) on a fat basis). The DDT total (sigma DDT) level was 0.067 mg kg(-1) on a fat basis. Comparing the previous study (1994) and the present one (2002-03), organochlorine pesticide levels were decreased. HCB decreased 3.7 times from 0.033 to 0.009 mg kg(-1) on a fat basis; beta-HCH decreased 3.8 times from 0.149 to 0.039 mg kg(-1) on a fat basis; pp'-DDE did not reveal a significant difference at 0.026 versus 0.025 mg kg(-1) on a fat basis. However, pp'-DDT decreased substantially, 6.7 times from 0.215 to 0.032 mg kg(-1) on a fat basis. The DDT total decreased 3.5 times from 0.236 to 0.067 mg kg(-1) on a fat basis. The tendency for reduced concentrations in organochlorine pesticide levels in Mexican cows is caused by their substitution with pyrethroids used in agriculture and by the Mexican Ministry of Health in sanitary programmes.

Persistent organochlorine pesticides in Mexican butter.

Organochlorine pesticides have been used in Mexico in malaria control programmes against ectoparasites and as seed dresser. Owing to their chemical stability, they tend to accumulate in the lipid part of the organisms. The stored pesticides are excreted with the endogenous fat during milk production. The aim was to monitor the organochlorine pesticide levels in butter manufactured in Mexico. From the pesticides, only HCB, beta-HCH, pp'-DDT, op'-DDT and pp'-DDE with major frequency and levels were detected. The HCB mean level was low at 0.008 mg kg(-1) on a fat basis. From the HCH isomer, only the beta-HCH at 0.065 mg kg(-1) on a fat basis was determined, remaining as the main contaminant of the monitored butters. Among DDTs, pp'-DDE was the major constituent (0.043 mg kg(-1) on a fat basis) followed by pp'-DDT (0.036 mg kg(-1)) and op'-DDT (0.009 mg kg(-1)). Comparing the previous study (1994) and this one (2001), all organochlorine pesticides had a descendent tendency; beta-HCH decreased from 0.095 to 0.065 mg kg(-1) on a fat basis, whereas the total DDT decreased from 0.056 to 0.047 mg kg(-1), pp'-DDT from 0.050 to 0.036 mg kg(-1), op'-DDT from 0.018 to 0.009 mg kg(-1), while pp'-DDE increased from 0.032 to 0.043 mg kg(-1). The decreased DDT levels in Mexican butters is caused by the substitution of organochlorine insecticides with pyrethroids used by the Mexican Ministry of Health since 1999 in sanitary programmes.

Persistent organochlorine pesticide levels in cow's milk samples from tropical regions of Mexico.

Organochlorine pesticides have been used in agriculture as a seed dresser, in sanitation, in malaria control programmes and in livestock to combat ectoparasites. Their residues accumulate in lipid-rich tissues due to their chemical stability and persistence. In the body they circulate throughout all compartments, deposit themselves in adipose fat and can be excreted during lactation. These pesticides are applied in tropical zones and drift to areas where cattle graze. Therefore, analyses of cow's milk samples can serve as an indicator of environmental and cows' exposure to them. One hundred and fifty milk samples were taken each year in 1998 and 2001 and analysed to determine concentrations of HCB, beta-HCH, pp"-DDE, op'-DDT and pp'-DDT. Results obtained indicate that beta-HCH is one of the main contaminants (0.106 and 0.087 mg x kg(-1) on fat basis) followed by pp'-DDT (0.078 and 0.037 mg x kg(-1) on fat basis) and pp'-DDE (0.051 and 0.033 mg x kg(-1) on fat basis). The HCB and op'-DDT were detected in lower quantities respectively (0.008 and 0.006 mg x kg(-1), and 0.031 and 0.010 mg x kg(-1) on fat basis). When comparing the results obtained with those from the previous study, it was noted that DDT levels decreased significantly in 2001 as a result of the substitution of the organochlorine insecticides with pyrethroids sprayed by the Mexican Ministry of Health to combat malaria since 1999.

Organochlorine pesticide levels in maternal adipose tissue, maternal blood serum, umbilical blood serum, and milk from inhabitants of Veracruz, Mexico.

Organochlorine pesticides, due to their persistence, accumulate in food chains and cause elevated contamination in human beings. These residues bioconcentrate in lipid-rich tissues according to the equilibrium pattern of internal transport and lipid tissue content. The analyses of maternal adipose tissue, maternal blood serum, umbilical blood serum, colostrum, and mature milk indicate circulation of these compounds through all compartments of the maternal body, including their crossover of the placental barrier. The greatest residue levels found correspond to DDTs, with highest levels determined in colostrum (5.71 mg/kg of DDT total), followed by adipose tissue with 5.66 mg/kg and in mature milk with 4.70 mg/kg. Among DDTs, pp'DDE is the most predominant compound. The paired analyses of organochlorine pesticide residue levels between mother blood serum and umbilical blood serum demonstrate significant correlation and their transfer from mother to fetus through the placenta. The paired analyses of adipose tissue and colostrum and mature milk contamination levels indicate a high degree of coherence, principally of DDT, in the body and lactation as a decontamination means.

Carry-over of persistent organochlorine pesticides through placenta to fetus.

OBJECTIVE: As a consequence of environmental exposure, organochlorine pesticides accumulate in lipid rich-tissues such as maternal adipose tissue and partition to maternal blood serum and umbilical blood serum. To establish their distribution in the human body, the concentration gradients of organochlorine pesticides between these compartments were determined. MATERIAL AND METHODS: Maternal adipose tissue, blood serum and umbilical blood serum samples from 64 volunteers admitted for cesarean delivery at Hospital Benito Coquet Lagunes were studied in Veracruz during 1997 and 1998. The pesticide residues were determined by gas chromatography and results obtained from different sample groups were analyzed using Pearson correlation coefficients and simple lineal regression. RESULTS: Significant results expressed on fat basis of organochlorine pesticides indicate that 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) levels are higher in maternal adipose tissue (4.51 mg/kg DDE and 1.27 mg/kg pp'DDT), maternal blood serum (4.45 mg/kg DDE and 0.78 mg/kg pp'DDT), and umbilical blood serum (4.70 mg/kg DDE and 0.88 mg/kg pp'DDT), due to greater affinity of DDT for lipids. CONCLUSIONS: The statistical evaluation of results and the pairing of samples analyzed indicate that absorbed organochlorine pesticides cross the placental barrier and reach a balanced state between mother and fetus.

Time trend of organochlorine pesticide residues in human adipose tissue in Veracruz, Mexico: 1988-1997 survey.

The monitoring study of 287 human adipose tissue samples collected from 1988 to 1997 was used to determine the contamination levels of organochlorine pesticides. The results obtained indicate DDT as dominant. The fluctuation of DDT levels during the study period reveal a descent tendency and are closely related to the pp'-DDE content. The results, classified according to the origin of donors, indicate a higher contamination of the suburban zone. This difference was caused by diminished use of DDT and its substitution by Malathion and pyrethroids.

Organochlorine pesticide residues in cow's milk and butter in Mexico.

This monitoring study of 355 samples of cow's milk collected from the central region of Veracruz state and 448 samples of national butter brands was conducted to determine the contamination levels of organochlorine pesticides. The results obtained for mean HCH levels were 0.094 and 0.093 mg/kg on fat basis in cow's milk and butter samples, respectively. The mean DDT levels were 0.159 and 0.049 mg/kg, respectively. In relation to cow's milk, the total HCH levels in Veracruz state were higher but total DDT levels were comparable to those reported in other countries. On the other hand, organochlorine levels detected in national brand butter samples were lower than those found in other countries, where these pesticides are still used in sanitary actions. These results confirmed that dairy products in Mexico presented organochlorine pesticide residues (owing to their use in sanitary actions) indicating a human exposure through these food products.

Levels of organochlorine pesticides in Mexican butter.

Organochlorine pesticide residues were analyzed in 345 samples of butter purchased from Mexican supermarkets in 1994. Three national brands and one foreign brand were analyzed. Most samples contained residues of gama-HCH (91%), HCB (90%), and p,p'-DDE (88%). Residues of alpha-HCH (63%), p,p'-DDT (42%), beta-HCH (38%), o,p'-DDT (17%), heptachlor epoxide (7%), and endosulfane sulfate (3%) were also detected. Mean values of pesticide residues determined were 0.093 mg/kg fat for total HCH and 0.056 mg/kg for total DDT. Mean values of organochlorine pesticide residues in Mexican butter were comparable with those in a foreign brand.

Organochlorine pesticide residues in adipose tissue of Mexicans.

Concentrations of organochlorine insecticide residues such as DDT, DDE, gamma- and beta-HCH were determined in human adipose tissue samples obtained during autopsies from urban and suburban areas of Veracruz city, the state of Veracruz and out-of-state areas, collected during 1988 and 1991. The mean levels of total DDT, which constitutes the predominant accumulated pesticide, decreased from 17.45 mg/kg in 1988 to 14.06 mg/kg in 1991. The highest levels of total DDT were determined in persons from suburban areas of Veracruz city and among persons over 51 years old with the highest levels of contamination observed in patients dying of cardiovascular disorders.