Stefan M. Waliszewski

Genotoxic biomonitoring of agricultural workers exposed to pesticides in the north of Sinaloa State, Mexico

Genotoxic damage was evaluated in 70 agricultural workers, 25 women and 45 men, exposed to pesticides in Las Grullas, Ahome, Sinaloa, Mexico, with an average of 7 years of exposure. The effect was detected through the sister chromatid exchanges (SCE) in lymphocytes of peripheral blood and micronuclei (MN) and other nuclear anomalies (NA) in buccal exfoliated cells. Also, the influence on cellular proliferation kinetics (CPK) was studied by means of the replication index (RI) and the cytotoxic effect was examined with the mitotic index (MI). The non-exposed group consisted of 70 other persons, 21 women and 47 men from the city of Los Mochis, Sinaloa, Mexico. Significant differences between the exposed and the non-exposed groups were observed in SCE, CPK, MI, MN and NA. Analysis of variance revealed that age, gender, smoking and alcohol consumption did not have a significant effect on genetic damage. However, there was a correlation between exposure time to pesticides and SCE frequency. These results could have been due to the exposure of workers to pesticides containing different chemical compounds. This study afforded valuable data to estimate the possible risk to health associated with pesticide exposure.

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

This monitoring study of 355 samples of cows 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 cows milk and butter samples, respectively. The mean DDT levels were 0.159 and 0.049 mg/kg, respectively. In relation to cows 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.

Detection of some organochlorine pesticides in cow's milk

This monitoring study of 192 samples of cows milk collected from the central region of Veracruz state was conducted to determine the contamination levels of organochlorine pesticides. The results obtained for mean DDT and HCH levels were 0.057 and 0.098 mg/kg respectively expressed on fat basis and are within FAO tolerances and similar to those found in other tropical countries.

Extraction and clean-up methods for organochlorine pesticides determination in milk

Organochlorine pesticides (OCPs) can cause environmental damage and human health risks since they are lipophilic compounds with high resistance to degradation and long half-lives in humans. As most persistent OCPs have been banned years ago, it is expected to find these compounds at trace levels in environment. Therefore, increasingly sensitive and reliable analytical techniques are required to ensure effective monitoring of these compounds. The aim of this review is to discuss extraction and clean-up methods used to monitor OCP residues in milk, reported in the last 20 years. To carry out this review, an exhaustive bibliographic review was conducted. Despite the disadvantages of conventional extraction and clean-up methods, such as liquid-liquid, solid-phase or Soxhlet extractions, these procedures are still used due to their reliability. New extraction methods, like solid-phase microextraction, matrix solid-phase dispersion or QuEChERS, have not been thoroughly evaluated for OCP determination in milk. Almost all the methodologies analyzed in this review presented good performance characteristics according to the performance acceptability criteria set in SANCOs procedure. Comparison between limits of quantification (LOQ) and detection (LOD), for the reported methodologies, is not always possible due to the heterogeneity of the units. Thus, researchers should take into account an homogenization of LOD and LOQ units, according to the international regulations and MRLs established. Finally, more research is necessary to obtain the ideal methodology for OCPs determination in milk, which comprises the environmentally friendly characteristics of the new techniques and the reliability of the traditional methodologies.

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.

Persistent organochlorine pesticides in blood serum and whole blood

Since organochlorine pesticides were introduced for plant protection and sanitation, they have been of great benefit in the control of pest populations and in combating the spread of infectious diseases. Unfortunately, they accumulate in the environment and this has resulted in a ban on their use. Nevertheless, they are still widely used in tropical countries as the insecticides of choice. An analytical procedure was elaborated to find out the extent of contamination of the human body by persistent residues of organochlorine pesticides and to determine the gradient between adipose tissue and biological fluids, which correlates with bioaccumulation and dissipation processes. The method has two important advantages: it is a simple, low-cost semi-micro, and it makes it possible to determine free and bound pesticides.

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, β-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 β-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; β-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.

Circadian Nursing Induces PER1 Protein in Neuroendocrine Tyrosine Hydroxylase Neurones in the Rabbit Doe

Rabbit does nurse their pups once a day with circadian periodicity and pups ingest up to 35% of their body weight in milk in < 5 min. In the doe, there is a massive release of prolactin. We hypothesised that periodic suckling synchronises dopaminergic populations that control prolactin secretion. We explored this by immunohistochemical colocalisation of PER1 protein, the product of the clock gene Per1 on tyrosine hydroxylase (TH) cells in three dopaminergic populations: tuberoinfundibular dopaminergic (TIDA), periventricular hypophyseal dopaminergic (PHDA) and incertohypothalamic dopaminergic (IHDA) cells. PER1/TH colocalisation was explored every 4 h through a complete 24‐h cycle at postpartum day 7 in does that nursed their pups either at 10.00 h (ZT03) or at 02.00 h (ZT19; ZT0 = 07.00 h, time of lights on). Nonpregnant, nonlactating females were used as controls. In control females, there was a rhythm of PER1 that peaks at ZT15. By contrast, in nursed does, the PER1 peak shifted in parallel to scheduled nursing in TIDA and PHDA cells but not in IHDA cells, which are not related to the control of prolactin. Next, we determined that the absence of suckling for 48 h significantly decreases the number of PER1/TH colocalised cells in PHDA but not TIDA cells. Locomotor behaviour in control subjects was maximal at around the time of lights on but, in nursed females, shifted at around the time of scheduled nursing. Finally, in the suprachiasmatic nucleus, there is a maximal expression of PER1 at ZT11 in the three groups. However, this maximal expression was significantly lower in the nursed groups in relation to the control group and in the groups deprived of nursing for 48 h. We conclude that suckling synchronises dopaminergic cells related to the control of prolactin and appears to be a nonphotic stimulus for the suprachiasmatic nucleus.

Determination of selected chlorinated pesticides, bound and free, in human semen

The content of chlorinated pesticide residues and their metabolites in semen specimens from 44 random donors was studied. Forty-four ejaculates were mixed to make a pool of semen and recovery studies were made on five-gram samples. A previously developed technique was modified for compounds free and bound with endogenous substances in human semen, a body fluid which contains genetic material. The new procedure is characterized by very good recoveries (>90%) and standard deviation (S.D.) less than 6.5 for fortified samples of semen following incubation. It requires simple, easily available, and inexpensive reagents which make the method an adequate, precise, and reasonably cheap tool, applicable in a wide range of laboratories.

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), β-hexachlorocyclohexane (HCH), γ-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, β-HCH mean concentration was 0.039 mg kg−1 and γ-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 (σ 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; β-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.