Carcinogen DNA adducts and the risk of colon cancer: case-control study.

Colorectal cancer represents 8.5% of all tumours at the King Faisal Specialist Hospital & Research Centre. Environmental and dietary carcinogens such as polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs) have long been suspected to play a prominent role in colon cancer aetiology. We designed a case-control study to test the hypothesis of whether or not the presence of DNA adducts can play a role in the aetiology of colon cancer. DNA adducts were measured in 24 cancerous and 20 non-cancerous tissue samples of newly diagnosed colon cancer patients by (32)P-post-labelling technique. Normal tissue from 19 hospital patients served as controls. The mean levels of adducts per 10(10) nucleotides in cancerous and non-cancerous tissue were 151.75+/-217.27 and 114.81+/-186.10, respectively; however, only adducts in cancerous tissue were significantly higher than controls (32.78+/-57.51 per 10(10) nucleotides) with p-values of 0.017. No BPDE-DNA adducts were found. No relationship was found between urinary cotinine as a marker of tobacco smoke and 1-hydroxypyrene as an indicator of an individual's internal dose of PAHs and DNA adducts. In a logistic regression model, only adducts in cancerous tissue were associated with the subsequent risk of colon cancer, with an odds ratio of 3.587 (95% confidence interval 0.833-15.448) after adjustment for age and the duration of living in the current region, but of a borderline significance (p=0.086). Although it is difficult to arrive at a definite conclusion from a small dataset, our preliminary results suggest the potential role of DNA adducts in the colon carcinogenesis process. Additional studies with larger sample sizes are needed to confirm our preliminary finding. It is also important to identify the structural characterization of these unknown DNA adducts in order to have a better understanding of whether or not environmental carcinogens play a role in the aetiology of colon cancer.

Report on the levels of cadmium, lead, and mercury in imported rice grain samples.

In an attempt to know whether highly consumed food might contribute to metal exposure, we analyzed cadmium, lead, and mercury in 27 rice grain samples commonly consumed in Saudi Arabia by atomic absorption spectrometry after acid digestion. The mean concentrations and ranges of cadmium, lead, and mercury in tested rice samples were 20.261 (range

Levels of cadmium, lead, and mercury in human brain tumors.

This article reports on the levels of cadmium, lead, and mercury in 21 benign brain tumors and 23 malignant brain tumors. All measurements were performed by atomic absorption spectrometry following digestion by nitric acid. Average concentrations of cadmium, lead, and mercury in brain tumors were 2.02 (ND-72.78), 0.625 (ND-83.13), and 0.118 (ND-1.96) microg/g wet weight, respectively. Our values were higher than data reported by others.

Relationships between blood lead concentrations, intelligence, and academic achievement of Saudi Arabian schoolgirls.

This cross-sectional study examined the association between blood lead levels and neuropsychological and behavioural problems of 533 schoolgirls (6-12 years of age) who attended public schools in Riyadh, Capital of Saudi Arabia. Regression models were used to determine the best predictors of Beery VMI Saudi-based standard scores, TONI Saudi-based scores and rank percentile. The mean blood lead level was 8.11 +/- 3.50 micrograms/dl in the range of 2.3 to 27.36 micrograms/dl. Significant negative associations were noted between blood lead levels and Beery VMI Saudi-based standard scores as well as rank percentile. Lead had no effect on TONI Saudi-based standard scores. Beery VMI Saudi-based standard scores, TONI Saudi-based standard scores and rank percentiles were inversely related to pupils with blood lead levels > 9 micrograms/dl. These findings attest an association between neuropsychological and behavioural impairment and lead exposure at blood lead levels in the range of 9.02 to 27.36 micrograms/dl. The results of this study should be seriously considered by public health authorities to give more attention to this pediatric health problem.

Determinants of blood lead levels in Saudi Arabian schoolgirls.

Blood lead levels were measured in 538 girls aged 6 to 12 years who attended primary public schools in Riyadh, Saudi Arabia. Of the 538 screened children, 24.4% had blood lead levels > or =10 microg/dL, the Centers for Disease Control's level of concern. Variation in the blood lead levels was investigated with respect to a number of risk factors. The main determinant of blood lead levels was the regional location of the school. Pupils who attended schools located in the Central region of Riyadh had significantly higher blood lead concentrations than did pupils who attended schools in the peripheral areas. This is most likely to be due to the heavy vehicular emissions in the Central region. Other variables such as low family income, grade, and application of kohl to the child's eyes and/or umbilicus at birth were also contributors to the blood lead levels. These observations emphasize the importance of health education programs to promote the reduction of lead exposure in the general population.

Urinary mercury levels in females: influence of skin-lightening creams and dental amalgam fillings.

The influence of application of skin-lightening creams and dental amalgam fillings on the urinary mercury (Hg) level was evaluated in 225 females (ages 17 to 58 years) living in Riyadh, capital of Saudi Arabia. The arithmetic mean of the urinary Hg level was 6.96 +/- 20.43 micrograms 1(-1), in the range 0 to 204.8 micrograms 1(-1). The mean urinary Hg level adjusted by creatinine (Cr) was 11.22 +/- 37.23 micrograms g-1 Cr, in the range 0 to 459.37 micrograms g-1. No significant difference in urinary Hg was noted between the females regarding the use of skin-lightening creams. On the other hand, results showed that urinary Hg concentration was influenced by the use and number of dental amalgam fillings. No women were identified with symptoms or signs that could be attributed to Hg intoxication. Urine analyses for creatinine, urea, uric acid, phosphorus, magnesium, glucose and calcium showed significant correlation with urinary Hg. This suggests that chronic exposure to Hg may be associated with a deterioration of renal function.

Aluminum in Saudi children.

Aluminum was determined in serum samples obtained from 533 Saudi female pupils aged 6-8 years who attended primary public school in Riyadh City, Capital of Saudi Arabia. The aluminum mean value was 23.21 +/- 15.25 micrograms l(-1) in the range of 5.98-206.93 micrograms l(-1). Serum aluminum levels of pupils attending the Northern school area were higher than levels found in pupils from other school areas (Southern, Eastern and Central). Renal variables had no correlation with serum aluminum. On the other hand, a significant positive correlation was found between serum aluminium above 49.2 micrograms l(-1) and urea (r = 0.6, P < 0.002). Although 53% of the screened schools had aluminum in water above the European Union (EU) acceptable limit of 50 micrograms l(-1), there were no differences in aluminum in water between the four different school areas in Riyadh. Factors such as drinking water, diet and the use of aluminum utensils may have contributed to this result. As there is a bulk of literature which highlights the adverse developmental effects of aluminum on children and infants, it would be advantageous to establish regular aluminum monitoring.