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.

Selenium status in Saudi Arabia.

Selenium (Se) is a naturally occurring trace element that is essential for animal and human nutrition, but the range between dietary requirements and toxic levels is relatively narrow. In this review, we are interested in the beneficial effects of selenium and we report on a number of studies of the selenium status of different populations in Saudi Arabia. The Status reflects the geographical area inhabited by the populations. Apart from the few available studies reviewed here, no data on the human status of Se in Saudi Arabia has been obtained. A further objective of this paper is throw some the light on the direction of future studies.

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.

The distribution of selenium levels in Saudi dairy farms: a preliminary report from Al-Kharj.

A survey was undertaken within four dairy farms in Al-Kharj area, Saudi Arabia, to measure the selenium (Se) content in the soil, alfalfa, and water samples. Selenium was determined by Inductively Coupled Plasma Atomic Emission Spectrometry. Selenium content in the studied soil samples was low, and, in some farms, the Se content of alfalfa approached that in the low-Se zone in China. This may be reflected in the dietary Se-intake level of the Saudi population with an increased risk for developing Se deficiency-associated diseases. We suggest that extensive surveys of the Se status should be carried out in Saudi Arabia. Moreover, Se supplementation of the soil may be advisable.

Survey of trace elements in household and bottled drinking water samples collected in Riyadh, Saudi Arabia.

Total dissolved beryllium (Be), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), mercury (Hg), nickel (Ni), selenium (Se), strontium (Sr), vanadium (V) and zinc (Zn) were measured in the drinking water of 101 households and 21 samples of retail bottled waters purchased in Riyadh, Saudi Arabia to ascertain the water quality for human consumption. The Inductively Coupled Plasma Spectrometer (ICP) was used for analysis. First-draw Fe, Mn, Ni and Zn concentrations decreased significantly after 10 min of flushing in the morning. Cd, Fe, Hg, Ni and Zn in some cases exceeded the guideline limits recommended by the EEC and WHO.

Sources of lead in Saudi Arabia: a review.

Lead is a poison that affects virtually every system in the body. Children are more vulnerable to lead exposure than adults because of the frequency of pica, hand-to-mouth activity, and a greater rate of intestinal absorption and retention. Very acute lead exposure in children (blood lead levels > 80 microg/dL) can cause coma, convulsions, and even death. Lower levels cause adverse effects on the central nervous system, kidney, and hematopoietic system. Several studies have identified harmful effects of lead in children at blood lead levels as low as 10 microg/dL. Recently, the Center for Disease Control (CDC) has cut the lead allowable threshold level from 25 microg/dL of blood to 10 microg/dL. This review summarizes the main sources of lead exposure that one could expect in a modern society such as Saudi Arabia.

Residue levels of organochlorinated insecticides in breast milk: a preliminary report from Al-Kharj, Saudi Arabia.

Breast milk samples obtained from 115 mothers residing in Al-Kharj area, Saudi Arabia, were quantified by gas chromatography and confirmed by gas chromatography-mass spectrometry for lindane, heptachlor, heptachlor epoxide, dieldrin, endrin, p,p-DDE, p,p-DDD, and p,p-DDT. The results showed that 80.9% of the samples contained p,p-DDT, 93.9% p,p-DDE, and 74.8% p,p-DDD. Whereas lindane, heptachlor, heptachlor-epoxide, dieldrin, and endrin were found in 23.5, 20.9, 36.5, 48.7, and 32.2% screened samples, respectively. Results of this survey clearly show that infants were exposed to organochlorinated pesticides. Although the levels of organochlorinated pesticides reported here are lower than those reported from several other countries, the maximum daily intakes of those pesticides exceeded the WHO/UNEP Acceptable Daily Intakes for a 5-kg infant. This finding warrants further research to determine the magnitude of the problem in Saudi Arabia. As there is a bulk of literature that highlights the adverse health effects of organochlorinated pesticides on children and infants, it would be advantageous to establish a regular organochlorinated pesticides monitoring program.

Selenium levels in infant milk formula.

Twenty-four brands of commercial infant milk formula were collected and analysed for selenium by inductively coupled plasma spectrometry with the hydride t-system after an acid digestion procedure. The mean selenium concentration was 49.0 +/- 11.55 micrograms l-1, with a range from 26-68 micrograms l-1, resulting in an adequate daily selenium intake for infants aged from zero to six months consuming 0.75 l milk daily as set by the US National Research Council in 1989.

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.

Mercury content in skin-lightening creams and potential hazards to the health of Saudi Women.

It seems evident from a wealth of scientific research that mercury is toxic. Because of the nature of the Saudi markets, different brands of skin-lightening creams are widely available. In this study, 38 skin-lightening cream samples were collected and analyzed for mercury by inductively coupled plasma spectrometry after an acid digestion procedure. About 45% of the tested skin-lightening cream samples contained mercury at levels well above the FDA's acceptable limit of 1 ppm. These findings are alarming and have wide legal and educational implications for Saudi Arabia in particular and developing countries in general. Further investigation for possible adverse health effects is also needed.

Selenium levels in breast milk and cow's milk: a preliminary report from Saudi Arabia.

We measured the selenium in 117 milk samples by means of inductively coupled plasma spectrometry with the hydride t-system. The samples were collected from healthy lactating mothers living in the Al-Kharj area in Saudi Arabia and from seven brands of Saudi fresh cow's milk. The concentration of selenium in breast milk significantly decreases toward the end of lactation. Our results also showed that the selenium concentration in breast milk is also influenced by the number of breast feedings per day. Further studies are needed to evaluate the selenium status in Saudi infants. The selenium concentration in local cow's milk samples was significantly higher than in the breast milk samples.

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.