Urinary dialkyl phosphate levels before and after first season chlorpyrifos spraying amongst farm workers in the Western Cape, South Africa

The study investigated urinary levels of dialkyl phosphates resulting from pesticide exposure amongst 40 farm workers. Workers were tested (urinary dialkyl phosphate levels, anthropometry, short exposure questionnaire) before and after the first day of seasonal chlorpyrifos spraying. Median baseline urinary dialkyl phosphates was high amongst both non-applicators (1587.5 μg/g creatinine, n = 8) and applicators (365.6 μg/g creatinine, n = 9). There was not much evidence of an increase in post-spray dialkyl phosphates levels from pre-spray levels amongst both applicators and non-applicators. Hours mixing, spraying, driving a tractor and hours worked by non-applicators were not significantly associated with an increase in post-spray dialkyl phosphate levels, adjusting for age, height, weight, gender, use of empty pesticide containers and self-reported kidney problems. Past applicator status was weakly positively associated with pre-spray dialkyl phosphate levels adjusting for age, height, weight, and gender, self-reported kidney problems, smoking and alcohol (β= 1019.5, p = 0.307, R2 = 0.28). The high dialkyl phosphate levels call for an epidemiological investigation into the health effects of organophosphorous pesticides.     

Oxidative DNA damage estimated by urinary 8-hydroxydeoxyguanosine: influence of taxi driving,smoking and areca chewing

Nitrogen oxides (NOx) and polycyclic aromatic hydrocarbons are common air pollutants generated from automobile exhaust and cigarette smoke. This study was to investigate urinary 8-hydroxydeoxyguanosine (8-OHdG) as an effective biomarker on DNA damage from traffic exhaust and/or smoking in exposed and non-exposed individuals. With subject consents, the levels of plasma NOx, urinary 1-hydroxypyrene (1-OHP) and 8-OHdG were determined for 95 male taxi drivers and 75 male community residents as the reference group. After adjusting for associate variables, there was a significant correlation between the levels of urinary 8-OHdG and 1-OHP but not NOx. The average level of urinary 8-OHdG was significantly higher in drivers than in community men (13.4+/-4.7 vs. 11.5+/-4.7 microg/g creatinine in mean+/-standard deviation). Compared with non-smoking community men, the multivariate logistic regression showed that the odds ratios (OR) of having elevated levels of urinary 8-OHdG (greater than the overall median value, 12.1 microg/g creatinine) were 6.6 (95% confidence interval (CI)=2.1-20.8) for smoking community men, 5.0 (95% CI=1.7-14.7) for non-smoking taxi drivers and 4.6 (95% CI=1.4-15.0) for smoking taxi drivers. Higher risk was also observed for areca quid chewers compared with non-chewers (OR=1.6; 95% CI=1.1-3.6). In conclusion, taxi driving and smoking may contribute independently to elevated DNA damage using urinary 8-OHdG levels as a sensitive biomarker. This effect is most potent on heavy smokers.     

Bioaccumulation studies of organochlorinated pesticides in tissues of Cyprinus carpio

Freshwater fish Cyprinus carpio was selected for the study of bioaccumulation of organochlorinated pesticides in tissues like gills, muscle, intestine, kidney, and liver in a continuous fed system. The pesticides used were Aldrin, Dieldrin, BHC, and DDT. The bioaccumulation of Dieldrin was maximum of 85.0 microg g(-1) wet weight in liver tissue while minimum of 7.30 microg g(-1) wet weight for DDT at 30 days exposure time. Bioconcentration factor (BCF) has followed the same trend in liver tissue for Dieldrin and DDT. The rate of bioaccumulation was found to be maximum of 4.3879 microg g(-1) wet weight in liver tissue and minimum of 0.0021 microg g(-1) wet weight in gill tissue for 30 days exposure. As evidenced by the increasing values of BCF, pesticide uptake also showed increased trend with the increase in exposure time. A high correlation coefficient ranging between 0.7247 and 0.9616 between the pesticide concentration and exposure time was observed. Based on actual BCF values, log Kow were calculated and the values are well within the reported values of 6.5 indicating efficient relationship between BCF and log Kow because beyond the 6.5 the bioconcentration levels off.     

Effects of lead and cadmium exposure from electronic waste on child physical growth

Many studies indicate that lead (Pb) and cadmium (Cd) exposure may alter bone development through both direct and indirect mechanisms, increasing the risk of osteoporosis later in life. The aim of this study was to investigate the association between Pb and Cd exposure, physical growth, and bone and calcium metabolism in children of an electronic waste (e-waste) processing area. We recruited 246 children (3–8 years) in a kindergarten located in Guiyu, China. Blood lead levels (BLLs) and blood cadmium levels (BCLs) of recruited children were measured as biomarkers for exposure. Serum calcium, osteocalcin, bone alkaline phosphatase, and urinary deoxypyridinoline were used as biomarkers for bone and calcium metabolism. Physical indexes such as height, weight, and head and chest circumference were also measured. The mean values of BLLs and BCLs obtained were 7.30 μg/dL and 0.69 μg/L, respectively. The average of BCLs increased with age. In multiple linear regression analysis, BLLs were negatively correlated with both height and weight, and positively correlated with bone resorption biomarkers. Neither bone nor calcium metabolic biomarkers showed significant correlation with cadmium. Childhood lead exposure affected both physical development and increased bone resorption of children in Guiyu. Primitive e-waste recycling may threaten the health of children with elevated BLL which may eventually cause adult osteoporosis.     

Residues of p,p’-DDT and hexachlorobenzene in human milk from Indonesian women

Milk from Indonesian women (n = 4) was analysed for p,p’-DDT and the fungicide, hexachlorobenzene (HCB). p,p’-DDT was found in all of the samples and at levels that are amongst the highest reported anywhere in the world in 3 of the samples. HCB was found in all 4 samples, 1 sample had an exceptionally high level. The high residue of HCB suggested exposure by eating dressed grain, major environmental contamination or direct exposure when handling the fungicide. These are the first data on pesticide residues in milk from Indonesian women which demonstrate general exposure to p,p’-DDT and HCB.     

Pesticide risk assessment: A study on inhalation and dermal exposure to 2,4-D and paraquat among Malaysian paddy farmers

A cross-section analytical study was conducted to evaluate the risk of pesticide exposure to those applying the Class II pesticides 2,4-D and paraquat in the paddy-growing areas of Kerian, Perak, Malaysia. It investigated the influence of weather on exposure as well as documented health problems commonly related to pesticide exposure. Potential inhalation and dermal exposure for 140 paddy farmers (handlers of pesticides) were assessed. Results showed that while temperature and humidity affected exposure, windspeed had the strongest impact on pesticide exposure via inhalation. However, the degree of exposure to both herbicides via inhalation was below the permissible exposure limits set by United States National Institute of Occupational Safety and Health (NIOSH). Dermal Exposure Assessment Method (DREAM) readings showed that dermal exposure with manual spraying ranged from moderate to high. With motorized sprayers, however, the level of dermal exposure ranged from low to moderate. Dermal exposure was significantly negatively correlated with the usage of protective clothing. Various types of deleterious health effects were detected among users of manual knapsack sprayers. Long-term spraying activities were positively correlated with increasing levels of the gamma-glutamyl transpeptidase (GGT) liver enzyme. The type of spraying equipment, usage of proper protective clothing and adherence to correct spraying practices were found to be the most important factors influencing the degree of pesticide exposure among those applying pesticides.     

Mercury in dental amalgam: Are our health care workers at risk?

Dental amalgam in fillings exposes workers to mercury. The exposure to mercury was investigated among 1871 dental health care workers. The aim of the study was to evaluate the risk of mercury exposure among dental compared to nondental health care workers and to determine other risk factors for mercury exposure. Respondents answered questionnaires to obtain demographic, personal, professional, and workplace information and were examined for their own amalgam fillings. Chronic mercury exposure was assessed through urinary mercury levels. In total, 1409 dental and 462 nondental health care workers participated in the study. Median urine mercury levels for dental and nondental health care workers were 2.75 μg/L (interquartile range [IQR] = 3.0175) and 2.66 μg/L (IQR = 3.04) respectively. For mercury exposure, there were no significant risk factor found among the workers involved within the dental care. The Mann–Whitney test showed that urine mercury levels were significantly different between respondents who eat seafood more than 5 times per week compared to those who eat it less frequently or not at all (p = 0.003). The urinary mercury levels indicated significant difference between dental workers in their practice using squeeze cloths (Mann–Whitney test, p = 0.03). Multiple logistic regression showed that only the usage of cosmetic products that might contain mercury was found to be significantly associated with the urinary mercury levels (odds ratio [OR] = 15.237; CI: 3.612–64.276). Therefore, mean urinary mercury levels of health care workers were low. Exposure to dental amalgam is not associated with high mercury exposure. However, usage of cosmetic products containing mercury and high seafood consumption may lead to the increase of exposure to mercury.

Implications: Exposure to the high levels of mercury from dental amalgam can lead to serious health effects among the dental health care workers. Nationwide chronic mercury exposure among dental personnel was assessed through urinary mercury levels. Findings suggest low urinary mercury levels of these health care workers. Exposure to dental amalgam is not associated with high mercury exposure. However, the usage of cosmetic products containing mercury and high seafood consumption may lead to the increase of exposure to mercury.     

Organochlorine contaminants in hair of adolescents from Iassy, Romania

Human hair samples (n=42) from Iassy county (Eastern Romania) collected in 2002-2003 from adolescents were analyzed for hexachlorocyclohexane (HCH) isomers, p,p'-DDT and its metabolites, hexachlorobenzene (HCB), chlordane and metabolites and 5 polychlorinated biphenyl (PCB) congeners. Very low levels were found for HCB and oxychlordane (0.8 and 2.5 ng g(-1)) indicating a low usage of these pesticide formulations in the studied area. In case of HCHs, gamma-HCH isomer was measured at higher median concentrations (79 ng g(-1) hair) compared to the beta-HCH isomer (55 ng g(-1)), which generally is the most prevalent from HCHs. The DDTs profile consisted in p,p'-DDE and p,p'-DDT which levels correspond to 81% of sum DDTs. Very high median concentrations measured for p,p'-DDT (192 ng g(-1)) combined with lower values for p,p'-DDE/p,p'-DDT of 0.4 (from 0.20 to 2.0) in all hair samples suggest recent exposure to "fresh" DDT. When gender was considered, significantly higher concentrations for most of the investigated contaminants were found in girls hair compared to boys. Very high levels were found in the present study for HCHs and DDTs compared to samples from Greece, Western Europe and China. In case of PCBs, the levels found in Romanian samples were found to be in the same range compared to other previously published data.     

The sorptive capacity of an aquatic macrophyte for the pesticide aminocarb

Abstract

Ceratophyllum demersum exposed to a constant 1 μg/rnl aminocarb exhibited a large capacity for the sorption of the pesticide, up to 400 μg/g fresh weight in the dark and 1000 μg/g fresh weight in the light. Smaller, actively growing sprigs sorbed 5 times more pesticide per gm fresh weight than larger, older sprigs, although total uptake per plant was greater in the larger plants. Membrane conformation and integrity appear to be important factors in determining the capacity of this aquatic plant for pesticide sorption.     

The relationship of 3-PBA pyrethroids metabolite and male reproductive hormones among non-occupational exposure males

Many pesticides possess hormonal activities and have been classified as endocrine disrupting chemicals. Synthetic pyrethroids are one kind of the most common pesticides used in the world. In the present study, we explored the association between serum reproductive hormone levels and urinary creatine (CR) adjusted concentration of 3-phenoxybenzoic acid (3-PBA), a general metabolite of pyrethroids, in Chinese adult men. The study subjects (n=212) were from the affiliated hospitals of Nanjing Medical University. By using GC-MS, urinary 3-PBA level of each subject was measured and adjusted by urinary CR. Blood samples were collected for measuring the serum levels of reproductive hormones, including follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), testosterone (T) and prolactin (PRL). All the subjects had detectable levels of 3-PBA in their urine samples. The median concentration of 3-PBA was 0.815 microg g (-1)of CR. The results showed that there was positive associations between the levels of serum LH and 3-PBA (p=0.013) but negative associations between E2 and 3-PBA level (p=0.022), and the adjusting p-value was 0.044 for LH and E2, which suggested that pyrethroids are capable of disrupting the male endocrine function. In adult men, urinary 3-PBA levels were associated with increased LH and reduced E2 levels. On a population level, these reductions show potential public health importance because of widespread exposure to these pesticides.     

Evaluation of protective effects of sulforaphane on DNA damage caused by exposure to low levels of pesticide mixture using comet assay

The objective of the study was to evaluate the potential risk of DNA damage due to exposure to a mixture of the most widely used pesticides, namely endosulfan, chlorpyriphos and thiram at an environmentally relevant concentration (5 μM each) and the DNA protective capacity of sulforaphane (SFN) (10–30 μg/mL). DNA damage in human lymphocytes was ascertained with Single Cell Gel Electrophoresis (SCGE), also called Comet Assay. For positive control, H₂O₂ at 100 mM was used. The pesticide mixture produced DNA damage at the concentration used in the lymphocytes. SFN was able to offer a statistically significant (P < 0.01), concentration-dependant protection to DNA damage between 10–20 μg/mL in both the pre-incubation and co-incubation strategies. The results indicate that exposure to low levels of these pesticide mixtures can induce DNA damage, and the presence of SFN in diet may reduce the incidence of genetic damage, especially in farm workers. However, it is not clear whether SFN is involved in quenching of the free radicals generated by the pesticide mixture or it is involved in DNA repair mechanism.     

The current status of osteoporosis after 15 years of reduced cadmium exposure among residents living in cadmium-contaminated areas in northwestern Thailand

The purposes of this study were to determine the prevalence of osteoporosis after 15 years of reduced cadmium exposure and to determine the association between urinary cadmium (U-Cd) and osteoporosis. The study was conducted with 937 participants (109 males, 828 females) living in a cadmium-contaminated area in northwestern Thailand. All participants were required to respond to a questionnaire. Bone mineral density (BMD) was investigated by measurements taken at the calcaneus by dual-energy X-ray absorptiometry. U-Cd, which reflects the amount of cadmium contained in the body, was measured by atomic absorption spectrophotometry (AAS). The geometric mean of U-Cd was significantly higher in males than in females (p < 0.001). The mean level of BMD for females was found to be statistically significantly lower than that for males (p < 0.001). Increasing U-Cd levels were correlated with decreasing levels of BMD. The association between U-Cd and osteoporosis appeared to exist only at concentrations of U-Cd ≥ 10 μg/g creatinine (OR = 2.7, 95% CI = 1.2–5.9). It can be concluded that despite discontinued or reduced cadmium exposure for more than 10 years, the effect of cadmium toxicity on bone, which is stronger in women, continues, as cadmium, once absorbed, will accumulate in the human body for a long time due to its extremely long half-life.

     

Manganese concentrations in maternal–infant blood and birth weight

Manganese (Mn) is an essential mineral nutrient in mammals. The physiological role of Mn in animal models is well documented, but little is known about the adverse effects of Mn deficiency or overexposure in humans, including pregnancy outcomes such as birth weight. We examined the relationship of the maternal and cord blood Mn levels with birth weight in a cohort of 172 mother–infant pairs born in Shanghai, China. Non-linear spline and quadratic regression models were used to test the hypothesis of an inverted U-shaped association between the Mn levels and birth weight. The median (range) levels of Mn in the maternal and cord blood were 5.38 (2.34–30.37) μg/dL and 7.66 (2.57–34.23) μg/dL, respectively. An inverted U-shaped relationship was observed between maternal Mn and birth weight after adjusting for potential confounders. The birth weight increased with Mn levels up to 4.18 μg/dL, and a slight reduction in weight was observed at higher levels. The cord blood Mn levels were not found to be associated with birth weight. Both lower and higher Mn exposures are associated with lower birth weight, which may influence important developmental parameters; the association of higher Mn levels with lower weight was weak and imprecise.     

Risk for estrogen-dependent diseases in relation to phthalate exposure and polymorphisms of CYP17A1 and estrogen receptor genes

Evidence has shown that polymorphisms of various genes known to be involved in estrogen biosynthesis and function are associated with estrogen-dependent diseases (EDDs). These genes include CYP17A1, estrogen receptor 1 (ESR1), and 2 (ESR2). Phthalates are considered estrogenic endocrine disruptors, and recent research has suggested that they may act as a risk factor for EDDs. However, extremely few studies have assessed the effects of gene–environment interaction on these diseases. We recruited 44 patients with endometriosis or adenomyosis, 36 patients with leiomyoma, and 69 healthy controls from a medical center in Taiwan between 2005 and 2007. Urine samples were collected and analyzed for seven phthalate metabolites using liquid chromatography tandem mass spectrometry. Peripheral lymphocytes were used for DNA extraction to determine the genotype of CYP17A1, ESR1, and ESR2. Compared to controls, patients with leiomyoma had significantly higher levels of total urinary mono-ethylhexyl phthalate (ΣMEHP) (52.1 vs. 29.6 μg/g creatinine, p?=?0.040), mono-n-butyl phthalate (MnBP) (75.4 vs. 51.3 μg/g creatinine, p?=?0.019), and monoethyl phthalate (MEP) (103.7 vs. 59.3 μg/g creatinine, p?=?0.031). In contrast, patients with endometriosis or adenomyosis showed a marginally increased level of urinary MEHP only. Subjects who were homozygous for both the ESR1 C allele (rs2234693) and CYP17A1 C allele (rs743572) showed a significantly increased risk for leiomyoma (OR?=?19.8; 95 % CI, 1.70; 231.5; p?=?0.017) relative to subjects with other genotypes of ESR1 and CYP17A1. These results were obtained after adjusting for age, cigarette smoking, MEHP level, GSTM1 genotype and other covariates. Our results suggested that both CYP17A1 and ESR1 polymorphisms may modulate the effects of phthalate exposure on the development of leiomyoma.     

The association between maternal nonylphenol exposure and parity on neonatal birth weight: A cohort study in Taiwan

Background

The aim of this study was to explore the association between NP exposure and parity and their effect on neonatal birth weight.

Methods

A cohort of pregnant women was established in a medical center in North Taiwan. Urinary NP concentration was determined by high-performance liquid chromatography coupled with fluorescent detection and adjusted using creatinine. A multivariable regression model was fit to determine the association between the maternal NP level in each trimester and neonatal birth weight. The odds ratios (ORs) of infant birth weight below the 10th, 25th, and 50th percentiles, comparing pregnant women with the different NP exposure levels, was estimated using a logistic regression.

Results

Of the 162 pregnant women in the study, 99 were multiparas and 63 were primiparas. After adjusting for other covariates, the NP level in the second trimester had a significant association with birth weight in the primiparas (β = −182.49 g, p value = 0.02). The OR of low infant birth weight, comparing pregnant women with different NP levels, was increased by decreasing the cutoff percentile for birth weight (OR = 1.18 for the 50th percentile, 2.12 for the 25th percentile, and 7.81 for the 10th percentile). The odds of primiparas with high NP level having a low neonatal birth weight increased to 3.87, 11.77, and 9.40 for the three different percentiles (p value < 0.05).

Conclusion

Maternal NP exposure level is associated with an increased risk of low neonatal weight. Primiparas are especially at risk, and the second trimester of pregnancy may be the critical stage of exposure.     

Biological monitoring of chlorpyrifos exposure to rice farmers in Vietnam

Chlorpyrifos is the most common organophosphate insecticide registered for use in Vietnam and is widely used in agriculture, particularly rice farming. However, chlorpyrifos exposure to and adverse effects on farmers has not been evaluated. In this study, biological monitoring of chlorpyrifos exposure in a group of rice farmers was conducted after a typical application event using back-pack spraying.Urine samples (24 h) were collected from the rice farmers before and post insecticide application. Samples were analysed for 3,5,6-trichloropyridinol (TCP), the major urinary metabolite of chlorpyrifos, using an enzymatic pre-treatment before extraction followed by HPLC-MS/MS. Absorbed Daily Dose (ADD) of chlorpyrifos for farmers were then estimated from urinary TCP levels, expressed as μg g⁻¹ creatinine. The analytical method for urinary TCP had a low detection limit (0.6 μg L⁻¹), acceptable recovery values (80-114%), and low relative percentage differences in duplicate and repeated samples.Post-application chlorpyrifos ADD of farmers varied from 0.4 to 94.2 μg kg⁻¹ (body weight) d⁻¹ with a mean of 19.4 μg kg⁻¹ d⁻¹ which was approximately 80-fold higher than the mean baseline exposure level (0.24 μg kg⁻¹ d⁻¹). Hazard Quotients (ratio of the mean ADD for rice farmers to acute oral reference dose) calculated using acute oral reference doses recommended by United States and Australian agencies varied from 2.1 (Australian NRA), 4.2 (US EPA) to 6.9 (ATSDR).Biological monitoring using HPLC-MS/MS analysis of urinary TCP (24 h) was found to be an effective method for measuring chlorpyrifos exposure among farmers. This case study found that Vietnamese rice farmers had relatively high exposures to chlorpyrifos after application, which were likely to have adverse health effects.     

Exposure to low doses of endosulfan and chlorpyrifos modifies endogenous antioxidants in tissues of rats

Two experiments were conducted in male SD rats (225-250 g) to determine changes in the activities of endogenous antioxidants superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and concentrations of glutathione (GSH) in tissues after exposure to low doses of endosulfan and chlorpyrifos using a whole body exposure technique. In both experiments, 6 rats/group were exposed 3 hr/day, 5 days/week for 30 days to: 0 (control), 5, 10, 20, 40 and 60% of LD50 of either pesticide in 50% ethanol; actual concentrations were: endosulfan = 0, 0.5, 1.0, 2.0, 4.0, 6.0 mg/250 g body weight; chlorpyrifos = 0, 1.9, 3.8, 7.6, 15.2, and 22.8 mg/250 g body weight. Endosulfan decreased erythrocyte SOD by 21% in all groups and chlorpyrifos increased SOD by 18% in groups 40 and 60. Liver SOD was 12%-20% lower after endosulfan exposure; lung SOD was altered: endosulfan decreased activity by 21% and 51% and chlorpyrifos by 58 and 75% in the 40 and 60 groups, respectively (P < or = 0.05). Both pesticides increased plasma GPX activity at lower levels and reduced it by 26% and 19% in groups 40 and 60, respectively (P < or = 0.05). Liver GPX increased in the 60 group and lung GPX declined between 20% and 38% after endosulfan exposure. GSH in the liver and lung: endosulfan reduced GSH by about 30% at lower levels and increased by 41% or 70% at higher levels; chlorpyrifos decreased GSH by 28-40% in 20 and 60 groups, respectively (P < or = 0.05). Exposure to low, increasing levels of endosulfan and chlorpyrifos can differentially modify endogenous antioxidants SOD, GPX and GSH, which may lead to the development of oxidative stress in some tissues.     

Urinary biomarkers and low-level environmental benzene concentration: assessing occupational and general exposure

The categories of urban workers undergoing prolonged exposure to gasoline due to vehicle emissions, evaporation and traffic fumes are considered occupationally exposed to benzene, even if at low concentrations. The aim of this study was to evaluate the specificity of unmetabolized benzene excreted in urine (UBz) and S-phenylmercapturic acid (SPMA) as biomarkers of exposure to very low levels of benzene, and to study the impact of putative individual confounders like smoking and alcohol habits, co-exposure to other toxicants and body mass index on the exposure assessment. Environmental and biological monitoring of exposure to benzene were performed in 114 Urban Policemen. The mean value of UBz in non-smokers was significantly lower than in either groups of light to moderate smokers and heavy smokers (0.24, 1.82 and 2.82 microg L(-1), respectively). On the contrary, SPMA values did not discriminate exposure resulting from smoking habits. Moreover, the concentration of UBz in non-smokers appears to be correlated with environmental benzene concentration (BenzA) (R(2)=0.13, beta=0.37, p=0.002). On the other hand, no significant correlation was found between SPMA concentration (corrected for creatinine excretion and log transformed, LogSPMA) and LogBenzA (R(2)=0.003, beta=0.05, p=0.6). Our findings reinforce previous research on the use of unmetabolized urinary benzene as a specific and sensitive biomarker of low-level exposure to benzene and confirm that smoking habits strongly influence the excretion of UBz.     

Organochlorine contaminants in complete clutches of Morelet's crocodile (Crocodylus moreletii) eggs from Belize

Seven complete clutches of Morelet's crocodile (Crocodylus moreletii) eggs were collected in northern Belize and examined for organochlorine (OC) pesticide residues. The primary OC detected, p,p-DDE, was found in every egg analyzed (n=175). Other OCs detected included p,p-DDT, p,p-DDD, methoxychlor, aldrin, and endosulfan I. Concentrations of individual OCs ranged from 4 ppb (ng chemical/g egg wet weight) to greater than 500 ppb. A statistical evaluation of p,p-DDE levels in three complete clutches was used to derive the minimum number of eggs needed from a clutch to precisely determine the mean p,p-DDE concentration representative of that clutch. Sample sizes of 8 (80% confidence level) and 11 (90% confidence level) were determined to yield an accurate estimate of contaminant levels in a full clutch of eggs. The statistically recommended sample size of 11 eggs (at 90% confidence level) was successfully tested on the four additional clutches.     

Increased urinary 8-hydroxy-2��-deoxyguanosine levels in workers exposed to di-(2-ethylhexyl) phthalate in a waste plastic recycling site in China

Background

Di-(2-ethylhexyl) phthalate (DEHP) is a common plasticizer used in industrial and diverse consumer products. Animal studies indicate DEHP caused developmental, reproductive, and hepatic toxicities. However, human studies of the potential effects of DEHP are limited.

Methods

The exposed site with a history of over 20 years of waste plastic recycling was located in Hunan Province, China. The reference site without known DEHP pollution source was about 50 km far away from the exposed site. In this study, 181 workers working in plastic waste recycling and 160 gender?Cage matched farmers were recruited. DEHP concentrations in water and cultivated soil samples, serum thyroid-stimulating hormone, malondialdehyde (MDA), superoxide dismutase (SOD), urinary 8-hydroxy-2??-deoxyguanosine (8-OHdG), and micronuclei frequency in human capillary blood lymphocytes were analyzed.

Results

Mean levels of DEHP were greater in environment at the recycling site than at reference site (industry wastewater for the exposed: 42.43 ??g/l; well water: 14.20 vs. 0.79 ??g/l, pond water: 135.68 vs. 0.37 ??g/l, cultivated soil: 13.07 vs. 0.81 mg/kg, p?p?p?Conclusions The occupational DEHP exposure might contribute to oxidative deoxyribonucleic acid damage in the male workers.