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Background Exposure to endocrine-disrupting chemicals, such as persistent organochlorine pesticides, has been suggested to increase the risk of testicular germ cell tumors (TGCTs). Methods To study the relationship of POP exposure to TGCT risk, prediagnostic serum samples from 754 case subjects and 928 control subjects enrolled in the Servicemen's Testicular Tumor Environmental and Endocrine Determinants Study were analyzed for cis-nonachlor, trans-nonachlor, oxychlordane, total chlordanes, [beta]-hexachlorocyclohexane, mirex, p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), and p,p'-dichlorodiphenyltrichloroethane. Adjusted odds ratios (ORs) and their associated 95% confidence intervals (Cls) for the risk of TGCT overall and for the histological subgroups, seminoma and nonseminoma, were estimated using multivariable logistic regression. All statistical tests were two-sided. Results TGCT risk was statistically significantly associated with higher plasma levels of p,p'-DDE (for highest quartile [Q4] vs lowest quartile [Q1], OR = 1.71, 95% CI = 1.23 to 2.38, [P.sub. trend] = .0002) and of twO chlordane components, cis-nonachlor (Q4 vs Q1, OR = 1.56, 95% CI = 1.11 to 2.18, [P.trend = .009) and trans-nonachlor (Q4 vs Q1, OR = 1.46, 95% CI = 1.07 to 2.00, [P.sub.trend] = .026). Seminoma risk was statistically significantly associated with p,p'-DDE (Q4 vs Q1, OR = 1.91, 95% CI = 1.22 to 2.99, [P.sub. trend] = .0008), cis-nonachlor (Q4 vs Q1, OR = 1.93, 95% CI = 1.27 to 2.93, [P.sub. trend] = .0045), trans-nonachlor (Q4 vs Q1, OR = 1.72, 95% CI = 1.11 to 2.67, [P.sub. trend] = .033), and a chlordane metabolite, oxychlordane (Q4 vs Q1, OR = 1.64, 95% CI = 1.04 to 2.60, Ptrend = .048), whereas nonseminoma risk showed a statistically significant association with p,p'-DDE only (Q4 vs Q1, OR = 1.63, 95% CI = 1.10 to 2.42, [P.sub. trend] = .0044). Conclusions Increased exposure to p,p'-DDE may be associated with the risk of both seminomatous and nonseminomatous TGCTs, whereas exposure to chlordane compounds and metabolites may be associated with the risk of seminoma. Because evidence suggests that TGCT is initiated in very early life, it is possible that exposure to these persistent organic pesticides during fetal life or via breast feeding may increase the risk of TGCT in young men.

Background: 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) exposure has been demonstrated to cause liver tumors in laboratory rodents. DDT's persistent metabolite and environmental degradation product, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), has also been associated with liver tumors in laboratory animals. Whether DDT and DDE are associated with hepatocarcinogenesis in humans is not clear. Methods: We carried out a nested case-control study among the participants of the Nutritional Intervention Trials in Linxian, China. The case group included 168 individuals who developed liver cancer during the trials, and the control group included 385 individuals frequency-matched on age and sex who were alive and well at the end of the study. Serum concentrations of DDT and DDE were measured by gas chromatography--mass spectrometry. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using multivariable analysis. Results: In multivariable-adjusted models, the risk of developing liver cancer increased with increased serum DDT concentration (OR for quintile 1 versus quintile 5 = 3.8, 95% CI = 1.7 to 8.6, [P.sub.trend] = .0024). In contrast, there was no statistically significant association between liver cancer and serum DDE concentration. The association between high serum DDT concentration and liver cancer was stronger among individuals with DDE concentrations below the median value (odds ratio for tertile 3 versus tertile 1 = 3.55, 95% CI = 1.45 to 8.74) than those with concentrations above the median (OR = 1.70, 95% CI = 0.97 to 2.98). A calculation of crude liver cancer risk found that there would be 26 liver cancers per 100000 persons per year in the lowest quintile of DDT exposure versus 46 liver cancers per 100000 persons per year in the highest quintile of DDT exposure. Conclusions: DDT may be a risk factor for liver cancer, particularly among persons with lower DDE concentrations. Risk may be particularly increased among persons exposed directly to DDT (resulting in a higher ratio of DDT to DDE) or, alternatively, risk may be associated with individual ability to metabolize DDT to DDE.

Mercury is used widely for gold extraction in French Guiana and throughout the entire Amazon basin. To evaluate contamination among the general population, the authors chose individuals who attended 13 health centers and maternity hospitals dispersed geographically across the territory and served Guiana's different populations. Five hundred individuals (109 pregnant women, 255 'other' adults, and 136 children) who received care at one of the centers were selected randomly for this study. Each individual answered a questionnaire and provided a hair sample. The authors determined mercury in hair with atomic absorption spectrometry. The following mean levels of mercury were observed: 1.6 [micro]g/g (95% confidence interval [CI] = 1.3, 1.9) among pregnant women; 3.4 [micro]/g (95% CI = 3.0, 3.9) among other adults; and 2.5 [micro]/g (95% CI = 2.1, 3.0) among children. Diet factors contributed the most to mercury levels, especially consumption of freshwater fish (mean = 6.7 [micro]/g for individuals who ate fish more than 5 times/wk) and livers from game. Other factors, including age, dental amalgams, use of skin-lightening cosmetics, and residence near a gold-mining community, did not contribute significantly to mercury levels. Overall, 12% of the samples contained mercury levels in excess of 10 [micro]/g, but in some Amerindian communities up to 79% of the children had hair mercury levels that exceeded 10 [micro]/g. The results of this study indicated that (a) diet played a predominant role in total mercury burden, and (b) in some communities, mercury contamination exceeded safe levels., PRODUCTION of gold in French Guiana started in the 1850s. Production decreased after World War II, but recently gold-mining activities have increased. Over time, an estimated 200 tons of gold [...]

The authors conducted a survey during 1992 to evaluate blood levels of lead and mercury in Inuit adults of Nunavik (Arctic Quebec, Canada). Blood samples obtained from 492 participants (209 males and 283 females; mean age = 35 yr) were analyzed for lead and total mercury; mean (geometric) concentrations were 0.42 [micro]mol/l (range = 0.04-2.28 [micro]mol/l) and 79.6 nmol/l (range = 4-560 nmol/l), respectively. Concentrations of omega-3 fatty acid in plasma phospholipids--a biomarker of marine food consumption--were correlated with mercury (r = .56, p [is less than] .001) and, to a lesser extent, with blood lead levels (r = .31, p [is less than] .001). Analyses of variance further revealed that smoking, age, and consumption of waterfowl were associated with lead concentrations ([r.sup.2] = .30, p [is less than] .001), whereas age and consumption of seal and beluga whale were related to total mercury levels ([r.sup.2] = .30, p [is less than] .001). A significant proportion of reproductive-age women had lead and mercury concentrations that exceeded those that have been reportedly associated with subtle neurodevelopmental deficits in other populations., MERCURY AND LEAD are widespread environmental contaminants that originate from both anthropogenic (e.g., mining, smelting, fossil fuel burning, waste incineration) and natural (e.g., local geology, volcanoes, degassing in aquatic environments) [...]

The authors evaluated lead exposure of Canadians (Montreal) who fished the nearby St. Lawrence River. From screening interviews conducted with 1,118 fishers on-site during the winter and fall of 1996, the authors selected 60 Montrealers who consumed at least one sportfish meal per week and 72 who consumed less than one sportfIsh meal per week. Fishers at the higher level of sportfish consumption had elevated blood lead concentrations, compared with fishers who ate little sportfish (geometric mean = 57.4 [micro]g/l vs. 48.2 [micro]g/l, respectively; p [is less than] .05). This result was surprising inasmuch as fish is not considered a significant source of lead. In addition to sportfish consumption, age, sex, occupation, smoking, and waterfowl consumption also showed independent associations with blood lead levels. Among frequent (i.e., [is greater than or equal to] 1 meal/wk) consumers of sportfish, ingestion of waterfowl was associated with higher blood lead levels (geometric mean = 69.4 [micro]g/l vs. 51.8 [micro]g/l, respectively; p [is less than] .05); this association was not present for infrequent consumers. In multivariate analysis, the association of higher blood lead levels with sportfish consumption could be accounted for in large part by waterfowl consumption among frequent consumers of sportfish., ALTHOUGH FRESHWATER FISH contains little lead, tests of consumers of Great Lakes sportfish have shown higher than expected levels of blood lead.[1,2] In a recent study of contaminant exposure among [...]

Abstract: Quality specifications (QS) are proposed for lead in blood and for aluminium, copper, selenium and zinc in serum as part of the aim to set standards of performance for laboratories so that results can be demonstrated to be fit for the purpose to which they are applied. The QS were established taking account of the analytical state-of-the-art, physiological variations in the concentrations of the analyte and the clinical purpose for which the assay is to be used. A procedure was devised that uses these QS to give equivalence of assessment among external quality assessment schemes (EQAS), thus avoiding conflicting information which has been demonstrated in the past. Advantages of this procedure are: to provide direct comparison of performance of laboratories taking part in different schemes, to provide equivalence of assessment of laboratory performance necessary to establish mutual recognition agreements, and to demonstrate the fitness for purpose of results from participants.

Abstract: Most people in any community come into contact with chemicals that are potentially harmful to their health. Some elements are essential to health and inadequate amounts in food may also lead to ill health. Measurement of chemicals in blood, urine or other specimens is a fundamental feature of studies undertaken in the field of Occupational and Environmental Laboratory Medicine (OELM). Results are used to assess the risk for either overexposure or deficiency of essential nutrients. External Quality Assessment Schemes (EQAS) aid laboratories to achieve accurate and consistent data and 11 organisers of EQAS in Europe and North America are working to improve the effectiveness of their activities. The aims of the Network of EQAS Organisers in OELM are to stimulate improvements in analytical results, establish equivalence of assessment among Schemes, collaborate to enhance the practice of EQA including whenever possible to warrant traceability of EQAS to primary standards.

Abandoned radar line stations in the North American arctic and sub-arctic regions are point sources of contamination, especially for PCBs. Few data exist with respect to human body burden of organochlorines OCs in residents of communities located in close proximity to these radar line sites. We compared plasma OC concentration unadjusted for total lipids frequency distribution data using log-linear contingency modelling for Fort Albany First Nation, the site of an abandoned Mid-Canada Radar Line station, and two comparison populations the neighbouring community of Kashechewan First Nation without such a radar installation, and Hamilton, a city in southern Ontario, Canada. This type of analysis is important as it allows for an initial investigation of contaminant data without imputing any values. The two-state log-linear model employing both non-detectable and detectable concentration frequencies and applicable to PCB congeners 28 and 105 and cis-nonachlor and the four-state log-linear model using quartile concentration frequencies for Aroclor 1260, PCB congeners 99,118,138,153,156,170,180,183,187, β-HCH, p,p′-DDT p,p′-DDE, HCB, mirex, oxychlordane, and trans-nonachlor revealed that the effects of subject gender were inconsequential. Significant differences p< 0.05 between the groups examined were attributable to the effect of location on the frequency of detection of OCs or on their differential distribution among the concentration quartiles. In general, people from Hamilton had higher frequencies of non-detections and of concentrations in the first quartile p< 0.05 for most OCs compared to people from Fort Albany and Kashechewan who consume a traditional diet of wild meats that does not include marine mammals. An unexpected finding was that, for Kashechewan males, the frequency of many OCs was significantly higher p< 0.05 in the 4th concentration quartile than that predicted by the four-state log-linear model, but significantly lower than expected in the 1st quartile for β-HCH. The levels of PCBs found for women in Fort Albany and Kashechewan were greater than those reported for Dene First Nation people and Métis mixed heritage of the western Northwest Territories NWT who did not consume marine mammals, and for Inuit living in the central NWT occasional consumers of marine mammals. Moreover, the levels of total p,p′-DDT were greater for Fort Albany and Kashechewan women compared to these same aboriginal groups.

Fishing and fish consumption are widely practiced among members of certain ethnocultural groups. Informal assessment led us to ascribe high levels of consumption of locally caught sportfish to Montrealers of Asian origin and to hypothesize that their choices of species and fish organs differ from those of the majority group. An exploratory assessment of contaminant bioindicators reflective of St. Lawrence River fish consumption was conducted in late 1995 among nine Vietnamese and nine Bangladeshi Montreal sportfishers identified by community contacts. Vietnamese participants, six men and three women, were 27–70 (median 36) years of age and had immigrated to Canada 3–20 (median 7) years earlier. In contrast, the nine Bangladeshi males aged 28–41 (median 34) years had been in Canada for 2–13 (median 4) years. Bio-indicator concentrations among Bangladeshi and Vietnamese participants are compared to those found for majority-community Montreal-area high-level consumers recruited on the St. Lawrence River during winter 1995. All results are presented as the median and 90th percentile. Hair mercury concentrations were higher for both Vietnamese (1.2, 4.6 μg/g) and Bangladeshis (1.1, 2.3 μg/g) than for majority-community sportfishers (0.7, 1.9 μg/g). Certain organochlorine levels, specifically total PCB (estimated by plasma Aroclor 1260),p,p′-DDT,p,p′-DDE, andB-BHC, were highest in the Bangladeshis compared to Vietnamese and to majority-community sportfishers. In contrast, plasma levels of other pesticides were low in all three groups, including mirex, chlordane, andcis-nonachlor. A correlation between plasmap,p′-DDT levels and recency of arrival in Canada was found for the Bangladeshis. These data suggest a distinct pattern of tissue organochlorines, which we postulate relates to exposure prior to arrival in Canada and perhaps to the ongoing consumption of foods (other than St. Lawrence River sportfish) specific to these groups.

A 1995 pilot study assessed sport fish consumption and contaminant exposure among Montreal-area residents fishing the frozen St. Lawrence River. Interviews conducted among 223 ice fishers met on-site were used to create an index of estimated exposure to fish-borne contaminants. A second-stage assessment of sport fish consumption and tissue contaminant burdens included 25 interviewees at the highest level of estimated contaminant exposure (of 38, or 66% of those solicited) and 15 low-exposure fishers (of 41, or 37% of those solicited). High-level fisher–consumers reported eating 0.92±0.99 sport fish meals/week during the previous 3 weeks compared to 0.38±0.21 (P<0.05) for the low-level group. Based on the product of consumption frequency times mass of sport fish meals consumed, high-level consumers ate a mean of 18.3 kg of sport fish annually versus 3.3 kg for the low-level consumers. Tissue contaminant assessments showed significant (P<0.05) groupwise differences: 0–1 cm hair mercury (median 0.73 μg/g for the high versus 0.23 μg/g for the low group), lipid-adjusted plasma PCB congeners (Aroclor 1260: median 0.77 μg/g versus 0.47μg/g), and lipid-adjusted plasma DDE (median 0.35 μg/g versus 0.26 μg/g). No participant had a hair mercury or plasma DDE concentration above Health Canada recommendations but 2/25 high-level participants (8%) had plasma Aroclor 1260 concentrations above recommended limits. The results of this pilot study suggest that a small number of Montreal-area sportfishers consume their catch as often as three times weekly and that those consuming sport fish frequently have significantly higher tissue levels of mercury, PCBs, and DDE than do infrequent consumers. On the other hand, compared to other groups in Quebec, such as the Inuit or commercial fishers on the North Shore of the Gulf of St. Lawrence, Montreal-area sportfishers eat less fish and have lower tissue concentrations of fish-related contaminants.

PCB,p,p′-DDE, and mirex levels were examined in blood plasma samples of 232 anglers from Cornwall and Mississauga, Ontario, in a pilot study to establish the feasibility and suitability of using a cohort of Ontario fish license holders for large-scale health studies. Great Lakes fish, waterfowl, and ocean fish consumption were examined as predictors of contaminant levels using regression analysis, with adjustment for age, gender, and community. Levels of Great Lakes fish and waterfowl consumption and contaminant levels were generally low in comparison with those observed in other Great Lakes studies. However, even within these low levels, Great Lakes fish consumption was associated with increased blood plasma PCB levels in men and mirex levels in both men and women. Waterfowl consumption was associated with higher plasma PCB (men and women), DDE (men only), and mirex levels (men and Cornwall women), and requires further exploration. We conclude that other study designs are required (to identify high consumers) for carrying out studies of health effects associated with high levels of Great Lakes fish and waterfowl consumption.

From the clinical chemist's point of view, environmental toxicology can be defined as the identification or quantitation or both of environmental toxicants, their metabolites, and the biochemical consequences in easily accessible human specimens. Requirements as to specificity, accuracy, precision, and sensitivity will vary depending on the purpose of the analysis (e.g., diagnosis of acute intoxication vs. population baseline study). Laboratories must therefore clearly indicate the scope of their analytic methods. To ensure consistency of results, quality guidelines, such as International Standards Organization (ISO) guide 25, should be adhered to. However, to demonstrate accuracy, external proficiency assessment is required. Interlaboratory comparison programs, by using representative reference material, can document laboratory performance over time. Examples taken from the Quebec Toxicology Centre's program for toxic metals in biologic fluids indicate that laboratory performance has improved in recent years. The quality of results is generally adequate for most applications of environmental toxicology measurements.