### Page 1 of 76 

# APPENDIX B

### Page 2 of 76 TABLE OF CONTENTS

APPENDIX B.1: MEMORANDUM IN SUPPOR T OF 2003 EPA IRED S UMMARIZING EPA’S SYN THESIS OF ATRAZINE
CANCER EPIDEMIOLOGY DATA (OCTOBER 2003)

................................ ................................ ................................ ............ 3

APPENDIX B.2: LITERATURE REVIEW ME THODOLOGY: ATRAZINE CANCER EPIDEMIOLOGY EVALUATION

................... 17

APPENDIX B

- 3: REVIEW OF ATRAZIN E CANCER EPIDEMIOLOG Y STUDIES PUBLISHED PRIOR TO 2003 AND PR EVIOUSLY
REVIEWED BY EPA

................................ ................................ ................................ ................................ ........................ 18

APPENDIX B.4: REVIEW OF AGRICULTURAL HEAL TH STUDY (AHS) NESTE D CASE

- CONTROL ANALYSES

......................... 41

APPENDIX B.5: REVIEW OF ATRAZINE CANCER E PIDEMIOLOGY STUDIES PUBLISHED SINCE 2003

................................ . 48

### Page 3 of 76 APPENDIX B.1: MEMO RANDUM IN SUPPORT OF 2003 EPA IRED SUMMAR IZING EPA’S SYNTHESIS OF A TRAZINE CANCER EPIDE MIOLOGY DATA (OCTOBE R 2003)

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES

October 28, 2003

MEMORANDUM

SUBJECT: Review of Atrazine Cancer Epidemiology DP Barcode D295200, Chemical #080803

FROM: Jerome Blondell, Ph.D., Health Statistician Chemistry and Exposure Branch Health Effects Division (7509C)

Vicki Dellarco, Ph.D., Senior Science Advisor Health Effects Division (7509C)

THRU: Francis B. Suhre, Chief Chemistry and Exposure Branch Health Effects Division (7509C)

Margaret Stasikowski, Director Health Effects Division (7509C)

TO: Eric Olson, Ph.D., PM Team Reviewer Michael Goodis, Product Manager Special Review and Reregistration Division (7508C)

This review summarizes scientific studies related to atrazine and cancer epidemiology including a consideration of animal mode of action related to selected cancers. The review starts with an examination of animal mode of action issues related to prostat e and ovarian cancers and non

Hodgkin’s lymphoma. This section is followed by a review of EPA findings concerning prostate cancer in a manufacturing plant, the Agricultural Health Study, and two California studies. The following section addresses the evi dence concerning non

- Hodgkin’s lymphoma and then, other cancers. The review concludes with a summary of three published reviews of atrazine and cancer

### Page 4 of 76 epidemiology published 1996

- 1999, followed by a listing of those studies published since 1999 and consid ering their impact on the weight

- of

- evidence. In order to be comprehensive all known epidemiologic studies of atrazine and triazines have been included. The U.S. Environmental Protection Agency (EPA) requested a review of atrazine and prostate cancer by the Scientific Advisory Panel (SAP) made up of outside experts. A report of the SAP findings (meeting minutes) from the July 17, 2003 meeting can be found at http://www.epa.gov/scipoly/sap/. This review considers the SAP findings and, where appropriate, revises the Agency’s findings related to atrazine and prostate cancer. This review also explains why studies of other cancers where not presented to the Panel at the July 2003 meeting. To assist the reader, an outline of this review is provided below:

I. Examination of prostate and ovarian cancers and NHL in the context of the animal mode of action II. Atrazine and prostate cancer e pidemiology A. Prostate Cancer

- Manufacturing plant study B. Prostate Cancer

- Agricultural Health Study in Iowa and North Carolina C. Prostate Cancer

- Pesticide use data and cancer incidence in California counties D. Prostate Cancer

- Overall conclu sion III. Atrazine and epidemiology of Non

- Hodgkin’s Lymphoma IV. Atrazine and epidemiology related to other cancers V. Results of other reviews of cancer and atrazine through 1999 VI. Studies published since 1999 or not included in the three publis hed reviews VII. EPA Conclusion: Atrazine exposure and NHL and other cancers

I. Examination of prostate and ovarian cancers and NHL in the context of the animal mode of action

As discussed in the January 31, 2003 Interim Reregistration Eligibility Decision, atrazine’s mode of action (i.e., a decrease LH surge, failed ovulation and estrous cycle disruption) for induction of mammary gland tumors (the only tumor observed in animal bioassays) in SD female rats is not considered relevant to humans. Beca use the epidemiology literature on atrazine (triazines) report that atrazine exposure may be associated with an increased incidence of prostate and ovarian cancers and NHL, the available chronic toxicity animal bioassays were closely examined for any indic ation of either prostate, ovarian cancer or NHL, as well as the etiology of these tumor types.

The prostate glands in male laboratory animals do not appear to be a target of atrazine toxicity. Subchronic and chronic rodent and dog studies and the multigeneration rat studies conducted for atrazine and its major metabolites have not demonstrated trea tment related tumors or prostatitis and only shown inconsistent changes in prostates weights. The SD and Fisher rats and CD

- 1 mice are poor models for evaluating prostate cancer. Atrazine has been shown to result in prostatic inflammation of the adult ra t offspring (Stoker et al., 1999) but this is not due to direct treatment of the offspring, but rather treatment of the dams. In this case, atrazine leads to a decrease in early lactational exposure to prolactin (via treatment of the mothers). Alteration s in neonatal prolactin regulation lead to hyperprolactemia, which in turns lead to the prostatic inflammation found in the adult offspring. This work supports the neuroendocrine mode of action for atrazine rather than a mode of action that would explain prostate cancer in adult male workers. Although the etiology of prostate cancer is not clearly understood, the hormonal changes caused by atrazine would be in the opposite direction (i.e., decreased prolactin) of what would be expected for the development of prostate cancer. Furthermore, it has not been clearly established that prostatitis increases the risk to prostate cancer. Therefore, the animal data do not support a mechanism for atrazine contributing to the onset or promotion of prostate cancer in humans.

### Page 5 of 76 5

Ovarian tumors in most laboratory animals are a rare occurrence (Damjanov, 1989). A dose

related increase in ovarian tumor incidence is not seen in any study using atrazine, simazine or propazine, and in all studies, the incidences of ovarian t umors are (as would be expected) very low. Although the causes of ovarian cancer are not definitively known, the key events in the mode of action established for atrazine, i.e., decreased serum LH levels and a decreased number of ovulations over a lifetim e, are the opposite of the events hypothesized to be associated with ovarian carcinogenesis. Some hypotheses have been advanced for ovarian carcinogenesis with the predominant hypotheses being the "incessant ovulation" hypothesis and the "gonadotropin" hy pothesis (e.g., Fathalla, 1971). This hypothesis suggests that damage to the ovarian epithelium, resulting from frequent ovulations, leads to increased risk of cancer as this leads to increased epithelial cell proliferation. It should be noted that epide miology studies show that factors which decrease the number of lifetime ovulations

- such as pregnancy, breast

feeding and oral contraceptive use

- reduce ovarian cancer risk (Berchuck and Carney, 1997). Therefore, animal data do not support a biologicall y plausible mechanism for atrazine contributing to ovarian cancer in humans.

There was not an increase in any dose group for a lymphoma of any type, including non

Hodgkin’s lymphomas (NHL) in atrazine treated SD or F344 rats. The simazine chronic bioassa y using both sexes of SD rat also failed to see any lymphomas in any animal in any dose group (McCormick, 1988). Likewise, no animal in either of the two groups examined (control and high dose tested

- 1000 ppm) in the propazine chronic bioassay, had a ly mphoma of any type (Jessup, 1980). The alterations in reproductive hormones that atrazine exposure is associated with have not been linked to an increased risk of NHL. NHLs are a broad group of neoplasias which originate from lymphoid tissues such as B

- c ells, T

- cells and histiocytes, though the vast majority are B

- cell in origin. The etiology of NHLs are unclear. Generally speaking, increased risk of developing NHL appears to be associated with conditions or xenobiotic exposures that result in immune dy sfunction (Scherr and Mueller, 1996). An association between NHL and reproductive hormones such as LH, FSH, estrogens and prolactin, does not appear to be present. A mechanistic role for atrazine contributing to NHL has not been identified in laboratory studies.

In summary, multiple animal bioassays do not reveal an increased incidence of tumors at any endocrine site other than mammary gland in female SD rats. Other endocrine tumors that have been raised in epidemiological studies can not be bi ologically tied to atrazine’s mode of action (i.e., decrease prolactin, decrease LH and suppression of ovulation). Thus, at this time, based on the available animal cancer and mode of action data and epidemiological studies, there is no tumor endpoint on which to base a cancer risk assessment for atrazine. EPA has considered other possible modes of action (e.g., stimulation of aromatase activity) and finds that there are inadequate data to support these hypotheses. EPA’s Office of Research and Developmen t National Health and Environmental Effects Laboratory is currently conducting a detailed investigation of the effects of atrazine and related chlorotriazines on aromatase activity and steroidogenesis in an effort to determine whether or not these compound s can change estrone, estradiol and testostosterone synthesis in response to atrazine treatment in rats. As additional data become available, EPA will review them.

Berchuck A, Carney M. Human ovarian cancer of the surface epithelium. Biochem Pharmacol

. 1997 Sep 1;54(5):541_4.

### Page 6 of 76 6

Bosland MC. Male reproductive system. In Carcinogenesis. Eds., MP Waalkes, JM Ward. New Your: Raven Press, Ltd., 1994, pp. 339

- 402.

Damjanov I., Ovarian tumours in laboratory and domestic animals. Curr Top Pathol. 1989;78:1_10.

Fathalla MF. Incessant ovulation__a factor in ovarian neoplasia? Lancet. 1971 Jul 17;2(7716):163.

Jessup, D. 1980. Two year oral chronic toxicity study in rats. IRDC study no. 382

- 007. MRID 00041408; Acc. No. 219502401.

McCormick, C.C . and Arthur, A.T. Simazine

- Technical: 104

- Week Oral Chronic Toxicity and Carcinogenicity Study in Rats. 1988. Study Number: 2

- 0011

- 09. MRID number: 406144

- 05. Pharmaceuticals Division, Ciba

- Geigy Corp., Summit, NJ.

Scherr PA and Mueller NE, Non

- Ho dgkin’s lymphomas, in Eds D. Schottenfeld and JF Fraumeni Jr.. Cancer Epidemiology and Prevention New York, Oxford University Press, 1996, pgs. 920

- 945.

Stoker, T.E., Robbinette, C.L., Cooper, R.L. 2000.Maternal exposure to atrazine during lactation suppresses suckling_induced prolactin release and results in prostatitis in the adult offspring. Toxicol Sci. 1999 Nov;52(1):68_79.

II. Atrazine and prostate cancer epidemiology

The following review addresses epidemiology related to prostate cancer, non

- Hodgkin’s lymphoma, other cancers and includes a brief summary of earlier reviews and the most recently submitted studies related to atrazine and triazines.

A. Prostate Cancer

- Manufacturing plant study

An epidemiology study was c onducted of workers at the Syngenta St. Gabriel plant where atrazine is manufactured. That study reported a statistically significant increase in the incidence of prostate cancer among plant workers. The Agency, upon review of this study, requested addit ional information on the exposure profile of the employees diagnosed with prostate cancer and this information was provided and reviewed. To further analyze the question of exposure a nested

case

- control study was proposed by Syngenta and conducted for th em by Health Practice Exponent Inc. (Hessel et al. 2003). Preliminary results of this study, a review by the Agency, comments from four external peer reviewers, a Syngenta

- sponsored expert panel review, and comments by the Natural Resources Defense Counci l were provided to the EPA’s Scientific Advisory Panel in July of 2003. EPA’s view of the study was that the increase in prostate cancer

### Page 7 of 76 observed in the St. Gabriel workers was probably due to the increase in PSA screening for these workers.

The Panel wa s requested to comment on the Agency’s conclusion regarding prostate cancer and particularly the results from this study. The specific Agency conclusion that EPA asked the SAP to comment on was: “Due to the lack of a detailed exposure analysis based on jo b history and the limited statistical power due to the small sample size, atrazine could not be ruled out as a potential cause but a role for atrazine seems unlikely.”

The Panel’s analysis of the St. Gabriel study differed to a degree from the Agency’s c onclusion. The SAP did conclude that “the increase in Prostate Specific Antigen (PSA) screening at the St. Gabriel plant likely led to an increase in the detection of cases of prostate cancer.” Further, the Panel noted that “[s]ubstantive and persuasive ar guments have been made to support the EPA’s conclusion that PSA screening could explain the observed increase in prostate cancer incidence in the workers.” Nonetheless, the Panel did not believe there was sufficient evidence to conclude that it was “unlik ely” that atrazine had a role in the increased prostate cancer cases “given the severe limitations of the St. Gabriel study, particularly those pertaining to small sample size, questionable exposure assessment and lack of an appropriate comparison group.” According to the SAP, PSA screening may be only a “partial explanation” for the increase in prostate cancer and that “atrazine cannot be ruled out as a potential cause.”

The Agency agrees with the SAP’s analysis and has rewritten its co nclusion as follows:

The increase in prostate cancer incidence at the St. Gabriel plant in Louisiana is consistent with the intensive PSA screening. This is because prostate cancer was found primarily in active employees who received intensive prostate s pecific antigen (PSA) screening, there was no increase in advanced tumors or mortality, and proximity to atrazine manufacturing did not appear to be correlated with risk. No evidence was identified that permit a determination that some of the increase wa s likely due to exposure to atrazine although atrazine exposure cannot be ruled out at this time. However, the study was insufficiently large and suffered from other limitations that prevent a determination that all of the increase in prostate cancer was probably due to the intensive screening program.

One of EPA’s external reviewers agreed with this finding regarding the role of PSA screening. Dr. Edward Giovannucci of the Harvard School of Public Health stated, “Thus, the increased excess of prostate c ancer observed in the Novartis study is compatible with increases expected in a population that is receiving intensive PSA screening.” Another reviewer, Dr. Aaron Blair of the National Cancer Institute, though not in full agreement with Dr. Giovannucci, agreed that there was evidence to “suggest that PSA screening may well explain the excess incidence of prostate cancer in this cohort.”

The Scientific Advisory Panel suggested that the Agency consider additional analysis of the St. Gabriel cohort. However, the resulting sample size would still limit the opportunity to draw further conclusions. The Agency questions whether additional anal ysis is warranted for other potential risk factors (such as smoking, diet and previous work history, and non

- occupational or pre

- employment exposure to triazine herbicides). Because of the way the study was designed

### Page 8 of 76 this information is not available to inv estigators and it may not be feasible to obtain such information. The same applies to the suggested analysis of family history, history of prostate disease, (e.g., benign prostatic hypertrophy and prostatitis), and additional biologic samples that allow D NA extraction. The St. Gabriel study was a study based on available records and it might be difficult or impossible for investigators to obtain permission from all or most subjects or next

- of

- kin to get the additional information outlined by the SAP. The SAP repeatedly acknowledges “The St. Gabriel cohort study suffered from several limitations that could lead to negative findings in epidemiologic studies of similar design, particularly with regard to the very small sample size” which can greatly hinder t he statistical power to detect an effect.

In October, 2003, Syngenta provided a completed report on the nested case

- control study (cases and controls selected from within the cohort) by Health Practice Exponent Inc. that examined in more detail t he exposure of 12 of 17 prostate cancer cases and examined the effect of screening on prostate cancer incidence (Hessel et al. 2003). EPA has not yet reviewed this study in depth, but a preliminary reading did not find any evidence that prostate cancers

c ould be attributed to atrazine exposure. Statistical analysis suggest that PSA screening would explain some or all of the elevated rates of prostate cancer. The study authors concluded “There is no evidence for an association between atrazine exposure an d prostate cancer among the workers at the Syngenta plant in St. Gabriel. The increased incidence of prostate cancer observed in the previous study could be explained by the PSA screening program.”

B. Prostate Cancer

- Agricultural Health Study in Iowa and North Carolina

Tied into the assessment of atrazine and prostate cancer is the recently published study Alavanja et al. (2003). This large prospective cohort study of 55,332 male pesticide applicators, known as the Agricultural Health Study, reporte d on the risk of prostate cancer and computed odds ratios for individual pesticides within the cohort. For atrazine the reported odds ratio (ratio of odds in favor of disease among exposed to the odds of disease among the unexposed, an odds ratio of 1.0 i mplies no increased risk from exposure) was 0.94 for ever/never use reported by questionnaire with a 95% confidence interval of 0.78 to 1.14. The Agricultural Health Study has a number of advantages over other epidemiologic studies of pesticides. It is t he largest study of its kind, determines exposure prior to disease (thus, eliminating recall bias), analyzes a wide variety of potential and known confounders including other pesticide exposures, and has greater statistical power to detect small effects.

The Scientific Advisory Panel expressed concern that the use of ever/never use atrazine was “likely an inappropriate exposure metric” and that other factors such as measures of continuous or intermittent use should be considered. The Panel appeared to p lace little weight on the dose

response analysis based on cumulative exposure which combined duration, frequency, and intensity into one metric that did not show any association between atrazine and prostate cancer. The Agency agrees that other exposure m etrics might be considered but disagrees that ever/never use and cumulative exposure is an inappropriate measure. Available pesticide usage data suggest that the pattern of use of atrazine as a preharvest herbicide limits variability in duration, frequenc y, and intensity of use and the dose

- response analysis is a sufficient measure to account for this source of variation.

The Scientific Advisory Panel expressed concern that this study had a short follow

- up period “with exposure information collected at t he start of follow

- up” and incorrectly stated this was less

### Page 9 of 76 than five years. Because study subjects were queried about past as well as present use of atrazine, the follow

- up period was much longer than five years. The National Cancer Institute is plannin g to redo the prostate cancer study with a much larger cohort next year when the sample size will be approximately twice as large. However, given the relatively tight confidence interval on the current estimate and the lack of any evidence of dose

- respons e, the Agency does not expect the new study to produce results different from those already reported. Nevertheless, the Agency will revisit and revise these conclusions if the updated prostate cancer study produces different results suggesting a risk from exposure to atrazine.

C. Prostate Cancer

- Pesticide use data and cancer incidence in California counties

Two studies were conducted in California which has maintained a population

- based cancer registry since 1988 and a state

- wide pesticide use reporting system. Mills (1998) obtained 1993 pesticide usage data for six pesticides with a suspicion of carcinogenicity based on other toxicologic and epidemiologic studies. These data were compared using regression analysis with county age

- and ra ce

- adjusted cancer incidence rates (1988

- 92). A borderline statistically significant correlation was found between atrazine usage and prostate cancer in black males, but not among Hispanic, White, or Asian males. This study is subject to aggregation bia s because the exposure of individuals in the county was not measured. EPA considers such studies useful for guiding future studies, but not for reaching conclusions about causation.

A second study by Mills and Yang (2003) examined the effect of simazine rather than atrazine on prostate cancer among members of the United Farm Workers of America. The study found a borderline significant association between high simazine use and prostate cancer. Like the earlier Mills (1998) study, this study suffers from aggregation bias and a crude measure of exposure (total poundage of active ingredient by crop and county for a given time period) which may not reflect exposure among farmworkers, 90% of whom are not actively involved in applying or handling pesticides (1 999

- 2002 data from presentation on National Agricultural Workers Survey by S. Gabbard, J. Nakamoto, and D. Carroll, September 24, 2003, funded by the Department of Labor). The use of total poundage of active ingredient by county was not normalized by numb er of workers and is especially problematic because it correlates with the size of the crop and acreage in the county and many other factors which might have little to do with exposure of farmworkers. For example, a county with double the poundage would b e counted as having double exposure, even if it also had double the number of farmworkers and their exposure was the same in both counties.

D. Prostate Cancer

- Overall conclusion

Studies of manufacturing and farming populations do not support a findin g that atrazine is a likely cause of prostate cancer. The Scientific Advisory Panel stated that neither the Syngenta St. Gabriel Plant study or the Agricultural Health Study were “sufficient for EPA to conclude that there is no causal association between atrazine exposure and prostate cancer.” However, the Agency does not find any results among these studies that would lead us to conclude that potential cancer risk is likely from exposure to atrazine.

III. Atrazine and epidemiology of non

- Hodgkin’s lymphoma

### Page 10 of 76 The National Cancer Institute has performed a number of studies of non

- Hodgkin’s lymphoma (NHL) in farming populations. The key findings related to atrazine are noted below.

A study by Schroeder et al. 2001 examined two subtypes of NHL for association with pesticide exposure based on earlier data from Iowa and Minnesota. The negative NHL subtype was significantly associated with 5 pesticides. For atrazine, the odds ratio was borderline significant (Odds ratio = 1.7 with 95% confidence interval 1.0

- 2.8). The Schroeder study cautiously stated “In conclusion, we found weak to relatively strong associations between many agricultural exposures and t(14;18)

- positive, but not t(14;18)

- negative NHL.” and “Causal relationships . . . are plausib le, but associations should be confirmed in a larger study.”

The study by Schroeder et al. (2001) contrasted with an earlier study by Zahm et al. (1993) conducted in these same two states plus Kansas and Nebraska which concluded, “In our judgment, these data provide little evidence that atrazine is associated with NHL among white men.”

Added to these two conflicting studies is a study by DeRoos et al. (2003) published electronically in September 2003. EPA has not had time to review this study in dept h, but did not find evidence sufficient to implicate atrazine as a likely cause of NHL. This study stated that “Reported use of several individual pesticides was associated with increased NHL incidence” but that “limitations of our data hinder the infere nces we can make regarding specific pesticides”. The hierarchical regression odds ratio (odds ratio adjusted for the effect of exposure to other pesticides) for atrazine was 1.5 (95% CI = 1.0 to 2.2) which, like the study by Schroeder et al (2001), has bo rderline significance. Studies with borderline significance increase the likelihood that chance or some confounder may be an explanation for the observed findings. The authors caution that “some of the positive results could be due to chance” though adju stment for the influence of other pesticides in the analysis makes this somewhat less likely.

Given the conflicting results and the extreme caution exhibited by the National Cancer Institute (NCI) in making its conclusion regarding specific pesticides, the EPA has concluded that evidence is not sufficient to implicate atrazine as a likely cause of non

- Hodgkin’s lymphoma. Nevertheless, EPA will consider these studies in conjunction with other evidence and may request additional external review. An exhau stive and thorough analysis of non

- Hodgkin’s lymphoma and pesticide use is planned by NCI for 2004

- 5. This analysis will include consideration of NHL subtypes and many other factors as well. Absent compelling information in the interim, EPA has determine d that a thorough review of atrazine and NHL should be conducted when the NCI data are available.

IV. Atrazine and epidemiology related to other cancers

Other cancers besides prostate and non

- Hodgkin’s lymphoma were found to have an elevated

, though not statistically significant, increase in risk at the St. Gabriel plant (Delzell et al. 2001). Other studies have suggested an increased risk for ovarian, breast, and other cancers. However, these studies are at best preliminary and should not serve as a basis for implicating atrazine as a human carcinogen due to their methodological limitations and the absence of replication in other populations. The National Cancer Institute is planning a review of atrazine and all types of cancers in 2004. Given the much larger sample size and strengths of this

### Page 11 of 76 Agricultural Health Study, the Agency has decided further review of other cancers and atrazine should take place when results from this planned analysis are available. However, if other studies or ad ditional compelling evidence becomes available in the interim, the Agency will expeditiously review the new evidence and the potential risk resulting from exposure to atrazine. A summary of evidence from previous reviews of atrazine and cancer epidemiolog y, and studies published subsequently, are reviewed in the following section

V. Results of other reviews of cancer and atrazine through 1999

Three reviews of triazines including atrazine and cancer epidemiology have been reported in the 1996

- 1999 time period:

IARC. 1999. IARC Monographs on the evaluation of carcinogenic risks to humans. Volume 73: Some chemicals that cause tumours of the kidney or urinary bladder in rodents and some other substances. World Health Organization, Lyon, France.

Neuberger JS. 1996. Atrazine and/or triazine herbicides exposure and cancer: an epidemiologic review. Journal of Agromedicine 3(2):9

- 30.

Sathiakumar N, Delzell E. 1997. A review of epidemiologic studies of triazine herbicides and

cancer. Critical Rev iews in Toxicology 27:599

- 613.

These three reviews identified the 10 case

- control studies (see numbered references at the end of this review, 1

- 10) and two published cohort studies of workers exposed to triazines at manufacturing plants (11

- 12).

Neuberg er (1996) concluded “based on the data to date . . . there is no convincing evidence of a causal association between atrazine and/or triazine(s) and colon cancer, soft tissue sarcoma, Hodgkin’s disease, multiple myeloma, or leukemia. . . .There is a sugges tion of a possible association between atrazine and/or triazine(s) with ovarian cancer and non

- Hodgkin’s lymphoma. However, the ovarian cancer study needs to be replicated and the NHL studies fall short of providing conclusive evidence of risk because the results could be due to chance, bias, or confounding.”

Sathiakumar and Delzell (1997) concluded “The available epidemiologic studies, singly and collectively, do not provide any consistent, convincing evidence of a causal relationship between exposure to triazine herbicides and cancer in humans.”

The International Agency for Research on Cancer (1999) summarized the human carcinogenicity data as follows:

A combined analysis of results of two cohort studies of agricultural chemical production wor kers in the United States showed decreased mortality from cancers at all sites combined among the subset of workers who had had definite or probable exposures to triazine. Site

- specific analyses in this subset of workers yielded no significant findings; a non

- significant increase in

### Page 12 of 76 the number of deaths from non

- Hodgkin’s lymphoma was seen, but was based on very few observed cases.

A pooled analysis of the results of three population

- based case

- control studies of men in Kansas, eastern Nebraska and Iowa

- M innesota, United States, in which the risk for non

Hodgkin’s lymphoma in relation to exposure to atrazine and other herbicides on farms was evaluated, showed a significant association; however, the association was weaker when adjustment was made for report ed use of phenoxyacetic acid herbicides or organophosphate insecticides. A sub

- analysis of results for farmers in Nebraska, the State in which the most detailed information on atrazine use was available, showed no excess risk for non

- Hodgkin’s lymphoma am ong farmers who had used atrazine for at least 15 years, after adjustment for use of other pesticides. In a case

- control study of non

- Hodgkin’s lymphoma among women in eastern Nebraska, a slight, nonsignificant increase in risk was seen. In all these stu dies, the farmers tended to have an increased risk for non

- Hodgkin’s lymphoma, but the excess could not be attributed to atrazine.

Less information was available to evaluate the assoication between exposure to atrazine and other cancers of the lymphatic a nd haematopoietic tissues. One study of Hodgkin disease in Kansas, one study of leukaemia in Iowa

- Minnesota and one study of multiple myeloma from Iowa gave no indication of excess risk among persons handling triazine herbicides.

In a population

- based st udy in Italy, definite exposure to triazines was associated with a two

- to threefold increase of borderline significance in the risk for ovarian cancer. The study was small, and potential confounding by exposure to other herbicides was not controlled in t he analysis.

Based on these findings the IARC concluded “There is inadequate evidence in humans for the carcinogenicity of atrazine.” In a critique of IARC monographs, Huff (2002) questioned the decision on atrazine and animal carcinogenicity and based this partly on the Delzell et al. (2001) report showing increased risk for prostate cancer and above expected levels for certain cancers including buccal cavity (3 observed, 2.1 expected), esophagus (2 observed, 0.7 expected), stomach (2 observed , 0.9 expected), bladder (3 observed, 1.6 expected), thyroid (2 observed, 0.6 expected) and leukemia/lymphomas (7 observed, 4.5 expected). These data are based on Table 7 of the Syngenta report by Delzell et al. (2001). This table shows 9 different estim ates of risk, not counting prostate (already discussed) and certain grouped categories. Therefore, 6 of 9 categories exhibited an excess, though statistically insignificant risk. Chance alone is a possible explanation for such findings. In addition, bia s and confounding could produce such results. Therefore, these elevated, nonsignficant incidence ratios must be considered preliminary findings. Until these findings are replicated in other studies that address the serious methodological limitations (esp ecially the low statistical power) of the present study, they should be regarded as spurious or suggestive at best. Therefore, the EPA disagrees with Huff (2002) that the epidemiology studies provide support for a revision of the IARC classification for

a trazine.

Independent of these three reviews, EPA has performed internal reviews of all of the above studies which had statistically significant findings relevant to atrazine or triazines including additional updates to the manufacturing plant studies subm itted to EPA but not published. With the exception of the possible association with ovarian cancer, which EPA reviewers stated needed to be confirmed in other populations, the Agency did not find convincing evidence of an association between triazines or atrazine and cancer.

### Page 13 of 76 Huff J. 2002. IARC monographs, industry influence, and upgrading, downgrading, and under_grading chemicals: a personal point of view. International Agency for Research on Cancer. Int J Occup Environ Health . 8(3):249

- 70.

VI. Stud ies published since 1999 or not included in the three published reviews

The following six studies were reviewed by EPA and submitted to the Scientific Advisory Panel for review in July 2003.

Alavanja MCR, Samanic C, Dosemeci M, et al. 2003. Use of agricu ltural pesticides and prostate cancer risk in the Agricultural Health Study cohort. Am J Epidemiol 157:800

- 814.

Delzell E, et al. 2001. Cancer Incidence Among Workers in Triazine

- related Operations at the Novartis St. Gabriel Plant” Oct. 12, 2001. MRID # 451521

- 01 and 455184

- 01, Chemical #080803. [Technical Report 170 pp.]

MacLennan PA, Delzell E, Sathiakumar N, et al. 2002. Cancer incidence among triazine herbicide manufacturing workers. J Occup Environ Med. 44:1048

- 1058.

MacLennan PA, Delzell E, Sa thiakumar N, et al. 2003. Mortality among triazine herbicide manufacturing workers. J Toxicol Environ Health A 66(6):501

- 517.

Mills PK. 1998. Correlation analysis of pesticide use data and cancer incidence rates in California counties. Arch Environ Hea lth . 53:410

- 3.

Mills PK, Yang R. Prostate cancer risk in California farm workers. 2003. J Occup Environ Med

. 45:249

- 258. Results from the Alavanja (2003), Delzell (2001), Mills (1998), and Mills and Yang (2003) have already been discussed abov e. The two reports by MacLennan et al. are updates to the two earlier reports by Sathiakumar (1992, 1995). Most of the results in these two studies are covered in much more detail by Delzell et al. (2001) which has already been discussed above in the sec tions on prostate cancer and other cancers. The mortality study (MacLennan et al. 2003) did find a borderline significant result for non

- Hodgkin’s lymphoma based on 4 observed deaths versus 1.1 deaths expected. The authors noted, however, that “one of th e decedents whose death certificate included a diagnosis of NHL had medical records, including a biopsy report that indicated a diagnosis of poorly differentiated nasopharyngeal cancer. This case was not removed from our analysis. To have done so would h ave introduced a bias because there is no satisfactory procedure for removing similarly misclassified cases from the numerator of general population mortality rates used to calculate the expected number of deaths. Our data were not of adequate statistical precision to demonstrate trends in NHL rates or SMRs by years worked and years since hire.” This acknowledgment of bias based on a misclassified case means that borderline statistically significant finding would no longer be significant if the case

were excluded. As stated above, this evidence is not sufficient to support a finding that atrazine is a likely cause of non

- Hodgkin’s lymphoma.

The following six studies, including two published since July 2003 meeting were not submitted to the Scientific Adv isory Panel.

### Page 14 of 76 De Roos AJ, Zahm SH, Cantor KP, Weisenburger DD, Holmes FF, Burmeister LF, Blair A. 2003. Integrative assessment of multiple pesticides as risk factors for non

- Hodgkin’s lymphoma among men. Occup Environ Med 60:e11.(http://www.occenvmed.com/cgi/content/full/60/9/e11)

Hessel PA, Kalmes R, Smith TJ, Lau E, Mink P, Mandel J. 2003. A Nested Case

- Control Study of Prostate Cancer and Atrazine Exposure. Final Report, October 3, 2003 performed by Health Practice E xponent, Inc. and submitted by Syngenta Crop Protection, Inc.

Hopenhayn

- Rich C, Stump ML, Browning SR. 2002. Regional assessment of atrazine exposure and incidence of breast and ovarian cancers in Kentucky. Arch Environ Contam Toxicol 42:127

- 136.

Kettl es MA, Browning SR, Prince TS, Horstman SW. 1997. Triazine herbicide exposure and breast cancer incidence: an ecologic study of Kentucky counties. Environmental Health Perspectives 105:1222

- 1227.

Schroeder JC, Olshan AF, Baric R, et al. 2001. Agricult ural risk factors for t(14;18) subtypes of

non

- Hodgkin's lymphoma. Epidemiology 12:701

- 709.

Van Leeuwen JA, Waltner

- Toews D, Abernathy T, et al. 1999. Associations between stomach cancer incidence and drinking water contamination with atrazine and nitrate in Ontario (Canada) agroecosystems, 1987

- 1991. Int J Epidemiol. 28:836

- 40. DeRoos et al. (2003), Hessel et al. (2003), Schroeder et al. (2001) have already been discussed above. Hessel et al. (2003) is discussed at the end of the section on “Prostate Cancer

- Manufacturing Plant Study”. DeRoos et al. (2003) and Schroeder et al. (2001) are discussed in the section on non

- Hodgkin’s lymphoma.

The other three studies by Hopenhayn

- Rich et al. (2002), Kettles et al. (1997), and Van Leeuwen et al. (1999) are ecological studies where the unit of analysis are populations or groups of people rather than individuals. An earlier study by Kettles et al (1997) suggested an association between triazine exposure and breast cancer in Kentucky. However, a later follow

up study by Hopenhayn

- Rich et al. (2002) did not support this finding for Kentucky and instead found results suggesting a protective effect for atrazine for ovarian cancer and no effect on breast cancer. The Hopenhayn

- Rich et al. study was based on 5 year, age

- adjusted cancer rates which are likely to be more stable than the two year r ates used by Kettles et al. A study by Van Leeuwen et al. (1999) found a positive association between atrazine water contamination levels and stomach cancer among 40 ecodistricts in Ontario, Canada, and a negative association with colon cancer suggesting a protective effect for atrazine. The authors “noted that

so

- called ‘ecologic studies’, the type of analysis conducted in this research, have a number of weaknesses, including ecologic fallacy and multiple collinearity.” Stomach cancer has been declining for many years and is likely associated with a number of dietary and lifestyle factors, not controlled for in the Van Leewen et al. (1999) study (Cancer Rates and Risks, 4 th edition, National Cancer Institute 1996). All of these studies are subject to ag gregation bias because the actual exposures of individuals in the county/district or how long they resided there is not known. As noted in standard epidemiology texts, ecologic studies “can suggest avenues of research that may be promising . . . In and of themselves, however, they do not demonstrate that a causal association exists” (Gordis L. Epidemiology. W.B. Saunders Company, Philadelphia, 1996). The authors themselves warn “conclusions concerning causality cannot be drawn” (Kettles et al. 1997). An ecologic study in Kentucky of similar design to those above,

### Page 15 of 76 found a whole host of factors that vary across an urban

- rural gradient (Blondell JM. Urban

- rural factors affecting cancer mortality in Kentucky, 1950

- 1969. Cancer Detection and Prevention 11:2 09

- 223, 1988). Persons living in rural areas differ not only in terms of pesticide exposures, but also diet, parity, physical activity, exposure to viruses, and other lifestyle factors. Appropriate controls are critical when studying the relationship bet ween pesticide exposure and

cancer.

VII. EPA Conclusion: Atrazine exposure and NHL and other cancers

The Agency does not find any results among the available studies that would lead us to conclude that potential cancer risk is likely from exposure to a trazine. EPA plans to revisit this conclusion upon receipt of new studies, especially those from NCI’s Agricultural Health Study on atrazine and all cancers, prostate cancer, and non

- Hodgkin’s lymphoma, all of which are planned for completion in the next 1

- 2 years.

### Page 16 of 76 Numbered references

1. Brown LM, Blair A, Gibson R, et al. 1990. Pesticide exposures and other agricultural risk factors for leukemia among men in Iowa and Minnesota. Cancer Research 50:6585

- 6591.

2. Brown LM, Burmeister LF Everett GD, et al. 1993. Pesticide exposures and multiple myeloma in Iowa men. Cancer Causes Control 4:153

- 156.

3. Burmeister LF. 1990. Cancer in Iowa farmers: recent results. Am J Ind Med 18:295

- 301.

4. Cantor KP, Blair A, Everett G, et al. 1992. Pesticides and other agricultural risk factors for

non

- Hodgkin’s lymphoma among men in Iowa and Minnesota. Cancer Research 52:2447

- 2455.

5. Donna A, Crosignani P, Robutti F, et al. 1989. Triazine herbicides and ovarian epith elial neoplasms. Scan J Work Environ Health 15:47

- 53.

6. Hoar SK, Blair A, Holmes FF, et al. 1986. Agricultural herbicide use and risk of lymphoma and soft

- tissue sarcoma. JAMA. 256:1141

- 7.

7. Hoar SK, Blair A, Holmes FF, et al. 1985. Herbicides and col on cancer. Lancet

. 1(8440):1277

- 8.

8. Hoar

- Zahm S, Weisenburger DD, Babbitt PA, et al. 1988. Case

- control study of non

Hodgkin’s lymphoma and agricultural factors in eastern Nebraska (abstract). Am J Epidemiol 128:901.

9. Zahm SH, Wisenburger DD, Canto r KP, et al. 1993a. Role of the herbicide atrazine in the development of non

- Hodgkin’s lymphoma. Scan J Work Environ Health 19:108

- 114.

10. Zahm SH, Weisenburger DD, Saal RC, et al. 1993b. The role of agricultural pesticide use in the development of n on

- Hodgkin's lymphoma in women. Arch Environ Health . 48(5):353

- 358.

11. Sathiakumar N, Delzell E, Austin H, Cole P. 1992. A follow

- up study of agricultural chemical production workers. American Journal of Industrial Medicine 21:320

- 330.

12. Sathiakuma r N, Delzell E, Cole P. 1995. Mortality among workers at two triazine manufacturing plants. American Journal of Industrial Medicine 29:143

- 151.

cc: atrazine file (080803) 

### Catherine Eiden (7509C)

### Page 17 of 76 APPENDIX B.2: LITERATURE REVIEW ME THODOLOGY: ATRAZINE CANCER EPIDEMIOLOGY EVALUAT ION

To identify the epidemiological investigations of the association between atrazine exposure and adverse health effects (both cancer and non

- cancer), we queried PubMed/Medline and the Institute of Scientific Information’s We b of Science. We also performed limited searches using Google.Scholar. Querying these three search engines is considered a comprehensive way to identify relevant articles (Falagas, 2008). A forth biomedical/scientific search engine Scopus is not available to EPA scientists at this time. PubMed is the most commonly used biomedical search engine used by researchers today, however Web of Science offers similar journal coverage in addition to citation mapping capabilities. We performed citation mapping using We b of Science, examining other articles which referenced the articles included in the literature review, to identify additional relevant research articles.

We generated the following search strings. Emphasis was placed upon identification of all possible epidemiological studies available, and the ability to use the identical search string in both PubMed/Medline and Web of Science. Regarding Google.Scholar, we attempted use of similar search strings as well as the advanced search capabilities available [htt p://scholar.google.com/advanced_scholar_search?hl=en&as_sdt=20000].

The search strings are found below:

PubMed : (atrazine[tw] OR (triazine*[tw] AND (pesticide*[tw] OR herbicide*[tw]))) AND (epidemiolog*[tw] OR cohort*[tw] OR case

- control*[tw] OR cluster* [tw] OR environmental exposure*[tw] OR occupational exposure*[tw] OR ecologic stud*[tw] OR aggregate stud*[tw])

Web of Science

After elimination of duplicates with identical citations between the two search engines, we initially identified 386 articles of potential interest. Upon review of the titles, we determined that 135 were investigations of human healt h effects, in contrast to environmental science or biology research papers. Of these 135, we eliminated an additional 46 studies that reported on exposure assessment methodology only; these are not further evaluated in the chapter. We then performed an abs tract review of the remaining 89 papers and eliminated an additional 22 that were review articles or editorial or other opinion narratives published in the open literature. Therefore, there were 67 epidemiological investigations of the cancer and non

- cance r health effects of atrazine. : atrazine OR (triazine* AND (pesticide* OR herbicide*))) AND (epidemiolog* OR cohort* OR (case

- control OR case

- control's OR case

- controled OR

case - controlled OR case

- controlling OR case

- controls) OR cluster* OR "environmental exposure" OR "environmental exposures" OR "occupational exposure" OR "occupational exposures" OR "ecologic study" OR "ecologic studies" OR "aggregate study" OR "aggregate studies")

In the review reflected herein (the July 2011 FIFRA SAP), we are only considering the cancer related epidemiology studies. EPA repeated the literature search using similar methodology

### Page 18 of 76 through April 2011 to assure that all rel evant atrazine cancer studies are included in the current cancer epidemiology evaluation. There were 38 cancer epidemiology studies included in our full

- text review of the epidemiology literature based upon this literature search. Through reference review, EPA identified three additional studies, however these were ultimately excluded because the three studies measured simazine, and not atrazine or triazine exposure, in association with cancers (breast and gastric cancers measured) that also used an aggrega te exposure assessment method (P. K. Mills & Yang, 2007; Reyn olds et al., 2004; Reynolds et al., 2005) . One additional study from the Agricultural Health Study (AHS) published subsequent to April 2011 was also included (Beane

- Freeman et al. 2011), and one study was added based upon reference list review (Ruder et al. 2004). The list below delineates the articles included in our full

- text review:



### APPENDIX B

- 3: REVIEW OF ATRAZIN E CANCER EPIDEMIOLOG Y STUD IES PUBLISHED PRIOR TO 2 003 AND PREVIOUSLY R EVIEWED BY EPA

Table B

- 3a: Summary of Epidemiology Studies

Study Health Outcome Study Design Study Population Exposure Relevant Association Hoar, Holmes Boysen **et al.** (1985) Colon Cancer Retrospective, Case

- Control Cases: Cancer patients diagnoses in Kansas during 1976

- 82 Controls: Individuals recruited by random digit dialing from Medicare and State mortality files Self

- Reported Pesticide Use 1.4 (0.2

– 7.9) Triazine OR (95%CI):

Hoar, Blair, Holmes, et al. (1986) Lymphoma, Soft

- Tissue Sarcoma Retrospective Case

- Control Cases : White, male cancer patients diagnoses in Kansas during 1976

- 82 Controls : Frequency

matched controls recruited by random digit dialing from Medicare and St ate mortality files Self

- Reported Pesticide Use, Telephone Interview (1982

- 1984) STS: null, not shown Triazine OR (95% CI):

Hodgkin’s Disease: null, not shown NHL: 2.5 (1.2, 5.4) NHL (never use phenoxy herbicide): 2.2 (0.4, 9.1)

Brown, Blair, and Gibson **et al.**  (1990) Leukemia Retrospective Case

- Control Cases: Male cases identified through Iowa Tumor Registry and Minnesota surveillance of hospital/labs Controls: Frequency

matched sample of

men In

- Person Interview

– Self

Reported Pesticide Use Triazine OR (95% CI) 1.1 (0.8

- 1.5) :

### Page 19 of 76 Study Health Outcome Study Design Study Population Exposure Relevant Association Brown, Burmeister, Everett, and Blair (1993) Multiple Myeloma Retrospective Case

- Control Cases : Male cases identified through Iowa Tumor Registry Controls : Frequency

matched sample of men general population In

- Person Interview

- Self

reported Pesticide Use 0.80 (0.40

- 1.6) Atrazine OR 95% CI):

Cantor, Blair, Everett **et al.** (1992) Non

- Hodgkin’s Lymphoma Retrospective, Case

- Control Cases: Male cases identi fied through Iowa Tumor Registry and Minnesota surveillance of hospital/labs Controls: Frequency

matched sample of

men In

- Person Interview

– Self

Reported Pesticide Use Triazine OR (95% CI) 1.1 (0.8

- 1.6) :

Zahm, Weisenburger, Cantor **et al.** (1993) Non

- Hodgkin’s Lymphoma Retrospective, Pooled Case

Control Cases: White males ascertained from registries/surveillance programs in Nebraska, Iowa

Minnesota, and Kansas Controls: Individuals randomly selected from the same geographic location as cases and frequency matched by race, gender, age group, and vital status In

- Person Interview

– Self

Reported Pesticide Use Unadjusted Pooled Atrazine OR (95% CI):

1.4 (1.1

– 1.8) Adjusted for OP pesticides 1.2 (0.9

– 1.7)

Zahm and Babbit (1993) Non

- Hodgkin’s Lymphoma Retrospective, Case

- Control Cases: Women, aged 21 years or older, who were from eastern Nebraska and were diagnosed during July 1 1983 and June 30, 1986 Controls: Individuals recruited using random digit dialing and 3:1 frequency matched by race, sex, vital status, and age Telephone Interview

– Self

Reported Pesticide Use 1.2 (0.6

– 2.6) Triazine Class OR (95% CI):

Clavel, Hemon, and Mandereau **et al.**  (1996) Hair y

- cell Leukemia Retrospective, Case

- Control Cases: Male cases identified through 18 French hospitals Controls: Hospital matched men that were primarily admitted to orthopedic and rheumatology departments In

- Person Interview

– Self

Reported Pesticide Use Triazine ORs(95% CI) “Possible of Definite” :

1.9 (1.0

- 3.5) “Definite” 2.4 (1.2

- 4.8)

### Page 20 of 76 Study Health Outcome Study Design Study Population Exposure Relevant Association Donna, Crosignani, Robutti **et al.** (1989) Ovarian Epithelial Neoplasms Retrospective, Case

- Control Cases: Female cases ascertained from Alessandria Hospital Cancer Register Controls: Age

matched females, randomly selected from electoral rolls of municipalities in the study area Self

- Reported Pesticide Use Triazine ORs (90% CI) “Definite” :

2.7 (1.0

- 6.9) “Po ssibly” 1.8 (0.9

- 3.5)

Kettles, Browning, and Prince **et al.** (1997) Breast Cancer Ecologic Individuals living in Kentucky during 1991

- 1994 Exposure indices based on trizaine ground and drinking water levels, corn acreage, and atrazine sales 1.07 (1.01

- 1.14) High Exposed Category OR (95% CI)

1.2 (1.13

- 1.28)

Hopenhayn

Rich, Stump, and Browning (2002) Breast and ovarian cancer Ecologic Individuals living in Kentucky during 1993

- 1997 Aggregate exposure indices based on atrazine drinking water levels, corn acreage, and atrazine sales Null association reported

Sathiakumar , Delzell , and Cole (1996) Mortality Retrospective, pooled cohort Employees from two atrazine production plants located in Alabama and Louisiana Exposure classifications based on job title and function “Definite of probable” Overall SMR (95% CI)

87 (75

– 99) “Possible” 99 (83

– 117)

“Definite of probable” Cancer SMR (95% CI)

85 (46

– 142) “Possible” 120 (80

– 172)

MacLennan, Delzell , Sathiakumar **et al.** (2002) All Cancers, but emphasis on prostate

cancer Retrospective cohort LA atrazine plant workers ascertained from employment records and followed from 1985

- 1997 Not Applicable

114 ( 83

– 152) All Cancer SIRs (95% CI)

All Employees Prostate Cancer SIRs (95% CI)

217 ( 94

– 428) Active Employees Only 300 (110

– 652)

### Page 21 of 76 Study Health Outcome Study Design Study Population Exposure Relevant Association MacLennan, Delzell, Nalini, and Myers (2003) Mortality, by Cause of Death Retrospective, mortality LA atrazine plant workers ascertained from employment records and followed from 1970

- 1997 Not Applicable

160 (95% CI: 66

– 160) All Cancer SMR (95% CI)

329 (95% CI: 40

– 1190) NHL SMR (95% CI)

Hessel, Kalmes, Smith **et al.** (2004) Prostate Cancer Prospective, Nested Case

Control Cases: Workers in LA atrazine production facility who were diagnosed with prostate cancer Controls: Randomly selected workers from same facility who were matched to cases on race and year of birth Atrazine exposure index based on job title/department, categories based on job title and department All subjects OR (95% CI) Average exposure :

0.87 (0.46

– 1.30) Duration of exposure 1.30 (1.06

– 1.66) Cumulative exposure 1.30 (1.06

– 1.66) OR for those ≥1 PSA test (95% CI) Average exposure :

0.82 (0.36

– 1.47) Duration of exposure 0.96 (0.71

– 1.30) Cumulative exposure 0.98 (0.91

– 1.05) Mills (1998) County

- level Cancer Incidence Ecologic Individuals living in CA counties during 1988

- 1992 County

- level Atrazine Usage

Hispanic Only Atrazine Usage Correlation Coefficients

Leukemia

– r = 0.40 brain cancer

– r = 0.54 testicular

cancer

– r = 0.41 Blacks Only Prostate Cancer

– r = 0.67

### Page 22 of 76 Study Health Outcome Study Design Study Population Exposure Relevant Association Mills (2003) Prostate Cancer Nested Case Control study Cases : Ascertained through CA cancer registry among United Farmworkers Union members (1987

- 1999) Controls : Frequency matched Union members (age, vital status) Union records and state pesticide use reporting (PUR) records ( simazine , not atrazine) OR Simazine : 1.5 (1.0, 2.28)

Schroeder Olshan, Baric et al. (2001) Non

- Hodgkin’s Lymphoma Retrospective, Case

- Control Cases: Males aged 30 years or older diagnosed wit h NHL during March 1981

- October 1983 and identified through the State Health Registry of Iowa. Controls: Males recruited through random

- digit dialing, Medicare files, and state death certificates In

- Person Interview

– Self

Reported Pesticide Use 1.7 (1.0

- 2.8) Atrazine OR (95% CI)

Van Leeuwen JA, Waltner

Toews D, Abernathy T, Smi B, Shoukri M (1999). Cancer of the stomach, colon, ovaries, bladder, and Non

- Hodgkin’s Lymphoma Ecologic 40 Ecodistricts in Ontario, Canada during 1987

- 1991 Ecodistrict

- level water contamination and agricultural practice data - Atrazine and Stomach Cancer Positive Association:

- Atrazine and Colon Cancer Negative Association:

### 23 Hoar SK, Blair A, Holmes FF, Boysen C, Robel RJ (1985). Herbicides and Colon Cancer. **Lancet** ; 1(8440):1277

- 1278.
Health Outcome Study Design Study Population Exposure Reported Association Colon Cancer Population

- based Case

- Control Cases: Cancer patients diagnoses in Kansas during 1976

- 82 Controls: Individuals recruited by random digit dialing from Medicare and State mortality files Self

- Reported Pesticide Use Triazine OR 1.4 (0.2

– 7.9)

Hoar, Holmes, Boysen et al. (1985) conducted a population

- based case

- control study to investigate the association between colon cancer and exposure to herbicides. Cases (n=57) were diagnosed with colon cancer in Kansas during 1976

- 82 and controls (n=948) were selected by random digit dialing from Medicare and State mortality records. Hoar, Holmes Boysen et al. (1985) did not describe their data collection methods or statistical methods used to evaluate the association between colon cancer and exposure to herbicides. While this was the case, investigators reported odds ratios (OR) for both years of herbicide use and herbicide group (i.e., Phenoxys, Uracil, Triazine, and Amides).

EPA Review of Results Hoar, Holmes Boysen et al. (1985) reported that employ ment on a farm was associated with a

non

- significant increase in colon cancer risk (OR = 1.6, 95% CI: 0.8

– 3.5), which was similar to the risk in farmers who did not report using herbicides. With regard to self

- reported use of herbicides, the investigato rs reported that the risk of colon cancer among farmers who reported mixing herbicides was similar to the risk in farmers who never reported using herbicides, and there was a lack of dose

- response relationship between years of herbicide use and colon

cance r risk. Investigators reported specific associations for classes of herbicides including triazines (OR 1.4, 95% CI 0.2, 7.9), and although elevated, positive associations were observed, confidence bounds were wide, sample size was small to make these esti mate with precision. Based on these reported findings, the investigators suggest that the study results do not support an association between colon cancer and herbicide exposure. Given the limitations, namely small sample size and inadequate information in this report concerning study design and methods, the study should be considered exploratory. The report does not provide strong evidence as to the possible association between colon cancer and self

- reported herbicide use.

### 24 Hoar SK, Blair A, Holmes FF, Boys e CD, Robel RJ, Hoover R, Fraumeni JF. Agricultural Herbicide Use and Risk of Lymphoma and Soft

- Tissue Sarcoma (1986). JAMA. 9;256: 1141

- 1147.

Health Outcome Study Design Study Population Exposure Reported Association Hoar, Blair, Holmes, et al. (1986) Lymphoma, Soft

- Tissue Sarcoma Population

- based Case

Control Cases : White, male cancer patients diagnoses in Kansas during 1976

- 82 Controls : Frequency

- matched controls recruited by random digit dialing from Medicare and State mortality files Self

- Reported Pesticide Use, Telephone Interview (1982

- 1984), validated through sales records

Hoar et al. (1985) conducted a case

- control study to investigate the association between lymphomas and soft

- tissue sarcoma with exposure to herbicides. Cases were diagnosed in Kansas during 1976

- 82 and controls were selected by random digit dialing from Medicare and State mortality records. Cases of soft

- tissues sarcoma (n=200), Hodgkin’s disease (n=173), and non

- Hodgkin lymphoma (NHL) (n=200) were identified, and 87% of cancers were reviewed by pathologist. Pesticide exposure information was collected through telephone interview during 1982

- 1984 time period and included information about farm practices, pesticide and herbicide use as well as use of personal protect ive equipment (PPE). Investigators achieved a 93% response rate among those eligible for inclusion. Importantly, a small validation study (n=130) was performed within this study in which authors compared reported pesticide usage with pesticide sales record s. Authors performed both age

- stratified analyses and unmatched logistic regression techniques to evaluate the relation between herbicide use and these cancer outcomes.

EPA Review of Results:

Authors reported a border

- line statistically significant assoc iation between farming and NHL (OR 1.4, 95% CI 0.9, 2.1), and authors observed a trend by years and days per year of herbicide use. Elevated odds of NHL were reported comparing ever

- and never use of triazines (OR 2.5, 95% CI 1.2, 5.4), however adjusting f or use of other pesticides (through restriction), and the risk estimate was attenuated, and was not statistically different from the null (OR 2.2, 95% CI 0.40, 9.1). Authors did not observe a trend by number of acres treated with herbicide, or with days p er year participants reported mixing and loading herbicides. Overall, the results of this initial analysis were not strongly suggestive of a link between herbicides and/or triazines and NHL or other lymphohematopoietic cancers evaluated. Small sample size, numerous statistical comparisons, and non

- specific nature of exposure measurement were key limitations.

### 25 Brown LM, Blair A, Gibson R, Everett GD, Cantor KP, Schuman LM, Burmeister LF, Van Lier SF, and Dick F (1990). Pesticide Exposures and Other Agricult ural Risk Factors for Leukemia among Men in Iowa and Minnesota. **Cancer Research** ; 50:6585

- 6591.
Health Outcome Study Design Study Population Exposure Reported Association Leukemia Retrospective Case

Control Cases: Male cases identified through Iowa Tumor Registry and Minnesota surveillance of hospital/labs Controls: Frequency

matched sample of men In

- Person Interview

– Self

- Reported Pesticide Use Triazine OR (95% CI): 1.1 (0.8

- 1.5) Atrazine OR (95%CI): 1.0 (0. 6

- 1.5)

Brown, Blair, and Gibson et al. (1990) conducted a case

- control study to investigate the association between pesticide exposure and leukemia. Authors recruited white, male participants at least age 30 years into the study, given known role of age, gender and racial the epidemiology of these cancers. In Iowa, cases were ascertained from March 1982 to October 1983 using the Iowa Tumor Registry. In Minnesota, cases were identified through a surveillance network of hospitals and pathology laboratories within October 1980 to September 1982. Controls were recruited separately using random digit dialing, Medicare records, or state death certificates. Cases and controls were frequency matched by 5

- year age group, vital status at interview, and state of residence. Upon selection into the study , in

- person interviews were conducted using a standardized questionnaire to obtain information on residential history, drinking water sources, non

- farm occupational history, smoking and alcohol usage, medical conductions, family cancer history, and farm ac tivities. In order to assess pesticide exposure, subjects were asked to recall their use of 24 animal insecticides, 34 crop insecticides, 38 herbicides, and 16 fungicides. Subjects reporting pesticide usage were then asked to recall the first and last ye ar the pesticide was used and whether they personally mixed or applied the pesticide. In addition, supplemental interviewers were performed to ascertain frequency and duration of pesticide use among a sub

- set of the sample (n=92 cases, n=211 controls). In terviews were completed for 86% of cases and 77% of controls, resulting in a final study population of 578 cases and 1,245 controls. Logistic regression was used to estimate the association between leukemia and self

- reported atrazine use, adjusting for pot ential confounders, including vital status, age, state, tobacco use, family history of lymphopoietic cancer, high

- risk occupations, and high

- risk exposures (i.e., self reported exposure to benzene, naphtha, and hair dyes).

EPA Review of Results 

### Overall, Brown, Blair, and Gibson et al. (1990) reported a small significant risk for all leukemia (OR 1.2, 95%CI: 1.0

– 1.5) among men who lived or worked on a farm as an adult, but did not identify significant associations for fungicide, herbicide, or in secticide pesticide classes. Similarly, neither the ORs reported for the Trizaine Herbicides (OR 1.1, 95% CI: 0.8

– 1.5) nor atrazine (OR 1.0, 95%CI: 0.6

– 1.5) statistically differed from unity. While the study did not report significantly elevated ORs f or Triazine Herbicides or atrazine, Brown, Blair, and Gibson et al. (1990) was primarily an exploratory study that focused broadly on the potential association between pesticide exposure and leukemia and performed multiple statistical comparisons involving both broad pesticide classes and particular pesticides with each class. Several suggestive findings were reported, however results concerning atrazine were unremarkable with respect to the magnitude and direction of association, and lack of an exposure

- r esponse relation overall. Given

### 26 the study’s exploratory focus, the study does not provide strong evidence concerning the association between leukemia and atrazine use specifically.

Brown 

### LM
, Burmeister LF, Everett GD ,and Blair A. Pesticide Exposure and M ultiple Myeloma in Iowa Men (1993). Cancer Causes and Control. 4:153

- 156.
Health Outcome Study Design Study Population Exposure Reported Association

Multiple Myeloma Retrospective Case

- Control Cases : Male cases identified through Iowa Tumor Registry Controls : Frequency

matched sample of men general population In

- Person Interview

- Self

reported Pesticide Use 0.80 (0.40

- 1.6) Atrazine OR 95% CI):

Brown, Blair, and Gibson et al. (1993) conducted a case

- control study to investigate the association between pesticide exposure and multiple myeloma. The study was conducted within the same overall series of population

- based case

- control studies noted above in Brown et al (1990). Autho rs recruited white males, residing in Iowa, aged 30 years or older diagnosed with multiple myeloma into the study as the case series. In Iowa, cases were ascertained from March 1982 to October 1983 using the Iowa Tumor Registry. Controls were recruited

s eparately using random digit dialing, Medicare records, or state death certificates and frequency matched to cases by 5

- year age group, vital status at interview, and state of residence. After recruiting cases and controls, in

- person interviews were condu cted using a standardized questionnaire to obtain information on residential history, drinking water sources,

non

- farm occupational history, smoking and alcohol usage, medical conductions, family cancer history, and farm activities. In order to assess pes ticide exposure, subjects were asked to recall their use of 24 animal insecticides, 34 crop insecticides, 38 herbicides, and 16 fungicides. Subjects reporting pesticide usage were then asked to recall the first and last year the pesticide was used and whe ther they personally mixed or applied the pesticide. Information concerning frequency and duration of use was available for a small subset of the study population. Interviews were completed for 86% of cases and 77% of controls, resulting in a final study population of 173 cases and 650 controls. Authors performed logistic regression to estimate the association between multiple myeloma and self

- reported atrazine, adjusting for vital status, age, other suspected factors were not confounders in this associati on.

Brown et al. (1993) reported an inverse association between number of years on the farm and multiple myeloma risk in this study. The results for any use of herbicide and use of atrazine specifically were similarly unremarkable (OR atrazine use 0.80, 95% CI 0.40, 1.6), based upon 12 and 74 atrazine exposed cases of multiple myeloma, respectively. Authors did not observe evidence of an association with multiple myeloma in this study. Authors noted that for other pesticide

- cancer a ssociation, the risk estimate (OR) for living participants was lower than for proxies for cases, indicating recall bias or exposure measurement error in the recall of pesticide use by proxy respondents may have affected these results. The role of chance du e to multiple statistical comparisons cannot be excluded either, although the results for atrazine are unremarkable. EPA notes that the median last year of farming in this study sample is 1968; atrazine was first introduced into the marketplace in 1959. Th erefore, it is possible that atrazine exposure potential was low within this sample. Given the lack of evidence of an association, and EPA Review of Results:

### 27 the exploratory nature of the study including evaluation of many different pesticide

- multiple myeloma risk combinations, this study provides limited evidence as to the nature of the association between atrazine and multiple myeloma.



### Cantor KP, Blair A, Everett G, Gibson R, Burmeister LF, Brown LM, Schuman L, and Dick FR (1992). Pesticide and Other Agricultural Risk Factor s for Non

Hodgkin’s Lymphoma among Men in Iowa and Minnesota. **Cancer Research** ; 52:2447

- 2455.

Health Outcome Study Design Study Population Exposure Reported Association Non

- Hodgkin’s Lymphoma Retrospective, Case

Control Cases: Male cases identified through Iowa Tumor Registry and Minnesota surveillance of hospital/labs Controls: Frequency

matched sample of men Self

- Reported Pesticide Use Triazine OR (95% CI) 1.1 (0.8

- 1.6) :

Cantor, Blair, Everett et al. (1992) conducted a case

- control study using the same design as Brown, Blair, and Gibson et al. (1990) to investigate the link between pesticide exposure and

non

- Hodgkin lymphoma (NHL). NHL cases among white males aged 30 years or older were ascertained u sing the Iowa State Health Registry and Minnesota surveillance program of hospitals and pathology laboratory records. Similarly, controls were recruited through either random digit dialing, Medicare records, or state death certificates and frequency match ed by 5

- year age group, vital status at interview, and state of residence. After recruiting cases and controls, in

- person interviews were conducted using a standardized questionnaire that was similar to the instrument used in Brown, Blair, and Gibson et al. (1990). As part of the questionnaire, subjects were asked to recall their use of 23 animal insecticides, 34 crop insecticides, 38 herbicides, and 16 fungicides. If subjects recalled using a particular pesticide, they were subsequently asked to recal l the first and last year the pesticide was used, the method of application, and whether they personally mixed or applied the pesticide. Interviews were completed for 89% of cases and 77% of controls, resulting in a final study population of 622 cases and 1,245 controls after pathology reviews to confirm each subject’s NHL status. Logistic regression was then used to control for potential confounders and calculate ORs for NHL by specific classes of pesticides, including triazine herbicides. In addition t o this analysis, the investigators also evaluated odds of disease by year of first use of pesticides, before and after 1965. According to the investigators, 1965 was selected as a cut

- off in this analysis because “it was 15

- 18 years prior to diagnosis, a reasonable minimal period for latency.”

EPA Review of Results Cantor, Blair, Everett et al. (1992) reported that there was a small, marginally significant association between NHL and ever living or working on a farm as an adult (OR = 1.2, 95% CI: 1.0

– 1.5). While this overall association was observed, the investigators also reported that there was non

- statistically significant association between NHL and the variables first year farmed, last year farmed, and average number of acres farmed. With regard to NHL and self

reported pesticide use, the investigators reported that several positive asso ciations were observed, but that no single family of herbicides was significantly associated with overall NHL risk. Similarly, there was no statistical association between NHL and self

- reported triazine use (OR 1.2, 95% CI: 0.8

– 1.6). Authors did not ob serve significant differences in estimates when stratifying by year of first use. Limitations of the study include the broad nature of the investigation estimating the association between NHL and self

- reported use of multiple types of pesticides including triazines, the small number of exposed cases, and limited exposure

### 28 assessment based upon self

- reported questionnaire. However strengths include relatively low potential for several potential biases (selection, recall bias) through design and analysis. Over all, this study does not suggest a statistical association between atrazine and NHL.

Clavel J, Hemon D, Mandereau L, Delemotte B, Severin F, Flandrin G (1996). Farming, Pesticide Use, and Hairy

- Cell Leukemia. **Scand J Work Environ Health** ; 22:2985

- 93.
Health Outcome Study Design Study Population Exposure Reported Association Hairy

- cell Leukemia Retrospective, Case

Control Cases: Male cases identified through 18 French hospitals Controls: Hospital matched men that were primarily admitted to orthopedic and rheumatology departments Self

- Reported Pesticide Use Triazine ORs “Possible of Definite” :

1.9 (1.0

- 3.5) “Definite” 2.4 (1.2

- 4.8) Adjusted for OP Pesticides 2.0 (0.7

- 5.6)

Clavel, Hemon, and Mandereau et al. (1992) conducted a hospital

- based case

- control study to investigate the association between farming and pesticide use and hairy

- cell leukemia (HCL). Researchers included male, HCL cases who had been diagnosed within one of 18 French hospitals during January 1980 to January 1990. The cases were then matched to controls who were admitted to the same hospital but different clinical departments, primarily in orthopedic and rheumatology departments, during the same period. After recruitment, study subjects were mailed a self

- administered questionnaire that included questions on sociodemographic characteristics, smoking status, occupation history, and leisure

- time activities. Following this self

- administered questionnaire, s ubjects who had been employed as farmers were given an in

person interview by a trained study staff member to obtain more detailed information on pesticide usage. Based on this secondary interview, two of the investigators, who were blinded to subject’s c ase

- control status, classified subjects as “possibly” or definitely” exposed to pesticides. In addition to these exposure categories, the investigators also attempted to create a quantitative exposure index using respondent data and professional judgment on potential spray height, equipment, and relevant exposure route. Interviews were completed for 60% of cases and 52% of controls, resulting in a final study population of 226 NHL cases and 425 hospital

- matched controls. Logistic regression was then used to estimate the association, adjusting for age, state, vita status, smoking history, family history, and non

- farm jobs.

EPA Review of Results Clavel, Hemon, and Mandereau et al. (1992) reported that that NHL cases were more likely to have worked at six months on a farm, resulting in an overall OR for all farmers of 1.5 (95%CI: 1.0

– 2.2). When further stratified into farm owner and agricultural laborer groups, the investigators observed the same general association, although only the OR estimate for far mworkers was statistically significant (Farm Owner OR = 1.9, 95% CI: 1.1

– 3.2; Agricultural Laborer OR = 1.2, 95% CI: 0.7

– 1.9). With regard to self

- reported pesticide use, the investigators reported similar associations. Specifically, the overall OR o f possible or definite pesticide exposure was 1.5 (95%CI: 1.0

– 2.3) and OR estimates for 19 more specific types of insecticides, fungicides, and herbicides were all elevated. Similarly, the same general association was observed between HCL and triazine h erbicides (Possible or Definite Triazine OR = 1.9, 95% CI: 1.0

– 3.5; Definite Triazine OR = 2.4, 95% CI: 1.2

– 4.8). However, when restricting to only those who reported never using organophosphate pesticides, the association was no longer significantly elevated. Authors stated that controls were similar to the general population of the area in terms of major demographic and other characteristics, and that cases were selected from all cases identified in this time period, arguing against a role of select ion bias in these findings. However, authors did not provide information as to the comparability of

### 29 the included and excluded cases; authors noted deceased cases were not considered for inclusion by proxy. Participants were blinded to study hypothesis, red ucing the potential for recall bias as an explanation for findings. Adjustment for confounding by organophosphate exposure, through restriction, is a strength of the study and decreases uncertainties concerning the results. Limitations of the study for the purpose of information the nature of the causal association, if any, include the exploratory nature of the design, small number of exposed cases, and residual uncertainties surrounding the hospital based selection process. Overall, the study does not offe r compelling evidence in support of an association between triazines and HCL in this population.

Donna A, Crosignani P, Robitta F, Betta PG, Bocca R, Mariani N, Ferrario F, Fissi R, and Berrine F (1989). Trazine herbicides and ovarian epithelial noeplasm s. **Scand J Work Environ Health**  ; 15:47

- 53.
Health Outcome Study Design Study Population Exposure Reported Association Ovarian Epithelial Neoplasms Case

- Control Cases: Female cases ascertained from Alessandria Hospital Cancer Register Controls: Age

- matched females, randomly selected from electoral rolls of municipalities in the study area Self

- Reported Pesticide Use Triazine RRs (90% CI) “Definite” :

2.7 (1.0

- 6.9) “Possibly” 1.8 (0.9

- 3.5)

Donna, Crosignani, Robutti et al. (1989) conducted a population

- based case

- control study to investigate the association between ovarian epithelial neoplasms and exposure to triazine herbicide exposure. The study population consisted of women from Alessandria Province, Italy, who (i) had at least one ovary, (ii) were in the age range 20 to 69 years olds, and (iii) were residents of the municipality during the study period July 1, 1980 to June 30, 1985. Cases were ascertained from the study population using the Alessandria Hospital Cancer Registry and age matched controls were recruited randomly using electoral rolls of municipalities within the study area. After recruiting cases and controls, a questionnaire was used to obtain information on reproductive factors that may be risk factors f or ovarian cancer. As part of the questionnaire, occupational history information was obtained and triazine herbicide exposure was assessed by requesting study participants to recall herbicide use. Subjects were designated as “definitely exposed” to tria zine herbicides if they were involved in the preparation or use of triazine herbicides or who worked in corn cultivation with reported use of herbicides. Some subjects did not meet this definition, but were designated as “possibly exposed” because accordin g to local agricultural experts, triazines were used in all herbicide

- treated corn cultivation in Allesandria Province after 1964. Lastly, subjects were designated as “unexposed” if the investigators determined that professional or domestic triazine expo sure was unlikely. In addition to these exposure categories, the investigators also considered the possible duration of exposure by considering the number of years each individual had an occupation that could have resulted in trizaine herbicide exposure. After obtaining questionnaire response data, the investigators used logistic regression to calculate rate ratios and 90% CIs.

EPA Review of Results This study built upon initial investigations by the same researchers reported in Donna et al. (1984). However, in the original investigation, herbicide use and not specific types, were evaluated in association with ovarian cancer. Donna, Crosignani, Robutt i et al. (1989) reported a positive association between those “definitely” (OR 2.7, 95% CI 1.0, 6.9) and “possibly”

### 30 triazine exposed (OR 1.8, 95% CI 0.90, 3.5) groups and ovarian epithelial neoplasms. Elevated odds ratios were also observed in association with women who reported agricultural use only, however precision was reduced: definite exposed triazines 2.8 (95% CI 0.90, 8.1), probably triazine exposed 2.1 (95% CI 0.8, 5.4). Estimates were adjusted for ovarian cancer risk factors including age, number of live births and use of oral contraceptives. Authors were able to recruit a high proportion of the eligible population, 94% of cases and 91% of controls. In addition, pesticide exposure questionnaire data were relatively detailed and included informatio n concerning many different aspects of farming and other pesticide exposures. However, authors did not adjust for use of other pesticides, which is a limitation of the study. The probabilistic nature of the exposure assessment method likely results in some misclassification, however this may be comparable to the potential recall issues inherent in remembering past exposures. Another strength of the study is the use of blinding measures for the interviewer, reducing this potential bias in the study, and the use of two separate exposure measurement experts who independently rated participants as “definitely” or “probably” exposed to triazines. The major limitation of this investigation is the relatively small number of triazine exposed ovarian cancer cases and the lack of adjustment for other pesticides in the risk estimate. Overall, the study provided some evidence of a possible association between triazine exposure and ovarian cancer, however limitations of the study present some uncertainty in interpretation to inform causal inference.

Zahm SH, Babbit PA (1993). The Role of Agricultural Pesticide Use in the development of Non

- Hodgkin’s Lymphoma in Women. **Archives of Environmental Health** ; 48(5): 353

- 358.
Health Outcome Study Design Study Population Exposure Reported Association Non

- Hodgkin’s Lymphoma Retrospective, Case

Control Cases: Women, aged 21 years or older, who were from eastern Nebraska and were diagnosed during July 1 1983 and June 30, 1986 Controls: Individuals recruited using random digit dialing and 3:1 frequency matched by race, sex, vital status, and age Telephone Interview

– Self

Reported Pesticide Use Triazine Class OR (95% CI): 1.2 (0.6

– 2.6)

Zahm and Babbit (1993) conducted a case

- control study to investigate the association between

non

- Hodgkin lymphoma (NHL) and agricultural pesticide use. The study was conducted among the same series of population

- based case control studies conducted by the NCI in the early 1980s and reported earlier (See Brown et al. 1990 and 1993; Cantor et al. 1992). Nebraska was the only study site within these series of studies that ascertained outcome and exposure information for females. Therefore, this study populati on included women aged 21 years or older who resided in 66 counties in eastern Nebraska ascertained through the state Lymphoma Study Group. Controls were recruited using random digit dialing and 3:1 frequency matched by race, sex, vital status, and age. A fter recruiting cases and controls, telephone interviews were conducted with cases and controls or a proxy respondent. As part of the telephone interview, study subjects were asked to recall their pesticide usage, application method, and use of personal p rotective equipment. In total, 184 cases and 707 controls were successfully interviewed (response rate of 89% and 86% for cases and controls, respectively). The investigators then evaluated the association between NHL and agricultural pesticide exposure by calculating age

- stratified ORs.

### 31 EPA Review of Results Overall, Zahm and Babbit (1993) reported that neither use of insecticides nor herbicides was associated with NHL. With regard to herbicide use on farms, the investigators reported non

significant ORs for self

- reported use of both any herbicide (OR = 0.7, 95% CI: 0.4

– 1.2) and triazines in particular (OR = 1.2, 95% CI: 0.6

– 2.6). The latter estimate was based upon 12 exposed cases and 38 exposed controls. The relation between atrazine and NHL am ong women was positively elevated, but based upon only 1 and 2 exposed cases and controls respectively, and is therefore an unstable estimate of the association. As with other studies in this series, the results should also be interpreted with caution beca use of the broad focus of the study in which multiple associations were evaluated, and no hypothesis for atrazine was specifically identified. Similarly, the investigators also relied on study subjects to recall past pesticide usage to assess exposure to triazines and other pesticides, which may have resulted in exposure misclassification, but likely non

- differential in nature as participants were blinded to the study hypothesis. In addition, as acknowledged by the investigators, the basic survey questions on pesticide usage may not adequately reflect the activities through which farm women are exposed to pesticides, leading to additional potential for exposure measurement error. In this exploratory study among women, authors did not observe evidence of an association with pesticides overall or triazines specifically. The small sample size, exposure measurement error due to the differences in exposure profile between men and women, and hypothesis

- generating nature of the study limit use of these data to inf orm the nature of the atrazine

- NHL association among women. Authors did not observe evidence of a link in this study.

Zahm SH, Weisenburger DD, Cantor KP, Holmes FF, Blair A (1993). Role of the herbicide atrazine in the development of non

- Hodgkin’s lymp homa. **Scand J Work Environ Health** ; 19:108

- 114.
Health Outcome Study Design Study Population Exposure Reported Association Non

- Hodgkin’s Lymphoma Retrospective, Pooled Case

- Control Cases: White males ascertained from registries/surveillance programs in Nebraska, Iowa

- Minnesota, and Kansas Controls: Individuals randomly selected from the same geographic location as cases and frequency matched by race, gender, age group, and vital status In

- Person Interview

– Self

- Reported Pesticide Use Pooled Atrazine Use OR (95%Ci): Unadjusted 1.4 (1.1

– 1.8) Adjusted for OP pesticides 1.2 (0.9

– 1.7)

Zahm, Weisenburger, Cantor et al. (1993) conducted a pooled case

- control analysis of the association be tween non

- Hodgkin lymphoma (NHL) and atrazine exposure using data from the three population

- based case

- controls studies performed by the NCI in the early 1980s (See Brown et al. 1990, 1993; Cantor et al. 1992; Hoar et al. 1986). Details of the design and methods of these studies have been discussed above. Briefly, cases were identified using separate state disease registries and/or surveillance programs. The matched controls were randomly selected from the same geographic location as cases and frequency m atched by race, gender, age group, and vital status at time of interview. In each of the three study groups, interviews were conducted with study subjects or a proxy respondent. Questions regarding atrazine use varied slightly between study groups. In pa rticular, questions on atrazine use were open

- ended in both the Nebraska and Kansas study groups ( i.e. , specific herbicides were not

### 32 named when asking questions) whereas a direct was questions on the use of atrazine was included in the Iowa

- Minnesota study group interview. After collecting questionnaire data, the investigators then evaluated the association between NHL and atrazine by calculating ORs, stratified by age and state. The investigators also adjusted their atrazine ORs for other potential agric ultural exposures by stratifying their results by use of 2,4

- D and organophosphate(OP) insecticides.

EPA Review of Results Zahm, Weisenburger, Cantor et al. (1993) reported that atrazine use was associated with a significant 40% excess risk of NHL, based on a pooled OR of 1.4 (95% CI: 1

- 1

- 1.8). The investigators noted, however, that other pesticides were associated with NHL and attempted to adjust their OR for use of 2,4

- D and OP insecticides. Based on this adjustment, the investigators reported that the OR for atrazine was reduced to a non

- significant association of 1.2 (95% CI: 0.9

– 1.7). Similarly, the investigators also performed additional analysis u sing data from the Nebraska study, which obtained the most detailed data. Based on this analysis, the investigators reported that increased ORs were generally observed for duration of atrazine use, average number of days atrazine was handled, and year of first use of atrazine. When these results were adjusted for OP use, however, the OR estimates were below unity, suggesting that atrazine is not associated with NHL. Overall, the investigators conducted a pooled study that enabled the investigators to con duct a more thorough investigation of the association between atrazine exposure and NHL. Strengths and limitations of individual studies are noted above and not repeated herein. Concerning the pooled analysis, authors maximized use of all available data, a t the time, and results supported a conclusion of no association between atrazine and NHL due to the lack of an observed association in the presence of use of other pesticides, lack of a trend by duration and frequency of use, and inclusion of a large samp le through the pooling analysis.

Kettles MA, Browning SR, Prince TS, and Horstman SW (1997). Triazine Herbicide Exposure and Breast Cancer Incidence: An Ecologic Study of Kentucky Counties. **Environmental Health Perspectives** ; 105(11): 1222

- 1227.
Health Outcome Study Design Study Population Exposure Reported Association Breast Cancer Ecologic Individuals living in Kentucky during 1991

- 1994 Exposure indices based on trizaine ground and drinking water levels, corn acreage, and atrazine sales 1.07 (1.01

- 1.14) High Exposed Category OR (95% CI)

1.2 (1.13

- 1.28)

Kettles, Browning, and Prince et al. (1997) conducted an ecologic study to examine the association between breast cancer incidence and triazine herbicide exposure. The study was designed using county

- level data from 120 counties in Kentucky. County breas t cancer incidence rates were calculated using Kentucky’s statewide cancer registry for the years 1991

- 1994. Triazine herbicide exposure was then assessed using data on ground and drinking water contamination, corn acreage, and pesticide usage by applicat ors. Ground water data was obtained from the Kentucky Geological Survey, which conducted a voluntary study of wells in Kentucky during 1990 to 1991, representing 2.3% of the state’s wells. Triazine contaminant data for drinking water was obtained from Ken tucky’s Division of Water, which is responsible for performing water testing of faucets from non

- randomly selected homes in Kentucky counties. Kentucky’s Division of Water only reports results as positive or negative, so actual concentration data was avai lable for the investigators analysis. Corn acreage, pesticide usage data were both reported on the county

- level, so additional analysis was needed to estimate county

- level values.

### 33 Using these four data sources, the investigators determined the quartile di stribution for each exposure variable and assigned each county a score from 0 to 4 for each exposure category. The investigators then created a composite exposure variable by summing each county’s four separate scores, producing a range of county scores f rom 3 to 16. After performing their exposure assessment, the investigators performed two Poisson regression analyses to estimate odds ratios for the four exposure categories and composite exposure variable.

EPA Review of Results Kettles, Browning, and Pr ince et al. (1997) report a small statistically significant association between breast cancer and the water contaminants. However, the investigators also indicate that the results were not consistent between 1991

- 92 and 1993

- 94, with a significant associa tion between surface water and breast cancer during 1991

- 92 and a significant association between ground water and breast cancer during 1993

- 94. While the water contaminant associations were not consistent between time periods, the investigators did repor t that their composite exposure variable was associated with breast cancer during both 1991

- 92 and 1993

- 94 (i.e., Medium and High Exposed County ORs = 1.09 (1.04

- 1.14), 1.07 (1.01

- 1.14) and 1.14 (1.08

- 1.19), 1.20 (1.13

- 1.28) for 1991

- 92 and 1993

- 94, respec tively). Overall, the study provides exploratory results that suggest there may be an association between atrazine exposure and breast cancer. While this is the case, the study’s ecologic design limits its application in establishing direct casual infere nce because of the exploratory nature of ecologic studies. For example, as discussed by the investigators, the ecologic exposure assessment may bias the results if county

- level characteristics do not accurately reflect individual characteristics within

co unties.

Hopenhayn

- Rich C, Stump ML, and Browning SR (2002). Regional Assessment of Atrazine and Incidence of Breast and Ovarian Cancers in Kentucky. **Arch. Environ. Contam. Toxicol.**  ; 42:127

- 136.
Health Outcome Study Design Study Population Exposure Reported Association Breast and ovarian

cancer Ecologic Individuals living in Kentucky during 1993

- 1997 Aggregate exposure indices based on atrazine drinking water levels, corn acreage, and atrazine sales Null association reported

Based similar methods as Kettles, Browning, and Prince et al. (1997), Hopenhayn

- Rich, Stump, and Browning (2002) conducted an ecologic study to investigate the association between the county

- level incidence of breast/ovarian cancer and potential atrazine e xposure. The study population was individuals in Kentucky, grouped by county and 15 Area Development Districts. Based on the population in each county and ADD, the investigators used the Kentucky Cancer Registry to estimate five

- year ovarian and breast c ancer age

- adjusted incidence rates for the period 1993

- 1997. When assessing atrazine exposure, the investigators considered Kentucky data on atrazine levels in drinking water, acreage of corn planted, and atrazine sales. Drinking water data was obtained from Kentucky’s Division of Water and contained information on ground and surface water sources of drinking water in Kentucky. Using this data, mean atrazine levels were calculated for individual counties in Kentucky. County

- level corn acreage data was

o btained from Kentucky’s Department of Agriculture. The investigators considered all available acreage data from the 1970

- 2000, but only used data from the 1970s in their analysis because of the latency period from the time of exposure to development of c ancer. Lastly, county

- level atrazine sales data from 1997 was obtained from Kentucky’s Department of Agriculture. The investigators then determined the quartile distribution and assigned a score to each county (0

- 3

### 34 corresponding to each county). Using these scores, the investigators calculated a composite score based on all three data sources to give a total score of 0

- 9. After performing their exposure assessment, the investigators used Poisson regression to estimate crude rate ratios and adjusted rat e ratios, controlling for demographic covariates, at both the county and ADD

level.

EPA Review of Results Hopenhayn

- Rich, Stump, and Browning (2002) report that their study did not provide evidence that supports an association between atrazine exposure and county level incidence of breast or ovarian cancer and further suggest that their data suggest an inverse association between their corn acreage metric and ovarian cancer. As with most ecologic studies, however, these results should be considered expl oratory findings that should be interpreted with caution because characteristics at the county

- level may not represent individual

- level characteristics. Additionally, as highlighted by the investigators, there was limited variability in county

- level drink ing water, with weighted mean atrazine concentrations ranging from 0.21μg/L to 1.19μg/L. Therefore, the small range drinking water levels may have been insufficient for performing county

- level comparisons. The authors also indicate that there was a weak correlation between corn acreage and atrazine sales, which was unexpected. As such, the study provides exploratory information on the aggregate relation between atrazine exposure and breast or ovarian cancer in Kentucky.

Sathiakumar N, Delzell E, and Cole P (1996). Mortality among Workers at Two Triazine Herbicide Manufacturing Plants. **American Journal of Industrial Medicine** ; 29:143

- 151.
Health Outcome Study Design Study Population Exposure Reported Association Mortality Retrospective, pooled cohort Employees from two atrazine production plants located in Alabama and Louisiana Exposure classifications based on job title and function Overall SMR (95% CI) “Definite of probable” 87 (75

– 99) “Possible” 99 (83

– 117 ) Cancer SMR (95% CI) “Definite of probable” 85 (46

– 142) “Possible” 120 (80

– 172)

Sathiakumar , Delzell , and Cole (1996) conducted a pooled analysis of two previous studies (Sathiakumar et al. , 1992; Delzell et al. , 1989) that examined the incidence of mortality of employees in two triazine production plants in Alabama (AL) and Louisiana (LA). Based on these two previous studies, Sathiakumar , Delzell , and Cole (1996) excluded employees who worked in managerial po sitions and were not exposed to triazines and obtain employment and vital status data on 3,675 male employees and 1,472 male and female employees from the AL and LA plants, respectively. The investigators then developed a triazine exposure classification system, based on job titles and functions, and classified study subjects’ exposure as either “definite,” “probable,” or “possible.” Based on this classification system, disease mortality rates of each group were compared with the general population of me n in the U.S., in Alabama, or in Louisiana by calculating standardized mortality ratios (SMR).

EPA Review of Results Sathiakumar , Delzell , and Cole (1996) reported that the overall mortality in the entire cohort of AL and LA plant workers was lower tha n the general U.S. population of men (SMR = 87, 95%CI: 75

– 99). The investigators also reported that study subjects that performed “definite” or “probable” triazine

- related work had similar patterns of mortality as the overall population of

### 35 workers. The se results were statistically imprecise, however, because of the small number of deaths for most types of cancer and other causes of death. As a result, the study may have had insufficient statistical power to observe differences between the study populat ion and general population of the men in the U.S. or respective study states. In addition to this limitation, Sathiakumar , Delzell , and Cole (1996) also noted that study subjects were relatively young, with only 13% of the total person

- years in the 45+ year age group. As such, the study may have limited ability to evaluate cancer and other disease with long latency periods. Due these limitations, the study findings are inconclusive with regard the nature of the relation between occupational (manufactu ring) triazine exposure and overall mortality.

MacLennan PA, Delzell E, Sathiakumar N, Myers SL, Cheng H, Grizzle W, Chen VW, and Wu XC (2002). Cancer Incidence among Triazine Herbicide Manufacturing Workers. **Journal of Occupational and Environmental M edicine**  ; 44(11):1048

- 1058.
Health Outcome Study Design Study Population Exposure Reported Association All Cancers, but emphasis on prostate

cancer Retrospective cohort LA atrazine plant workers ascertained from employment records and followed from 1985

- 1997 Not Applicable SIR = 114, 95% CI: 83

– 152 SIR = 217, 95% CI: 94

– 428 SIR = 300, 95% CI: 110

– 652

MacLennan, Delzell , Sathiakumar et al. (2002) evaluated the cancer incidence and characteristics of a prostate

- specific antigen (PSA) screening program among workers at an atrazine production plant in St. Gabriel, Louisiana (LA). The study population included 2,045 plant employees who had lived in LA in or after 1985, worked at the plant for at least six months by 1992, and performed a job activ ity that could have involved contact with triazines or precursor chemicals. The study population consisted of three general groups of employees

– company employees, contract production employees, and contract maintenance employees, who worked at the compa ny since 1970, 1977, and 1985, respectively. The investigators then used the LA Tumor Registry to identify cancer cases during the follow

- up period January 1, 1985 through December 31, 1997. In addition to examining the LA Tumor Registry, the investigator s also reviewed medical examination records and PSA testing at the LA plant. After identifying employees and obtaining medical information, the investigators compared the study subjects’ cancer incidence rates with the rates of the general population of t he LA industrial corridor. This comparison was performed by calculating standardized cancer incidence ratios for all employees and then stratified by race, gender, years worked, and employees group. The investigators then determined the proportion of mal e employees that received PSA tests, restricting the analysis to only men with no previous prostate cancer diagnosis, and calculated the prostate cancer detection rate among active LA plant employees.

EPA Review of Results MacLennan, Delzell , Sathiakumar et al. (2002) reported that the study population had a total of 46 cancer cases, compared with 40 expected cases based on the general population in the LA industrial corridor (SIR = 114, 95% CI: 83

– 152). With regard to p rostate cancer, the investigators reported that there was a larger than expected number of prostate cancer cases in company employees, although this increase was not statistically significant (SIR = 217, 95% CI: 94

– 428). When stratified by employment st atus (active/inactive), however, the investigators reported that active employees had a significantly higher number of prostate cancer cases than the general population in the LA industrial corridor (SIR = 300, 95% CI: 110

– 652). Based on this reported a ssociation, the investigators suggest that there was an increased incidence of prostate cancer in the study population of LA atrazine plant employees, but also caution that the increased incidence was observed primarily in active employees who may have had greater

### 36 access to medical screenings than the general population in the LA industrial corridor. As a result, medical screening for prostate cancer may explain part of the excess of prostate cancer cases in the study population. Additionally, the study d id not specifically evaluate individual worker’s exposure to atrazine, making it difficult to determine if employees performed job functions that resulted in greater atrazine exposure than other employees in the study population. In summary, the study pro vides exploratory information on the incidence of cancer in a LA plant where employees may contact atrazine, but suggest the role of cancer screening program, detection bias, may influence these findings.

MacLennan P, Delzell E, Nalini S, and Myers S (200 3). Mortality Among Triazine Herbicide Manufacturing Workers. **Journal of Toxicology and Environmental Health, Part A**  ; 66:501

- 517.
Health Outcome Study Design Study Population Exposure Reported Association All Mortality Retrospective cohort LA atrazine plant workers ascertained from employment records and followed from 1970

- 1997 Not Applicable

160 (95% CI: 66

– 160) All Cancer SMR (95% CI)

329 (95% CI: 40

– 1190) NHL SMR (95% CI)

MacLennan, Delzell, Nalini, and Myers (2003) conducted a retrospective study of a triazine manufacturing plant in Louisiana (LA) to investigate if workers exposed to triazines have greater mortality rates than the general population in the LA industrial corridor. The study population consisted of individuals who worked at the plan t for at least six months by the end of 1992 and had worked in a job that could involve potential contact triazines or raw materials used to make triazines. The follow

- up start years of the study were 1970, 1977, and 1983 for company employees, contract p roduction workers, and contract maintenance workers (due to differences in employment records), respectively, and the follow

- up end date was December 31, 1997. As part of follow

- up, the investigators used personnel records to identify workers in three emp loyee groups and ascertain work history information, including age and demographic information, and start/end dates for employment periods. After identifying the study population, the investigators determined each subject’s vital status as of December 31, 1997 by reviewing records of the plant, Social Security Administration, the National Death Index, and LA and Texas Division of Motor Vehicle. After determining the vital status of study subjects, the investigators compared the study group’s mortality rat es with the general population of the LA industrial corridor using standardized mortality ratios (SMRs).

EPA Review of Results MacLennan, Delzell, Nalini, and Myers (2003) report that the overall SMR for all diseases was 72 (95% CI: 57

– 89), suggesting that the study group’s mortality rate was 28% lower than the rate for the general population in the LA industrial corridor. With regard to cancer, the investigators reported the SMR for all cancers combined was 160 (95% CI: 66

– 160), indicating that the re was not a significant difference between the rate of cancer deaths in the study group and general population in the LA industrial corridor. Similarly, the investigators also reported that white males included in this study were observed to have lower mortality rate from cancer (SMR = 82 (95% CI: 41

– 147), whereas non

- white men and women in the study group had elevated SMRs (SMRs = 139 (95% CI: 60

– 274) and 348 (95% CI: 72

– 1018), although none of these SMRs were statistically significant. The inves tigators also reported that there were increased deaths of non

- Hodgkin lymphoma in the study group (SMR = 329 (95% CI: 40

–

### 37 1190). The validity of this conclusion is questionable, however, because the SMR estimate is

non

- significant and unstable due to th e small number of NHL cases (n<5) in both the study group and general population in the LA industrial corridor. Moreover, only 18% of the study group was 45 years or older. As a result, the study may have a somewhat limited ability to evaluate associatio ns with cancer and other diseases with long latency periods. Based on the investigators’ findings, the results suggest that the overall mortality rate in the cohort of LA atrazine plant workers was lower than general population in the LA industrial corrid or. The study provided only limited information on cancer mortality, however, because of the relatively small number of cancer deaths that occurred in both the study group and reference population.

Hessel PA, Kalmes R, Smith TJ, Lau E, Mink PJ, Mandel J (2004). A Nested Case

- Control Study of Prostate Cancer and Atrazine Exposure. Journal of Occupational and Environmental Medicine; 46(4):379

- 385.
Health Outcome Study Design Study Population Exposure Reported Association Prostate Cancer Prospective, Nested Case

Control Cases: Workers in LA atrazine production facility who were diagnosed with prostate cancer Controls: Randomly selected workers from same facility who were matched to cases on race and year of birth Atrazine exposure categories based on job title and department Average exposure: 0.87 (0.46

– 1.30) All subjects (12 cases, 130 controls)

Duration of exposure: 1.30 (1.06

– 1.66) Cumulative exposure: 1.01 (0.95

– 1.07)

Those with ≥1 PSA test (10 cases, 48 contr ols) Average exposure: 0.82 (0.36

– 1.47) Duration of exposure: 0.96 (0.71

– 1.30) Cumulative exposure: 0.98 (0.91

– 1.05)

Hessel, Kalmes, Smith et al. (2004) performed a follow

- up nested case

- control study within the triazine manufacturing plant cohort noted above (Sathiakumar et al. 1996, MacLennan et al. 2002 and 2003) to investigate the association between prostate cancer and atrazine exposure, while accounting for the potential influence of an on

- site prostate screening program. All study subjects were males who worked in an atrazine production plant in Louisiana. A total of 14 prostate cancer cases were identified through the company’s medical scr eening program (8 cases among company workers identified in previous study through 1997 and 6 additional cases identified in 1998 and 1999). Controls were then randomly recruited and matched to cases based on race and year of birth. After recruiting case s and controls, the investigators assessed atrazine exposure using a tiered exposure index using (i) time

- weighted exposure intensity scores, based on five exposure categories and monitoring data that suggested that dust and airborne atrazine concentration s in the plant were higher in 1970

- 1984 relative to 1985

- 1999, (ii) duration of exposure in days, and (iii) cumulative exposure, which was calculated as the product of the time

- weighted intensity scores and duration of exposure. The investigators then per formed an analysis to evaluate the role of prostate screening on cancer patterns and used logistic regression to evaluate the association between prostate cancer and atrazine exposure.

EPA Review of Results Hessel, Kalmes, Smith et al. (2004) reported tha t while cases and controls were comparable in their year of hire, controls were more likely to have terminated employment before 1990. As a result of this finding, the investigators indicated that cases were more likely to have received the PSA testing th at was introduced in the plant in the 1990s. As a result, the investigators suggest

### 38 that the increased PSA testing alone could have accounted for the increased prostate cancer incidence reported in MacLennan, Delzell, Nalini, and Myers (2003). The invest igators further report that the results suggest that PSA testing may influence the association between atrazine exposure and prostate cancer in the plant study. More specifically, the investigators reported that duration of atrazine exposure was significa ntly associated with prostate cancer (OR = 1.30, 95% CI: 1.06

– 1.66) when study subject PSA testing was not considered. When the investigators excluded individuals with more than one PSA test, however, the significant association was no longer observed ( OR = 0.96, 95% CI: 0.71

– 1.30). Based on this finding the results suggest that increased PSA testing may have resulted in the observed association between atrazine exposure and prostate cancer.

Mills PK (1998). Correlation Analysis of Pesticide Use Da ta and Cancer Incidence Rates in California Counties. **Archives of Environmental health** ; 53(6): 410

- 13.
Health Outcome Study Design Study Population Exposure Reported Association County

- level Cancer Incidence Ecologic Individuals living in CA counties during 1988

- 1992 County

- level Atrazine Usage Atrazine Usage Correlation Coefficients Hispanic Only Leukemia

– r = 0.40 brain cancer

– r = 0.54 testicular cancer

– r = 0.41 Blacks Only Prostate Cancer

– r = 0.67

Mills (1998) conducted ecologic study to examine the association between county

- level cancer incidence rates and pesticide use. The study focused on lymphoma, leukemia, soft tissue sarcoma, prostate cancer, brain cancer, and testicular cancer and used the California Cancer Registry to calculate age

- adjusted incidence rates for each county in California during 1988

- 1992. Pearson correlation coefficients were then calculated to evaluate the correlation between county

- level incidence rates and 1993 county

- level pesticide usage data on atrazine, 2

- 4

- D, Captan, Diazinon, Difocol, and Trifluraline, which is collected by California’s Department of Pesticide Regulation.

EPA Review of Results Overall, Mills (1998) reported that the majority of correlation coefficients calculated implied there

was no corr elation between pesticide use and cancer

- incidence rates, i.e. , the correlation coefficients were low. With regard to atrazine, the Mills reported that there were somewhat elevated correlation coefficients between county

- level atrazine usage and leukemia, brain cancer, and testicular cancer for Hispanics ( r = 0.40, 0.54, and 0.41, respectively). Similarly, Mills also reported that the correlation between county

- level atrazine usage and prostate cancer in black males was r = 0.67. While these correlation s are reported in Mills (1998), the author also notes that the results should be interpreted due to the limitations of the studies ecologic design. Given the limitations of ecologic design for the purpose of informing the true nature of the relation betwe en atrazine and these cancer sites, these data not informative. However, EPA considers these data in conjunction with other analytic studies performed subsequently.

Mills PK and Yang R (2003). Prostate Cancer in California Farm Workers. Journal of Occu pational and Environmental Medicine; 45(3):249

- 258.
Health Outcome Study Design Study Population Exposure Reported Association Prostate Cancer Nested Case

- Control Cases: United Farm Worker (UFW) members County

- level pesticide usage data Simizine OR (95% CI)

### 39 ascertained through the California Cancer Registry Controls: Randomly selected cancer

- free UFW members, 5:1 frequency matched based on age linked to cases and controls based on employment records 1.53 (1.02

- 2.28)

Mills and Yang (2003) conducted a nested case

- control study to investigate the association between pesticide exposure and prostate cancer in a cohort of farmworkers in California. The study population selected for the study was California farmworkers that were members of the United Farm W orkers (UFW) of America, a largely Hispanic labor union that has existed since the mid

- 1960s. Based on this study population, the investigators identified prostate cancer cases using the California Cancer Registry for the years 1987

- 1999. Controls were r andomly selected from the remaining cancer

- free member of UFW and matched to prostate cancers cases on a 5:1 ratio based on age. After identifying cases and controls, the investigators performed a pesticide exposure assessment for each study subject using pesticide usage data from the California County Agricultural Commission that included farmer reports on the type of pesticides applied, location and timing of application, application method, acres treated, and total amount of active ingredient applied. Using this pesticide data on 16 different pesticides, the investigators calculated county

- level annual pesticide usage and linked UFW cases and controls to particular years and counties based on UFW employee records. This linked annual county

- level usage data was then summed for each study subject and weighted scheme was applied in which heavier weights were assigned to chemicals with signal words indicating higher toxicity ( i.e. , danger/poison= 3, warning= 2, caution= 1).

EPA Review of Results

Mills and Yang (2003) reported that there was an increased risk of prostate cancer for dichlorovos, lindane, heptachlor, and simizine, but none of the other 12 pesticides evaluated in their study. Of the four pesticides with positive association, only the OR for s imizine was statistically significant (OR = 1.53, 95% CI: 1.02

- 2.28). The investigators also analyzed the gradient of risk with use of simizine and the other pesticides. Based on this analysis, the investigators reported that the OR estimates increased n on

- significantly from 1.52 (95% CI: 1.00

- 2.34) in Level 2 exposure category to 1.81 (95% CI: 0.93

– 3.53). While the investigators reported these positive associations, the study findings should generally be considered exploratory. As with several of the previous studies reviewed in this Appendix, the study had broad research focus that evaluated the association between prostate cancer and multiple different pesticides. Additionally, the investigators also utilized county

- level pesticide use data to esti mate each study subject’s potential pesticide exposure. While this approach takes advantage of existing data, it may also introduce uncertainty into the results because county

level pesticide usage may not accurately reflect individual

- level exposure. Fu rther, this study provides no information about atrazine, only simazine, a member of the triazine common mechanism group; this study was discussed by EPA in the 2003 IRED.

Schroeder JC, Loshan AF, Baric R, Dent GA, Weinberg CR, Yount B, Cerhan JR, Lynch CF, Scuman LM, Tolbert PE, Rothman N, Cantor KP, and Blair (2001). Agricultural Risk Factors for t(14;18) Subtypes of Non

- Hodgkin’s Lymphoma. **Epidemiology** ; 12(6): 701

- 708.
Health Outcome Study Design Study Population Exposure Reported Association Non

- Hodgkin’s Lymphoma (NHL) Retrospective, Case

- Control Cases: Males aged 30 years or older diagnosed with NHL during In

- Person Interview

– Self

Atrazine OR (95% CI)

### 40 March 1981

- October 1983 and identified through the State Health Registry of Iowa. Controls: Males recruited through random

- digit dialing, Medicare files, and state death certificates Reported Pesticide Use 1.7 (1.0

- 2.8)

Schroeder, Loshan, Baric et al. (2001) indicate that the t(14;18) translocatio n is common somatic mutation that is believed to be an early component step in the pathogenesis of particular NHL subtypes and suggest that t(14;18)

- positive NHL cases may share a common casual factors. Based on this hypothesis, Schroeder, Loshan, Baric e t al. (2001) conducted a

case

- control study to examine if t(14;18) subgrouping enhances the ability to identify NHL risk factors among participants in the NCI sponsored population

- based case control studies mentioned above (See Brown et al. 1990, 1993; Can tor et al. 1992; Hoar Zahm 1993, 1993 (women only)). Among this series of studies, 780 cases were identified in white men aged 30 years or older, who were diagnosed between March 1981 and October 1983 and identified through the State health Registry of Io wa. Similarly, 1245 controls were recruited using random digit dialing, Medicare files, and state death certificate files and frequency matched to controls based on age, state, and vital status. After selecting cases and controls, the t(14;18) translocat ion status of cases was determined by analyzing archived biological samples. Based on this laboratory analysis, the investigators were able to determine NHL cases in which the t(14;18) translocation has occurred, i. e, positive cases. The investigators the n conducted in

person interviews to collect information concerning sociodemographic characteristics, tobacco and alcohol use, hobbies, pets, medical history, and occupational history. Based on the interview, participants who were identified as farmers wer e asked more detailed questions about their past use of pesticides and other farm activities. The investigators then used statistical

based simulation approach (i.e., Expectation

- Maximization algorithm) to impute t(14;18) subtypes for cases because archiv ed biological samples were not available for 70% of cases. After using this algorithm, unconditional logistic regression was used to evaluate the association between NHL t(14;18) subtypes and pesticide exposure with NHL.

EPA Review of Results



### Given the study sample was derived from the NCI conducted population based case control studies, the strengths and weaknesses of these studies apply equally to this investigation. Schroeder et al. (2001) reported non

- significantly elevated odds of NHL

amon g those exposed to atrazine and with the t(14:18) translocation (OR 1.7, 95% CI 1.0, 2.8), but not among those without the translocation (OR 1.0 (95% CI 0.60, 1.5). This is similar to the result reported in association with ever farming: OR for those with the t(14:18) translocation 1.4 (95% CI 0.9, 2.3), those without the t(14:18) translocation 1.0 (95% CI 0.8, 1.4). Authors did not observe an exposure

- response trend in these data, nor did they observe a link with duration of crop farming or livestock husba ndry. Other pesticide

- NHL associations were also modified by the t(14:18) translocation. Many suspected confounding variables were not associated with pesticide use or NHL in this study. Authors state the study offers some evidence of heterogeneity of eff ect by presence of the t(14:18) chromosomal translocation in the association between certain pesticides, possibly including atrazine, and NHL, however additional studies are needed to better understand whether effect modification is present, and present in other study populations. Results suggest future epidemiologic analyses may consider measurement

### 41 of the t(14:18) translocation, when possible, to clarify the nature of the association between the putative exposure and NHL.

Van Leeuwen JA, Waltner

- Toews D, Abernathy T, Smi B, Shoukri M (1999). Association between stomach cancer incidence and drinking water contamination with atrazine and nitrate in Ontario (Canada) agroecosystems, 1987

- 1991. **International Journal of Epidemiology** ; 28:836

- 840.

Health Outcom e Study Design Study Population Exposure Reported Association Cancer of the stomach, colon, ovaries, bladder, and Non

- Hodgkin’s Lymphoma Ecologic 40 Ecodistricts in Ontario, Canada during 1987

- 1991 Ecodistrict

- level water contamination and agricultural practice data - Atrazine and Stomach Cancer Positive Association:

- Atrazine and Colon Cancer Negative Association:



### Van Leeuwen , Waltner

- Toews D, Abernathy et al. (1999) conducted an ecologic study to investigate if there was an association cancer and atrazine and/or nitrate contamination and pesticide use practices during 1987

- 1991. The investigators used the Ontario Cancer Registry to estimate cancer incidence ratios in 40 ecodistricts in Ontario during 1987

- 1991. Using the Ontario Cancer Registry, age and sex

- specific standardized incidence rates were estimated for cancer of the stomach, colon, ovaries, bladder, and Non

- Hodgkin’s Lymphoma. The investigators evaluated population

- level exposure in each ecodistrict using water contamination available through the Ontario Drinking Water Surveillance Program and the Ontario Farm Groundwater Quality Survey. Based on these data sources, weighted average atrazine and nitrate levels were calculated based on population served within each ecodistrict. In addi tion to water contamination, the investigators evaluated land

- use data on pesticide, fertilizer, and manure applications that was available through the Canada Census of Agriculture and Survey of Pesticide Use in Ontario. The association between ecodistric t incidence of cancer and atrazine and nitrate levels was then evaluated using least squared regression analyses.

EPA Review of Results 

### As an ecologic analysis, this study aided hypothesis generation and is noted by several authors of analytic study desig ns as a rationale for their investigation. Independently, however, the study design does not offer evidence as to the nature of the association between triazine and various cancer sites evaluated. The relation with gastric and colon cancers is noted.

APPENDIX B.4: REVIEW OF AGRICULTURAL HEAL TH STUDY (AHS) NESTE D CASE

- CONTROL ANALYSES

Background



### Since 2003 there have been six nested case

- control analyses within the AHS which evaluated use of a number of agricultural pesticides, including the herbicide atrazine, in association with specific anatomical cancer sites. These include investigations of prostate (Alavanja et al. 2003) , lung (Alavanja et al. 2004) colorectal (Lee et al. 2007)

### 42 breast (among female spouses and female applicators in the AHS) (Enge l et al. 2005) pancreatic cancers (Andreotti et al., 2009) as well as cutaneous melanoma (Dennis, Lynch, Sandler, & Alavanja, 2010) . Concerning the evaluation of cutaneous melanoma and lung cancer with atrazine use, authors stated they did not observe any evidence of an exposure

- response trend, and, therefore, did not report atrazine

- specific risk estimates. For this reason, these studies are not further discussed in this appendix. In combination, these studies provide an important database of epidemiologic evidence pertaining to atrazine carcinogenicity. However, it is important to note that these studies were hypothesis

- generating in nature and did not posit a specific hypothesis or biological mechanism as to the carcinogenic mode of action of atrazine pe r se

. Given the similarity in design and methods across these investigations nested within the AHS, they are considered together in this Appendix. Table B

- 3a summarizes these study results. A general overview of the AHS including study design and methods , as well as specific case

- control study results is presented. EPA’s summary and review of these studies is also presented below.

Brief Overview of Design and Methods

The Agricultural Health Study (AHS) is a large, prospective cohort study comprised of p rivate and commercial pesticide applicators in Iowa and North Carolina. The study includes 57,310 licensed pesticide applicators, comprising 52,394 private applicators and 4,916 commercial applicators, as well as 32,346 spouses of pesticide applicators. R esearchers successfully recruited 82% of the target population into the AHS cohort which represents a high recruitment rate for an epidemiologic study. While farmer and pesticide applicator participants in the AHS are generally healthier than the overall U .S. population, AHS participants have a higher rate of some cancers including prostate, ovarian, lip, multiple myeloma (Alavanja et al., 2005; Koutros et al., 2010) . Lower rates of smoking and alcohol use, and the physically demanding nature of the occupat ion are health protective factors in the AHS population, and pesticides, viruses (animals), bacteria, sunlight, and other non

- pesticide chemicals may be putative risk factors for carcinogenesis among these farmers.

Pesticide applicators must obtain a lic ense from the state to purchase and use restricted

- use pesticides. Participants in the AHS were enrolled into the study at county pesticide licensing facilities and were asked to complete a 21

- page written enrollment questionnaire. Enrollment occurred ov er a period of 4

- years, December 13, 1993 to December 31, 1997 (“Phase I”). The Phase 1 “enrollment” questionnaire solicited information concerning types of agricultural crops and livestock produced, types of pesticides used, pesticide application methods , use of personal protective equipment, and, lifestyle factors such as smoking and alcohol intake. A portion of the cohort also completed a “take

- home” questionnaire (~40%) in which additional lifestyle (e.g., diet) and chemical exposure information (i.e. , an additional 28 chemicals) was ascertained.

To determine case

- and vital

- status, cohort members were linked to state cancer registries in Iowa and North Carolina and the state death registries and the National Death Index, respectively. Linking was accomplished through use of social security

### 43 number, first and last name, date of birth, and gender. Study participants who were alive but no longer residing in either study states were identified through the Federal Internal Revenue Service address file, motor vehicle registration records, and the restricted

- use pesticide license and certification records of the departments of agriculture in Iowa and North Carolina. Less than 2% of the cohort has been “lost

- to

follow

- up,” i.e., can no longer be located fo r purposes of the study. This is a very low percentage lost to follow

- up, reducing the chance of selection bias in this prospective cohort study.

To measure atrazine exposure, AHS researchers considered three exposure metrics: (i) whether participants eve r used the herbicide; (ii) the cumulative exposure days (the total number of exposure days per year, and total number of years in lifetime); and, (iii) an intensity weighted cumulative exposure metric. Exposure information was collected via self

- report que stionnaire responses. The “ever used” metric dichotomized atrazine exposure into ever/never categories where “ever used” reflects at least time use during the working lifetime. The lifetime exposure

- days metric was calculated by taking the product of the t otal number of years atrazine was applied and the number of days per year atrazine was applied. The intensity

- weighted lifetime exposure day metric includes: the frequency and duration of application (lifetime exposure days), application methods, mixing and equipment repair status, and use of personal protective equipment. These factors were weighted to reflect the intensity of the exposure based on monitoring data available in the published literature. Methods of pesticide exposure assessment used in th e AHS have been reviewed extensively and shown to have high reliability and validity (Blair et al., 2002; Blair et al., 2011; Hoppin, Yucel, Dosemeci, & Sandler, 2002)

.
Results of Nested Case

- Control Analyses

Prostate Cancer

Alavanja et al. (2003) evaluated prevalence of pesticide usage between cases of prostate cancer (n=566) diagnosed through 1999, and AHS cohort members without a prostate cancer diagnosis (n=54,766). In this study, researchers examined 47 different pesticid es in association with incident prostate cancer, including atrazine. The odds of prostate cancer comparing ever

- users of atrazine to never users did not differ from the null (OR 0.94, 95% CI 0.78, 1.14). Across quintiles of cumulative pesticide exposure da ys, no evidence of a trend for atrazine was observed (p for linear trend 0.34), and odds ratios were not elevated: 1.0 (reference), 1.02 (95% CI 0.79, 1.31), 0.91 (95% CI 0.71, 1.18), 0.89 (95% CI 0.65, 1.23), 0.82 (95% CI 0.54, 1.25), and 0.97 (95% CI 0.6 3, 1.48). Further, there was no evidence of heterogeneity of results by presence of a first

degree family history of prostate cancer; the interaction rate ratio was 1.52 (95% CI 0.88, 2.62), p for interaction 0.13). Researchers were able to control for ag e, race and family history, in addition to use of other correlated pesticides and confounding variables in the analyses presented. Strengths of this study include the ability to adjust for prostate cancer risk factors as well as other potentially confoundi ng variables, the sample size and ability to investigate atrazine exposure using several different exposure metrics, including the investigation of an exposure

- response trend. In addition, as a

### 44 nested study within the prospective cohort, issues regarding t emporality of the exposure

- disease relation are reduced. Overall, authors did not observe evidence of a statistical association between atrazine use and prostate cancer.

Breast Cancer

Engel et al. (2007) evaluated the risk of breast cancer in association with several pesticides including atrazine among female spouses in the AHS. Both direct and indirect pesticide exposure was estimated for wives based upon applicator husband’s questionn aire responses. There were 309 new cases of breast cancer diagnosed through 2000 among 30,454 female spouses. Overall as a group these women as a group experienced fewer cases of breast cancer than the general population of the respective AHS study states (IA and NC). Concerning atrazine use, women who reported directly applying atrazine ever in their lifetime were not observed to have an increased risk of breast cancer (OR 0.70, 95% CI 0.40, 1.2), however only 11 atrazine exposed breast cancer cases were i ncluded in the analysis (Engel et al., 2005)

. Similarly, among women whose husband’s reported ever

- using atrazine as compared to women who never used atrazine, no increased risks were observed (OR 1.1, 95% CI0.70, 1.6). Analyses were adjusted for age, race and state of residence as other breast cancer risk factors were not confounding variables in this association. Authors attempted to stratify by state of residence, but there were too few direct users of atrazine in North Carolina, one of the two AHS study states, to perform this analysis. Authors did not report a difference in the indirect exposure to atrazine and breast cancer association by state of residence. Authors reported that overall a woman’s risk of breast cancer increased with closer residential home proximity to an agricultural field, however this finding is not specific to atrazine use. Strengths of the study include the quality of the outcome assessment, ability to adjust for several potential confounding variables, and study design which assu res exposure precedes disease. However, the authors were only able to investigate ever

- use of atrazine at this time, and no exposure

response information was attempted. Overall, these data are not supportive of an association between atrazine use and breas t cancer risk.

Colorectal Cancer

Lee et al. (2007) explored the association between use of many different pesticides and the odds of being diagnosed with colorectal cancer (analyzed separately as colon cancer, rectal cancer and colorectal cancer (groupin g cancers of the colon and rectum). In a large nested case

- control analysis within the cohort (n=56,813), investigators compared pesticide use including atrazine between 305 colorectal cancer cases, and all other non

- colorectal cases in the AHS cohort who met the eligibility criteria. Cancer cases diagnosed through 2002 were included in the analysis. Overall, among the 50 pesticides evaluated, researchers observed few instances of an association between pesticide use and this cancer. Concerning atrazine, au thors did not observe evidence of an association between ever use of atrazine and colorectal cancer (OR 0.9, 95% CI 0.70, 1.2), colon cancer (OR 0.80, 95% CI 0.60, 1.1), or rectum (OR 1.2, 95% CI 0.70. 2.0), adjusting for age, smoking and total days of use of all pesticides. There were over 30 atrazine exposed cancer cases in each analysis. In this investigation, authors only

### 45 reported the atrazine ever

- use exposure metric, as no evidence of an atrazine exposure

- response trend was observed. Authors state tha t the reliable method of lifetime exposure assessment, high validity in the method of cancer ascertainment, the use of appropriate measurements of and adjustments for relevant confounders (including use of other pesticides), are strengths of this study. Ov erall, this study did not observe evidence of an association between atrazine use and colorectal cancer.

Pancreatic Cancer

Andreotti et al. (2009) compared pesticide use, including atrazine, between 93 pancreatic cancer cases and 52,721 non

- cancer privat e applicators and 29,782 spouses of applicators. Cancer cases were diagnosed through 2004. Adjusting for age, smoking, diabetes status and applicator type, authors did not observe evidence of a statistical association with ever use of atrazine (OR 0.70, 95 % CI 0.40, 1.2). Further, authors evaluated exposure response trends by comparing never users with those in the lower

- and upper

- half of the exposure distribution (intensity

- weighted exposure days split at the median among controls) and did not observe evi dence of a difference in odds by exposure category (1.0, lower OR 0.80, 95% CI 0.50, 1.5), upper OR 0.60, 95% CI 0.30, 1.2), nor did researchers report evidence of a trend (p for trend 0.12). Authors could not adjust for a family history of pancreatic canc er due to lack of specific information regarding family history of this type of cancer. Family history is a strong risk factor for pancreatic cancer. Authors posited no a priori association between atrazine use and pancreatic cancer, and authors did not ob serve evidence of a link between use of this herbicide and this anatomical cancer site. Strengths of this investigation are the relatively large sample size and number of exposed cases (n ≥15) for a study of pancreatic cancer, a rare cancer outcome in the p opulation. In addition, the prospective nature of the study design ameliorates concerns regarding the temporality of the exposure

- disease relation, and the large amount of information collected through the AHS allowed investigators to investigate and stati stical control for a number of confounding variables in the analysis. As a hypothesis

- generating analysis, and lack of biologically plausible connection between atrazine and pancreatic cancer, or lack thereof, these data are considered preliminary at this time. The current study does not suggest an association between atrazine use and pancreatic cancer exists.

Strengths and Weaknesses of AHS Studies

The AHS includes both strengths and weaknesses. The large sample size and sufficient statistical power to investigate the potential association between atrazine use and several cancer sites including prostate cancer is a strength of the study. In addition, given the prospective study design the potential for recall bias (differential exposure measurement error ) is eliminated, as pesticide exposure information was collected prior to the identification of disease. Exposure measurement error exists in this study (Blair et al., 2011) , however it is likely non

- differential in nature and would attenuate, and not fals ely inflate, measured risk estimates. This is particularly true for two

- level exposure metrics. Selection bias is considered of low potential as very few participants have been lost to follow

- up in this cohort ( i.e ., few participants dropped out of study o r were unable to be followed through other means). In this cohort, cancer cases were ascertained

### 46 through linkage with state cancer registries, and include histopathological confirmation as well as information as to stage and grade of cancer at diagnosis. H igh quality outcome ascertainment reduces the potential for outcome measurement error. The AHS collects a vast amount of information for use in statistical analysis including prostate cancer risk factors such as age, race and family history of prostate can cer; cancer risk factors such as smoking and alcohol use; and, use of other correlated pesticides. Lastly, the AHS exposure measurement tools have been illustrated to be valid (Hoppin et al., 2002) and reliable (Blair et al., 2002) , and provide a quantitat ive measure of pesticide exposure over the working lifetime.

In combination, these studies provide an important database of epidemiologic evidence pertaining to atrazine carcinogenicity. However, it is important to note that most of these studies are hyp othesis

- generating in nature and did not propose a specific biological mechanism as to the carcinogenic mode of action of atrazine per se . The recent evaluation (Beane Freeman et al., 2011) was able to test hypotheses related to prostate, breast, ovarian a nd NHL as these sites have been previously suggested to be related to atrazine use. This study extends research from the cohort initially reported in 2004 (Rusiecki et al., 2004). These results are discussed within EPA study reviews included in Appendix B

- 5.

### 47 Table B

- 4a: Summary of AHS Nested Case

- Control Study Results Cancer Endpoint Sample Size Exposure Assessment Adjustment Risk Ratio

Prostate 566 cases, 54,766 controls; self

- reported use atrazine age, family history of prostate cancer ever

- use atrazine: OR 0.94

( 95% CI 0.78

- 1.14) (OR per quintile LTED ~1.0, p

- trend, 0.34) Lung 57,284 pesticide applicators and 32,333 spouses; 300 Lung cancer

cases self

- reported use atrazine n/a no exposure

response trend observed triazines/atrazine; no results shown Breast 309 cases, 30,454 controls self

- reported use atrazine age, race OR 0.70 (95% CI 0.4, 1.2) among wives who directly apply Colorectal 305 cases, 56,813 controls self

- reported use atrazine Age, smoking, state, total days of pesticide application among all enrolment applicators. Colorectal : ever

use atrazine OR=0.9 (95% CI 0.70, 1.2); Colon OR=0.8 ( 95% CI 0.60, 1.1); Rectum OR=1.2

(95% CI 0.70, 2.0) Pancreatic 93 incident pancreatic

cancer cases, 82,503 cancer

free controls self

- reported use atrazine age, smoking, diabetes, applicator type, 5 most highly correlated pesticides OR 0.70 (95% CI 0.4

- 1.2)

Cutaneous Melanoma 150 incident melanomas among 24,704

applicators self

- reported use atrazine n/a no exposure

response trend observed triazines/atrazine; no results shown

### 48 APPENDIX B.5: REVIEW OF ATRAZINE CANCER E PIDEMIOLOGY STUDIES PUBLISHED SINCE 2003

Beane

- Freeman et al. (2011). Atrazine and Cancer Incidence Among Pesticide Applicators in the Agricultural Health Study (AHS)

Researchers with the Agricultural Health Study (AHS) recently updated their previous atrazine cohort analysis (Rusiecki et al., 2004) with approximately twice as many cancer cases (Beane Freema n et al., 2011). The recent evaluation included 3,146 cases of cancer whereas the preliminary atrazine cohort study included 1,785 cancer cases. In addition, as compared to the initial analysis Beane

- Freeman et al. (2011) included use of an updated exposur e algorithm that increased the protective factor for use of chemical resistant gloves, and weighted more heavily the exposure potential for use of broadcast spray application methods, among other changes noted by authors.
In their updated analysis, Beane

- F reeman et al. (2011) included 53,663 private and commercial pesticide applicators, after excluding participants due to prevalent cancers and missing information. Authors assigned atrazine exposure categories based upon all cancer cases combined, and report ed results for atrazine

- cancer associations for which 20 atrazine exposed cancer cases were observed. In addition, based on a priori information, authors also evaluated the relation between atrazine and breast and ovarian cancers. Authors were able to adju st for age, race, gender, smoking, alcohol use, education, state of residence, family history of specific cancers, applicator type (private or commercial), and ever

- use of other pesticides highly correlated with atrazine use including dicamba, cyanazine, m etolochlor, trifluralin, and 2,4

- dichlorophenoxyacetic acid (2,4

- D).
Concerning the evaluation of both lung and bladder cancer, authors further adjusted for smoking using various other metrics ( e.g. , pack years smoked). In the evaluation of both breast an d ovarian cancers, authors used exact methods to calculate the confidence bounds as the number of female applicators who were exposed to atrazine and diagnosed with these cancers was small. Because the lowest exposed group, and not the no exposed group, wa s more similar to the upper quartiles of atrazine exposure, authors utilized the lowest exposed category as the referent. Authors stated that results, were similar using either reference group. Additionally, authors stratified by state and applicator type to learn whether evidence of effect modification by these factors was present.
Authors noted that while more private than commercial applicators reported using atrazine, the number of exposure days was greater among commercial applicators. Overall, author s observed no association between atrazine use and all cancers combined, or with either prostate, or lung cancers which are among the most common cancers in the population. Among 29 male cases of thyroid cancer, authors observed some evidence of an associa tion with both lifetime days (LTED) of use and intensity

weighted lifetime days (IWED) of use, but no linear trends across quartiles of atrazine exposure (p for trend LTED 0.61, IWED 0.08). Comparing the upper

- quartile to the lowest quartile, elevated odds of thyroid cancer were observed for both LTED (OR 2.32,

### 49 95% CI 0.66, 8.22), and IWED (OR 4.84, 95% CI 1.31, 17.93). Authors also noted that adjustment for body mass index (BMI), a known risk factor for thyroid cancer, did not alter the inferences for the atrazine

- thyroid cancer association. As noted by authors, there are several cautions to consider in the interpretation of these data including: the test for linear trend was not significant; the exposure

- response trend was not monotonic in nature; the conf idence bounds were wide and included 1.0 for some quartiles; and there were less than five exposed cases in some exposure groups. In addition, there were too few exposed cases to examine atrazine

- thyroid cancer by gender, only one female atrazine exposed case of thyroid cancer, by state or by applicator type. This is the only point estimate identified in the atrazine cancer epidemiology literature for thyroid cancer.
Authors also investigated the association between atrazine exposure with breast and ovaria n cancers among female pesticide applicators enrolled in the AHS. However, because there are few female cancer cases in the AHS, investigators were only able to consider ever

- use of atrazine in association with these cancer outcomes; authors did not perfor m an exposure

- response evaluation. Among 36 breast cancer cases in the cohort, authors observed a slight statistically association with atrazine (OR ever use atrazine 1.14 (95% CI 0.47, 2.50), compared to never users of atrazine), however results were no t significant and confidence bounds was wide. Results were similar comparing the upper

- and lower

- exposed groups, divided at the median, according to the authors. Among nine cases of ovarian cancer, authors did observe evidence of an association: OR ever use atrazine 2.91 (95% CI 0.56, 13.60). There were four atrazine exposed ovarian cancer cases, and five never users of atrazine included in this analysis; authors stated that all nine of the cases reported days of atrazine use that were within the lower ha lf of the exposure distribution, i.e., below the median (p50). Authors adjusted for age only in both the breast and ovarian cancer analysis, as other cancer risk factors were not confounders in the association with atrazine.
Additionally, authors also obs erved that there were over 300 incident cases of lymphohematopoietic cancers diagnosed between enrollment and 2007 among 36, 357 atrazine users. The authors observed no evidence of an association with any lymphohematopoietic cancer, including non

- Hodgkin lymphoma (NHL), or NHL sub

- type using with the cumulative exposure measure of the intensity

- weighted exposure measure. Across quartiles of atrazine exposure and within specific lymphohematopoietic cancer sub

- types, risk estimates with atrazine did not appr eciably differ from the null. Specifically, confidence bounds included 1.0 in each comparison, and tests of linear trend were not statistically significant. In addition, authors did not observe evidence of interaction (supra

- additive effects) between atra zine exposure and other pesticides (alachlor, carbofuran, diazinon) as noted in other population

- based studies (De Roos et al., 2003)

. Concerning other anatomical cancer sites, some evidence of significant or borderline significant putative (esophageal, o ral cavity) as well as protective (pancreatic, laryngeal) associations with atrazine were observed. However, given the lack of a priori hypothesis, multiple statistical comparisons made within the study, and lack of biological plausible link, authors did n ot report these as notable results.

### 50 Beane

- Freeman et al. (2011) observed some evidence of an association between atrazine and thyroid as well as ovarian cancer, but overall there was no evidence of an association with all cancers combined, or wi th most of the specific anatomical cancer sites evaluated. Authors noted that both thyroid and ovarian cancers are hormonally

responsive, endocrine or reproductive system cancers, and given the understood mode of action of atrazine, neuroendocrine effects, these statistical associations were plausible. However, limited evidence in the experimental literature, as well as within other published epidemiology studies, suggest an association between atrazine and these cancer sites. Authors note that chance canno t be excluded as a rationale for these findings, however a limited number of other epidemiology studies have documented a possible link with ovarian cancer. EPA identified no other investigation of a link with thyroid cancer however. Concerning the ovarian cancer finding, as stated above, authors were only able to evaluate ever

- use of atrazine in relation to this cancer site; no exposure

- response analysis could be performed. Factors that support the association include the relative strength of the associati on, possible biological role, and lack of significant biases in the analysis including selection bias, or confounding bias, or temporal bias are strengths of this study. EPA notes that no specific mechanism for atrazine in the etiology of these cancers has been identified. The thyroid cancer finding requires replication and further study, as this point estimate is the only one available in the literature to EPA’s knowledge. EPA Review

It is notable that authors observed no evidence of an association with prostate canc er in this study. This investigation, similar to the initial atrazine cohort analysis by Rusiecki et al. (2004), was sufficiently statistically powered to observe an association, if one existed. Similarly, authors did not observe evidence of a link with lu ng, breast (ever

- use of atrazine only), or colorectal cancer, among the most common cancers in the U.S. In addition, the lack of evidence of a statistical association with leukemia or lymphomas, including several sub

- types of these cancers, is notable give n there was some weak evidence of a role for atrazine in these cancers published earlier in the literature, and reviewed by EPA within the Chapter.
Strengths and limitations of the AHS have been noted elsewhere (Appendix B

- 4). Briefly, the large sample siz e and prospective nature of the study, as well as the extensive exposure measurement and data collection allow robust epidemiological investigation of pesticide in association with atrazine. In addition, study design and methods significantly reduce the po ssibility for several systematic biases including selection bias (low loss to follow up rates), confounding bias (demographic, cancer risk factors, and use of other pesticide information available for use in statistical analysis), and high

- quality retrospe ctive exposure analysis reduces the potential for exposure measurement error. However, regarding exposure measurement error, authors acknowledge this likely occurred and have performed evaluations to determine the extent of the influence of this bias on ri sk estimates (Blair et al., 2011) . Weaknesses include utilization of ever

- use of atrazine exposure metric in the breast and ovarian cancer analysis, possibility of exposure measurement error which likely, but not always, results in non

- differential exposur e misclassification, and the possibility of unmeasured

### 51 confounding variables in the estimation of this association. Further, the study is comprised of demographically white, male pesticide applicators. Therefore, information concerning the nature of the as sociation between atrazine and cancer in other populations is also needed.
Overall, the researchers observed some evidence of a possible association between atrazine and ovarian and thyroid cancers; however lack of an exposure

- response analysis and small number of exposed cases as well as the lack of other corroborating information in the epidemiologic literature limit the ability to make a determination of causality at this time. Concerning other anatomical cancer sites inkling prostate, lung, colorectal, breast (ever

- use of atrazine only), and lymphohematopoietic cancers including NHL and NHL sub

- types, authors did not observe evidence of an association with lifetime use of atrazine in this cohort.

Carreon et al. 2005. “ Gliomas and Farm Pesticide Exposu re in Women: The Upper Midwest Health Study.”

Ruder et al. 2004. “ Gliomas and Farm Pesticide Exposure in Men: The Upper Midwest Health Study.”

Authors performed a population

- based case control investigation of the association between pesticide exposure a nd gliomas, a type of brain cancers, among participants living in the upper mid

- western states of Iowa, Michigan, Minnesota, and Wisconsin. Authors separately reported results for men (Ruder et al. 2004) and women (Carreon et al. 2005), but both reports em anated from the same study. The study by Carreon et al. (2005) provides complete detail regarding study design and methods. Therefore, these studies are considered together herein.

Authors performed the study within several counties among the four study states with high agricultural use, and low population density, i.e. , less than 250,000 persons within major population areas. Researchers included histopathologically confirmed glioma cases diagnosed between 1995

- 97 through rapid case ascertainment (case i dentified in the database within 3 weeks of diagnosis). Cases were identified through interaction with medical offices or neurosurgeons; authors reported that case ascertainment rates ranged from 65% to 86% across the four study states. Authors did not exc lude participants who had a previous cancer diagnosis. Controls were women without a glioma diagnosis. Cases and controls were frequency

- matched 1:1.5 on 10

- year age categories, based upon the distribution of glioma cases in the state in previous years (ex pected distribution of cases based upon past population prevalence). Cases and controls resided in the same state, but not necessarily in the same counties within the state. Researchers identified controls through either state DMV (ages 18

- 65), or state he alth care files (ages 65

- 80).

Upon receipt of physician consent, cases first received a letter of introduction, followed by an in person interview. Those who refused to participate were asked to complete a

### 52 short questionnaire collecting information on relevant demographics. Women were asked whether they lived or worked on a farm, and if so when and how long. Among women who indicated they directly applied pesticides, a list of pesticides was provided. Researchers restricted the period of exposure assess ment through 1993, as cases were diagnosed 1995

- 97 and pesticide exposures within 2 years of diagnosis were likely not relevant to the development of the disease, if an association exists. Authors used a previously validated questionnaire to collect inform ation concerning pesticide exposure. Upon completion of the self

- administered questionnaire, a trained industrial hygiene professional reviewed the responses, and participants were contacted again if additional information was needed. Researchers used a pu blicly available (NIOSH) database to identify the active ingredients associated with the reported trade names from the list provided to participants. Authors utilized the same information collection methods between cases and controls including a standardiz ed interview, intermittent re

training of interviews within the study period, and blinding of interviews to the study hypothesis. If selected cases were unable to participate due to death or incapacitation, a first

- degree relative was sought as a proxy res pondent.

The final study sample included 341 cases and 527 controls which was 90% and 76% of the eligible cases and controls respectively. Most of the participants were non

Hispanic white (97%). All statistical analyses were adjusted for age and state (ma tching variables). Analyses suggest the control series was comparable to the general population; cases were selected among all cases in the study area and ascertainment rates were moderate to high across the study states (65

- 82%). Forty

- three percent of

ca ses and 2% of controls responded by proxy. Cases were younger than controls and lived on a farm for a shorter period of time. Women were less likely to apply pesticides, but more likely to launder pesticides in the overall study sample.

Authors reported little evidence of an association between triazine or atrazine use and gliomas. The results include: ever

- use of an herbicide, OR 1.0 (95% CI 0.6, 1.5); triazine OR 1.0 (95% CI 0.6, 1.7); and atrazine OR 1.1 (95% CI 0.7, 1.8). The risk estimate for atrazin e excluding proxy respondents was slightly higher, but did not reach statistical significance. Similarly, authors reported no evidence of an association between triazine use and glioma among men in a separate publication (Ruder et al. 2004).

EPA Review

Authors performed a hypothesis

- generating evaluation of pesticide exposure in relation to glioma diagnosis. There are many strengths to this study. Investigators were able to compare characteristics of those included and excluded from the study and assess potential systematic bias. Through design, authors modeled exposure information that preceded disease diagnosis, use of a 2

- year lag in pesticide exposure. Authors used several quality assurance and control methods including standardized interview techniq ues, as well as interviewer training and blinding to study hypothesis to reduce observer bias. However, there are some limitations to consider including differential

### 53 recruitment rates between cases and controls (90% and 76% between cases and controls), and the differential use of proxy respondents between cases and controls. These differences may lead to systematic biases in the study. While authors used expert judgment to assign exposure category which is an improvement over other commonly used methods, so me exposure measurement error likely occurs.

Selection bias in a case

- control study could occur if the control series is not a good approximation of the population from which the cases arose. In this study, authors acknowledged some under

- ascertainment o f cases when compared to state cancer registries (14

- 35% under

- ascertainment). Given the difficulty discerning symptoms of glioma, e.g. , disrupted mental functioning, from other common morbidities of older age, there is a known under

- ascertainment of gliom a among the elderly. Authors did not comment as to the possible ways included and excluded cases compared. Differences between included and excluded cases could include dissimilarities in access to health care, health seeking behaviors, severity of symptom s possibly related to progression of tumor or severity. If these differences were related to pesticide exposure, a selection bias could have occurred, however this possibility has not been assessed. Authors note that controls are similar to the underlying general population on several important characteristics indicating controls are a representative sample of the general population. However, cases may not be representative of all cases.

It should be noted that brain cancers are a diverse group of brain c ancers. In this study, authors restricted case selection to histopathologically confirmed cases of glioma. The homogeneity in case definition likely resulted in improved precision in the risk estimates presented, however there are sub

- types of glioma. Auth ors did not restrict eligibility to only primary cancers, therefore secondary cancers may have been included in this study. Authors did not comment as to the possible effect of including primary and secondary cases in the study, however this decision may h ave obscured true associations.

Recall of pesticide exposure information over a lifetime is always a challenge. When studying brain tumors (glioma), it is possible that this recall is influenced by the disease, i.e. , those with the disease would have a mo re difficult experience recalling exposure. Among 43% of the cases and 2 % of controls, family proxies were used to provide pesticide exposure recall. Non

- differential recall bias is likely to have occurred, thereby reducing the magnitude of the risk estim ate toward the null value. In addition, as authors acknowledge, given the large proportion of proxy respondents a differential recall bias cannot be completely excluded as an explanation for the findings, however the comparability of results between the di rect respondents and the proxy and direct respondents grouped together somewhat lessens this concern. Overall, authors did not observe evidence of an association between atrazine and glioma in this hypothesis

generating study, however the potential influen ce of systematic biases including information, and possibly selection bias, is not discussed by authors. The study provides insufficient information to assess whether an association exists.

De Roos et al. 2003, “Integrative assessment of multiple pesticides as risk factors for

non

- Hodgkin’s lymphoma among men.” [Occup Environ Med 2003;60:e11]

### 54 Summary

Authors performed a pooled analysis of three population

- based case control studies conduct ed by the National Cancer Institute in the Midwestern United States in the mid

1980’s (See Appendix B

- 3) to investigate the link between pesticide use and non

Hodgkin lymphoma (NHL). Analyses were largely hypothesis

- generating and exploratory in nature, h owever authors note previous research regarding potential association between both lindane and atrazine with NHL cases as a priori hypotheses of interest in the pooled analysis.

Specific observations (data points) from three population case

- control studie s were “pooled” in this one analysis of the association between pesticide use and NHL. Hierarchal regression techniques use available information (pesticide class, functional group, carcinogenic classification) to estimate a “prior” distribution of the pe sticide

- NHL risk relations, and adjust observed associations (results of pooled analysis) toward the “prior” distribution, thereby using other information to inform the true shape of the exposure

- response curve in the current evaluation using these techniq ues. Hierarchal regression can add precision and accuracy to risk estimates, reflective of the quality of the “prior” distribution.

Although each of the three population

- based case

- control studies reflected slightly different enrollment criteria, outcome ascertainment, exposure assessment methods, among other differences, authors determined it was appropriate to pool the data. As discussed briefly in Appendix B

- 3, cases were ascertained through either hospital

based registries or state cancer registries in the mid

- 1980s. For this study, cases ascertained through the three afore mentioned studies, were matched to geographic

specific population controls on age, race, gender and whether a proxy respondent was used (if selected case or control had died). Author s excluded women (too few) and those who used pesticides less than 18 years of age only (no adult use). Only pesticides reported across all three studies, and for which at least 20 participants reported using were included. Participants with missing inform ation for any of the pesticides included in the pooled study were also excluded. After exclusions, 650 NHL cases and 1933 matched controls were selected into the pooled analysis.

Based upon responses in the three studies and the degree of missing pesticide exposure data, authors selected 47 pesticides to be part of the hierarchal, multi

variable, pesticide adjusted analyses. Logistic regression analyses were adjusted for age, geogr aphic area. Hierarchal regression techniques included retaining the maximum likelihood estimates (MLE) of the pesticide

- NHL logistic regression, and regressing those estimates on the “prior” distributions of NHL risk in association with specific pesticides . “Prior” distributions were defined considering pesticide class, functional group and cancer classification. These adjusted priors were then regressed on the coefficients from the first (logistic) regression model, to obtain an hierarchal adjusted estimat e of specific pesticide

- NHL combinations, while controlling for all other (47) pesticides and assuming a certain parameter for population variance, based upon

### 55 the prior distribution. In sensitivity analyses, authors also ran models assuming no prior infor mation, i.e. , all pesticides had an equal probability of association with NHL, regardless of class, functional group or previous cancer classification. Researchers also modeled NHL risk in association with total number of pesticides ever used in the lifeti me, and total number of “potentially carcinogenic” pesticides defined based upon previous research.

Overall, authors did not observe strong evidence of specific associations between pesticides and NHL in this pooled analysis. However, researchers reported statistically

significant 50% increased odds of NHL in association with exposure to atrazine (hierarchal regression adjusted odds ratio (OR) 1.5 (95% confidence interval (95% CI), 1.0 to 2.2)), adjusting for exposure to all other pesticides (47). A positi ve association between glyphosate and NHL was also observed (hierarchal regression adjusted OR 1.6 (95% CI 0.9 to 2.8). Researchers reported approximately 2

- fold increased odds of NHL for participants who reported using 5 or more pesticides, or 5 or more “ potentially carcinogenic” pesticides. In a joint

- effects model, those who used both atrazine and alachlor were reported to have a 60% increased odds of NHL in comparison to those who used neither of these 2 herbicides.

EPA Review

Authors reported that the use of “adjusted priors” had little effect on point estimates, indicating the prior knowledge of general associations between these pesticides and NHL is limited. A main strength of the study is the analysis of atrazine

- NHL risk while controlling for several other pesticide exposures over the lifetime (47 pesticide co

adjusted in the analysis) using hierarchal regression techniques. Both the study design (pooled data analysis), and analysis (hierarchal regression) enhanced statistical power, and augme nted the precision and accuracy (mutual adjustment) of the risk estimates.

The selection of cases was clearly stated in the paper (and original papers), and the method of control selection likely allows for a reasonable and valid sample of the target pop ulation from which the cases arose. While selection of a control series that is representative of the source population from which the cases arose is often a challenge in population

- based case

- control studies, comparability of cases and controls across

man y demographic characteristics through use of matching in the study design, and the lack of strong statistical associations across the 47 pesticides, which would have been expected if an error in design had occurred, argue against a role of selection bias.

Cases were either hospital

- based or identified through state cancer registries, and case ascertainment during the time period of these three pooled studies was relatively high. In all instances, cases were pathologically confirmed, which enhances the val idity of the outcome assessment. For both cases and controls, information concerning pesticide exposure and other relevant demographic information was similar, however it is noted that for the states NE, IA, and MN, specific pesticide prompts were provided (“did you ever use X?”) while in KA an open ended question was used. However, authors report

### 56 that pesticide use was similar by state and case

- control status (this argues against information bias).

Limitations include the assessment of an ever

- use pestic ide exposure metric only, which disallows an assessment of exposure

- response trends. However, the primary goal of the authors was to present multi

- pesticide adjusted estimates of specific active ingredients linked with incident NHL across these studies. A validity study performed within one of the three pooled studies (pesticide sales records) indicated pesticide exposure was reported accurately by participants. Pesticide exposure assessment did reflect exposure over the lifetime, relevant to the etiology o f NHL as cancers are expected to have a 5

- 20 year latency period between exposure and development (and/or diagnosis) of disease, however no information as to trend, range of exposure, or measurement of exposure during critical adult or even early life expo sures is possible given the method of exposure assessment.

Authors measured lifetime pesticide use, prior to cancer diagnosis, targeting an assessment of incident cancer in association with pesticide use. Relevant confounders including age, race, gender, other pesticide exposure (the primary goal of the analysis), education, were measured and considered for analysis. Only those variables that were shown to be confounders in this study were included in final models, enhancing the statistical power of the s tudy.

Overall, the pooled analysis performed by DeRoos et al. (2003) provided a weighted average of the individual risk estimates reported in the three population

- based case control studies upon which the pooling was based; the use of prior distributions , albeit defined broadly, were not additionally informative in this analysis. While statistically significant results were observed for the association between NHL and atrazine, authors themselves cautioned against using specific pesticide

- NHL estimates to make causal inference, given the exploratory nature of the underlying studies and multiple statistical tests performed within the pooled study. Therefore, while the pooled study reduces the influence of random variability through increasing sample size (p ooling), and the hierarchal methods and parsimonious models selected further refine the estimate, results are only weakly suggestive of a possible link between atrazine and NHL.

MacElroy et al. 2007 “Risk of breast cancer for women living in rural areas f rom adult exposure to atrazine from well water in Wisconsin.”

Authors performed a population

- based case

- control study of atrazine exposure and breast cancer among 22,495 women residing in the state of Wisconsin. Women were eligible for inclusion in this s tudy if the following criteria applied: English

- speakers, residence in the study area, age 20

- 79, listed telephone number. Cases included women who were diagnosed with breast cancer between the years 1988 and 2001, and reported to the state tumor registry. Controls were randomly selected from state DMV (20

- 65 years) and Health Care Finance Administration (65

- 79 years) records to roughly approximate the age distribution of cases (10

- year age categories), and for whom no previous breast cancer diagnosis was m ade. Eighty

- three percent of eligible cases and

### 57 controls were enrolled into this study. Investigators were interested in atrazine exposure from untreated well water used for drinking water. Therefore, authors restricted the study population to those who re sided in a rural area for whom well

- water would likely supply local drinking water defined as a region with no public water system. Upon applications of the eligibility and restriction criteria, 3,275 case and 3,669 controls were selected into this study.

Participants were first contacted through a mailing, followed by a 40

- minute structured interview via telephone. The data collection period spanned 13 years, 1988

- 2001, and reflected three separate case

- control studies over this time period. Researchers

s olicited information regarding basic demographics, breast cancer risk factors, and residential history. Data were requested for the reference year: the year of diagnosis for cases, and the year approximating a case diagnosis year for the controls. Intervie wers were largely blinded to case

- status; interviewers reported knowledge of case

- status (obtained during the course of the interview process) in 12% of case interviews and 21% of control interviews.

Concentration of atrazine and atrazine metabolites in well water which provided the sole residential drinking water source for participants in this study was measured in a state survey of pesticide contamination during three survey years: 1994, 1996, and 2001. Using a stratified random sample approach, repres entative atrazine well water concentrations were measured in one well within each “civil section,” a sub

- unit of the county defined in public land use surveys. Exposure assessment was pseudo

- ecologic in nature in that the atrazine concentration in well wat er within the “civil section” was assumed to represent the well water (drinking water) concentration for individual participant residences within that “civil section.” Across the three sampling years, well water samples were taken during both an atrazine “high use” period (May

- Oct.) and an atrazine “low use” period (Oct.

- May). In addition, for a sub

- set of the wells measured, repeated measures were taken between 2 sampling years. Investigators measured parent atrazine and chlorinated metabolites (deethylat razine, deisoatrazine, diaminoatrazine). To estimate atrazine exposure between sampling years of 1994, 1996, and 2001 to the entire study period of 1988

- 2001, authors utilized a “national neighborhood interpolation” method using geographic information syst em software (ArcGIS). Authors considered atrazine well water concentration within the entire state and within the highest agricultural area of the state separately, the south central WI region.

Authors estimated the association between atrazine concentration in well water and breast cancer risk using logistic regression, and modeling atrazine exposure as both a categorical (<0.15 ppb, 0.15

- 0.50 ppb, 0.50

- 1.0 ppb, 1.01

- 2.99 ppb, and greater than 3 ppb) using the lowest exposure group as referent, and as a continuous variable. In this study, approximately 20% of wells had measurable levels of atrazine, approximately 3% of the concentrations were greater than 3 ppb, the regulatory limit at the time o f the study. In the agriculturally intensive south central region of the state, 34% of wells had measurable atrazine concentrations. Researchers report that atrazine concentrations were decreasing over the period of the study.

### 58 Authors did not observe evi dence of an association between atrazine concentration in well water and breast cancer. Comparing those in the moderately high category to the lowest exposure category, minimal increased odds of disease were reported (OR 1.10, 95% CI 0.90, 1.40). Among par ticipants in the highest atrazine exposure area, odds of breast cancer was non

- statistically significantly elevated to 1.3 (95% CI 0.30, 5.0), however precision was low (n=3 atrazine exposed cases in the upper category).

EPA Review

This study presents l imited evidence of a role for atrazine drinking water exposure in relation to breast cancer. Authors utilized an available state survey of well water pesticide concentrations, including atrazine, geo

- coded residential address, and advanced methods to inter polate between study years to assess atrazine exposure through untreated well

- water supplied drinking water. There are several strengths to this method of exposure assessment. As compared to previous studies on this topic, which are largely ecologic study designs (with the exception of the AHS study of breast cancer among pesticide applicator’s spouses), these researchers were able to estimate atrazine drinking water concentrations in individual participants. They used a sophisticated method of interpolatin g aggregate data across study years, i.e. , national neighborhood interpolation which uses a weighted average which can change over time. Restricting the sample to rural residents, using untreated well water as the drinking water source represented a highly exposed sample of the general population enhancing the possibility of noting an effect if one exists. Collection of extensive residential histories allowed authors to characterize the method of exposure assessment, i.e., how well current residential addre ss approximate exposure during the critical exposure window during adulthood. In addition, authors collected well

characterized, high

- quality information regarding established breast cancer risk factors on an individual level for use in the statistical ana lyses of these data.

However, using these exposure methods, there are numerous possibilities for exposure measurement error in this study, several are acknowledged by the authors. Matching geo

- coded residence with concentration of atrazine in a well withi n the same “civil section,” authors assumed the atrazine concentration in one well would approximate all residential drinking water exposure supplied by wells. This is essentially a pseudo

ecologic method of exposure assessment, and likely resulted in a re asonable accurate ranking of atrazine exposure among the participants; however, some degree of exposure misclassification likely occurred. Authors summarized (averaged) atrazine well water concentration within study year, and then interpolated atrazine wel l water concentrations from the sampling sites to the entire state region. These modeling decisions likely resulted in a loss of precision, and represents lack of refinement in the exposure data, although the neighborhood interpolation method allows exposu res to fluctuate over time.

Authors discuss the role of residential mobility in relation to the method of exposure assessment, and conclude that because a majority of women resided in the current

### 59 (reference year) residential address for more than 10 year s, geo

- coding current address to measure with atrazine well water in the area is a good measure of lifetime (or at least ~20 year latency period of cancer) exposure. However, for a women diagnosed early in life, this exposure period may represent a lifetim e (childhood home), and for women diagnosed later in life the exposure period may or may not reflect the relevant etiologic window for breast cancer. In addition, authors assumed untreated well water concentrations approximate drinking water concentrations , and acknowledge likely non

differential measurement error in the lack of information regarding non

- residential drinking water consumption (bottled water, workplace, and restaurant). In addition, the etiologic risk factors, including the role of inherited genes, for breast cancers diagnosed in the 3 rd 

### and 4 th 

### decades of life in contrast to later life diagnoses likely differ. This may have resulted in a heterogeneity in the breast cancer cases, and possibly reduced the ability to see an association. Stratif ication by age category would have been informative. Results may have been affected by potential exposure measurement error and outcome heterogeneity, or no true association exists. This study is insufficient to determine whether an association between atr azine and breast cancer exists, however the data to not support the assertion.

Authors performed a hypothesis

- testing, cohort study using ecolog ic exposure assessment methods to evaluate the association between atrazine exposure and breast cancer among Latinas diagnosed with breast cancer. Invasive breast cancer cases were identified from the California state cancer registry (CCR) between the year s 1988 and 1999. The CCR collected information regarding tumor characteristics, diagnosis date and treatments, relevant demographic and reproductive history information. Counties for which fewer than 10 breast cancer cases were diagnosed in the study perio d were excluded. Individual level breast cancer data were compared with county level pesticide exposure, and grouped demographic data. Mills and Yang 2006. “Regression Analysis of Pesticide Use and Breast Cancer Incidence in California Latinas”

Pesticide use information between the years 1970 and 1988 was obtained from the California state pesticide use registry (PUR). Pesticide applications must be reported to the state and are recorded in a database (1970

- 1988). The database includes information concerning application date, location, crop, number of acres applied, pounds active ingredient per acre, among other r elevant information. Researchers examined associations for two time periods, by county and by pesticide type. Authors were interested in six pesticides, including atrazine and simazine.
Authors calculated standardized incidence ratios (SIR) using for 1988

- 1993 and then for 1994

- 1999 to reflect secular changes in breast cancer trends (screening, diagnostic tools, knowledge in population), and to examine latency between exposure and diagnosis. Pesticide exposure was categorized into quartiles, and estimates w ere adjusted for age, socio

- economic status (SES) and fertility. Co

- variables were defined at the group level, i.e., average household income for county as a measure of SES.

### 60 There were 23,513 incident cases of breast cancer in this study diagnosed and

reco rded at the CCR between the years 1988 and 1999. Established breast cancer risk factors were significantly associated with the outcome in this study population, e.g., age at first birth, parity. Adjusting for age and other co

- variables, authors reported no association between atrazine exposure and breast cancer comparing the highest and lowest quartiles of exposure (1988

- 1993: OR 0.86 (95% CI 0.70, 1.05); 1994

- 1999 OR 0.87 (95% CI 0.73, 1.04), p>0.05). Authors reported a slight elevated odds of breast

canc er in association with simazine exposure; however, results were not statistically significant.

Authors performed a large, cohort study of pesticide exposure and breast cancer in a highly exposed group among CA Latinas. Using high quality cancer registry outcome ascertainment was high and data quality acceptable. Using state pesticide use records is an innovative method to assess exposure, and is novel in its use of available data sources to address a public health concern. In this study, establis hed breast cancer risk factors were indeed significantly associated with breast cancer in this study. EPA Review

The major limitation of this study is the essentially ecologic nature of the exposure assessment. While useful in establishing support for novel hypothes es, these methods are limited utility in pesticide risk assessment. Authors assumed PUR reports for the county were a good approximation of pesticide exposure of women diagnosed with breast cancer. However, EPA notes the women may not have resided in the p lace of residence at the time of diagnosis for a 15

- 20 year period, an adequate latency period. Use of demographic data measured at the aggregate level in multi

- variable regression analyses is questioned.
Overall, this study is supportive of the conclusion that atrazine exposure is not related to breast cancer risk. However, because of the lack of individual level exposure and confounder information, an association cannot be ruled out based upon this study. This study included a large sample size, with high quality outcome measurement, information on relevant confounding variables, and took place among a highly exposed population. However, the ecologic exposure methods limit use in risk assessment. It is not known with certainty whether the women with breast cancer had the levels of atrazine exposure assigned them in this study.
Muir et al. (2004) “Breast cancer incidence and its possible spatial association with pesticide application in two counties of England.”

Authors performed an ecologic analysis of the possible association between pesticide usage including atrazine and breast cancer rates in 2 counties in England, Lincolnshire and Leichestershire. Researchers included all cases of breast cancer diagnosed among women, ages 45 years and greater in these 2 counties between the years 1988 and 1991. Cancer cases were ascertained through regional cancer registry (Trent Cancer Registry). Residential address at the time of diagnosis was coded into an electoral ward, and breast cancer incidence rates within each ward were calculated adjusting by age using the 1991 national census, and using the national population of England and

### 61 Wales as the standard population ( i.e. , the number of breast cancer cases within each ward/the number of breast cancer cases in England/W ales, adjusting using age distribution recorded in 1991 national census).

Pesticide exposure was measured at the group level. A pesticide usage survey for 1991 was used to determined the total kg of active ingredient applied per kilometer by each ward wi thin the 2 counties of England represented in the study. Pesticide level data were initially available at the “parish” level, and researchers calculated pesticide usage at the “ward” level using “proportional redistribution approach” which is essentially a weighted average of kg applied by proportion of parish represented by the ward. Investigators included atrazine, aldicarb, lindane and cyanazine in the study as these were identified as potentially estrogenic substances by the study authors and hypothesiz ed to play an etiologic role in breast cancer development.

Authors calculated the correlation between geographic areas (the wards) using 2 GIS

based techniques, black

- white join

- count, and Moran I statistics. In addition, researchers performed regression analysis based using group

- level breast cancer IRR as the dependent variable and pesticide usage by ward as independent variables. They did not adjust for other pesticides, or breast cancer risk factors. Authors stratified rural and urban wards in the anal ysis. Authors reported no significant correlations (“clusters”) of breast cancer by geographic area. Furthermore, authors observed no association between average pesticide usage by ward and breast cancer IRR in urban or rural areas of Lincolnshire, or urba n areas of Leichershire. Authors did note a statistically significant (p<0.05) positive change in slope of breast cancer incidence rates and 1

- unit change in kg of atrazine used per km 2 

### (slope 0.17 (0.03, 0.31)). Authors observed similar result for aldicar b and lindane.

EPA Review

Authors performed an ecologic analysis of breast cancer incidence in association with pesticide usage including atrazine. The researchers noted the inherent limitations of the study design, but suggest the results of this work supports excluding the possibility of a strong, positive association between atrazine usage and breast cancer among women diagnosed later in life (otherwise these study would have detected greater associations). Strengths of this ecologic study include use of sophisticated, GIS

- based analytic techniques to discern correlations and associations using these aggregate data. Given that this study was performed during a time period in which the possibility of a “breast cancer cluster” was discussed in the media, the use of aggregate data, collected for a purpose other than epidemiologic investigation was likely a strength, as information bias due to differential pesticide recall is eliminated. However, the observation of associations between atrazine use in the w ard and breast cancer incidence in only one of the two counties in the study weakens the argument of evidence of a true association. In addition to the well

- known limitations of ecologic design, a number of additional design and measurement decisions may h ave weakened the strength of the associations including use of residential address at breast cancer diagnosis as a surrogate for lifetime residence and therefore pesticide exposure; the

### 62 use of usage data as a surrogate for individual/group exposure; the us e of 1991 usage data as representative of earlier, etiologically relevant time periods (1970s, 1980s for diagnoses 1988

- 1991); lack of confounder measurement and analytic adjustment. Overall, authors are likely correct in the assertion that there is not a true, strongly positive association between atrazine (or the other pesticides measured) and breast cancer, however this study design, given its known limitations, cannot persuasively argue in favor or in opposition to a true positive association.

Orsi et al. (2009). “ Occupational exposure to pesticides and lymphoid neoplasms among men: results of a French case

- control study.” [ Occup Environ Med . 2009 May ; 66(5): 291

– 298. ]

Researchers evaluated the association between farming and pesticide exposure speci fically, and lymphoid neoplasms including non

- Hodgkin’s lymphoma (NHL), multiple myeloma (MM), Hodgkin’s lymphoma (HL), and lymphoid proliferative syndrome (LPS) in a hospital

- based case control study. This study took place in France, and recruitment occur red 2000 to 2004.

Cases and controls were recruited among 6 hospitals in France in the cities of Brest, Caen, Nantes, Lille, Toulouse and Bordeaux. Eligibility criteria included age range 20

- 75 years, and residence within the respective hospital catchment areas. Cases eligibility included recent diagnosis (within 3 months; 18 months for LPS) [WHO ICD

- 0

- 3], and included both histopathological and cytological confirmation of neoplasm by a panel (size not stated) of pathologists and hematologists. Eligibility included no history of lymphoid neoplasms, residence in hospital catchment area, admission to hospital for conditions not likely related to either LN or pesticide exposure. For this study, females and persons with a history of immunosuppression or who rep orted use of immunosuppressive drugs were excluded. Application of eligibility criteria resulted in 491 cases and 456 controls selected into the study. Controls were individually matched to cases on age, gender and center.

Two exposure questionnaires were administered to study participants: a self

administered questionnaire and a structured in

- person interview by trained interviewers and pesticide use expert. In addition to basic demographic, medical history, and residential and occupational history, a det ailed job history including pesticide exposure was obtained from those who reported working in agriculture for at least 6 months. Regarding farm

- related exposures, crop type, animal husbandry activities, pesticide use, and duration of pesticide use (months ) information was obtained or derived from the obtained information. Industrial hygienists and professionals expert in assessing pesticide exposure re

- interviewed those who provided insufficiently detailed information during the structured interview and pe sticide exposure questions (77%). Upon completion of data collection, exposure experts matched participant responses with publicly available data sets to estimate pesticide exposure experienced (based on job history, crop and animals on farm, time period o f employment, etc.) for missing responses. Authors modeled pesticide exposure as ever

- use of any pesticide, any class of pesticide (e.g., herbicide, insecticide), and any sub

- class (e.g., triazine). Based upon

### 63 the total number of months/years in employment in agricultural job, authors modeled duration of pesticide exposure classified as none, less than the median number of months, and greater than or equal to the number of months. Trends were assessed using median of each category. Using publicly available pesticide usage databases, industrial hygienists assigned a probability of use of particular pesticide groups by respondents given the time period of employment, type of farm (mixed v. single), and crops or livestock on the farm, and classified the probabi lity of particular pesticide exposure using this information (definite or probable). Pesticide exposure intensity was not modeled due to inadequate data. Interviewers were blinded as to case

- status. All interviewers were performed with the same structured questionnaire and were performed in the same manner.

Researchers utilized unconditional logistic regression to estimate the associations between pesticide use and LN, and LN subtypes. Authors report associations with employment in farming; corn farming i n association with NHL, HL, MM, HCL; ever use of any pesticide in association with NHL, HL, and MM. For triazine specifically, associations were observed with HCL (OR 5.1, 95% CI 1.4

- 19.3). In addition, triazine use was associated with NHL (diffuse large c ell lymphoma 8/20 OR 2.1 [95% CI 0.8

– 5.0]) and follicular lymphoma 4/20, OR 2.3 [95% CI, 0.7

– 7.7]), but not with chronic lymphocytic leukemia 4/17 OR 0.9 [95% CI 0.3

– 3.0].

Sensitivity analyses using various lag times (10, 20, 30, 40 years), or considerat ion of only pesticide exposure which occurred in certain points in time ( e.g ., 30

- 40 years ago) did not change risk estimates. Use of conditional (individual matching) logistic regression, or collapsing of all possible pesticide exposures with the no expos ed group in comparison with the definite exposed group did not change results. Adjustment for known LN risk factors, other co

- variables, or iterative exclusion of certain admission reasons, and co

- adjustment for other pesticide exposure did not appreciably change results.

EPA Review

Authors performed a hypothesis

- generating study of the link between pesticide exposure and LN, and LN sub

- types including NHL. Eligibility criteria and inclusion and exclusion factors were clearly delineated by authors. Use of hospital

- based controls can be problematic in population

- based studies due to the uncertainty as to whether the cases and controls were derived from the same source population. In this study, authors did not comment as to whether the cancer centers at the respective recruitment sites were reflective of primary or tertiary care facilities, and similarly whether the non

- cancer departments (rheumatology, osteopathy) were reflective of the same level of care, i.e., whether the same types of patients would be p resent in each department/center. It is difficult to assess the possibility of selection bias in this study. In addition, after individual matching, authors reported significant differences by age and center, the matching variables, suggesting the matching process may not have been fully successful. Co

- factors that are typically confounders in studies of LN were not confounders in this study. However comparison of the prevalence of smoking and

### 64 alcohol use between controls and the general population were sim ilar, and comparison of pesticide use between controls and regional agricultural population were also similar which argues against the role of selection bias if cases were a representative sample of all cases. It seems unlikely that pesticide use would inf luence case selection given the design of the study, but information to assess the possibility is not provided. In addition, the age range for HCL and other LN differed greatly; possibly two study samples ought to have been devised.

Authors performed a r easonable measure of pesticide exposure, albeit only ever use of any pesticide, pesticide functional class, or sub

- group (triazine) were measured. This study offers no additional information as to the association between atrazine use and LN. Authors used 2 questionnaires, a self

- administered and a structured questionnaire by a trained interviewer; this is a superior method of exposure assessment as compared to self

- report questionnaire only. Participants were re

- contacted if additional information was neede d, and the rate of re

- interview was similar between cases and controls. Differential exposure misclassification was unlikely because cases and controls had a similar level of missingness in data (cases were not reporting differently than controls), and the re

- interview rate was also similar between groups. In addition, as stated earlier, participants were blinded as to the study hypothesis. Non

- differential misclassification may have occurred, although use of two questionnaires and trained interview likely lessened the effects of this bias. Similarly, cancer outcome was histologically and pathologically confirmed reducing potential information bias in outcome measurement. Authors achieved high participation rates which reduces the chance of selection bias. T he interviewers were blinded as to case

- status, reducing the potential for bias. Iterative removal of each of the six centers from the whole analysis in a sensitivity exercise did not result in differences in the risk estimates, arguing against a role for center effects in the overall results. Several sensitivity analyses suggest the results are not likely explained by other factors such as lag or latency of effect, use of hospital based controls from other departments that may also be related to the exposu re, or co

exposure to other pesticides. However, as pesticide exposure was only measured at the

ever

- use level, residual confounding may still have occurred, which would tend to reduce the size of the effect estimate. As reported by the authors, the study is under

powered to see results OR<1.7. Non

- differential exposure misclassification may have additional reduced study power. Use of blinding/masking techniques to both the study hypothesis as well as case and control status by both lab technicians and trai ned interviewers enhanced the validity of results and reduced uncertainties such as recall bias and ascertainment bias. Survival bias is less likely as all cases were recruited within 3 months of diagnosis, 18 months with respect to LPS.

Authors suggest an association between triazine use and LN may be present, specifically with HCL, NHL and FL. Strengths of this study include the performance of several sensitivity analyses to reduce some sources of uncertainty, and use of 2 levels of pesticide exposure d ata collection by trained, blinded interviewers. However, the relatively low statistical power and relatively wide confidence bounds suggest lack of precision in the estimates and inability to exclude chance as an explanation for these findings. Given the lack of comparability between cases and controls and lack of

### 65 information regarding control selection, selection bias may have been possible. Exposure assessment reflects ever

- use over a lifetime and disallowed more refined analysis for risk assessment. Whi le authors observed suggestive association between triazines and lymphoid neoplasms, limitations present reduce weight of the study for use in overall evidence base for atrazine carcinogenicity.

Rull et al. (2009). “ Residential Proximity to Agricultural Pesticide Applications and Childhood Acute Lymphoblastic Leukemia.”

This study was performed within the Northern California Childhood Leukemia Study. Cases of pediatric acute lymphocytic leukemia (ALL) were selected in two different study phases (I and II ) between 1995

- 2002 in 35 counties in the San Francisco Bay area, and the agriculturally intensive Central Valley. Cases were identified through rapid case ascertainment (RCA) within 72 hours of diagnosis. RCA aids epidemiologic evaluations through reduced recall problems (less time between diagnosis and recall period). Controls were individually matched to cases (1:1 or 1:2 in phases I and II, respectively) on the following factors: age, sex, maternal race, Hispanic ethnicity. Maternal county of residence at birth was used as a matching factor for phase I but not phase II of the study. Participants were eligible if the mothers resided in the study area, if the child was less than 15 years of age at diagnosis or referent year (controls), if ALL was first can cer ever diagnosed, and if family were either English or Spanish speaking. Eligible controls were identified using vital records.

Maternal residence at birth was compared with state pesticide use records (PUR) to estimate pesticide exposure. Participants provided extensive residential history information, in addition to demographic, health status, and other exposure information. Questionnaires were completed by participating mothers (self

- report) initially, and an in

person follow

- up interview was later sc heduled. Because California state pesticide use reporting began only in 1990, all cases and controls for this analysis were restricted to those born after 1990. Among the 600 active ingredients with reported pesticide applications during the study period i n proximity to participant homes, authors restricted the pesticide exposure analysis to 118 active ingredients for which there was some evidence of cancer, developmental or reproductive health effects, or evidence of endocrine disruption (adjudicated by au thors); or, frequency of use was high. Authors summarized evidence to create six toxicity categories for grouped analysis.

Authors considered participants who resided within 0.5 miles of pesticide applications to be exposed to pesticides. They defined th e non

- exposed referent group as those with less than 1 pound (lb) active ingredient (a.i.) applied per square mile. Using lb ai/mi 2 

### as the exposure metric, investigators categorized cases and controls into a moderately exposed (1 st 

### to 49 th 

### percentile of ex posure), and highly exposed (50 th 

### percentile and above) exposed categories. Where possible, quartiles of exposure using the same exposure metric were categorized. Authors evaluated pesticide exposure over the child’s lifetime as well as restricting to the first year of life.

Using conditional logistic regression (comparing exposure prevalence between discordant case

- controls pairs), and additionally adjusting for household income in the

### 66 analysis, authors reported borderline significant associations between those in the moderately exposed category of triazines (OR 1.9 (95% CI 1.0, 3.7), but not among those in the most highly exposed category. Adjusting for exposure to other classes of pesticides, the magnitude of the association in the moderately exposed cat egory increased, however the precision decreased (OR 4.1, (95% CI 1.5, 11.1)). Authors did not observe evidence of an association with herbicide categories: OR 1.2 (95% CI 0.8, 1.9), and highly exposed: OR 0.9 (95% CI 0.5, 1.5)) for exposure to herbicides. There was no association between pediatric triazine exposure during the first year of life and ALL risk in this study. Triazines to which this study population was exposed included atrazine, cyanazine, prometryn, pymetrozine, and simzine.

EPA Review

Au thors performed a hypothesis

- generating, population based case

- control study of pediatric ALL in relation to pesticide exposure. Strengths of the study include identification of cases through rapid case ascertainment (RCA) within 72 hours of diagnosis, thu s reducing the period of recall. In this study, pesticide exposure was estimated using residential history, so essentially participants were blinded to the study hypothesis reducing recall bias potential. The recruitment rate was high (84%), and the

cases and controls were similar on several (matching) factors, reducing the potential for selection bias. Further, as 100% of cases were identified and recruited in the study period, the population based controls, matched on important risk factors for either exp osure or disease, were likely a good approximation of the study population from which the pediatric cancers arose.

While the authors utilized more sophisticated methods of exposure measurement than have been employed in other investigations of childhood cancers, limitations, of course, still exist. These include the lack of information on critical windows of exposure for development of a pediatric cancer, and lack of precision of estimation of specific active ingredients with ALL. Authors utilized extensi ve, self

- reported residential histories over the time period of the child’s life provided by the mother (parent). Researchers then compared residential locations with publicly available pesticide use information to determine pesticide exposure status for e ach case and control. While studies have illustrated that residential proximity is a good surrogate for pesticide, authors acknowledge some degree of non

- differential misclassification of exposure likely occurred in this study which would tend to under

- est imate associations. In addition, as authors note, residential proximity alone was used to measure pesticide exposure, no attempt to modify the exposure estimate by weather conditions, temperature or other factors that may affect the potential for drift on the application day. In addition, through matching on county of maternal residence at the time of birth, authors may have inadvertently matched on the main exposure factors, i.e., pesticide exposure. In this case, reduced risk estimates would be anticipate d. Given these factors, the significant associations observed for triazines in relation to ALL are potentially notable.

### 67 The non

- monotonic risk pattern between the moderately exposed and highly exposed groups may be due to residual confounding, or sample s ize in each exposure category. Authors note that non

- monotonic trends may be explained by biological processes in which greater risk would be anticipated in the moderate exposure group but not the high exposure group due to compensatory mechanisms. It is n ot evident in these data which explanation is more plausible, however a conclusion in support of the alternative hypothesis are weak. The grouping of triazines together, some of which have different modes of action, argue against a biological explanation i n favor of methods related explanations, e.g., residual confounding, lack of precision in exposure estimation. Pesticide exposure measurement during gestation/pre

- natal period would have enhanced the specificity of the exposure estimate during a potentiall y critical window of exposure, i.e., fetal development. This is in general a limitation of this study. However, it is notable that post

- natal and early life exposures have been implicated in the etiology of childhood cancers, supporting a role for pesticid e, possibly some triazine exposures in these observed risk estimates. However, more refinement of pesticide exposure and replication of results are needed before a causal association can be posited.

Researchers with the Agricultural Health Study (AHS) examined the association between atrazine use and incident cancer among pesticide applicators enrolled in the AHS. This research ex tends the results of Alavanja et al. 2003 (a prostate cancer nested case control study). Rusiecki et al. 2004 “Cancer Incidence among Pesticide Applicators exposed to atrazine in the 

### Agricultural Health study (AHS)”

Cancer outcomes were ascertained through linkage with state cancer registries, and deaths were determined through linkage with the National Death Index (NDI). For the purposes of this investigation, participants end their time on study when one of the following events occurs: cancer diagnosis, death or loss to follow

- up through geographic relocation or other reasons. Cancer outcomes were obtained for each participant fr om the time of enrollment (1993

- 1997) through December 31, 2001. Participants contributed an average of 6.5 years on study.
Lifetime pesticide exposure was obtained through self

- administered questionnaire. Questionnaire information included not only pestic ide exposure, but also use of personal protection equipment (PPE), application methods, repair status, smoking, alcohol and other lifestyle factors, in addition to basic demographic information. Participants provided information concerning ever

- use of pest icides, number of days per year and number of years over the working lifetime. Compiling information from across the industrial hygiene and exposure assessment literature, AHS researchers modified lifetime days of exposure by intensity of exposure, using a validated intensity score. The intensity score reflects information concerning application method, PPE use, and percentage of time spent mixing and loading pesticides, and other factors.
Researchers included only new cancer cases diagnosed since enrollme nt, and excluded participants who provided no information concerning atrazine use during a lifetime. Only anatomical cancer sites for which at least 20 exposed cases were

### 68 diagnosed during the time period of follow

- up were included in the analysis. Risk est imates were adjusted for age, sex, education, alcohol consumption, family history of specific cancers, state, and smoking status. In addition, final statistical models included the ten most highly correlated/associated pesticides to adjust for co

- exposure to other pesticides (pesticide adjustment included: dicamba, cyanazine, alachlor, trifluralin, 2,4

- D, chlorimuron

- ethyl, metribuzin, butylate, phorate and heptachlor).
Among 53,943 AHS participants included in this study, 68% reported ever

- using atrazine during their lifetime. Demographic and other characteristics were similar between the three exposure comparison groups. Overall, researchers reported no significant associations between lifetime atrazine use and all cancer sites combined, and several speci fic anatomical cancer sites. No associations between use of atrazine and prostate cancer were observed across the quartiles of either cumulative lifetime days or intensity

- adjusted lifetime exposure days. However, the report suggested associations for non

- Hodgkin lymphoma, multiple myeloma, lung cancer, and bladder cancer. Authors also evaluated atrazine use in relation to oral, colon, rectum, pancreas, kidney, melanoma, or leukemia cancer sites and observed no evidence of an association. Authors describe i nitial suggested associations with these anatomical cancer sites as preliminary in this study.

EPA Review

Authors performed a well

- conducted, hypothesis

- generating analysis of atrazine use in association with several anatomical cancer sites providing some preliminary evidence that atrazine exposure may be associated with lung, bladder, NHL and multiple myeloma (MM). However, as authors note, exposure

- response trends are not monotonic and consistent; there are a small number of exposed cases for some of these sites; and, there is a lack of other evidence to support the hypothesis that atrazine exposure could be causally associated with these cancer outcomes.

For this study of atrazine exposure and cancer outcomes nested within the larger AHS, authors ex cluded participants who already experienced a cancer diagnosis at enrollment (a prevalent cancer case), as well as participants who did not provide any information regarding atrazine use. Authors reported no significant differences in the demographic or ex posure characteristics of those included and excluded from this study

. Pesticide exposure was assessed at enrollment, independent of later cancer diagnosis; therefore, exposure and other relevant information was collected in a similar manner between those exposed and unexposed to atrazine, and there is no probability of a recall bias influencing the results.

The semi

- quantitative exposure assessment method of AHS has been described and evaluated extensively in the literature. Essentially, self

- reported inf ormation concerning lifetime pesticide use was obtained through written questionnaire. Authors examined lifetime exposure days (LTED), and LTED modified by use of personal protective equipment (PPE) and other factors known as intensity

- weighted lifetime ex posure days in their analysis. Recently, use of these literature

- derived intensity scores has been

### 69 shown to be a valid and reliable method of assessing lifetime pesticide exposure (See Blair et al. 2011; Thomas et al. 2010). Authors note, however, that use of this exposure metric does not allow extensive refinement of exposure, i.e. , which decade of life did relevant exposure occur, and it only allows examination of pesticide exposure experienced as an adult. Similarly, the cancer diagnoses in this study were ascertained through linkage with state cancer registry; Iowa is a SEER state and North Carolina received a Silver rating from the National Association of Cancer Registries. All cancer diagnosis are pathology confirmed, including medical record review which reduces the chance of outcome measurement error and misclassification of disease.

Authors were able to effectively measure and control for potentially confounding variables including age, sex, education, alcohol use, family history of specific cance r (first degree), state and smoking status. For the assessment of lung cancer, authors were able to model smoking in several ways, a strength of this study. Criteria for inclusion of potentially confounding variables in the final model were conservative, i .e., a +/

- 10% change in point estimate. In addition, authors were able to adjust for use of ten most highly correlated pesticides associated with atrazine use, reducing the uncertainty that other pesticide exposure may also play a role in specific cancer outcomes. However, it should be noted that while authors could adjust of use of more than one pesticide in the lifetime, the exposure data were not refined enough to estimate co

exposure of multiple pesticides within a biologically relevant critical window of effect. However, use of both the no exposure and the low exposure groups as references (no exposure group not shown in paper), reduces the chance of residual confounding due to differences between the most highly exposed group and the referent.

The po ssibility of selection bias in this cohort study is low given less than 2% of the cohort has been lost to follow up at the time of this study. Exclusion of prevalent cases from the analysis reduces the chance of prevalence

- incidence bias, however it is pos sible some non

- cases are actually occult cancer cases. However, the AHS population is generally a healthy one. While it is difficult to recall exposures over a lifetime (recall), it is unlikely that cases and non

- cases recall pesticide exposure information differently given the prospective design of the study. Although pesticide exposure may be misclassified in some instances, it is likely this misclassification is

non

- differential in nature leading to an attenuation of the risk estimate in most instances.

With only 6.5 years on average on study at the time of this analysis, in many instances there were too few cancer cases to perform a robust statistical analysis. However, authors only presented risk estimates for cancer sites for which there were at leas t 20 exposed cases, limiting the role of low statistical power as an explanation for the research findings. The use of Poisson regression techniques, however, is appropriate given the prospective cohort design. It is noted that for atrazine

- prostate cancer association which was previously postulated, study power was 89% to detect an association if an association truly existed. Sensitivity analyses including use of both the no exposed and low exposed groups as referent to note the differences in risk estima tes and trends, in addition to the use of both primary and secondary incident cancer cases to increase the sample size resulted in few differences in the final estimates. Therefore,

### 70 authors reduced the chance that residual confounding or low statistical po wer explains these findings. Lastly, authors acknowledge that the characteristics of this cohort limit generalizability of the results. AHS participants are predominately male, Caucasian, and atrazine users are largely residents of Iowa.

Overall, authors performed a well

- conducted, hypothesis

- generating study of atrazine use in association with several anatomical cancer sites. Strengths of this study include large sample size; elimination of both recall and selection bias as an explanation for these findi ngs through study design and high retention rates, respectively; lifetime pesticide exposure assessment, refined with intensity

- weights, with high validity and reliability; high quality and complete outcome ascertainment through linkage with certified stat e cancer registries; and the ability to measure and adjust for most relevant confounding variables including other pesticide exposure. Limitations include the low number of exposed cases for some anatomical cancer sites evaluated, the result of exposure me asurement error may have attenuated some of these risk estimates, lack of refined exposure in the relevant critical time windows possibly including early life exposure, and possibility of unmeasured confounding by other pesticides or environmental/occupati onal exposures. AHS researchers have recently updated and extended this work (See Beane

- Freeman et al. 2011).

Thorpe et al. 2005 “Herbicides and Nitrates in Groundwater of Maryland and Childhood Cancers: A Geographic Information Systems Approach.”

Autho rs performed a GIS

- enhanced, ecologic analysis of four specific types of pediatric cancers (leukemia, NHL, bone, and brain) and pesticide exposure (atrazine, simazine, alachlor, metolachlor) and nitrate exposure measured in well

- water (drinking water

surro gate) in the state of Maryland. Investigators identified pediatric (ages 0

- 17 years) cancers in the state between the years 1992 and 1998. Case locations were geo

- coded using residential address at the time of diagnosis. Using the Census data, age

- adjusted pediatric cancer incidence rates were calculated by county and census

- tract.

Pesticide exposure was determined through USGS well water monitoring records, and state Department of Environment application records by county. There were 834 well sites for w hich pesticide/nitrate levels were measured. Detectable levels of atrazine were reported for 10% of the well

- sites; none of the well sites reflected atrazine exposure greater than the MCL (3 ug/L).

Using well

- site locations, 2 buffers were created to ref lect “exposed” areas. For pesticides, buffers reflecting concentrations both 0.15 ug/L to 0.50 ug/L, and greater than 0.50 ug/L were developed. Residences within the buffer were considered exposed. Population

- based controls were selected from Census record s to construct a 2x2 unadjusted contingency table of the crude association between atrazine exposure and the four pediatric cancers of interest.

Authors reported 689 pediatric cancer cases reported to the state registry during the study time period of 199 2

- 1998. Standardized incidence rates indicate the MD state

### 71 rates were less than the national rates (8.5 v. 14.2/100,000 children less than 17 years. In GIS

- enhanced cluster analysis, utilizing an NCI developed GIS

- add on software tool called SaTScan, autho rs identified the state county of Worchester as a cluster for these pediatric cancers (significant correlations of cases in this area). Regarding atrazine exposure, authors report no association with all four pediatric cancers combined (OR 1.1 (95% CI 0.78 , 1.56), p=0.66). Positive associations with both bone cancer and leukemia were also observed, although non

- statistically significant. A multiplicative joint effect was reported for exposure to atrazine, metolachlor and nitrate (OR 7.56 (95% CI 4.16, 13.73 ), although the estimate lacks precision.

EPA Review

Limitations of the ecologic design are noted by the authors; they describe the research as hypothesis generating. There are few other studies investigating this specific association, and unfortunately this study in itself offers little evidence in support or in opposition to the notion that atrazine exposure through drinking water (well water) may be associated with these type of pediatric cancers. Authors selected these pesticides for study due mainly to the high prevalence of use and exposure in the state . The known residential mobility of new mothers (new families) indicates the residential address at childhood cancer diagnosis may not represent the area of MD, or of the U.S. in which possible in utero , early post

- natal, or early life pesticide exposure m ay have occurred. In addition, it is not known whether well water pesticide concentration accurately reflects pesticide exposure, or exposure during critical windows of gestation or early life cancer. The role of genetic background in the etiology of these pediatric cancers in also unknown. The lack of a clear “cluster” or grouping of pediatric cancers by agricultural area argues against a true association. However, given the limitations of this study design, the study itself offers little evidence to infor m the nature of the association between atrazine and childhood cancers.

Authors performed a population based case control study of occupational and residen tial triazine exposure in association with epithelial ovarian cancer using state/regional cancer registries to identify ovarian cancer cases, and a combination of state level pesticide use reports and self

- reported pesticide exposure questionnaire data to assess triazine exposure. The study population included women living in the Central Valley and working in the state (CA). Cases were eligible if living in the central valley during the 2000

- 01 study period, diagnosed with epithelial ovarian cancer, at leas t 18 years old, and for whom a physician gave permission to contact (actively or passively). Controls were women who did not have an ovarian cancer diagnosis, who had at least one ovary (at risk of being a case), living in the same zip codes as cases (cont acted through random digit dialing), at least 18 years of age. Cases and controls were frequency matched on 5

- year age categories and race/ethnicity (non

- Hispanic white, Hispanic/Latina, other). Study participants were contacted first by letter and then th rough telephone interview. Telephone interview included collection of demographic Young et al. 2005. “ Triazine Herbicides and Epithelial Ovarian Cancer Risk in Central California.”

### 72 information, disease history, reproductive history, and employment history in agriculture. Variables such as location of employment, crops cultivated at farm of employment, j ob titles, and years of employment among other things were collected through the telephone interview from which occupational and residential pesticide usage was assessed using external data sources (aggregate level exposure assessment, pesticide usage at f arm

- site at time of employment used to assess individual exposure).

Authors utilized two databases available in the state of California to determine pesticide usage at the farm

- level. Using these two databases together, authors were able to re

construct h istorical pesticide usage at the farm level from the years 1974

- 1999. Pesticide exposure from occupation in agricultural setting reported by participants between 1950

- 1974 were set to missing, however authors did compare employment in agriculture pre

- and post the 1950

- 1974 period in their analyses. Using location of farm, crop type and other information authors were able to access state pesticide use records to determine the amount of triazine applied to the crop (cumulative exposure), and summed across em ployment periods within each individual. Researchers developed a job exposure matrix (JEM) using job title, crop type, number acres treated and other information, and assigned each participant a weighted cumulative pesticide exposure value. To examine resi dential triazine exposure, researchers considered residential proximity to a triazine application. Authors used an ever/never, cumulative exposure, and JEM weighted cumulative exposure score in their analysis.

Authors initially identified 652 ovarian canc er cases reported to the state/regional registries between the years 2000 and 2001. Among these cases, only 256 were interviewed based upon lack of eligibility, lack of accurate contact information, or refusal to participate (40% response rate). Authors re ported no differences in age or stage at diagnosis between cases included and excluded from study. Similarly, of 2,327 controls selected through random digit dialing, 1122 were interviewed (57% response rate). Authors evaluated total traizines (OR 1.34 (95 % confidence interval (95% CI) 0.77, 2.33), and independently atrazine (OR 0.76 (95% CI 0.16, 3.55)), simizine (OR 1.35, (95% CI 0.71, 2.39)) and cyanazine (OR 1.90 (95% CI 0.65, 5.56)) in association with ovarian cancer. Examining quintiles of total triaz ine exposure, no exposure

- response trend was observed (p=0.22), and modeling triazine exposure as a continuous variable authors did not observe evidence of a positive slope. Authors modeled the JEM weights as the maxima (instead of average), or as zero and observed little difference. Authors reported no evidence of effect modification by several variables evaluated including age, race/ethnic, first or second degree family relative with either breast or ovarian cancer, or tumor type.

EPA Review

Authors p erformed a hypothesis

- testing evaluation of the relation between triazine, including atrazine, pesticide exposure and ovarian cancer. They reported evidence of an increased odds of ovarian cancer in association with total triazine use, simazine and cyanazi ne use, however the risks estimated for individual triazines lack precision due to

### 73 the relatively low prevalence of use of triazines in this sample. Authors report no significant or positive association between atrazine exposure and ovarian cancer, althoug h the prevalence of exposure to atrazine is low in this cohort, reducing the statistical power to see an effect for atrazine specifically.

Authors included women, 18 years or older, who reported living in the 22 county area of the study who either had an ovarian cancer diagnosis or were at risk for the diagnosis (had at least one intact ovary). However, authors also used random digit dialing techniques to identify controls, and sent an introductory letter first to all participants. Therefore, participants must have had a telephone and accurate mailing address to participate in the study. Given the transient nature of some agricultural workforce members, these design decisions may have excluded women who had the greatest risk for pesticide exposure. The sim ilarity in age and tumor type between the cases included and excluded from the study suggest comparability between included and excluded cases, authors did not have the data to compare occupational pesticide use between these two groups. In addition, the m odest response rate (40% and 57%) in cases and controls, respectively, and differences between cases and controls in education level attained and percentage of foreign

- born participants adds to the concern that the sample may not be a good representation o f the target population of all females who may have had pesticide exposure in the workplace. In addition, authors excluded women who had died or were too ill to participate; authors did not obtain responses by proxy. While obtaining a proxy response requir ed added resources, and is often fraught with other uncertainties, i.e ., the accuracy of the proxy response, obtaining proxy response for a random subset of these excluded women may have been informative as to whether there were differences in reported pes ticide use. If pesticide exposure is causally linked to ovarian cancer, those who died or were too ill to participate within a 2 year period of diagnosis could also have been those most severely affected by the exposure, thus a bias could have been introdu ced.

Strength of the study includes histopathological confirmation of tumors, reducing outcome measurement error. Authors designed the study to assure only incident cancers were identified by restricting the years of cancer diagnosis to a recent period ( to the time period of study), and performing retrospective exposure analysis on the years prior. However, given the typically late stage of ovarian cancer development at diagnosis, lack of an ovarian cancer screening tool, and unfortunately short duration of the disease (rapid progress from diagnosis to death), and high case

- fatality rate, authors could have increased their study power to look at incident and prevalent cases combined.

Pesticide exposure was assessed through matching of both residence and workplace histories (farm site locations) with state pesticide use records from 1974

- 1999 which was obtained through self

- report in the telephone interview. If pesticide exposure occurred in the distant past, recall may have been imperfect and non

- differen tial exposure misclassification could have occurred. In addition, authors did not state whether participants or trained telephone interviewers were blinded to study hypothesis or to case

- control status, respectively. Authors developed an ever/never, cumula tive

### 74 exposure (total pounds per acre per crop), and a JEM weighted cumulative exposure metric. These exposure metrics range from likely more accurate and less precise (ever/never), to less accurate and more precise (JEM weighted cumulative exposure). Autho rs modeled exposure as categorical or continuous variables, maximizing statistical power of the study data. No exposure

- response trend was observed, however only quintiles of total triazine could be evaluated due to small sample size. Authors attempted to measure lifetime pesticide exposure in association with the cancer outcome, a strength of the study. It is possible that pesticide exposure decades prior to cancer diagnosis could be causally related to ovarian cancer. Authors could have evaluated latency by assuming certain lag

- times in the data analysis, i.e ., it is unlikely pesticide exposure a year prior to ovarian cancer diagnosis would be causally linked to the outcome.

Given the strengths and limitations of the research, this study cannot persuasiv ely support or reject the hypothesis that triazine exposure is linked to ovarian cancer.

Table B

- 5a: Summary of Study Results

Author Dat

e Study Design Cancer Endpoint Location Sample Size Exposure Assessment Adjustment Risk Ratio

Beane

Freema

n 201 1 occupationa l cohort all cancers IA and NC private and commercial

pesticide applicators 3,146 incident

cancers among 53,663 applicators self

- report atrazine use age, race, gender, smoking, alcohol use, education,

state of residence, family history

of speci fic
cancers, applicator type (private

or commercial), and ever

- use

of other pesticides No association most cancer including: all

cancers, prostate, breast, NHL. Thyroid : 1.0; q1 OR 4.55 (95% CI,1.27,16.24) ; q2 OR 1.16

(95% CI (0.23, 5.80); q3 OR 4.84 (95% CI, 1.31, 17.93) Carreon 200 5 population

based case

control glioma upper Midwest (IA, MN,MI,WI) 341 cases, 528 controls atrazine use by self

- report questionnaire age, education,

other pesticide OR 1.1 (95% CI 0.7

- 1.8) including

proxy respondents

DeRoos 200 3 pooled analysis (3

nested

case

control studies) NHL IA and MN, NE, KA 650 cases/1933

controls atrazine use by self

- report questionnaire

; validated age, study site, use of 47 other pesticides OR 1.6 (95% CI 1.1 to 2.5);

Hierarchal regression result: OR 1.5 (95% CI 1.0

- 2.5)

### 75 Table B

- 5a: Summary of Study Results

Author Dat

e Study Design Cancer Endpoint Location Sample Size Exposure Assessment Adjustment Risk Ratio

McElroy 200 7 population based case

control breast WI 3,275
cases, 3,669 controls Atrazine concentration

in drinking water: <0.15

ppb; 0.15

- 0.50 ppb; 0.50

- 1.0 ppb;

1.01

- 2.99 ppb; and greater than 3 ppb age, parity, phase of study, c ase

control status, age of menopause, body mass index, age at first full term pregnancy, menopausal status, age at

menarche, recent alcohol consumption,

education OR: 1.0 (ref); 1.1 (95% CI 0.7

– 1.5); 0.9 (95% CI 0.6

– 1.3); 0.9 (95% CI 0.6

– 1.4); 1.2 (95% CI

0.3

– 5.8)

Mills 200 6 cohort breast CA 23,513

cases agricultural atrazine applications reported to state Age at menarche, recent alcohol consumption,

education. IRR: 0.87 (95% CI 0.73

-

1.04);1988

- 1993: OR 0.86 (95% CI 0.70, 1.05); 1994

- 1999 OR 0.87 (95% CI 0.73, 1.04), p>0.05 Muir 200 4 ecologic breast Lincolnshire, Leichestershire , England aggregated data; 49 "wards" in Leichershire , rural areas atrazine use within ward unadjusted, regression analysis with

aggregate level data Slope: 0.17 (95% CI 0.03,

0.31); no evidence correlation

Orsi 200 9 hospital

based case

control lymphoma

s France 491 cases, 456 controls self

- reported triazine use age, study center, socio

economic

status NHL : OR 1.9(95% CI 0.9

- 3.8); HL: OR 3.2(95% CI 0.9

- 10.9); ABLN: OR 1.8(95% CI 1.0

- 3.3); HCL:

5.1(95% CI 1.4

- 19.3); FL: OR 2.30 (95%

CI 0.7

- 7.7) Rull 200 9 population based case

control pediatric acute lymphocyti c leukemia

(ALL) CA 213 cases, 268 matched controls proximity to triazine applications repor ted to state income, other pest OR 2.0 (95% CI 0.4

- 9.4)

Rusiecki 200 4 cohort all cancers IA and NC private and commercial

pesticide applicators 1,361

cancer
cases among 53,943 AHS applicators self

- report atrazine use age, sex, alcohol, live

on farm, smoking, education, family history,

state, 10 correlated pesticides all : OR 1.0 (95% CI 0.82

-

1.26); lung : OR 1.9 (95% CI 0.93

- 3.94); bladder : OR 3.06 (95% CI 0.86

- 10.8); NHL : OR 1.6 (95% CI 0.62

-

4.16); MM :

### 76 Table B

- 5a: Summary of Study Results

Author Dat

e Study Design Cancer Endpoint Location Sample Size Exposure Assessment Adjustment Risk Ratio

OR 1.6 (95% CI 0.37

- 7.01)

Thorpe 200 5 ecologic pediatric

cancers Maryland counties 689 pediatric
cancers, population

based controls atrazine concentration

in drinking

water contingency table analysis all pediatric

cancers: OR 1.1 (95% CI 0.78, 1.56); bone: OR 1.89 (95% CI 0.76

- 4.70); leukemia: OR 1.43 (95% CI

0.89

- 2.30) Young 200 5 population based case

control ovarian California 652 cases, 1122 controls self

- reported work, residential history and triazine use

reports age, race/ethnicity,

ever pregnant, breastfeeding , oral contraceptive s use, family

history, hormone replacement

therapy triazine : OR 1.34 (95% CI 0.77

– 2.30); atrazine : OR 0.76 (95% CI

0.16

- 3.55)