Herbicide, fumigant, and fungicide use and breast cancer risk among farmers' wives

Application of the Key Characteristics Framework to Identify Potential Breast Carcinogens Using Publicly Available in Vivo, in Vitro, and in Silico Data

BACKGROUND

Chemicals that induce mammary tumors in rodents or activate estrogen or progesterone signaling are likely to increase breast cancer (BC) risk. Identifying chemicals with these activities can prompt steps to protect human health.

OBJECTIVES

We compiled data on rodent tumors, endocrine activity, and genotoxicity to assess the key characteristics (KCs) of rodent mammary carcinogens (MCs), and to identify other chemicals that exhibit these effects and may therefore increase BC risk.

METHODS

Using authoritative databases, including International Agency for Research on Cancer (IARC) Monographs and the US Environmental Protection's (EPA) ToxCast, we selected chemicals that induce mammary tumors in rodents, stimulate estradiol or progesterone synthesis, or activate the estrogen receptor (ER) in vitro. We classified these chemicals by their genotoxicity and strength of endocrine activity and calculated the overrepresentation (enrichment) of these KCs among MCs. Finally, we evaluated whether these KCs predict whether a chemical is likely to induce mammary tumors.

RESULTS

We identified 279 MCs and an additional 642 chemicals that stimulate estrogen or progesterone signaling. MCs were significantly enriched for steroidogenicity, ER agonism, and genotoxicity, supporting the use of these KCs to predict whether a chemical is likely to induce rodent mammary tumors and, by inference, increase BC risk. More MCs were steroidogens than ER agonists, and many increased both estradiol and progesterone. Enrichment among MCs was greater for strong endocrine activity vs. weak or inactive, with a significant trend.

DISCUSSION

We identified hundreds of compounds that have biological activities that could increase BC risk and demonstrated that these activities are enriched among MCs. We argue that many of these should not be considered low hazard without investigating their ability to affect the breast, and chemicals with the strongest evidence can be targeted for exposure reduction. We describe ways to strengthen hazard identification, including improved assessments for mammary effects, developing assays for more KCs, and more comprehensive chemical testing. https://doi.org/10.1289/EHP13233.

Brief research report pesticide occupational exposure leads to significant inflammatory changes in normal mammary breast tissue

Studies have documented the high occurrence of several tumors, including female breast cancer, in populations occupationally exposed to pesticides worldwide. It is believed that in addition to direct DNA damage, other molecular alterations that indicate genomic instability are associated, such as epigenetic modifications and the production of inflammation mediators. The present study characterized the profile of inflammatory changes in the breast tissue of women without cancer occupationally exposed to pesticides. In samples of normal breast tissue collected during biopsy and evaluated as negative for cancer by a pathologist, oxidative stress levels were assessed as inflammatory markers through measurements of lipoperoxides and total antioxidant capacity of the sample (TRAP) by high-sensitivity chemiluminescence, as well as levels of nitric oxide (NOx) metabolites. The levels of inflammation-modulating transcription factors PPAR-γ (peroxisome proliferator-activated receptor gamma) and NF-κB (nuclear factor kappa B) were also quantified, in addition to the pro-inflammatory cytokines tumor necrosis factor-alpha (TNF-α) and interleukin 12 (IL-12). The levels of lipoperoxides, TRAP, and NOx were significantly lower in the exposed group. On the other hand, PPAR-γ levels were increased in the breast tissue of exposed women, with no variation in NF-κB. There was also a rise of TNF-α in exposed women samples without significant variations in IL-12 levels. These findings suggest an inflammatory signature of the breast tissue associated with pesticide exposure, which may trigger mechanisms related to mutations and breast carcinogenesis.

Safety Measures, Pesticide Concerns and Resources Utilized among Young Adult Workers: A Brief Report

INTRODUCTION

Resources on pesticide information are widely available; however, little is known about the concerns young agricultural workers have about pesticides, whether they use existing resources to find information about pesticides, and how these resources influence safety behaviors such as personal protective equipment (PPE) use.

OBJECTIVES

To examine demographic characteristics, safety measures, concerns about pesticide use and resources for pesticide information.

METHODS

Young agricultural workers were recruited through three collegiate agricultural programs and completed an online questionnaire related to pesticide safety and use.

RESULTS

Most participants who applied pesticides reported always wearing gloves (60.5%), using a tractor with an enclosed cab (68.4%), and always wearing long pants (76.3%). Among all participants, pesticide drift to crops (65.1%) and water contamination (62.3%) were the biggest concerns among young agricultural workers. The internet was the most utilized source to locate information about pesticides (76.4%), with the most common internet resources being online materials from universities or colleges (71.6%), the government (69.1%), or pesticide companies (66.7%). Accessibility (90.6%) and speed (78.3%) were the most common reasons for using the internet for information. Misinformation was the most common barrier (80.2%).

CONCLUSIONS

Future studies should examine the accuracy and accessibility of pesticide information available on the internet since young adult workers rely on these resources for pesticide information.

Exposure to pesticides and breast cancer in the city of Petrópolis, Brazil

To investigate the association between pesticide use and breast cancer. A hospital-based case-control study was conducted in Petrópolis city, Brazil. The study data were obtained through interviews, and the magnitude of the association between self-reported pesticide exposure and breast cancer was determined using unconditional logistic regression. A higher estimated risk for breast cancer was found in women exposed to pesticides for 10 or more years, where this association was not statistically significant after adjusting for potential confounders (OR = 1.40; 95% CI 0.85-2.49). A positive statistically significant association was found between breast cancer and higher educational level or previous use of hormone replacement therapy (HRT), whereas having had 2 or more pregnancies to term proved a protective factor. Further studies elucidating the contribution of pesticide exposure to the development of breast cancer are needed, given that current findings in the literature are conflicting.

Investigation of Relationships Between the Geospatial Distribution of Cancer Incidence and Estimated Pesticide Use in the U.S. West

The objective of the study was to evaluate the potential geospatial relationship between agricultural pesticide use and two cancer metrics (pediatric cancer incidence and total cancer incidence) across each of the 11 contiguous states in the Western United States at state and county resolution. The pesticide usage data were collected from the U.S. Geological Survey Pesticide National Synthesis Project database, while cancer data for each state were compiled from the National Cancer Institute State Cancer Profiles. At the state spatial scale, this study identified a significant positive association between the total mass of fumigants and pediatric cancer incidence, and also between the mass of one fumigant in particular, metam, and total cancer incidence (P-value < 0.05). At the county scale, the relationship of all cancer incidence to pesticide usage was evaluated using a multilevel model including pesticide mass and pesticide mass tertiles. Low pediatric cancer rates in many counties precluded this type of evaluation in association with pesticide usage. At the county scale, the multilevel model using fumigant mass, fumigant mass tertiles, county, and state predicted the total cancer incidence (R-squared = 0.95, NSE = 0.91, and Sum of square of residuals [SSR] = 8.22). Moreover, this study identified significant associations between total fumigant mass, high and medium tertiles of fumigant mass, total pesticide mass, and high tertiles of pesticide mass relative to total cancer incidence across counties. Fumigant application rate was shown to be important relative to the incidence of total cancer and pediatric cancer, at both state and county scales.

Antifungal Activity of Bacillus velezensis CE 100 against Anthracnose Disease (Colletotrichum gloeosporioides) and Growth Promotion of Walnut (Juglans regia L.) Trees

Walnut anthracnose caused by Colletotrichum gloeosporioides is a deleterious disease that severely affects the production of walnut (Juglans regia L.). The aim of this study was to assess the antifungal and growth promotion activities of Bacillus velezensis CE 100 as an alternative to chemical use in walnut production. The crude enzyme from B. velezensis CE 100 exhibited chitinase, protease, and β-l,3-glucanase activity and degraded the cell wall of C. gloeosporioides, causing the inhibition of spore germination and mycelial growth by 99.3% and 33.6% at 100 µL/mL, respectively. The field application of B. velezensis CE 100 culture broth resulted in a 1.3-fold and 6.9-fold decrease in anthracnose disease severity compared to the conventional and control groups, respectively. Moreover, B. velezensis CE 100 produced indole-3-acetic acid (up to 1.4 µg/mL) and exhibited the potential for ammonium production and phosphate solubilization to enhance the availability of essential nutrients. Thus, field inoculation of B. velezensis CE 100 improved walnut root development, increased nutrient uptake, enhanced chlorophyll content, and consequently improved total biomass by 1.5-fold and 2.0-fold compared to the conventional and control groups, respectively. These results demonstrate that B. velezensis CE 100 is an effective biocontrol agent against anthracnose disease and a potential plant growth-promoting bacteria in walnut tree production.

Community-based participatory design of a community health worker breast cancer training intervention for South Florida Latinx farmworkers

OBJECTIVE

Community health worker (CHW)-led education is an important strategy to increase awareness and access to breast cancer screening in medically-underserved communities. This study aimed to develop a context-specific, culturally-appropriate training intervention for South Florida CHWs to educate Latinx immigrant farmworkers on breast cancer and early detection.

METHODS

A community-based participatory research (CBPR) study, conducted 2017-2019, informed the design of a training curriculum for CHWs and educational dissemination materials. Twenty-two CHWs were trained and knowledge gains were measuring using a one-group pre-and post-test design. Triangulated evaluation consisted of field observations of CHW-client interactions, CHW self-reports, and rapid assessment surveys of community members.

RESULTS

A community stakeholder-informed breast cancer training curriculum resulted in significant, sustained breast cancer knowledge gains among CHWs when comparing pre-, post-, and 4-6 month post-training follow-up test scores. Field observations of educational material dissemination, CHW self-reported evaluations, and community rapid assessment surveys at three health fairs demonstrated this was an effective strategy to engage female Latinx farmworkers in breast cancer education.

CONCLUSIONS

Community and key stakeholder participation in the development of a breast cancer educational intervention allowed for tailored design priorities around knowledge-based content, comprehensiveness, relevance, appropriateness, and ease of dissemination to community members. This model of participatory CHW training intervention design can enable future train-the-trainer approaches to disseminate and scale-up evidence-based health education interventions.

Organophosphate Pesticide Exposure and Breast Cancer Risk: A Rapid Review of Human, Animal, and Cell-Based Studies

BACKGROUND

Organophosphate pesticides (OPs) are one of the most commonly used classes of insecticides in the U.S., and metabolites of OPs have been detected in the urine of >75% of the U.S.

POPULATION

While studies have shown that OP exposure is associated with risk of neurological diseases and some cancers, the relationship between OP exposure and breast cancer risk is not well understood.

METHODS

The aim of this rapid review was to systematically evaluate published literature on the relationship between OP exposure and breast cancer risk, including both epidemiologic and laboratory studies. Twenty-seven full-text articles were reviewed by searching on Pubmed, EMBASE, and Cochrane databases.

RESULTS

Some human studies showed that malathion, terbufos, and chlorpyrifos were positively associated with human breast cancer risk, and some laboratory studies demonstrated that malathion and chlorpyrifos have estrogenic potential and other cancer-promoting properties. However, the human studies were limited in number, mostly included agricultural settings in several geographical areas in the U.S., and did not address cumulative exposure.

CONCLUSIONS

Given the mixed results found in both human and laboratory studies, more research is needed to further examine the relationship between OP exposure and breast cancer risk, especially in humans in non-agricultural settings.