Estimated human intake of endogenous and exogenous hormones from beef in the United States

Hormonal growth promotants (HGPs) are widely used in US beef production to increase growth rate and feed efficiency. While the FDA authorizes the use of several HGPs, concerns exist regarding potential adverse health effects from human consumption of hormone residues in beef. These concerns are linked to the potential impact of hormone exposure on the risk of developing certain cancers, particularly hormone receptor-positive breast cancers, and the impact on pubertal timing, especially in girls. Despite the widespread use of HGPs and high beef consumption rates in the US, particularly among children, there's a limited understanding of the actual daily intake of these HGPs from beef. Existing studies measuring HGP residues in beef are scarce, and the USDA's National Residue Program has historically conducted limited and inconsistent testing. This study addresses this gap by aiming to provide an initial comprehensive assessment of human intake of HGPs from beef in the US, comparing estimates to established acceptable daily intakes (ADIs) to evaluate potential public health risks. The researchers specifically examined the impact across various age and gender groups, and explored potential socioeconomic disparities in HGP intake.

The literature review highlights the widespread use of HGPs in US beef production, citing USDA surveys indicating that a significant portion of feedlots use HGPs. The review also emphasizes the link between hormone exposure and cancer risk, particularly breast cancer, and the growing concerns about the effects of endocrine-disrupting chemicals (EDCs) on pubertal timing. A significant portion of the review focuses on the paucity of published studies measuring HGP residues in beef and particularly in US beef. The review critically assesses the limitations of the USDA's National Residue Program (NRP), which lacked comprehensive and consistent testing across different HGPs and tissues, making it difficult to accurately quantify human exposure. The review concludes by emphasizing the lack of comprehensive data on usual daily dietary intake of HGPs from beef in the US population and the need for comparison of estimated intake with established WHO acceptable daily intake (ADI) values to assess potential public health risks.

The study combined data from two sources: (1) dietary recall data from the 2015–2018 cycles of the National Health and Nutrition Examination Survey (NHANES) and (2) HGP concentrations measured in retail beef samples purchased across California. For NHANES data, the researchers focused on beef consumption, disaggregating foods containing beef into constituent ingredients and adjusting for cooking losses to obtain estimates of raw beef intake. Retail beef samples were collected from various retailers and regions of California, aiming for representativeness across different retailer types and geographic areas. Samples included various cuts and organs. Visible subcutaneous fat was separated from a subset of samples for separate analysis. HGP concentrations were measured using ultra-high performance liquid chromatography triple quadrupole-mass spectrometry (UHPLC-MS/MS). Non-detects were imputed. Three intake scenarios (typical, high, and maximum) were defined based on the distribution of measured HGP concentrations in the beef samples. The National Cancer Institute (NCI) method was employed to estimate the distribution of usual daily HGP intake from the NHANES data, accounting for within-person measurement error. The model included covariates such as age, gender, day of the week, and survey type. Hazard quotients (HQs) were calculated by dividing estimated intakes by the WHO ADIs. Additional analyses investigated socioeconomic determinants of HGP intake by comparing intake ratios across different race/ethnicity, income, and education levels using the NCI method and balanced repeated replication (BRR).

The study analyzed 397 beef samples (321 beef products, 76 fat subsamples) and detected several HGPs, with higher concentrations observed in fat compared to other tissues. The highest estimated HQs were for melengestrol acetate (MGA). Under the typical intake scenario, usual daily MGA intake was well below the ADI for all subgroups. Even under the maximum intake scenario, the 99th percentile of usual daily intake for MGA did not exceed the ADI for any group, although it reached 29% of the ADI for young boys (1–5 years). However, short-term intake estimates (two-day averages) for MGA under the maximum intake scenario equaled or exceeded the ADI for young girls and boys (ages 1–5). Analyses of socioeconomic factors revealed lower estimated MGA intake among non-Hispanic Black women and non-Hispanic Asian children, and a non-significant trend toward higher intake among higher-income women. Intakes of progesterone and testosterone were consistently very low relative to their ADIs across all scenarios and groups.

The findings suggest that usual daily intakes of the measured HGPs from beef consumption in the US are generally low relative to their established ADIs, providing a significant margin of safety for the average US consumer. However, the results highlight a potential concern regarding short-term, high-level MGA intake in young children, particularly under a maximum intake scenario. The study emphasizes the limitations of relying on current ADIs which are primarily based on studies in adult animals and may not fully capture the potential health risks to children during sensitive developmental periods. The observed socioeconomic disparities in MGA intake highlight potential for unequal exposure and risk, requiring further investigation into factors influencing beef consumption and dietary patterns among different groups. The authors emphasize the need for additional toxicological studies focusing on long-term, low-dose exposure to HGPs, especially during critical developmental stages to fully assess the public health implications.

This study provides a comprehensive assessment of HGP intake from beef in the US population. While usual daily intakes were generally low compared to ADIs, short-term MGA intake in young children may exceed the ADI under certain circumstances. The authors recommend further research, including toxicological studies of long-term, low-dose exposure during development, to refine risk assessment and inform public health recommendations.

The study's limitations include a non-random sample of retail beef from California, potentially not fully representative of US beef consumption; reliance on imputed values for non-detects; assumptions made in estimating beef intake from NHANES data; and the inability to account for potential HGP concentration differences by beef cut. Additionally, the study acknowledges potential biases in dietary recall data, particularly the inability to fully account for systematic errors. Despite these limitations, the authors maintain that their findings of generally low usual daily intake levels relative to ADIs are unlikely to be significantly affected by these factors.