Papers of the Month
By Mali Velasco
Factors related to decreased kidney function in migrant farm workers revealed
NIEHS-funded researchers reported lower kidney function in farm workers, particularly among those working in fields with conventional farming practices. The researchers examined factors that may play a role in chronic kidney disease of unknown origin, a condition linked to diverse and complex environmental influences.
Researchers enrolled more than 100 migrant and seasonal farm workers in Northern Mexico and randomly assigned them to work in certified organic or conventional farming areas. These field categories were used as a proxy for pesticide exposure. The scientists also enrolled 50 office workers within the same region to serve as a reference group. In addition to documenting demographic, behavioral, and occupational characteristics, they collected urine and blood samples prior to and late in the harvesting season. The team measured body temperature and heart rate before and during work shifts and evaluated heat strain and dehydration in relation to kidney function.
Pre-harvest, all participants had normal kidney function. By late harvest, the team found significantly lower kidney function among farm workers while no changes were detected in office workers. In particular, the authors reported that dehydration and heat strain were associated with worse kidney function. Farm workers in conventional fields had lower kidney function compared to those working in organic fields.
According to the team, these findings reveal that pesticide exposure should be considered in combination with heat strain and dehydration in the development of kidney disease, and that early and frequent monitoring for kidney health among those in high-risks jobs is critical.
Citation: Lopez-Galvez N, Wagoner R, Canales RA, Ernst K, Burgess JL, de Zapien J, Rosales C, Beamer P. 2021. Longitudinal assessment of kidney function in migrant farm workers. Environ Res. 202:111686.
Biosensor characterizes contaminants and potential health risks after disasters
A sophisticated biosensor may provide information about polycyclic aromatic hydrocarbon (PAH) distribution and potential toxicity in the aftermath of natural disasters, according to an NIEHS-funded study. By rapidly characterizing and prioritizing samples for study, the tool supports disaster research response where time and resources are limited.
Researchers compared a biosensor previously developed with NIEHS funding to expensive and time-consuming approaches. The tool measures PAHs in the liquid between sediment or soil particles, providing information about how much of the PAHs can be taken up by the body and potentially cause harm.
The scientists analyzed PAH levels and composition in samples collected before and after Hurricane Harvey hit the Houston area and compared them to samples from a river in Virginia with known PAH contamination. In general, they found higher levels of PAHs in Virginia and in Texas after the storm with distinct chemical compositions pointing to unique sources of PAHs. For example, wood treatment facilities accounted for most of the PAHs in Virginia, whereas some of the PAHs detected after Hurricane Harvey may be related to the presence of organic matter in floodwaters, according to the team.
Using thresholds developed by the U.S. Environmental Protection Agency, they reported that all samples had PAH levels below those which may harm human health but were above risk thresholds for animal health. There were strong correlations between results using the biosensor and the traditional approach, which the team cited as evidence for its utility in screening and predicting PAH levels and potential health risks.
Citation: Camargo K, Vogelbein MA, Horney JA, Dellapenna TM, Knap AH, Sericano JL, Wade TL, McDonald TJ, Chiu WA, Unger MA. 2022. Biosensor applications in contaminated estuaries: Implications for disaster research response. Environ Res. 204(Pt A):111893.
Microbiome affects early childhood behavior differently in girls and boys
Bacteria in the gut of young children may relate to behavioral disorders, affecting girls and boys differently, according to an NIEHS-funded study. This is one of the first studies to examine associations between the microbiome, the collection of bacteria and other microorganisms in the body, and a broad range of behavioral outcomes that may vary by sex.
Researchers followed 260 children over time, classifying their microbiomes at 6 weeks, 1 year, and 2 years of age. When participants were 3 years old, parents completed an assessment that measures behavioral and emotional characteristics in children.
The team found that higher microbiome diversity at 6 weeks was associated with decreased internalizing behavior and lower depression scores, especially among boys. Increased diversity at 2 years was associated with better social and adaptive skills among boys, but worse among girls. They also observed associations with specific microbiome species. For example, Bifidobacterium at 6 weeks was associated with better adaptive skills in boys, and Granulicatella was associated with worse anxiety scores among girls.
Researchers also identified relationships between functions microbes carry out, such as metabolizing or synthesizing biological molecules, and behavioral outcomes. For example, they observed an association between vitamin B6 biosynthesis and lower depression scores among boys. They noted that low dietary intake of B6, essential for making neurotransmitters, has previously been linked to adolescent depression.
According to the authors, these results provide some of the first evidence linking early-life microbiome and behavioral changes, potentially shedding light on critical windows where interventions may prove useful.
Citation: Laue HE, Karagas MR, Coker MO, Bellinger DC, Baker ER, Korrick SA, Madan JC. 2021. Sex-specific relationships of the infant microbiome and early-childhood behavioral outcomes. Pediatr Res. doi: 10.1038/s41390-021-01785-z. [Online 4 November 2021]
Phthalate exposure linked to early death
A new study funded by NIEHS reported that exposure to phthalates may be associated with increased mortality among U.S. adults. These deaths were estimated to result in up to $47 billion in lost economic productivity per year. Phthalates are found in many consumer products, particularly plastic food packaging and scented personal care products or cleaners.
Researchers leveraged a nationally representative cohort of more than 5,000 adults aged 20 years or older who participated in the U.S. National Health and Nutrition Examination Survey (NHANES) 2001–2010 and provided urine samples for phthalate degradation products, or metabolites. They linked participants to NHANES 2015 mortality data and used advanced statistical models to evaluate the risk of early death over an average of 10 years, controlling for preexisting heart disease, diabetes, cancer, and other common health conditions.
They observed increased mortality for all causes, including cardiovascular mortality and cancer, associated with high concentrations of phthalates in urine samples, especially for the metabolite 2-ethylhexylphthalate (DEHP). Extrapolating to the population of 55- to 64-year-olds in the U.S., they identified up to 107,283 deaths attributable to DEHP. The researchers then used sophisticated mathematical formulas to estimate the loss of economic productivity attributable to these deaths and observed a loss of $39.9–47.1 billion per year.
The study results demonstrate that there is a need for strategies to reduce exposures to these harmful contaminants, according to the authors.
Citation: Trasande L, Liu B, Bao W. 2022. Phthalates and attributable mortality: A population-based longitudinal cohort study and cost analysis. Environ Pollut 292(Pt A):118021.
(Mali Velasco is a research and communication specialist for MDB Inc., a contractor for the NIEHS Division of Extramural Research and Training.)