Biomarkers of Human Exposure to Carcinogens: An Overview

Environmental, occupational, or dietary exposure to certain chemicals has been shown to be associated with carcinogenesis in humans. In the 18th century, for example, Percival Pott (1775) noted a high incidence of scrotal cancer in chimney sweeps, which he attributed to their exposure to soot and a concomitant lack of bathing. Subsequent epidemiological studies have identified a number of additional carcinogenic agents, including aromatic amine-based dyes (Case et al., 1954), cigarette smoke (Wynder and Graham, 1950), asbestos (Doll, 1955), vinyl chloride (Creech and

Hemoglobin Adducts as Biomarkers of Exposure to and metabolic Activation of Carcinogenic Tobacco-Specific Nitrosamines

The carcinogenic tobacco-specific nitrosamines N-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-l-(3-pyridyl)-l-butanone (NNK) form hemoglobin adducts in laboratory animals and humans. These adducts release 4-hydroxy-l-(3-pyridyl)-l-butanone (HPB) upon mild base hydrolysis. HPB released from human hemoglobin can be quantified by gas chromatography-mass spectrometry. It is the only available biochemical marker for determination of exposure to, and metabolic activation of, carcinogens present only in tobacco. Levels of HPB were highest in snuff-dippers, followed by smokers and nonsmokers. Large interindividual variations in adduct levels were observed. The relationship between HPB levels in globin and DNA of rats treated with NNK has been investigated in order to aid in interpretation of the data from humans. These studies have provided the initial database for understanding the metabolic activation of tobacco-specific nitrosamines in humans.

Reduction in polycyclic aromatic hydrocarbon exposure in Beijing following China’s clean air actions

Exposure to polycyclic aromatic hydrocarbons(PAHs)in the Chinese population was among the highest globally and associated with various adverse effects.This study examines the impact of China’s twophase clean air initiatives,namely the Air Pollution Prevention and Control Action Plan(APPCAP)in2013–2017 and the Blue-Sky Defense War(BSDW)in 2018–2020,on PAH levels and human exposures in Beijing.To evaluate the effects of APPCAP,we measured 16 PAHs in 287 PM_(2.5)samples collected in Beijing and 9 PAH metabolites in 358 urine samples obtained from 54 individuals who traveled from Los Angeles to Beijing between 2014 and 2018.The concentration of PM_(2.5)-bound benzo[a]pyrene equivalents(BaPeq)decreased by 88.5%in 2014–2018 due to reduced traffic,coal,and biomass emissions.PAH metabolite concentrations in travelers’urine decreased by 52.3%in Beijing,correlated with changes in PM_(2.5)and NO2levels.In contrast,no significant changes were observed in Los Angeles.To evaluate BSDW’s effects,we collected 123 additional PM_(2.5)samples for PAH measurements in 2019–2021.We observed sustained reductions in BaPeq concentrations attributable to reductions in coal and biomass emissions during the BSDW phase,but those from traffic sources remained unchanged.After accounting for meteorological factors,China’s two-phase clean air initiatives jointly reduced Beijing’s PM_(2.5)-bound BaPeq concentrations by 96.6%from 2014 to 2021.These findings provide compelling evidence for the effectiveness of China’s clean air actions in mitigating population exposure to PAHs in Beijing.

Human biological monitoring of suspected .ndocrine-disrupting compounds

Endocrine-disrupting compounds are exogenous agents that interfere with the natural hormones of the body. Human biological monitoring is a powerful method for monitoring exposure to endocrine disrupting compounds. In this review, we describe human biological monitoring systems for different groups of endocrine disrupting compounds, polychiorinated biphenyls, brominated flame retardants, phthalates, alkylphenols, pesticides, metals, perfluronated compounds, parabens, ultraviolet filters, and organic solvents. The aspects discussed are origin to exposure, metabolism, matrices to analyse, analytical determination methods, determinants, and time trends.

Biomarkers of end of shift exposure to disinfection byproducts in nurses

Increased disinfectant use commonly takes place in hospitals and other health care settings. A cross-sectional study among active nurses in two Cypriot public hospitals（n = 179） was conducted to examine the prevalence of exposure to disinfection byproducts（DBPs）, such as trihalomethanes（THMs） using both self-reported information and biomarker measurements.The objectives of this study were to： i） quantify the magnitude and variability of occupational exposure to disinfectants/DBPs in nurses, ii） generate job exposure matrices（JEM） and job task exposure matrices（JTEM） for disinfectants, and iii） assess the major determinants of urinary THMs in nurses. End of shift urinary total THM values showed high variability among the nurses, but did not differ between hospitals. The disinfectant group of alcohols/phenols was used by 〉 98% of nurses, followed by octenidine（82%）, iodine and chlorine（39%, each）,chlorhexidine（25%）, formaldehyde（12%）, hydrogen peroxide（11%）, and peracetic acid/ammonia/quaternary ammonium compounds（QACs）, all being 〈 8% each. Chlorine use during the past 24 hr was associated with significantly（p 〈 0.05） lower brominated THMs（Br THMs） after adjusting for age, gender and BMI, while a positive association was shown for TCM and the sum of all THMs（TTHMs）, albeit not significant. Nurses were exposed to nearly double the levels of TTHMs and BrT HMs（median and IQR, 1027 [560, 2475] ng/g and 323 [212,497] ng/g, respectively） when compared to those of the general population（552 [309,989] ng/g and 152 [87,261] ng/g, respectively）. This was the first occupational health dataset reporting measurements of biomarkers of end of shift exposures to disinfectants/DBPs.