Occupational and Environmental Exposure to Mercury among Iranian Hairdressers

A Systematic Review of Mercury Exposures from Skin-Lightening Products

BACKGROUND

The Minamata Convention on Mercury (Article 4) prohibits the manufacture, import, or export of skin-lightening products containing mercury concentrations above 1 ppm. However, there is a lack of knowledge surrounding the global prevalence of mercury-added skin-lightening products.

OBJECTIVE

The objective of this study was to increase our understanding of worldwide human mercury exposure from skin-lightening products.

METHODS

A systematic search of peer-reviewed scientific literature was performed for relevant articles in four databases (PubMed, Web of Science Core Collection, Scopus, and TOXLINE). The search strategy, eligibility criteria, and data-extraction methods were established a priori. The search identified 2,303 unique scientific articles, of which 41 were ultimately deemed eligible for inclusion after iterative screens at the title, abstract, and whole-text levels. To facilitate data extraction and synthesis, all papers were organized according to four data groups a) "Mercury in products," b) "Usage of products," c) "Human biomarkers of exposure," and d) "Health impacts."

RESULTS

This review was based on data contained in 41 peer-reviewed scientific papers from 22 countries worldwide published between 2000 and 2022. In total, we captured mercury concentration values from 787 skin-lightening product samples [overall pooled central median mercury level was 0.49μg/g; interquartile range (IQR): 0.02-5.9] and 1,042 human biomarker measurements from 863 individuals. We also synthesized usage information from 3,898 individuals and self-reported health impacts associated with using mercury-added products from 832 individuals.

DISCUSSION

This review suggests that mercury widely exists as an active ingredient in many skin-lightening products worldwide and that users are at risk of variable and often high exposures. These synthesized findings identify data gaps and help increase our understanding of the health risks associated with the use of these products. https://doi.org/10.1289/EHP10808.

Hair mercury and risk assessment for consumption of contaminated seafood in residents from the coast of the Persian Gulf, Iran

The health risks of mercury exposure due to the high consumption of aquatic were assessed for fishermen and non-fishermen families living on the Bandar Abbas, Bushehr, and Mahshahr cities located in the coast of Persian Gulf (Iran). The mean hair mercury concentration of people in Bandar Abbas, Bushehr, and Mahshahr cities was obtained 1.56 ± 0.17, 1.97 ± 0.22, and 5.12 ± 0.3 μg g^-1, respectively. Hair mercury concentration in 8.8% of people exceeded the no observed adverse effects level (NOAEL) of 10 μg g^-1 declared by the World Health Organization (WHO). The fish and shrimps consumption, place of living, and fisher and non-fisherman family were variables that significantly effected on mercury levels in the hair. The effect of other factors (age, sex, and number of dental amalgam fillings) on hair mercury was not significant. The mean concentrations of mercury in three fish species in Mahshahr exceeded the recommended maximum standard level (0.5 μg g^-1) set by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA). The estimated weekly intake (EWI) for mercury in some fish species in Bandar Abbas, Bushehr, and Mahshahr was higher than the provisional tolerable weekly intake (1.6 μg kg^-1 bw) set by European Food Safety Authority (EFSA) for some groups. The significant positive correlation between daily mercury intake and hair mercury concentration of people (r = 0.64, P < 0.001) reasserts that the hair mercury concentration could be explained by fish consumption. HQ > 1 was obtained for women in child bearing age in fishermen families in Bandar Abbas and Bushehr cities, children in fishermen families in Bushehr, and for all groups of population except adult in non-fishermen families in Mahshahr. So, the limited consumption of some fish species for these groups of people is recommended. The maximum of allowable fish consumption rate was 0.70 meals/month for Pseudorhombus arsius from Mahshahr fish for women of child bearing age. Also, it is necessary to create and monitor and enforce environmental standards, preventing the entry of pollutants released into the marine aquatic environment without proper early treatment.

Determination of Mercury Daily Intake and Hair-to-Blood Mercury Concentration Ratio in People Resident of the Coast of the Persian Gulf, Iran

The objectives of this study were to understand the mercury daily intake and hair-to-blood mercury ratio in fishermen and non-fishermen families in the coast of the Persian Gulf in Iran. The mean mercury concentration in the hair of fishermen and non-fishermen families was 5.76 and 2.27 μg/g, respectively. The mean mercury concentrations of RBCs were obtained for fishermen families and non-fishermen families: 35.96 and 17.18 μg/L, respectively. Hair mercury concentrations in 17% of people were higher than 10 μg/g, the No Observed Adverse Effects Level set by the World Health Organization. 78% of people had a blood mercury value > 5.8 μg/L, the standard level set by the U.S. Environmental Protection Agency. A significant correlation (r = 0.94, p = 0.000) was seen between log hair and RBCs mercury concentrations. The mean mercury daily intake for fishermen and non-fishermen families was 0.42 and 0.20 µg/kg BW per day, respectively. The mean mercury daily intake of fishermen families was higher than the provisional tolerable daily intake (0.23 µg/kg BW per day) suggested by the Joint Expert Committee on Food Additives. Mercury daily intake significantly correlated with fish consumption (r = 0.50, p = 0.000) and log hair mercury (r = 0.88, p = 0.000). The total mean of hair-to-blood mercury concentration ratio was 306. We conclude that the use of mercury concentrations in the hair and RBCs could have been suitable biomarkers for predicting mercury exposure of people with a high rate of fish consumption.

Detection of Drugs in Nails: Three Year Experience

Nails (fingernails and toenails) are made of keratin. As the nail grows, substances incorporate into the keratin fibers where they can be detected 3-6 months after use. Samples are collected by clipping of 2-3 mm of nail from all fingers (100 mg). We present drug testing results from 10,349 nail samples collected from high-risk cases during a 3-year period of time. Samples were analyzed by validated analytical methods. The initial testing was performed mostly using enzyme-linked immunosorbent assay, but by liquid chromatography-tandem mass spectrometry (LC-MS-MS) as well. Presumptive positive samples were subjected to confirmatory testing with sample preparation procedures including washing, pulverizing, digestion and extraction optimized for each drug class. The total of 7,799 samples was analyzed for amphetamines. The concentrations ranged from 40 to 572,865 pg/mg (median, 100-3,687) for all amphetamine analytes. Amphetamine and methamphetamine were present in 14% of the samples, 22 samples were positive for 3,4-methylenedioxymethamphetamine (0.3%), 7 for methylenedioxyamphetamine (0.09%) and 4 for 3,4-methylenedioxy-N-ethylamphetamine (0.05%). Cocaine and related analytes were found in 5% samples (7,787 total), and the concentration range was 20-265,063 pg/mg (median 84-1,768). Opioids overall ranged from 40 to 118,229 pg/mg (median 123-830). The most prevalent opioid was oxycodone (15.1%) and hydrocodone (11.4%) compared with 1.0-3.6% for the others, including morphine, codeine, hydromorphone, methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine and oxymorphone. Carboxy-Δ-9-tetrahydrocannabinol positivity rate was 18.1% (0.04-262 pg/mg, median 6.41). Out of 3,039 samples, 756 were positive (24.9%) for ethyl glucuronide (20-3,754 pg/mg, median 88). Other drugs found in nails included barbiturates, benzodiazepines, ketamine, meperidine, tramadol, zolpidem, propoxyphene, naltrexone and buprenorphine. Nail analyses have become a reliable way of determining the long-term use and abuse of drugs. Extraction techniques are simple and produce accurate and precise results. Sensitive analytical instrumentation, mainly LC-MS-MS, allows for detection of femtogram (10(-15) g) quantities of substances in nails. Samples were from a high-risk population, therefore the extraordinary positivity rate was observed.