Feasibility of respirable crystalline silica exposure reduction in small-scale tanzanite mining in Tanzania.

INTRODUCTION: Respirable crystalline silica (RCS) exposures in tanzanite gem mining have been linked to tuberculosis and silicosis among miners. We conducted a plot study to assess RCS exposures and to introduce safer mining practices in one small-scale underground tanzanite mine. MATERIALS AND METHODS: Personal and area air samples for RCS were collected during tanzanite mining operations before and after improved work practices employed to reduce exposures and analyzed using X-ray diffraction. Area samples were collected at the rest area, located approximately 300 m underground and 100 m from other work activities. Improved practices included the use of wet drilling methods and drilling with new bits. RESULTS: A total of 33 personal and 4 area air samples were collected. Pre-intervention, mean exposures for all operations, drilling operations, non-drilling activities, and area samples were 122 mg/m3, 247 mg/m3, 34.3 mg/m3, and 1.95 mg/m3, respectively which exceeded the U.S. OSHA Permissible Exposure Limit (PEL) by 2,440 times for all operations, by 4,946 times for drilling operations, by 686 times for non-drilling activities and 39 times for area samples collected at an underground rest area. The post-intervention results showed a 99% reduction of RCS exposures for wet drilling operations, 98.5% reduction for non-drilling activities, and 36% reduction for area samples. Despite improvements, post-intervention RCS exposures during drilling had a mean of 2.08 mg/m3 or more than 41 times the OSHA PEL. CONCLUSIONS: We successfully piloted a program to work with small-scale tanzanite miners to reduce RCS exposures and raise awareness about the occupational health risks of RCS, though additional measures are recommended to further reduce RCS exposures. Similar programs should be taken to scale throughout underground mining sites in Tanzania and other countries.

Exposure hazards from continuing use and removal of asbestos cement products.

Asbestos cement (AC) is used in water pipes, roofing, exterior siding, water tanks, cooling towers, and other applications. Although the global market for asbestos is slowly shrinking, AC products continue to dominate the remaining uses in many countries. This review focuses on asbestos exposures during the installation, maintenance, and ultimate removal of these materials. This assessment summarizes the available published and unpublished reports of airborne asbestos exposures during the cutting and removal of AC pipes, roofing, sheets, and cooling tower components and the range of exposures associated with the most common work practices. Task-based exposures from cutting AC pipe ranged from 11.3 to 129.0 f/cm3 with a mean exposure of 53.8 f/cm3. Cutting flat boards and corrugated roofing AC sheets resulted in exposures ranging from 1.3 to 130.0 f/cm3 with a mean of 24.0 f/cm3. Exposures for power saw cutting of AC sheets and pipes fit lognormal distributions and suggest that more than 86% of these tasks with AC sheet and 100% of the tasks with AC pipe exceed the US short-term Excursion Limit. Intermittent high exposures from the ongoing use of AC products in countries around the world are associated with an increased lifetime risk of asbestos-related disease.

Metal exposures from source materials for artisanal aluminum cookware.

Artisanal aluminum cookware releases lead and other metals that pose significant health risk for people in low and middle-income countries. Cookware is made from recycled engine and electronic appliance parts, cans, and other materials. We obtained fourteen custom-made pots from Ghana, produced from seven different scrap aluminum sources. We sought to determine whether avoiding certain source materials could reduce leaching of metals. Cooking was simulated using dilute acetic acid and palm oil. Aluminum released from all pots exceeded recommended guidelines. Variable amounts of lead, cadmium, chromium, nickel and other metals were leached, with the most lead coming from auto radiators and mixed metals. Pots made from engine blocks did not yield detectable amounts of lead. All pots released potentially harmful concentrations of two or more metals. Selective scrap aluminum sourcing for recycled cookware does not avoid metal contamination of food, although some sources may release lower concentrations of certain metals.

Lead Industry Influence in the 21st Century: An Old Playbook for a "Modern Metal".

In recent years, lead poisoning has received increasing attention as lead production continues to grow and the industry shifts the most polluting processes (e.g., smelting ore and recycling batteries) to low- and middle-income countries. The hazards associated with lead exposures have been well known for centuries while the industry actively promoted lead products. Less well known is how the industry continues to promote the "safe and responsible" use of lead and support research to question the underlying science and avoid regulation. Here I explore the historical context for recent actions that the industry has taken to ensure its longevity. Lead industry associations continue to employ some of the same themes that have proven successful in the past. Efforts to forestall regulatory initiatives to reduce emissions and restrict lead applications continue. Large battery manufacturers and recyclers and their associations place blame on informal-sector recycling to draw focus away from their own emissions. They have sought the cooperation of hired scientific experts and have funded United Nations organizations and nongovernmental organizations to deflect attention from their own contributions to global lead poisoning. (Am J Public Health. 2022;112(S7):S723-S729. https://doi.org/10.2105/AJPH.2022.306960).

Urgent Need for a Comprehensive Public Health Response to Artisanal Small-Scale Mining.

Informal sector mining is a growing enterprise in countries around the world providing livelihood to >40 million self-employed miners. The use of mercury in gold processing has been the sole focus of most research and public health interventions in artisanal mining. Few programs work to improve health among communities mining other commodities including sand, aggregates, quartz, lead, gemstones, coal and other materials. Although mercury is a major environmental challenge in countries with extensive gold mining, artisanal miners are also exposed to silica dust, metals and other safety hazards. The available evidence regarding hazardous exposures among self-employed miners suggests that the public health implications are much broader. There is a growing body of evidence linking exposures to silica dust to tuberculosis and other lung diseases among artisanal miners. Studies have also documented exposures to lead and other metals including arsenic, cadmium, cobalt and chromium in informal mining communities. Silica-dust exposures are higher in artisanal mining than levels reported in large industrial mining. There is ample evidence that artisanal miners are experiencing health impacts not just from mercury but also from exposures to noise, silica dust and metals. Practical, low-cost solutions have been pilot tested and shown to reduce respirable silica dust and metal exposures among miners and ore processors. Governments, development agencies and global health funders should invest in comprehensive public health programs to respond to these needs.

Declining blood lead levels among small-scale miners participating in a safer mining pilot programme in Nigeria.

OBJECTIVES: Our objective was to monitor blood lead levels (BLLs) of miners and ore processors participating in a pilot programme to reduce lead poisoning and take-home exposures from artisanal small-scale gold mining. A medical surveillance programme was established to assess exposures as new methods aimed at reducing lead exposures from ore were introduced in a community in Nigeria where children experienced substantial lead-related morbidity and mortality. METHODS: Extensive outreach and education were offered to miners, and investments were made to adopt wet methods to reduce exposures during mining and processing. We conducted medical surveillance, including a physical exam and repeated blood lead testing, for 61 miners selected from among several hundred who participated in the safer mining pilot programme and consented to testing. Venous blood lead concentrations were analysed using the LeadCare II device at approximately 3-month intervals over a period of 19 months. RESULTS: Overall geometric mean (GM) BLLs decreased by 32% from 31.6 to 21.5 µg/dL during the 19-month project. Women had a somewhat lower reduction in GM BLLs (23%) compared with men (36%). There was a statistically significant reduction in log BLLs from baseline to the final test taken by each participant (p<0.001). CONCLUSIONS: The observed reductions in GM BLLs during the pilot intervention among this representative group of miners and ore processors demonstrated the effectiveness of the safer mining programme in this community. Such measures are feasible, cost-effective and can greatly improve health outcomes in mining communities.

Commentary health risks from climate fix: The downside of energy storage batteries.

Energy storage is the key component to almost all technologies arising in response to climate change. Although most lead batteries are recycled, the process as employed in the majority of recycling plants around the world is highly polluting. Lithium ion batteries, considered the most advanced battery for climate solutions, are employed in electric vehicles, solar lanterns, and increasingly in other energy storage applications. These are generally not being recycled as there are no available technologies to economically extract metals in a form that can be used to make new batteries or other high-value products. As the energy storage market is projected to grow rapidly in coming years, we must consider the impacts of increased mining, milling, smelting and recycling of these metals. Much of these materials will be extracted and processed in low and middle-income countries and eventually be recycled in these same jurisdictions with few regulations to protect public health and the environment. Technological responses to climate change must take account of potential health risks inherent in such products.

Reducing Lead and Silica Dust Exposures in Small-Scale Mining in Northern Nigeria.

Purpose: An ongoing health crisis across a large area of Northern Nigeria has resulted in hundreds of deaths and thousands of cases of lead poisoning from artisanal small-scale gold mining. Occupational Knowledge International (OK International) and Doctors Without Borders/Médecins Sans Frontières (MSF) have formed a partnership to conduct a pilot project to introduce safer mining practices in selected communities. The primary objective was to reduce lead exposures among artisanal small-scale miners and minimize take home exposures by reducing dust contamination on clothing and body surfaces. Methods: Personal air samples were collected from miners and ore processors before and after the introduction of wet spray misting in mine processing activities to crush and grind gold ore. We measured reductions in total airborne lead and respirable silica dust levels. A total of 44 air samples were collected for airborne lead using NIOSH method 7082 and 29 air samples for respirable silica dust with NIOSH method 7500. Results: Low-cost interventions to convert dry ore processing to wet methods with spray misting were effective at reducing arithmetic mean airborne lead levels by 95%. Mean airborne respirable silica (quartz) was reduced by 80% following the introduction of wet spray misting. Differences in geometric means between wet and dry ore processing methods were statistically significant for both airborne lead and respirable silica. Conclusions: This pilot project has been successful in working cooperatively with miners to provide them with the necessary information and tools to reduce exposures in mining and processing, and minimize off-site contamination. As silica dust is a significant risk factor for silicosis and tuberculosis (TB), this intervention could provide public health benefits to small-scale mining communities even in areas without significant lead concentrations in the ore. Significant reductions in respirable silica and lead exposures are feasible in low-resource, small-scale mining communities.

Soil contamination from lead battery manufacturing and recycling in seven African countries.

Lead battery recycling is a growing hazardous industry throughout Africa. We investigated potential soil contamination inside and outside formal sector recycling plants in seven countries. We collected 118 soil samples at 15 recycling plants and one battery manufacturing site and analyzed them for total lead. Lead levels in soils ranged from < 40-140,000mg/kg. Overall mean lead concentrations were ~23,200mg/kg but, average lead levels were 22-fold greater for soil samples from inside plant sites than from those collected outside these facilities. Arithmetic mean lead concentrations in soil samples from communities surrounding these plants were ~2600mg/kg. As the lead battery industry in Africa continues to expand, it is expected that the number and size of lead battery recycling plants will grow to meet the forecasted demand. There is an immediate need to address ongoing exposures in surrounding communities, emissions from this industry and to regulate site closure financing procedures to ensure that we do not leave behind a legacy of lead contamination that will impact millions in communities throughout Africa.

Blood Lead Levels among Children in Yaoundé Cameroon.

Blood lead levels (BLLs) are a useful indication of a population exposure to lead from environmental sources. No previous published study had reported BLLs in Cameroon. Our objective is to characterize exposure levels in children to inform policymakers of potential lead exposure sources. We tested the BLLs of 147 children aged 12 months to 6 years residing in Yaoundé, Cameroon, and conducted an extensive questionnaire with their parents or guardians to characterize potential exposure sources. The geometric mean BLL among this population was 8.0 µg/dl and arithmetic mean level was 8.7 µg/dl. These levels are more than sixfold higher than the geometric mean BLL reported in the U.S. and more than fivefold higher than those reported in France. In addition, 88% of the children tested had lead levels greater than 5 µg/dl. One limitation of the study is that the selection of the children sampled was not a random survey. The analysis of the responses to the questionnaire failed to uncover any specific exposure patterns. A statistically significant association was noted between the age of the child's home and the duration of exclusive breastfeeding with BLLs. The study points to a need for greater efforts to control sources of lead exposure in Cameroon.

Metal exposures from aluminum cookware: An unrecognized public health risk in developing countries.

Removing lead from gasoline has resulted in decreases in blood lead levels in most of the world, but blood lead levels remain elevated in low and middle-income countries compared to more developed countries. Several reasons for this difference have been investigated, but few studies have examined the potential contribution from locally-made aluminum cookware. In a previous study of cookware from a single African country, Cameroon, artisanal aluminum cookware that is made from scrap metal released significant quantities of lead. In this study, 42 intact aluminum cookware items from ten developing countries were tested for their potential to release lead and other metals during cooking. Fifteen items released ≥1 microgram of lead per serving (250mL) when tested by boiling with dilute acetic acid for 2h. One pot, from Viet Nam, released 33, 1126 and 1426 micrograms per serving in successive tests. Ten samples released >1 microgram of cadmium per serving, and fifteen items released >1 microgram of arsenic per serving. The mean exposure estimate for aluminum was 125mg per serving, more than six times the World Health Organization's Provisional Tolerable Weekly Intake of 20mg/day for a 70kg adult, and 40 of 42 items tested exceeded this level. We conducted preliminary assessments of three potential methods to reduce metal leaching from this cookware. Coating the cookware reduced aluminum exposure per serving by >98%, and similar reductions were seen for other metals as well. Potential exposure to metals by corrosion during cooking may pose a significant and largely unrecognized public health risk which deserves urgent attention.

Letter to the Editor Re: Andrew Turner, Emily R. Kearl, Kevin R. Solman Lead and other toxic metals in playground paints from South West England Science of the Total Environment 544 (2016) 460-466.

Turner's paper emphasizes "oral bioaccessibility" instead of focusing solely on total lead content. There is no evidence that solubility testing for lead levels in paint correlates with absorption or blood lead levels in exposed children. There are many considerations in determining exposure hazards to paint that are not evaluated in assessing solubility. Although we strongly support the conclusions and recommendations of the study, we are concerned that by reporting "oral bioaccessibility" others will focus on solubility in developing regulatory standards for lead levels in paint or in conducting exposure assessments. Standards for lead in paint should continue to be based on total lead content, not "oral bioaccessibility."

Silica Exposures in Artisanal Small-Scale Gold Mining in Tanzania and Implications for Tuberculosis Prevention.

Gold miners exposed to crystalline silica are at risk of silicosis, lung cancer, and experience higher incidence rates of pulmonary tuberculosis (TB). Although the hazards associated with mercury exposure in artisanal small-scale gold mining (ASGM) have been well documented, no published data was available on crystalline silica exposures in this population. Air sampling was conducted in the breathing zone of workers in five villages in Tanzania with battery-operated sampling pumps and bulk samples were collected to measure the type and concentration of crystalline silica in the ore. Samples were analyzed at an accredited laboratory with X-ray diffraction. Airborne crystalline silica exposures exceeded recommended limits for all tasks monitored with an average exposure of 16.85 mg/m(3) for underground drilling that was 337 fold greater than the recommended exposure limit (REL) published by the U.S. National Institute for Occupational Safety and Health (NIOSH) and 0.19 mg/m(3) for aboveground operations or 4-fold greater than the REL. The exposures measured raise concern for possible acute and chronic silicosis and are known to significantly contribute to TB incidence rates in mining communities. The use of wet methods could greatly reduce exposures and the risk of TB and silicosis in ASGM. Ongoing efforts to address mercury and other hazards in ASGM should incorporate crystalline silica dust controls.

Lead exposure from aluminum cookware in Cameroon.

Blood lead levels have decreased following the removal of lead from gasoline in most of the world. However, numerous recent studies provide evidence that elevated blood lead levels persist in many low and middle-income countries around the world at much higher prevalence than in the more developed countries. One potential source of lead exposure that has not been widely investigated is the leaching of lead from artisanal aluminum cookware, which is commonly used in the developing world. Twenty-nine samples of aluminum cookware and utensils manufactured by local artisans in Cameroon were collected and analyzed for their potential to release lead during cooking. Source materials for this cookware included scrap metal such as engine parts, radiators, cans, and construction materials. The lead content of this cookware is relatively low (<1000 ppm by X-ray fluorescence), however significant amounts of lead, as well as aluminum and cadmium were released from many of the samples using dilute acetic acid extractions at boiling and ambient temperatures. Potential exposures to lead per serving were estimated to be as high as 260 µg, indicating that such cookware can pose a serious health hazard. We conclude that lead, aluminum and cadmium can migrate from this aluminum cookware during cooking and enter food at levels exceeding recommended public health guidelines. Our results support the need to regulate lead content of materials used to manufacture these pots. Artisanal aluminum cookware may be a major contributor to lead poisoning throughout the developing world. Testing of aluminum cookware in other developing countries is warranted.