Perlite toxicology and epidemiology – a review

Figures & data

Figure 1. Ten largest perlite producers in 2011 ranked in descending order of output (% of world production). These accounted for 95% of world production of perlite (3 470 000 metric) Source: British Geological Survey, 2013.

Table 1. Chemical composition of Perlite from various sources.

Origin	US	Greece	Turkey	Hungary	Yemen	Korea	Bulgaria	Slovakia
SiO2	65–77.5	71–75	71–75	68–75	65–75	68–69	70–80	68–73
Al2O3	11–18	12–16	12.5–18	10–15	9.4–12.8	11.95–15.8	10–15	7.5–15
Na2O	2.4–4.6	3.0–4.0	2.9–4.0	2.8–4.5	3.37–4.25	3.2–4.4	<10	2.5–5.0
K2O	1.4–5.7	4.0–5.0	4.0–5.0	3.2–4.5	3.6–4.1	2–3.94	<10	2–5.5
Fe2O3	0.5–2.2	0.5–2.0	0.1–1.5	1.0–2.5	2.68–3.66	0.7–1.63	<1.5	1.0–2.0
MgO	0.1–0.7	0.2–0.7	0.03–0.5	0.2–1.5	0.5–0.93	0.35–0.48	<1.0	<1.0
CaO	0.5–3.6	0.5–1.5	0.5–2.0	1.5–2.0	0.87–1.84	1.57–1.89	<1.5	0.5–2.0
Loss on ignition	2–5	2–5	4.1	2.0–5.0	0.35–3.94	NR	<5	3.0–4.1
Source	Diverse	Sampatakakis et al., 2013	Doğan & Alkan, 2004; Kabra et al., 2013	Mineralholding Ltd.	Sa’ad et al., 2010	Noh & Boles, 1989	Yanevaet al., 2012	LB Minerals

Mineralholding Ltd. Data available at http://www.mineralholding.hu/ipariasvanyok/en/raw_perlite.html.

Data for US taken from various mines, mineral deposit reports, and technical data sheets. Illustrative sources include Coombs, 1952; Ennis, 2011; USEPA, 1995b; Huntting, 1949; Jaster, 1956; Rotella & Simandl, 1995; and Simandi et al., 1995. Endpoints of ranges may come from different deposits. Ore from all countries may contain additional minor components (e.g. TiO₂).

Table 2. Summary information on perlite.

Item
CAS/EINECS NO.	CAS: 130885-09-5 (perlite ore); EINECS: Not listed CAS: 093763-70-3 (expanded perlite);EINECS: Not listed; RTECS No. SD5254000; REACH Exempted according to art.2 par 7b and Annex V.7.
NAICS (2012) Codes	Mining: 212399 (All other non-metallic mineral mines) Processing: 327992 (Ground or treated mineral and earth manufacturing)
Composition	Varies with source, see Table 1.
Carcinogenicity	Not listed as a carcinogen by IARC, NTP, OSHA, or CA Prop 65. ACGIH: A4 – Not Classifiable as a Human Carcinogen Perlite does not meet the criteria for classification as hazardous according to EC Regulation 1272/2008 and Directive 67/548/EC as amended.
WHMIS	Does not meet criteria
FDA	GRAS SCOGS Report #61, 1979 (http://www.fda.gov/Food/IngredientsPackagingLabeling/GRAS/SCOGS/ucm260952.htm)
EFSA	EFSA approved in subcategory of binders, anticaking agents, and coagulants E 599 Panel on Additives and Products (http://www.efsa.europa.eu/en/search/doc/68e.pdf).
OELs for selected countries	OSHA PNOR: 15 mg/m^3 (total dust), 5 mg/m^3 (respirable fraction) 8-h TWA NIOSH REL: 10 mg/m^3 (total dust), 5 mg/m^3 (respirable fraction) 8-h TWA ACGIH TLV: PNOS 10 mg/m^3 (inhalable particles), 3 mg/m^3 (respirable fraction) 8-h TWA Australia: 10 mg/m^3, 8-h TWA Belgium: 10 mg/m^3 (inhalable particles), 2 mg/m^3 (respirable fraction) 8-h TWA Canada (Ontario, British Columbia): 10 mg/m^3, 8-h TWA, http://www.e-laws.gov.on.ca/html/regs/english/elaws_regs_900833_e.htm and http://www2.worksafebc.com/publications/ohsregulation/GuidelinePart5.asp?ReportID = 32895. China: 8 mg/m^3 (total dust), 4 mg/m^3 (respirable fraction) 8-h TWA (Liang et al., 2003) Denmark: 10 mg/m^3 (inhalable particles), 5 mg/m^3 (respirable fraction) 8-h TWA Greece: 10 mg/m^3 (inhalable particles), 5 mg/m^3 (respirable fraction) 8-h TWA Ireland: 10 mg/m^3 (inhalable particles), 5 mg/m^3 (respirable fraction) 8-h TWA^a Netherlands: 10 mg/m^3, 8-h TWA, as inhalable dust Spain: 10 mg/m^3 (inhalable particles), 3 mg/m^3 (respirable fraction) 8-h TWA^b UK: 10 mg/m^3 (inhalable particles), 4 mg/m^3 (respirable fraction) 8-h TWA
Potentially exposed cohort in the US	Total from NOES survey 215,854 persons in 1981–1983, see http://www.cdc.gov/noes/noes1/b0105sic.html.
Production (US)	Domestic production 424 000 metric tons; apparent consumption 557 000 metric tons (Bolen, 2013)
Major producing locations in US	The processed crude perlite was mined in eight mines located in Arizona, Idaho, Nevada, New Mexico, and Oregon (Bolen, 2012). Perlite was expanded at 50 plants located in 27 states (Bolen, 2013).

^aSee http://consultation.hsa.ie/general-applications/Chemical-Agents-Regulations-2011/public%20consultation%20draft%202011chemical%20agents%20COP%20January%202011.pdf.

^bSee http://www.insht.es/InshtWeb/Contenidos/Documentacion/TextosOnline/Valores_Limite/GT-LEPN024-07%20VLA%202008%20negro_2.pdf.

Figure 2. Estimated SMRs and 95% confidence intervals by cause of death for men and women of Milos, Greece, combined for the period 1999–2009. Source: Data presented in Sampatakakis et al., 2013.

Table 3. A summary of animal studies conducted with perlite.

Pathway	Species	Results	Source
Inhalation	Guinea pig & rat	In an 18-month inhalation study, guinea pigs and rats (numbers, strain, or sex not given) were exposed to perlite dust at a concentration of 226 mg/m^3. No significant pulmonary reaction, including fibrosis, was observed. No further details were given. The authors concluded that perlite acted as an inert or nuisance dust.	Vorwald, 1953, cited in Cooper, 1975 and Health Council of the Netherlands, 2003.
Inhalation	Guinea pig	Inhalation exposure of 284 mg/m^3, 8 h/d, 5.5 d/wk. for six months “appeared to stimulate the progression of experimental tuberculosis”. When exposure ceased the tuberculosis infection progressed for about eight months and then began to heal and ultimately was arrested.	Schepers, 1955 as reported in Cooper, 1975.
Inhalation	Guinea pig	Guinea pigs were exposed to perlite dust at mean airborne concentrations of 0 or 6.6 mg/ml for 30 min/d, 5 d/wk, for 24 wk. Another group was exposed to fir bark dust. Perlite mass median aerodynamic diameters (MMADs) ranged from 1.7 to 1.9 µm. No pulmonary fibrosis or extensive destruction of parenchymal tissues was observed, but the authors con noted “moderate to severe” changes in the lungs for both dusts. The authors concluded that perlite particles were more than just a nuisance dust.	McMichael et al., 1978, 1983. The reported dose might be a misprint, but is extremely high. Health Council of the Netherlands converted this to 6,600 mg/m^3 and noted it was unrealistically high.
Intratracheal injection	Guinea pig	Nine perlite products were tested in guinea pigs, by weekly intratracheal injection of 0.5 ml of a 5% perlite suspension in saline for 3 wk. At 4 to 12 months after the last injection, no evidence of pulmonary fibrosis was shown.	Vorwald, 1953, cited in Cooper 1975.
Intratracheal instillation	Rat	A single intratracheal instillation of a 75 mg/ml saline dose of perlite (18–30% quartz) produced a “foreign body reaction” in white male rats, but no pulmonary fibrosis was observed (post observation period not reported).	Timar et al., 1965 as cited in Health Council of the Netherlands, 2003.
Intratracheal instillation	Rat	A single 50 mg suspension of crude or expanded was administered intratracheally to albino rats. Nine months later, it was found that expanded perlite caused more lung fibrosis than crude perlite, but the degree of fibrosis was not reported.	Borshchevkii et al., 1967 as cited in Health Council of the Netherlands, 2003.
Intratracheal instillation	Rat	Rats given a single intratracheal instillation of 50 mg perlite dust showed pulmonary fibrosis at 12 to 18 months following administration. The perlite composition was not specified.	Liu et al., 1988, as cited in Health Council of the Netherlands, 2003.
Intratracheal instillation	Rat	Intratracheal infusing (instillation) of 5 mg perlite dust in 5% alcohol did not result in a strong pulmonary fibrogenic reaction in rats, at 12 wk after administration. No more details were provided.	Ueda et al., 1978 as cited in Health Council of the Netherlands, 2003.
Acute oral toxicity	Rat	Acute oral toxicity tests in rats ingesting perlite were performed by the Rosner-Hixon Laboratories in 1977. The results of the tests showed that the acute oral LD50 of perlites for rats is greater than the largest dose administered in the test (10 g/kg body weight).	Schundler Company, 2002, http://www.schundler.com/perlitehealth.htm.
Acute oral toxicity	Rat	In 1982, the WIL Research Laboratories conducted studies to examine the acute oral toxicity, if any, of agglomerated filter aid in albino rats. The study showed no signs of systemic toxicity, and concluded that the LD50 was greater than the highest dose level administered to the rats (10 g/kg body weight.)	Schundler Company, 2002, http://www.schundler.com/perlitehealth.htm.
Oral ingestion	Mouse	Ohkuma et al. (1972) and Itoh et al. (1981) performed acute toxicity studies using dd/y and C3H/He mice. The results showed no acute toxicity despite large doses. The estimated LD50 was 12 960 mg/kg or more in each case.	Cited in Sakai & Nagao, 1985.
Oral ingestion	Mouse	Groups of male and female mice were given diets containing 0%, 1%, 10%, 20% perlite for 28 wk. Appearance, behavior, and food consumption of mice of treated groups were not affected during the experimental period.	Sakai & Nagao, 1985.

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