Elemental mercury exposure: An evidence-based consensus guideline for out-of-hospital management

Figures & data

Table 1. Amount of elemental mercury in selected devices (118,119)

Device	Amount of elemental mercury
Fluorescent light	0.01–0.05 g
High intensity discharge lamp (HID, vapor)	0.02–0.25 g
Fever thermometer	0.5–0.7 g
Flame sensor (gas ranges)	1–2 g
Silent wall light switch (made before 1991)	2 g
Scientific/laboratory thermometer	up to 3 g
Household thermostat	3 g per switch
Electrical (tilt) switch	Small: 3.5 g Industrial: up to 3600 g (8 lbs)
Gas flow regulator ( installed before 1961)	100 g
Sphygmomanometer	150 g
Manometer/barometer	100–900 g

Table 2. Reference elemental mercury airborne concentrations

Airborne concentration (mg/m^3)	Comments	Agency^†
10	Immediately dangerous to life or health (IDLH) - maximum allowed for 30 min in an emergency	NIOSH
0.1	Legal airborne permissible occupational exposure limit (PEL)	OSHA
0.05	Recommended airborne exposure limit (REL) averaged over a 10-hr work shift	NIOSH
0.025	Recommended airborne exposure limit (threshold limit value, TLV) averaged over an 8-hr work shift	ACGIH
0.003	Recommended concentration after clean-up of commercial environment	ATSDR
0.001	Recommended breathing zone (5 ft from floor) limit in a home after an elemental mercury spill - can re-occupy if less than this concentration	ATSDR
0.0003	An estimate of a continuous inhalation exposure that is likely to be without an appreciable risk of deleterious effects during a lifetime (Reference Concentration, RfC)	US EPA
0.0002	An estimate of the daily human exposure that is likely to be without appreciable risk of adverse non‐cancer health effects over a specified duration of exposure (Minimum Risk Level, MRL)	ATSDR

*Adapted from the Wisconsin Division of Public Health, Department of Health and Family Services, State of Wisconsin. Human Health Hazards. Responding to Mercury Spills: Small Spill Response. Accessed on August 29, 2006 at <http://dhfs.wisconsin.gov/eh/HlthHaz/pdf/hgtherm.pdf>.

^†ACGIH: American Conference of Governmental Industrial Hygienists, ATSDR: Agency for Toxic Substances and Disease Registry, NIOSH: National Institute for Occupational Safety and Health, US EPA: United States Environmental Protection Agency.

Table 3. Summary of individual US poison control center guidelines, 2006

Poison control center	Fever thermometer spill potentially toxic	Rec. small spill clean-up by occupant	Rec. use of “spill kit” or sulfur powder	Rec. professional clean-up	Cautions against vacuuming	Rec. Hg environmental testing	Rec. blood or urine mercury testing	Disposal instructions	Clean-up referred to EPA, Health Dept.	Rec. follow-up call
1	No	Yes	No	No	Yes	No	No	Minimal; dispose of in well ventilated areas.	No	No
2	Yes	Yes	Yes	Yes, if spilled near heat source, air vent or vacuumed	Yes	Only if spill has been vacuumed	No	Hazardous waste	Yes	No
3	Yes	Yes	No	No	No	Special circumstances only	No	Hazardous waste	Yes	No
4	“Not likely”	Yes (<10 g)	Yes	Yes, if widespread or on carpet	Yes	No	Consider	Recycle center	Yes	No
5	Yes	Yes	Yes	Yes, if more than thermometer	Yes	Yes, for large spills	Consider for large spills	Hazardous waste	Yes, large spills	No
6	Implied yes	Yes, hard surfaces only	No	Yes, for spills on carpet	Yes	No	No	Double bag and place in outdoor trash	Yes	No
7	Yes	Yes	Yes	No	Yes, unless using binding agent (sulfur)	No	No	Hazardous waste	No	No

Table 4. Gastrointestinal mercury exposures with toxic effects and quantifiable exposure amounts

Approx. amount	Age	Mitigating circumstances	Effect severity	Onset	Elevated urine and/or blood mercury^†	Reference (LOE)
∼3 mL	39 yr	Peritoneal deposition of elemental mercury	Death	∼23 d	Yes	38 (4)
Up to 10 mL	68 yr	Peritoneal deposition of elemental mercury	Mod	NR	Yes	40 (6)
40 mL	26 yr	NR	Mild (local)	<4 hr	NR	42 (4)
60 mL	45 yr	Peritoneal spillage of mercury; also aspirated ingested mercury	Mod	NR	Yes	41 (6)
80 mL	25 yr	NT	? Mild (local)	NT	NR	43 (4)
220 mL (2 kg)	42 yr	Potential chronic occupational exposure; history of tremors, forgetfulness, fatigue, irritability; diabetes	Mod	NR	Yes	39 (4)

*Mild = effects not requiring chelation or hospital admission; Mod = effects necessitating chelation and/or hospitalization; Severe = life-threatening effects (e.g., seizures, respiratory depression, coma, hypotension); Local = GI effects (e.g., nausea, vomiting, diarrhea, abdominal pain) after ingestion or dermal effects (e.g., wound, swelling, erythema) after subcutaneous exposure.

^†Urine mercury ≥10 μg/L; blood mercury ≥10 μg/L; 24-hr urine mercury ≥15 μg (concentrations during chelation or after chelation challenge not considered).

NR: not reported.

NT: not fully translated.

Table 5. Soft tissue mercury exposures with toxic effects and quantifiable exposure amounts

Approx. amount	Age	Mitigating circumstances	Effect severity	Onset	Elevated urine and/or blood mercury^†	Reference (LOE)
Thermometer	15 yr	NR	Mod (local)	Over 2 d	NR	53 (4)
Thermometer	13 yr	NR	Mild (local)	2 yr	NR	52 (4)
Thermometer	11 yr	NR	Mod (local)	Over days	NR	54 (4)
Thermometer	2 yr	NR	Mod (local)	Over days	Yes	55 (4)

*Mild = effects not requiring chelation or hospital admission; Mod = effects necessitating chelation and/or hospitalization; Severe = life threatening effects (e.g., seizures, respiratory depression, coma, hypotension); Local = GI effects (e.g., nausea, vomiting, diarrhea, abdominal pain) after ingestion or dermal effects (e.g., wound, swelling, erythema) after subcutaneous exposure.

^†Urine mercury ≥10 μg/L; blood mercury ≥10 μg/L; 24-hr urine mercury ≥15 μg (concentrations during chelation or after chelation challenge not considered).

NR: not reported.

Table 6. Inhalational mercury exposures with toxic effects and quantitative air levels reported

Maximum air concentration (mg/m^3)	Approx. maximum exposure duration	Mitigating circumstances	No. with clinical effects	Effect severity^†	No. symptomatic with elevated urine and/or blood mercury^‡	Age	Reference (LOE)
0.0042	NR	Vacuumed	3	Mod	3	2–6 yr	64 (4)
0.0045	2 d	Also ingested mercury	1	Mild/Mod	1	2 yr	57 (4)
0.01	NR	NR	NR	Mild	NR	NR	57 (2b)
0.0238	NT	Heated	2	Mod	2	22 & 28 yr	65 (4)
0.04	NR	NR	2	Mod	NR	NR	8 (4)
0.03–0.7 (data from three incidents combined)	NR	No symptomatic patients had elevated blood conc.	98	Mild	NR	NR	6 (2b)
0.05	NR	Vacuumed	1	Mod	1	8 yr	15 (4)
>0.05	15 mo	NR	Several	Mod	Several	13 yr & NR	62 (4)
0.054	5 mo	NR	1	Mild/Mod	1	23 mo	77 (4)
0.06	17 wk	NR	1	Mod	1	3 yr	76 (4)
0.075	NR	NR	10	Mild	10	NR	59 (2b)
0.075	2 mo	Vacuumed	3	Mod	3	14–41 yr	71 (4)
0.078	6 wk	Vacuumed	2	Mild	2	9 & 35 yr	69 (4)
0.1–1	4 mo	Vacuumed	1	Mod	1	14 yr	78 (4)
0.14	3 mo	NR	3	Mod–Severe	3	10–17 yr	5 (4)
0.14	1–2 mo	Vacuumed	3	Mod–Severe	3	NR	68 (4)
0.15	1 wk	NR	Several	Mild	7	NR	7 (2b)
0.15–1	51–176 d	Vacuumed	8–12	Mild	11	12 yr, 14 yr, & NR	58 (2b)
0.193	NR	Gold extraction (heated)	8	Mod–Death	8	45 d–58 yr	75 (4)
0.4	3 mo	NR	2	Mod	2	11 & 15 yr	61 (4)
0.5	3–6 hr weekly ×  <1 yr	NR	2	Mild	2	17 & 37 yr	70 (4)
0.6	45 min	Heated; underlying occupational exposure	1	Mod	NR	50 yr	73 (4)
>0.7 (with oven on)	NR	Heated	1	Mod	NR	27 yr	66 (4)
0.786	NR	Heated	4	Death	4	40–88 yr	8 (4)
0.999	>3 d	Heated	2	Mild–Mod	1	NR	74 (4)
>1	NR	Vacuumed	2	Mod–Severe	2	4–11 yr	67 (4)
1.08	2½ mo	NR	10–11	Mild–Mod	4–11	13 yr & 6–18 yr	60 (4)
8	NR	NR	1	Mild	1	NR	82 (4)

*Breathing space measurements quoted whenever noted in article.

^†Mild = effects not requiring chelation or hospital admission; Mod = effects necessitating chelation and/or hospitalization; Severe = life-threatening effects (e.g., seizures, respiratory depression, coma, hypotension).

^‡Urine mercury ≥10 μg/L; blood mercury ≥10 μg/L; 24-hr urine mercury ≥15 μg (concentrations during chelation or after chelation challenge not considered).

NR: Not reported.

NT: Not fully translated.

Table 7. Inhalational mercury exposures with toxic effects and exposure amounts reported (quantified or semi-quantified)

Approx. amount	Approx. maximum exposure duration^§	Mitigating circumstances	No. with clinical effects	Effect severity	No. symptomatic with elevated urine and/or blood mercury^†	Age	Reference (LOE)
Thermometer	2–8 wk	Carpet	2	Mild–Mod	1	11 mo & 6 yr	23 (4)
Thermometer	3 mo	NR	1	Mod	1	28 mo	16 (4)
Thermometer	4 mo	Carpet, vacuumed	1	Mod	1	11 mo	18 (4)
Thermometer	8–9 mo	Carpet, floor heating	3	Mod	1	20 mo–6 yr	84 (4)
Thermometer	NT	NT	2	Mild	NT	NT	85 (4)
Thermometer	NT	Carpet	1	Mod	1 (with captopril)	32 mo	79 (4)
Thermometer	NR	NR	1–5	Mod	1–5	≥3 yr	21 (4)
Thermometer	NR	Heated	1	Mod	NR	27 yr	66 (4)
1.1 g (from a broken thermometer)	18 hr	Heated	3	Mod–Death	3	37–77 yr	80 (4)
10 g	NR	Heated	4	Mild–Death	NR	≥1 yr	83 (4)
2.5–5 mL	4 mo	Carpet, vacuumed	1	Mod	1	14 yr	78 (4)
5 mL	2 wk	Carpet	1	Mod	1	20 mo	22 (6)
>1–2 tsp	6 wk	Vacuumed	2	Mild	2	9 & 35 yr	69 (4)
0.5–1 oz	NR	Vacuumed?	2	Mod–Severe	2	4–11 yr	67 (4)
0.5 lb	45 min	Heated; underlying occupational exposure	1	Mod	NR	50 yr	73 (4)
20 cm^3	NR	Carpet	2	Mod	NR	NR	8 (4)
<1 oz	NR	NR	1	Mild	1	NR	72 (4)
<30 mL (data from three incidents combined)	NR	No symptomatic patients had confirmed elevated blood conc.	98	Mild	NR	NR	6 (2b)
1 lb	3 mo	NR	3	Mod–Severe	3	NR	5 (4)
1 lb	1–2 mo	Vacuumed	3	Mod–Severe	3	NR	68 (4)
0.9 kg	1 wk	NR	Several	Mild	7	NR	7 (2b)
2.3 kg	4 wk	Vacuumed	3	Mod	3	≥3½ yr	82 (4)
250 mL	2 mo	Vacuumed	3	Mod	3	14–41 yr	71 (4)
300 mL	51–176 d	Vacuumed	8–12	Mild	11	12 yr, 14 yr, & NR	58 (2b)
40 lb	>3 d	Heated	2	Mild–Mod	1	NR	74 (4)
Up to 5–10 L (70–100 kg)	NR	Vacuumed (in some households)	13	Mild–Mod	13	One <6 yr, others >6 yr	81 (4)

*Mild = effects not requiring chelation or hospital admission; Mod = effects necessitating chelation and/or hospitalization; Severe = life-threatening effects (e.g., seizures, respiratory depression, coma, hypotension).

^†Urine mercury ≥10 μg/L; blood mercury ≥10 μg/L; 24-hr urine mercury ≥15 μg (concentrations during chelation or after chelation challenge not considered).

NR: Not reported.

NT: Not fully translated.

Table

Grade of recommendation	Level of evidence	Description of study design
A	1a	Systematic review (with homogeneity) of randomized clinical trials
	1b	Individual randomized clinical trials (with narrow confidence interval)
	1c	All or none (all patients died before the drug became available, but some now survive on it; or when some patients died before the drug became available, but none now die on it.)
B	2a	Systematic review (with homogeneity) of cohort studies
	2b	Individual cohort study (including low quality randomized clinical trial)
	2c	“Outcomes” research
	3a	Systemic review (with homogeneity) of case-control studies
	3b	Individual case-control study
C	4	Case series, single case reports (and poor quality cohort and case control studies)
D	5	Expert opinion without explicit critical appraisal or based on physiology or bench research
Z	6	Abstracts

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