Sources and Toxicity of Mercury in the San Francisco Bay Area,

Overview

This source page is a mechanical bulk-ingest record for a PDF in the research-pulls corpus. It preserves source-level identity, routeable product/analyte scope, and exact extracted numeric lines for later human or fresh-context audit. It does not derive HMTc thresholds, percentiles, or brand-by-brand comparisons.

Key numbers

The worker extracted the full PDF text with layout preservation twice and compared extraction hashes before commit. The following lines are copied from numeric/table-bearing regions of the PDF and retain the source units and wording where legible:

tinal systems producing a wide range of symptoms (2, 3). size (5). In species that have been evaluated, methylmercury
malities observed in nearly 10% of children born near the are rendered inactive or inhibited in these reactions with
whales contains both methylmercury and PCBs; pilot whale Amalgams are comprised of 50% mercury by weight with
blubber is especially high in PCBs (17). Mercury concen- the other 50% comprised of other metal alloys. According to
and, to a lesser extent, in motor speed and visuospatial is inhaled into the lungs, where up to 80% is absorbed
detectable levels many years after initial exposure (1, 2, 20). and other organic mercury species (25). Of particular
mercury (0.23 μg/kg/day)
protective qualities (1). large discrepancy is mainly attributable to hypothetical
symptoms can include cognitive impairment, tremors, numbers, at 0.23 μg/Kg/day and 0.1 μg/Kg/day, illustrate the
mercury and lead salts. mercury emissions, contributing over 50% of the total global
has been observed. Heavy metals and pesticides in mining (37%, 727 tons), fossil fuel burning (25%, (484 tons),
combination may have a more severe impact on health nonferrous metal production (10%, 193 tons), cement
than their individual effects” (30). Despite its general high production (9%, 173 tons), large-scale gold production (5%,
standard of living, the United States ranks 46th in infant 97 tons), waste disposal (5%, 95 tons), contaminated sites
mortality rate (IMR) among nations in the report sub- (4%, 82.5 tons), primary ferrous metal production 2%, 45.5
mitted to the World Health Organization. In addition to tons), and the chlor-alkali industry and crematoriums (1%,
lbs of mercury to the environment. About 80–90% of it was mercury can be carried to these parks, both on fine particulate
(Table 1), mercury is generally found in low concentrations
95% of the total freshwater inflow, while the South Bay re- highest mercury concentrations generally found in sur-
ported 2.3 ppm mercury dry weight (Table 1). plankton have a mercury concentration of 10 ng/kg
625 ng/g (0.020 to 0.625 ppm). The EPA review explains such as the kingfisher, can bioaccumulate concentrations
However, as some information gaps exist, the text and tables methylation of inorganic Hg2+ to organic, MeHg, which is
Table 1: Environmental methylmercury concentrations measured in air, water, and sediments.
place during 1849–1981) (ppb).
2.3 ppm (dry weight) in SFO Bay’s reducing bacteria to transform elemental Hg to (42)
Kuwabara and coinvestigators (47) provided an example level II species often have MeHg concentrations of a few ppb.
Almaden, located in the SFBO Area several miles south of 0.009 ppm (9 ppb) in zooplankton and filter-feeding clams.
primarily of the taxa Merismopedia glauca, Cryptomonas MeHg can reach nearly 5 ppm, as shown in Table 3.
per gram dry weight (Table 2). These concentrations in break down; it binds to proteins found in visceral, muscular, and
Table 2: Methylmercury concentrations in representative trophic level I organisms.
Table 3: Methylmercury concentrations in representative trophic level II organisms.
Small-prey fish Range: 1.22–4.83 ppm (4)
accumulation. In fish, 95% of MeHg is readily absorbed in the and can be easily compared with feathers archived decades
Level III organisms are found in various taxonomic from 0.28–0.70 ppm, while eggs from the South Bay
have higher methylmercury levels than found in trophic 0.56–1.05 ppm.
In avian species, areas of mercury concentration are a mean concentration of 0.343 ppm (52), which is within the
Table 4: Methylmercury concentrations in representative trophic level III organisms.
Black sea bass 0.2 ppm (49)
National Recreation Area, San 0.3 ppm (mean) (52)
California clapper rail (eggs) 0.3–0.8 ppm (53)
of Pesticide Regulation (cdpr.ca.gov). Photo by Moose Peterson of Ackerman et al. (57) have reported about 48% of breeding
Wildlife Photography, http://www.moosepeterson.com. Forster’s terns and nearly 5% of stilts, avocets, and Caspian

Methods (brief)

SFO Bay samples analyzed Hg trapped in aquatic sediment allows sulfate-
Sediments collected from within SFO
(Secondary Consumers). Examples: dragonfly larvae, Cal- piscivorous birds collected from San Pablo Bay and Suisun
(54). larvae collected in selected freshwater marshes of GOGA had
tions of MeHg found in both eggs and blood samples of this
Forster’s tern (eggs) sampled
Seasonal range: Sticklebacks collected from the Alviso Slough, South San
test-kit/This test utilizes samples of hair, blood and urine to

Implications

This page makes the source discoverable for category-level evidence routing. Values remain source-native and should be used only with the stated matrix, species, basis, geography, and censoring context from the paper. The page does not convert total mercury to methylmercury or use total arsenic as inorganic arsenic.

Wiki pages this source may touch

Verification notes

Identity check: DOI, raw handle, candidate cite-key, and SHA-256 were compared against existing wiki/sources/ pages before creation.
Full-PDF read: pdftotext -layout was run on the full PDF twice; extracted text hashes matched before the page was written.
Numeric verification: numeric/table-bearing lines were selected mechanically from the verified extraction and preserved without unit conversion or rounding.
Brand firewall: the worker skips PDFs when extracted numeric lines appear brand/manufacturer-sensitive; this page contains category-level or species-level evidence only.
HMTc firewall: no threshold, percentile, pass/fail, clean/dirty, or certification math is stated.

Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised